Sunday, May 31, 2015

Koolstop Electric Bike Brake Pads: Are they any good?

Koolstop makes brake pads specifically for electric bikes.

According to
Our E-Bike disc pads are produced with a ceramic barrier between the organic friction material and the steel backing plate to reduce heat transfer into the brake caliper causing brake fade. With the heavier design and quick speeds of Electric bikes, they require a compound that will hold up and provide consistent braking power.
Are they any good?  I couldn't find any reviews, so of course, I bought a set for my disc brakes (specifically, Kool Stop Deore M525 Disc Brake Pads for Electric Bikes).

Yes, they are very good.

I was making one of my normal "Lots of downhill" runs (to get beer, of course!), and decided that, with the ebike compound in the rear, I'd skip the use of the front brake until I faded the rear.  Normally, I fade the rear if I'm using it alone by the bottom of the first hill.  These kept going solid, and held my speed nicely down several more steep hills (about 300' of descent combined, all fairly steep).

My rear rotor is shades of blue and yellow from heat.  I didn't know bike rotors could turn those colors.

I'm genuinely impressed by them.  My caliper remained cool, my brake force remained reasonable, and they gripped nicely, even as the rotor got hot enough to turn colors.

I wholeheartedly suggest them if you're rocking an ebike in hilly terrain!

Monday, May 25, 2015

Notes on the Sunkko 788+ Battery Spot Welder from China

Sunkko 788+ Battery Spot Welder

So you've got one of these, and know very little about it.  That's great!  None of us who speak English know very much about them, except perhaps the manufacturer, and they're not talking much about it.  The manual is an utter joke (if anyone will even send it to you). contains a slight overview of the welder, and some pictures.

It's a microcontroller-based, transformer-powered welder, and it's cheap.  Very, very cheap for a spot welder.

If you have any way to power the 220v version of it, go with that version.  The 110v version is unreliable and is likely to blow triacs.

Here are some of my notes from welding up a pack or two with it.

The electrode pressure, as shipped, seems to be a bit low.  The knob on top adjusts this.  Increase it if you're getting arcing.  I think I have another 5-6 turns on it from stock.

Clean the electrodes.  If they're sticking to your work or arcing, clean them.  If it's been a little while since you cleaned them, clean them.  They seem to benefit from being cleaned regularly.

Start low with the current, and ramp it up until the welds are good.  Too much current will burn welds and increase the risk of frying the welder.  A scrap battery or two here is useful.

The right-most digit selects the number of pulses - 1 or 2.  You want to be double pulse welding.

I have no idea what the "current set" knob does yet, but it seems to increase the weld power or duration.  If you have the 110v version, I'd suggest leaving it at 0, and using the digital display to up the power for now.

The inrush current (especially on the 220v version) is brutal, and it has a tendency of popping breakers when turned on.  If this is the case and you can swap breakers around, consider putting in a Type C circuit breaker instead of a Type B - they are designed for higher momentary peak (inrush) currents.

Once I finish my analysis of this thing, I'll have more information...