Sunday, June 7, 2015

Schwinn Tailwind Battery Pack Teardown and Analysis

Schwinn Tailwind.  The name rolls off the tongue.  The bike... well, we'll get there.  But in 2015, it probably doesn't roll at all, because it probably has a dead battery pack.  An incredibly built, radically over-engineered, insanely beautiful battery pack.



It's one of the earliest lithium powered electric bikes out there, and it was reasonably expensive - $3200, in early 2009!  It was also one of the earliest uses of the Toshiba SCiB (Super Charge ion Battery) technology - a very fancy Lithium Titanate battery, capable of some truly impressive recharge rates - 6C charge rates were well within it's capability (a 10 minute recharge time)!

The battery pack is removable, and slips easily into the back of the bike.  That's what I'm tearing apart today.


Keep going if you want to see inside.  After the teardown, there's more information, including some attempts to revive it.  And some complaints about Schwinn & Toshiba.




Teardown


This pack, as is the usual story, sat without being charged for some length of time, and now won't charge.  It's pretty much "how production ebike packs die."  I do prefer this over some of the cheap hobby lipo pack deaths, though... "dead and won't charge" does beat "flaming death" every time.

The end of the pack contains a power meter with a button.  Unsurprisingly, it doesn't show anything when the button is pressed.  I really like packs that show their charge, especially if they're removable.


The label informs us that we're looking at a Schwinn Tailwind - it's Advanced Lithium Ion Powered.  No, it's not powered by anything right now, but I suppose it was when it came from the factory.  And, as always, I'm going to "attempt to open, disassemble, or service the battery."  All three, actually.

Nicely, this label tells you how to store it, and that it should be charged regularly if in storage - which, of course, is never done.

Also of note is the claim that it's a 24VDC 4.2AH pack - that's barely 100WH!  They can't have released a bike with such a tiny pack, can they?  That has to be some sort of error... I hope.


The bottom of the pack contains 8 screws.  A running theme in this pack is the number of screws - it's insane.  I think I had nearly 40 screws out when I got all the way in, and there were plenty left that I didn't remove...


The back of the pack contains the +/- DC power connections, and the charge port.

The power output plates don't have any significant voltage on them, and are simply pressed into the power connections on the bike as the pack slides home.  The whole thing is built for quick removal, and for a low power 24v bike, it's probably just fine.

The charge port is a bit interesting - there's an inner plug (that the normal charger plugs into), a few small connections, and then two very large, high amperage outer plugs.  The large plugs aren't used for at-home charging, but they seem to be connected straight to the battery - they've got pack voltage on them, as I verify later.


With the first wave of screws out, the back pops off, and... there's another case inside.  Held in by 8 more screws.  That's 14, for those keeping count.  This is a very, very well protected set of cells.  The little circuit board that runs the LEDs is visible as well, on the right.


Looking at the back, the main connection plates are visible - they're actually fairly large!


Once the inner pack is out, the label is visible, and the capacity checks out.  100WH of Toshiba Lithium Ion Battery.  The pack is 7 years old and a month.  I'd say I was impressed, but I'd only be impressed if it was still working, which is entirely possible, had it not been drained.

Of course, this model number doesn't turn up anything in Google (until now).

The pack:
Toshiba Rechargeable Lithium-Ion Battery Pack
Model: TBPEB001*S
Date: May 5 2008
Capacity: 4.2AH
Voltage: 24V DC


The underside of the inner pack has a very serious looking metal plate on it, held down with yet more screws (8 - up to 22 screws).  Don't worry - I'll pop it open and see what's hiding in there!  You can also see the "Do not throw in the trash" label.


The other side of the pack is the same thing that was visible with the outer case separated.  There's a black plastic outer shell, and then the blue plastic that feels like some sort of cell casing.  So far, I see no evidence of any cylindrical cells in here.  If they're in there, I can't feel them.


My handy Radio Shack voltmeter (yes, it's cheap, but it's accurate and was upstairs) is useful to find out what the pack voltage is.  I previously mentioned that the big charging sockets were apparently connected to the pack.  They're showing 7.13 volts.  On a 24v pack with a ~2.3-2.5v chemistry... this isn't good.  That's very definitely a drained pack.


The two main power connections don't have pack voltage on them, but they're not quite zero either - they've got 0.013v across them, which stays fairly consistent.  I'm not sure if there's some sort of signaling that goes on from the bike or not, but they definitely have a voltage across them.

I should note at this point that I don't actually have the bike - only the battery pack.  So I can't reverse engineer the signaling, if there is any.  I was hoping it just put out a nice 24v when charged... *sigh*


More screws.  Another 7 screws (29) gets the side off.  Wow.  This is a fancy battery pack!  That's some serious computer-grade interconnect - though I'm suddenly less optimistic about getting the cells out.  There are definitely 10 cells, though, in a 10S1P configuration.

A while with my voltmeter clears up what this is (a lot of 0.65-0.8v cells).  The exposed metal is the cell terminals, with the raised loops connecting the two terminals.  You can trace the cells - starting at the left main terminal (which happens to be the negative terminal), the cell path goes left, down, all the way over to the right side, up a layer, the diagonal connect is used to go up another layer, then two left, down, and two left again to the positive terminal.  It's very well done, and overkill in the best kind of way.  I suspect the raised loops are used to deal with any thermal expansion of the pack, but whatever it is, the metal is very thick.  There's no question about this pack's current carrying ability.


Checking the voltage on the main terminals of the pack gives me the same voltage I saw on the charging ports, confirming that they are directly attached (for high current charging).  This is later confirmed by visual inspection of the BMS.


Two more screws (up to 31) for the main terminals, slide a ribbon cable out, and the BMS comes out.  And... wow.  This is a serious BMS, but annoyingly, the good stuff is potted over.  The center fuse is a 32V/60A fuse, and I don't doubt for a second that this BMS can take the current.


I'll get back to the BMS.  For now, I want to get in and look at the cells.  There are a few screws on each end, and then two in the middle (so another 6 screws - 37).  They come out with a bit of work.



Under the BMS is an off white sheet of plastic.  It's adhesive, so I pull it off, hoping for some more insight into the pack.  Not so lucky.  Just more cells.


At this point, I've got all the screws I can find out.  It's time to split the two plastic halves of the pack, and look at the cells to see what's in there.

This is my plan.  Unfortunately for my plan, Toshiba also used copious amounts of a very high quality adhesive to stick this pack together.  After about an hour, I gave up - I cannot get the inner pack apart beyond this point without destroying it, and I'm not going to do that.  So this is as far as I can get.

The pack seems to have 10 prismatic cells, nicely stacked.

The BMS takes another 2 screws to get apart (39), though there are plenty more to take out if you feel like it (the thing has screws going through the board into soldered joints - "belt and suspenders" does not begin to cover the construction here - it's capable of handling some serious current).



On the backside of the BMS, the heavy conductors are overlayed on the board, and are genuinely massive.  I think this BMS is capable of handling well beyond the 10A or so the bike claims to need.  I'm fairly confident the 60A fuse is conservative for this BMS.  I'm not sure what the pack can source, but the BMS is, by far, the most overbuilt unit I've ever seen.

If you look at the outer charging terminals, you'll see continuity from the positive lead, through the fuse, to the pack.  While the negative lead doesn't obviously connect to the negative terminal, I think there's a ground plane in here somewhere that connects everything together - the grounds are all tied together.


The metal cover alone is a serious piece of work.


Attempts at Recovery

My end goal here is a functioning pack.  As replacing the cells wasn't going to happen (I literally cannot find anything resembling those cells for sale), the next best thing is trying to bring them back up, voltage-wise, to a level that makes the BMS happy.

Lithium Titanate is supposed to be an incredibly safe, dimensionally stable, robust chemistry that can handle deep cycling without problems.  The batteries weren't totally dead, just a bit low - if 1.5v is empty, than 0.8v is not ideal, but isn't awful.  I wouldn't do this with a 4.2v lithium ion cell, but I feel more comfortable with these cells (after a lot of reading discussing the deep discharge behavior).

My approach was simple: Bring the cells back up, individually, to a balanced state.  The BMS had been disconnected for over a week, and my hope was that it would see the cells as "within range," and start doing it's BMS-thing again.

The first step, since the cells were a bit unbalanced, involved bringing the cells up to 2.0v per cell.  This, after a bit of rest, led to a voltage of 1.95-1.97v per cell.  No luck with the BMS.

I bulk charged the pack for a while longer, and after getting the pack up to around 23.2v (2.32+/- 0.01v/cell), the BMS still wanted nothing to do with the pack other than throwing errors on the LEDs.

After around 3 hours of playing with a variable voltage power supply, the pack, and the BMS, I gave up.  Even with the cells obviously in the middle of their charge range, the BMS wanted nothing to do with the pack.  Plugging in charging power would trigger the status LEDs to flash (a "full down to empty" walk, then all the LEDs flashing), so the BMS was online, but I could not get the BMS to take a charge from the "normal" charge ports, nor could I get it to put any voltage on the output plates.

There are some solutions to this problem, but they involve fully bypassing the BMS for output, and bulk charging with the high amperage ports.  I'm not sure if the BMS will still balance the cells or not if things are done this way, and I'm not going willing to do that on someone else's pack.  So, sadly, I was not able to restore this pack to functionality.

However, there are some interface ports on the BMS (two small 4-pin ports on the side).  If I can get some information about how to talk to the BMS, I might be able to figure out what's going on and how to make it happy again.  The chemistry should be just fine after a minor discharge, and it's just a problem with the BMS.

Another possibility is to replace the BMS with a more generic unit that handles the voltages involved.  This would be more work, but if I can get the charge/discharge curves for these cells, it's entirely possible.  Right now, though, I don't have enough time or information for either.  And I can't strip the BMS potting off, as it's not actually my pack.  Yet.

Analysis

I don't really understand this bike, or this battery pack.

As near as I can tell, the bike was released in early 2009 for Schwinn & Toshiba press coverage.  There's a lot of glowing press coverage about this Amazing Schwinn Electric Bicycle with an Incredible Toshiba SCiB Battery Pack, and not much else.  It apparently sold very poorly, as a year or two later, there were some insane closeout sales on the bike.

After that?  Not much except people trying to replace or repair broken battery packs.

There's a lot about this bike that doesn't make much sense to me.

The first is the battery capacity.  People are claiming an honest 10-15 mile range with some assist.  The battery pack is only 100Wh, though, and most pedal assists involve 15+WH/mi - so the bike shouldn't go beyond 7 miles on a charge, if that.  Unless the pedal assist is seriously weak, or the pack is actually more than 4.2AH, I can't figure out the disconnect between rated pack capacity and range.

On the other hand, the Schwinn page claims it's a 29.4v 10Ah pack.  This makes for a 300Wh pack, which makes a lot more sense for the observed range.  Except... the inner pack label claims it's a 4AH pack as well.  So I really have no idea what the actual capacity is, and I don't have a load bank to test it.  Nor do I know what the fully charged voltage is.  *sigh*

The second is the battery pack chemistry.  Schwinn is using a somewhat exotic chemistry in a pack, and the only real advantage over other available chemistries seems to be the fast charging capability.  I'm not sure why you need to charge a pack at a 6C rate (10 minute recharge), but this pack can do it without breathing hard.  If it's actually a 4AH pack, it can fast charge at almost 15C - the internal fuse is 60A, which is sort of nuts for a pack like this.  The pack can, in theory, source 1.5kW on a 250W bike.  I have no idea why.  It's radically, radically overbuilt for what it's being asked to do, and the BMS seems to be very sophisticated.

The stock home charger is a 29.4v, 8.4A charger - so a 2C rate, with a charged voltage of over 29v.

The only thing that makes any sense is that Schwinn wanted this bike to be used for delivery services or something, in which having a selection of packs charged would be useful.  This isn't mentioned in any of the press releases, but it's the only thing so far that makes sense of the pack design and chemistry.

The pack is insanely overbuilt physically as well, and I'm not sure why.

The whole thing feels like it was built, not to be a useful electric bike, but as a show-off project, by a company (Schwinn) that then got cold feet about the whole ebike thing.  Toshiba also seems to have contributed an exotic battery and a fancy BMS, with no documentation.  Schwinn don't seem to have any electric bikes for sale currently, despite the increasing popularity, legality, and the fact that they were one of the first with an electric bike for sale.

Schwinn Scrap

Currently, there are an awful lot of Schwinn Tailwind bikes that are basically scrap.  Nobody sells a replacement battery pack for them, and the stock battery pack is not easily convinced to operate again.  They're a very heavy bike without a motor.

This is unacceptable.

Request for Information

Schwinn.  Toshiba.  Your complete lack of information on this battery pack is turning what should be perfectly functional electric bikes into scrap.  You've picked an incredibly safe, high cycle life chemistry that, if drained slightly below what the BMS likes, is then unrecoverable due to the BMS.  Please publish some information on the packs and the BMS such that people can get the bikes running again.

Or don't.  Keep the Schwinn Tailwinds with dead batteries in garages, collecting dust, until they get scrapped as bad purchases by people who paid up to $3200 for one of them.  They carry the Schwinn name.

If you have information on these bikes, especially on the battery management system and how to communicate with it/reset it, I would genuinely like to hear from you.  Please, comment below.

Or if you've got a dead Tailwind, feel free to chime in and let me know how much you paid for it so you can join the voices saying, "This is absurd."

SCiB Battery Information

I've been able to obtain a bit of information about the Toshiba SCiB cells through various sources and a lot of reading.

The chemistry is normally set up with a low voltage cutoff of 1.8v/cell, a nominal voltage of 2.4v/cell, and a fully charged voltage of 2.8v/cell.  This pack, while charging, behaved in a reasonable manner for such voltages.

While it's not recommended, and obviously the BMS doesn't like it (or this post wouldn't exist), the chemistry will apparently recharge with no damage from a fully discharged state of 0v.  Don't do it often, and be careful while you do it, but being dimensionally stable, it should handle it just fine.  Which also means that charging from 0.5 or 1.0v is fine as well.

And Toshiba doesn't make the 4AH cells anymore.

87 comments:


  1. Ive got two of these I bought off ebay a few weeks ago. Both battery packs were able to be recovered via bulk charging and watching the individual cells to see if they stayed in balance. One the bms works fine and all features do as well. There seems to be bleeders under the pot material. the other is the same as your pack. Its fine but the bms wont let the charger see the pack so I use bullets and charge both packs with in parallel. The bleeders seem to work on the non-bms pack so I would say all Im losing is lvc on that one but that's not an issue my commute is 60% of the pack then I charge in the am. My guess is there is (given nothing seems wrong with the bms and the fuse has continuity) there is a software reset that is needed to be done to the bms's that aren't happy. Just a guess. Im going to try shorting pins together (you never know) on the "bad" bms one. But im not worried about using it with the bike without lvc. Id say charge and use.

    About charging the curve tosh picked (since I have one pack that works) is charge at 8.4 amps to 28 volts and stop. So nothing hard to emulate. After the factory charger stops charging the cells quickly drop down to 26 volts so 2.6 volts a cell is where they are really stopping. So charging to 26.5 volts and ending at 3 amps cutoff gives me the same result in case you want to charge it manually.
    Sure would like to find the reset switch/command.

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    1. Thank you! That is very useful!

      If I find out how to reset the BMS, I will certainly update this post with information on it. It did seem like the pack was balancing when charging through the high amperage connectors, which the bleeders working would explain.

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    2. I picked up a Scwhinn Tailwind for cheap, added a 24v 10Ahr bottle pack and love It! I also peeled the dead battery, and removed the BMS and charged it, trickle, then a 2A charge to 24v. I may use it for backup power. I have two 1000w hub motor conversions, so I know what it is to have a throttle and ability to hit 35mph on occaision.
      Love the ST, it makes me work! Internal shifting is cool, can downshift at rest no prob. Bike itself is tight and comfy, no customizing needed except a heavy kickstand and bottle mount. Steel rear rack is strong, handles panniers and basket loads well.Screw trying to figure out the battery! For what I paid, it's worth it for the rest wheel- I can't believe how much these detailed! Cheap rim liner, flat first day, big deal...tires Light enough to demand no flat liners anyhow. Again, love riding it.
      Margo.Allen@ymail.com 02/20/2017

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  2. Great article and teardown. I have a similar issue with a recently obtained Schwinn Global GDS.
    It has a Protanium Part# BP-L2410EH2 pack rated 24v 10Ah and should charge at 29-30v 2A.
    The pack is completely dead. I opened it (finding the same 25+ screws) and was able to access individual
    flat cells.
    I'd be willing to send it to you if you could swap out new cells for old ones, that exceeds my level of electrical comfort - howevre most of the plastic mounting posts are cracked, so other than the aluminum shell I'm not sure reusable the case is.

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    1. I believe the cells are flat, pouch-type cells. I'm not sure I have a source for those or not. I've had other queries on that pack, and I find a few places that list them, but cannot get their shopping carts or payment systems to work, so I'm not sure I can actually obtain them.

      Schwinn really has left a lot of people up a creek without a paddle with their ebike systems. Exotic batteries, and they stop supporting them as soon as they're done selling them.

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  3. First, excellent article.

    You are right about 'turning into scrap'. I have a tailwind. Variety of reasons why, but I have two packs. One is 100% dead. The other, one sent me as a 'free' replacement, is slowly dying. (The status starts falling to 2-3 dots w/in under half-a-mile, even with light usage ... I got the Tailwind to enable me to do a 30 mile roundtrip commute with some support. This battery dies with an 8 mile roundtrip with the same amount of electric support ...)

    I find it reprehensible that there is not some path for maintaining / upgrading these. What I would really like to do is upgrade into that 10Ah (or better) using more modern batteries. This should be open sourced to enable keeping these bikes rolling ...

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    1. You can certainly do such a thing, but there just aren't enough of these bikes out there to justify the engineering expense in building a pack commercially. There's plenty of space in the outer pack to put a nice set of batteries, and I strongly suspect it would be trivial to build a 10AH+ pack.

      Someone is trying to cram a 13.3AH pack into the outer shell on Endless Sphere: https://endless-sphere.com/forums/viewtopic.php?f=14&t=71453

      That said, I just don't think it's worth terribly much effort - I don't think the Tailwind is that good a bike. I've got one (on loan to a friend), and it's just not very good in my hilly area. I suspect it's nicer on the flats.

      If I were you, I'd buy a commercial 24v/15AH (or so) pack from someone, remove the Tailwind pack entirely, pop the battery contact spring housing open, and run the power lines from the 24v pack into there. Pull the spring contacts out if it's easy and run the lines through there. Hook up in whatever means needed, secure the pack on the rack, and call it good. If the bike works for you, that's going to be the best option, and it skips the engineering effort involved in making a custom pack to fit in the Tailwind pack form factor (which is sort of silly to start with). If you need it to be removable, use Anderson Powerpole connectors, and it'll be fine.

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  4. I have a Schwinn Tailwind with a dead battery. The bike has sat from some time because my commuting needs have changed, and I have another bike. It would be great to get the battery operational again. I would find some ideas that could possibly restore the battery of great interest.

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    1. I've written about bypassing the BMS here: http://syonyk.blogspot.com/2015/07/bypassing-schwinn-tailwind-battery.html

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  5. Great play by play. I love this bike - own 3 of them. Have been intermittently reading what I can since my first purchase when dealers were dumping them for a song, so I learned early on to baby the battery. It'll be a sad day for me when all the batteries finally die. I wonder about the feasibility of swapping to a different battery system.

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    1. On the plus side, if you're taking care of the batteries, they should basically last forever. The LTO chemistry is insanely long lived, so just don't let them go flat and they stand a good chance of lasting the rest of your life.

      As far as a different battery system goes, it's not hard. Find a pack that is around 28v fully charged, 24v nominal, and hook it up.

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  6. I have had a tailwind for a few year that I purchased through Performane bicycle at a close out price. I was commuting to work about 11 miles away. I had a pack on top of battery compartment and I carried the charger to recharge at work. On flat bike paths most of the way and really enjoyed riding to work. I'm 260 lbs so I never expected 20 mile range - my best estimate is 14 miles but depends on headwind and how much I work the assist. I've charged a few hundred times and I do not believe I've lost range.

    Big draw back was family did not appreciate that I had a motor although I did get some exercise. It is a heavy bike and great to not use motor for extended periods for a good work out / exercise. I just purchased one for my wife for $450 (had nice eBay bucks burning a whole in my pocket). For this price I figure I can keep at least one of these batteries running. The new EBay bike indicated that it has a working battery.

    Not a great bike but reasonably good. I actually really like the overall comfort of bike while riding. I also have high in canondale but the schwinn Tailwind is my go to bike. And looking forward to riding with wife who can now keep up. For me it's more about the extended range while bike riding that I like about this bike, overall comfort and I can get to work without needing to take a shower.

    I'll be disappointed if battery fails. Now having two batteries I have at least a backup. By babying batteries I always store indoors and charge often. Maybe there is something else I should be doing?

    Thanks for all the efforts to better understand battery and put some pressure on Schwinn and Toshiba. I too tried to contact both companies with no luck getting any support. Primarily Iwas just trying to buy a spare battery or figure out how to reset dead battery. I'm electrical engineer who made the switch to marketing many years ago. I can follow the technology but I any deep battery troubleshooting is outside my comfort zone.

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    1. Larame -

      The good news is that the lithium titanate batteries should last basically forever if well cared for. Charge them regularly, and you shouldn't have any trouble.

      If a pack does fail on you, it should be possible to obtain another 24v battery and wire it up to replace the stock pack - there doesn't seem to be any communication between the pack and bike other than voltage.

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  7. do you have a color picture of the connectors and wires that go from the brakes and motor and pedal control into the box that the battery slides up against? johnnjazz@hotmail.com thankyou.

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    1. I do not, sorry. I will probably do some more development on this bike at some point, though.

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  8. I'm buying 2, 20" frame, Tailwind bikes, battery's dead. I'm expecting to go for 24v, 15a liFePo4's. They are PAS. I wonder what kind of Nightmare it will be to add Thumb Throttle? Sparky

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    1. I don't think you can do that easily. You'd be better off replacing the whole power system if you're going to start modifying it.

      I'll be doing some additional posts on the Tailwind here soon, though - I have mine back (loaned it to a friend), and there is a steady stream of traffic to posts about it.

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    2. I heard crazy lennys ebikes in madison offers a throttle kits for 100 bucks. Dan

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    3. and has "new" tailwinds for 300 bucks

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  9. I have used the Schwinn Tailwind, and really enjoyed it! My sister and I used them to complete a 35 mile (each way) bike trip last summer. We went about 20 miles, then stopped for lunch, opting to 'charge up" the batteries while we ate. Since pedal assist is on an "on demand" basis, we opted to use it only when heading uphill, when facing a headwind, or to get out of a high traffic location more quickly. We had plenty of power left on the battery by the end of our trip, so we celebrated by using the highest level of pedal assist steadily for the last couple of miles. That was fun! Since you generally use the power only as needed (the bike rolls well unpowered), a battery range of 10-15 miles can reflect a ride range of double that. With the quick charge feature (a 10-15 minute charge while eating lunch), we were able to easily complete a ride of 30-40 miles.

    The rising interest in bike commuting makes E bikes a really good option for many city dwellers. I'd encourage SOMEONE to figure out the battery pack issue, so these "dead" Schwinn Tailwinds could be put back on the street.

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    1. It's not an awful bike, but it's not a very good electric bike either.

      I did figure out how to bypass the BMS - http://syonyk.blogspot.com/2015/07/bypassing-schwinn-tailwind-battery.html covers it. So you can make one with a dead battery usable.

      But there are radically better bikes on the market right now, for not that much more than a used Tailwind that requires a good bit of work to get functioning. If it's the best you can afford and you can do the battery repairs, sure - go for it. But it's not a good general solution. It's a niche bike, at best, and not an amazing one.

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  10. I like the blog, I'm an electronics engineer into anything green. I bought a Tailwind for $300 including delivery. I felt that even if I couldn't get it working, it would be worth it in parts. I'm working my way back to the batteries. The controller was, like most components on this bike, cheap Chinese made off the shelf stuff. I was really disappointed with the plastic lights - total value =$0.25! Handlebar components are all cheap. For what was intended to be a $2K bike, it sure has a lot of crappy components. Oh well, the sturdy frame will make an excellent experiment platform. It is a usable but heavy, sturdy bike, good when powered, no way otherwise. I'm starting on the battery pack, currently running 2 series 12V SLA batteries. First problem.. no (no-load) charger output. That has to be fixed first before I start on the battery pack. Anybody have a charger to loan? I don't even have a good bench supply yet. Cheers.

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  11. I'm having a blast investigating this bike. Did you know that you can still get a battery for this? 24v 36v 48v, in the exact same rack with controller? It appears that the only thing Schwinn here is the frame (recognizably strong and heavy). I'm just going to order a new rack.. in the meantime I'll play with the old battery pack..

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    1. Greg - would you be willing to contact me via the contact form? I'd be very interested in reporting some of what you're finding. Digging into it is still on my list of things to do, but TBH it's very far down on the list right now.

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  12. Hi Russell, sorry this is late. Sure, I would be happy to help in any way that I can. I'm using SLAs and trying to decide whether to source or build the new pack. SLAs on the rack make the bike pretty tipsy - and I'm just graduating from a wheelchair (accident last summer) so the leg muscles are weak, but riding is easier than walking. Enter the Schwinn Tailwind (or should we call it Tailspin?). I fell that it was worth the $300 to get me into the electric bike world.

    I'm planning on building a website too for electrical\renewable anything that interests me. I have lots of photos of the assembly and may write an assembly manual for the bike. All I got was the data sheets for some of the components. Trying to decide if there is any money to be made here... but either way it will be fun.

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    1. I doubt there's much money to be made, but it's very useful stuff to share - especially in our throwaway world.

      I've considered building a proper 18650 pack into the Tailwind enclosure - would you be interested in testing such a thing?

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    2. I am totally interested in helping with batteries any way that I can. How do I get to your contact form?

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    3. Contact form on the right column, below the "other posts" listing.

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  13. Hi Russel. Reading the previous posts I assume that 7 series of the typical 3.6 li-ion batteries should be ok if I want to make my own battery for this bike close to 24V, right? For example I have 14 LG cells of 3.6V and 2600mah. If I make a 7s2p pack should give 25.2V 5.2Ah, close to the original pack. Do you thing that might work?

    ReplyDelete
    Replies
    1. I think that sounds reasonable enough. 7S would be around 29.4v fully charged, which is close to the stock 28v, and the existing low voltage cutoff should be close. You'll probably want a voltmeter to monitor it or a BMS that will do it's own low voltage cutoff, though.

      Delete
    2. You are right. Always with a bms. I already found one with this configuration.. Now the problem is that the original charger has too high the Amps for the new cells. It's output is 29V and 8.4 amps! I guess it might hurt them, 2Amps should be enough. Any suggestions of how I can reduce that number instead of byuing a new charger? Thanks again!

      Delete
    3. Get a charger that matches your new pack. Don't try to modify the existing charger. It's designed to charge the LTO cells, not anything else.

      Delete
  14. I have 2 12 volt Mobility Scooter battery's in new condition. If they will work on the tailwind I will hook them up & mount them to the bike. This is my only transportation. I am desperate to have transportation. @ 61 years old I can't walk very far. Any help at all would be greatly appreciated. I can no longer afford a car. I will beg for advice if needed.

    ReplyDelete
    Replies
    1. They should work if you hook them in series.

      Delete
  15. Thank You ever so much. I paid 400.00 for the bike still in the box. It's a beautiful machine. I have built gas powered bikes & still have them. Can't put them in the rack on a bus because it has a gas tank. A battery will go boom too. Thankfully they are not smart enough to figure that out. I will wire it up & let you know the results.

    ReplyDelete
  16. Bought a Pannier bag for the top of the rear rack. From what you have discovered the battery controller should handle the load of the 12 amp hour batteries. Should give me about 55 miles between charges. Only getting about 15 with the stock battery. I have to make this work, or starve to death.

    ReplyDelete
    Replies
    1. The controller won't draw more than what it needs - the battery capacity doesn't matter. The power gauge may be slightly off, though.

      A 12Ah 24v pack (which is what you're building) is about 288Wh. The stock pack is around 100Wh. You should be able to reliably get 20 miles, but I wouldn't push the lead acid packs to a full discharge as they will die quickly. Try to keep them above 50% charged if you can for longevity - lead acid really, really doesn't like a full discharge.

      I'll be interested to see how this works out for you.

      Delete
  17. I am Very grateful Russell. I should have this going in about a week. I hope. Without the motor the bike is very hard on me. When I get this to work there should be hope for other Tailwind owners. Such a well made bike should not be left to rot in the garage.

    ReplyDelete
  18. Battery box is complete. Controller does not see the 25 volts. Looks like I will have to replace it also. Any ideas on what I should get? I have so much work in this I can't stop now.

    ReplyDelete
    Replies
    1. "Sunk Cost Fallacy" in action...

      Where are you tying the battery pack into the bike? There's a keyed switch on the left side of the front of the battery enclosure that needs to be turned on to power the handlebar controller.

      I'm really not sure about the nature of the controller - I haven't reverse engineered the whole bike. I suspect the box on the side of the front fork is the controller, but haven't verified this.

      Delete
  19. Hi everything on the bike is stock & working as of last week. I too the bms off the battery & mounted it back into the enclosure as if it was on the battery. Went Positve to pos , Neg to neg. The two large spring loaded where the battery makes contact shows 25 volts. Turn the key, push the handle bar button nothing. Should show three leds. nothing there.

    ReplyDelete
  20. Russell imagine the bike is stock with the exception of the 2 12v battery's in a bag on top of the rear rack. Voltage too the large flat connectors that meet to the key box mounted to the rack. Key is on, normally the pad on the handle bar shows 4 led's at full charge when the on button is depressed to On. Nothing happens at all. No lights no anything.

    ReplyDelete
  21. Hi, I just found a 24V 250W controller on EBay. Wired with very similar features the Tailwind has. It will take a month to get here. All I can figure is Schwinn built something in that Battery Management system that if it don't see everything it needs it won't activate. Paid 10.00 for the controller. If it angers me I will put a China Girl 66cc gas motor on it & just ride it as I would the bikes I built in the past. It's too sweet of a bike to give up on. But I'm not there yet. Hoping to make the electric work so the Bus will except it on the rack.

    ReplyDelete
  22. Russell I hope I am not annoying you. I have everything to make an ebike from scratch now, and I am searching for a wiring diagram to make it all work. Only thing I have seen yet on youtube is for kits that plug together. I just hope the controller comes with a diagram depicting what wire goes where.

    ReplyDelete
    Replies
    1. I doubt it will come with a wiring diagram. You're usually on your own with controllers from China - at best, they might have a set of labels on the sales page.

      I haven't really dug into the system, so I'll be interested to see what you find. Any chance you'd be willing to ship me the spare parts you pull off for analysis?

      Delete
  23. I will not mind that. All I have so far is the battery its self. I might be able to use what the bike came with, (I Hope). I have to wait till I have everything here first. My Buddy is a car mechanic & works for beer, for me, lol. has volunteered to help me figure this out. Are you really in S. Korea? That what my phone shows. I'm on my computer. I suspect the key box is proprietary to that battery pack. They do stuff like that. I just don't understand why they would build a bike like that & not at least offer a replacement battery. This is not a crap bike. Toshiba won't even admit they made the battery. It's too heavy for me to go any distance without the motor.

    ReplyDelete
    Replies
    1. South Korea? No, I live in the United States. And I don't really understand Toshiba and Schwinn either with this bike.

      Delete
  24. Cool :) Pacific Bicycles owns Schwinn now. China boo, 3200.00 bike you would think there would be parts for it. I paid 400.00 I have been riding bicycles for 55 years. Had one of the first Orange Krate 5 speed bikes. Schwinn is quality stuff, or used to be. I own M&S Motorized bikes. Retired now but I have two gas bike kits in the box left. I would hate to do that to such a fine machine as the Tailwind. Loosing that battery pack almost breaks my heart. The people that I bought the bike from want to sell me another complete bike. I just need the battery pack. I will make it work, just waiting on parts. Every time I ride one of my gas bikes some thug wants to steal it. Can't even leave it alone to get a beer. Let me see what We come up with & go from there.

    ReplyDelete
  25. Want to run this by you. I don't know how many of these Schwinn bikes are out there, but if we can come up with a marketable solution for this battery issue, I am sure there is $$$ to be made. I don't mind sharing.

    ReplyDelete
    Replies
    1. Generally, the only people buying Tailwinds are people who are getting them for nearly nothing, as you have done. My experience is that this group often does not have much interest in purchasing engineered solutions, and the volume would be low enough to require hand assembly of battery packs or other components.

      If I get bored, I may fill the entire battery pack with 18650s and see what kind of range I get, but fundamentally, I don't think the Tailwind is a very good bike, so I have no desire to spend that much time and energy on it.

      Delete
  26. I understand. I am poor & always attracted to a possible way to augment my income. I vape so I am very familiar with 18650's. If I could find them @ a reasonable price I would do the same. I just can't afford 8.00 a pop for them. I have read they work quite well. I would need battery sleds to put them together cause my soldering sux. My right shoulder is fake so I can't ride a motorcycle anymore. I respect your opinion of the bike. I think it's lovely. I would ride a 1500 watt fat tire bike if I could afford one. But I don't have 12,000 laying around.

    ReplyDelete
    Replies
    1. To assemble 18650 based packs, you really should be using spot welders - soldering is hard on the batteries and is not recommended by any battery manufacturer.

      You can get cells much cheaper, but you need to order in bulk - quantities of 500 or 1000 are the minimum that make any sense for good prices, as shipping is significant.

      If you're looking for an inexpensive fatbike, the Sondors is cheap and acceptable, but the Rad Rover is a 750W fatbike for $1600 (plus $200 shipping). It's a much better, more supported ebike, built by a company that actually stands behind their products instead of pretending they don't exist. I've got a review of it elsewhere on my blog.

      Delete
    2. Thanks, I copied the info. It will take me awhile to put 1800.00 together. I might can do it by Dec. I do appreciate your help. I sold my Harley about a year ago. I can't even afford to die. I will keep working on this bike issue. I'm not in any debt, that scares me to death. Will keep you informed.

      Delete
    3. I HAVE A SCHWINN TRAILWIND BATT. WORKING IN GOOD SHAPE CALL 1 850 466 3790 AND I WILL SEND IT TO YOU. HOOT

      Delete
  27. Awesome documentation. I tried repairing a SCib battery a few months back and recently documented my results in a similar maner (in swedish). http://batteridoktorn.se/dokumentation/toshiba-schwinn-tailwind/

    However the cells have degraded and wont hold either capacity or voltage so i doubt its possible to repair with the original cells since like all lithium cells, none last more then 6 years (shelf life).

    If you live in sweden i can help repair your Schwinn Tailwind battery. You can repair it yourself with 28 pcs 18650 cells and a new BMS + Charger.

    PS: Russell Graves, you dont need a spotwelder to make battery packs. Soldering is recommended if you are doing less than 5 packs. If you need any support, let me know at: http://batteridoktorn.se/kontakt/

    ReplyDelete
    Replies
    1. Patrik -

      The voltage drop you see shouldn't affect capacity that much on those. They're a really weird chemistry, but seem to behave. I suspect a lot of the self discharge-like behavior is the BMS being in an odd state.

      As for spot welding vs soldering, I entirely disagree with you. Every battery spec sheet I've read says "do not solder." The heat flux into the battery from soldering is radically, radically higher than from spot welding - I can hit a nickel strip with three welds and immediately touch the battery terminal afterwards without burning myself.

      If you're equipped for spot welding, dangerous goods shipping, and don't mind ordering specific cells, would you be interested in rebuilding BionX packs for European customers?

      Delete
  28. You always have to solder on batteries, the BMS and other cables cant be connected other ways. I use 450C for 3-5 sec. I usually use a spot welder but if the battery is 5 rows a spotwelder wont reach and i have to solder.

    I can accept foreign repairs in 2017. i currently have cue of over 40 batteries. I dont know of any shipping options in europe that can ship lithium ion batteries to/from sweden. Well not for under 150€. I can probably repair BionX. They only sold a maby 10 kits in sweden from what i know of so haven't had the pleasure of thinkering with them yet.

    Are you asking yourself or for someone else?

    ReplyDelete
    Replies
    1. The BMS and other cables should be soldered to nickel strips spot welded to the battery terminals - that's how I've always seen it done on packs I've torn down.

      I ask because I occasionally get requests for battery rebuilds from people over in Europe, and I don't want to deal with international dangerous goods shipping other than Canada.

      Delete
  29. Can i assume you are Russell Graves of electricbikeseattle.com?

    I dont have as much experience since i just started in april this year.

    Making the strips a bit longer and soldering to the end is common and good practice, for professionals.

    But i DIY bilder does not always have to be as perfect standards as a factory made battery.

    Buying a spotwelder for $200 is not recommended for anyone just trying to repair ONE pack. That's an insane amount of money for one tool AND most spotwelder WONT work in europe, only USA since most ouTlets in EU is restricted ti 16A AND the Sunkko like is poorly manufactureD so they wont even start unless 20A is possible which its only in USA which have 110V so they must use twice as much ampere in outlets. dO YOU KNOW OF any OTHER SPOTWELDERS brands, from our outside china?

    A MUCH better practice for amateur battery builders is using 18650 cells with soldering tabs. These are a bit more expensive but maby $10-20 more instead of $200 more. Its a lot easier ans safer to assemble then a spotwelder which is basically a welder and FORBIDDEN to use unless speciell safety measures is meet. Using a spotwelder at home is basically illegal in most countries and they can blind you or set fire to your apartment or they count fire upp your wires and burn town your house.

    Let me know if your hav e other opinions, but maby email is a better line of communications since dont regard tailwind anymore.

    I can maby accept packs from other EU copuntries in 2017. I currently have cue of over 40 batteriews that will take me 2-3 monts to finish.

    PS. can i also wsk why you have Walleräng in stock? For me its a overrated ebike that is not better than any other with shimano steps and why buy them from sweden when there are 100 of other ebikes with Steps? I know alactricbike.com also loves this ebike but ive ridden it a few times and im not impressed.

    Please respond to me at my email at: http://batteridoktorn.se/kontakt/

    ReplyDelete
    Replies
    1. Patrik -

      I have nothing to do with electricbikeseattle.com - sorry. I no longer even live anywhere near Seattle.

      I disagree with you on many points you've made, though.

      - A DIY builder should aim for the same standards as a factory made battery, or should not be building batteries. The cells don't know or care who built them, only that they are or are not overheated or abused during the build or operation process.

      - I don't think $200 is that insane for a spot welder to rebuild a pack. If one looks at the cost of replacement packs for many electric bikes, one can buy the cells, buy a spot welder, buy the strip, build a pack ones self, and still come out cheaper than the replacement pack through official channels. And one has a "free" tool after that.

      As far as the various welders go, I haven't found a good alternative to the Sunkko units, though they work well enough for me. Most of the problems with them tripping breakers can be resolved by using a more permissive breaker (higher surge current), which still meets legal requirements. One can get high quality capacitive discharge spot welders, but add another zero to the price - which is why I'm working on building one.

      I agree with you that solder tabs are a useful way to go for small volume packs, but often batteries with solder tabs will not fit into the previous enclosure. There's not much excess room in a typical ebike battery pack.

      As to your claims that a spot welder is "basically illegal in most countries," would you be willing to share some written laws that could be interpreted this way? Based on your comments about them, I don't believe you use one. A battery spot welder with nickel strip may have minor arcs at the point of contact, though this usually means you need to clean the rods. They are nowhere near the intensity or heat output of a standard stick welder/torch welder/etc, and I can put my finger on the connections made immediately after welding, which gives you an idea as to how little heat is put into the battery.

      However, given what seem to be your standards of battery pack building after four months, I can't say I'll be sending any business your way. The BionX packs require the use of a spot welder to build a replacement pack that will fit in the enclosure, and you don't seem to have such a device.

      Best of luck with your battery rebuilding business. I suggest learning how to do it properly, though.

      Delete
  30. http://m.ebay.com/itm/Schwinn-24v-29-4v-4-2-Ah-9BATT-e-bike-battery-REFURB-SERVICE-upgraded-to-10-AH-/222203845920?nav=SEARCH

    ReplyDelete
    Replies
    1. Is this your rebuild service, or just one you found? If it's yours, would you be willing to share what you're doing?

      Delete
    2. No, I saw it on eBay. He claims to bring it to 10 amp. I was looking for a different battery using the same technology. The BP-L2410EH2 from another Schwinn ebike. He will do those too. Free shipping both ways. I bought a different bike and I want to switch it to Lithium Titanate!

      Delete
    3. No, I saw it on eBay. He claims to bring it to 10 amp. I was looking for a different battery using the same technology. The BP-L2410EH2 from another Schwinn ebike. He will do those too. Free shipping both ways. I bought a different bike and I want to switch it to Lithium Titanate!

      Delete
  31. THANKS TO YOU MY TRAILWIN IS RUNNING 27.5 CHARGE-----25.7 AFTER 24 HOURS

    ReplyDelete
  32. Russell I am not a fair weather friend. Got the controller from china. The battery pack is all in a tidy package, just have to wire it. Plan to use the casing of the LiPo battery to give the bike a nice look. It will also house the new controller. I feel Schwinn & Toshiba used very poor judgment not supporting this bike. Hurts me to know a bike I have always relied on is made by peckerwoods. I hope they go broke.

    ReplyDelete
  33. I need a controller for my trailwind e-bike its a ananda 2415DLC-8JKOO SN D38416.21. What controller can I replace if with, were can I get it.

    ReplyDelete
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    1. This comment has been removed by the author.

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    2. Any 24v or 24v/36v brushless controller for sensored motors. This one will work, but you'll have to change the connectors on the display and motor hall connectors, or cut them off and join the wires directly. I very much doubt that you'll find a controller with the correct connectors.

      https://bmsbattery.com/ebike-kit/752-s-ku65-for-led810-250w15a-6mosfets-controller-ebike-kit.html

      Delete
  34. I'm just repairing a couple (his and hers), both with batteries that don't charge. The bikes were totally under-powered and short on range, so no point in carrying on with the same battery.

    I've done the first one. I chucked the whole battery, rack and everything, including the controller and control panel, and I replaced the battery with a generic Chinese 36v 10.6Ah lithium rack one, and the controller with a modern sine-wave 36v 15A one that comes with a LCD (S06S from BMSBattery). I had to cut the connectors off the motor wires and put my own ones on, and it was a bit of a pain to thread the wires through the frame (could've run them externally), but now it has 50% more torque, power and speed, and nearly three times the range than it had before.

    The original controller is a generic Chinese one from Ananda. I've run similar 24v ones before at 36v without problems, except that the control panel's battery display lights will be on all the time and the controller won't shut off at the correct voltage, which is no problem because the battery's BMS should do it anyway. In other words, you only need to replace the battery with a generic Chinese 36v rack battery. Most have a compartment at the front for the controller. If not, you can stick the controller in one of those tool bags that hang under the saddle.

    BMSBattery.com sell some rather nice downtube and rack-mounted 36v and 48v batteries that include 18A and 20A controllers with LCDs, which will give even more torque for hill-climbing. These motors can run happily up to 22 amps. I've run one at 48v and 18 amps, which could climb steep hills without pedalling and gave a top speed of 32 mph.

    ReplyDelete
    Replies
    1. David -

      Thanks for your great data on what's in the bike and how to replace things!

      Is the motor a sensorless brushless motor, or what exactly feeds into it?

      And do you have photos of your conversion? I'd love to do a post on what you've done, if you're willing to share!

      Delete
  35. Russell--thank you so much for your very thorough review. I read this one and the other one on the Schwinn Tailwind bike, as I am considering purchasing a used one myself. The biggest concern for me is how would I replace the battery when the time comes up (supposedly the one I am considering has a working battery).

    I read on Amazon that someone used the BiXPower 24V 11Ah High Capacity Light Weight Lithium Ion Electric Bicycle E-Bike Battery Pack on a Schwinn, but they did not specify that model. Do you think something like that could work? Would it require modifications like the ones you mention? I hope this is not too ignorant of a question.

    Thanks so much!

    ReplyDelete
    Replies
    1. You should be able to use one of those batteries if you need to - and I'd go so far as to say that you should just get that and skip the stock battery, which is 4Ah.

      It's apparently not too difficult to swap out all the electronics from battery to motor and make it more reasonable as well. I've got this on my list of things to play with and will document it at some point.

      Delete
    2. Thanks a lot, Russell! Keep us posted on progress.

      Delete
  36. Has anyone ran a tailwind on a 7s lithium ion pack? That would be 29.4 volts fully charged vs 26.0 for the stock Tailwind pack.

    I have two bikes both with working batteries but the range is only 10 miles or so with modest hills. The power isn't bad with a fully charged stock battery but gets sluggish when the pack is running low.

    ReplyDelete
  37. Great article, appreciate the info. I have a Schwinn World GSE. I found and can buy the battery you show, do you know if they are interchangeable? Rack looks the same but I can't tell the measurements. Link to the World GSE: https://electricbikereview.com/schwinn/world-gse/
    Thanks!

    ReplyDelete
  38. Has anyone had a good experience with the Tailwind battery system? Is it true that the life of the Titanate battery is only 6 years? I've read it can have more than 10,000 recharges. Has anyone documented the details on why the BMS on the tailwind "fails", and how it can be fixed or at least replaced so that the potential of the titanate battery system is realized?

    ReplyDelete
    Replies
    1. John - I made another post about the BMS and bypassing it. https://syonyk.blogspot.com/2015/07/bypassing-schwinn-tailwind-battery.html

      Delete
  39. A right to repair: why Nebraska farmers are taking on John Deere and Apple

    https://www.theguardian.com/environment/2017/mar/06/nebraska-farmers-right-to-repair-john-deere-apple?CMP=Share_AndroidApp_Copy_to_clipboard

    ReplyDelete
  40. We have 2 of the tailwind bikes. The first one we purchased at a local bike shop. That bike had a new battery pack installed and it works great! Goes at least 20 miles on a charge. The second one we bought for my husband and it had a modified battery. He rode it 3 times and the motor began making a loud noise and then quit working. He has tried it a couple of times again and the same thing happens each time. We are looking for a replacement for the front wheel with the motor, but after reading here it might just be the battery pack? Any suggestions?

    ReplyDelete
    Replies
    1. It's unlikely that the battery pack would cause motor noise, unfortunately.

      Delete
  41. Thanks for the reply! I think your right it's not the battery. We are getting a replacement wheel and hopefully it will work. We really love theses bikes! May have to save up and start looking for new ones as we ride these a lot!

    ReplyDelete
  42. Looking for a replacement front hub motor for my '09 Schwinn World GSE I was referred to Raleigh Electric in Simi Valley (turns out I don't need to replace the motor!) but they referred me to this company who rebuilds the battery packs:

    https://ebikemarketplace.com

    ReplyDelete
    Replies
    1. Page with Schwinn Tailwind battery replacement:

      https://ebikemarketplace.com/blogs/news/schwinn-tailwind-e-bike-battery-replacement

      Delete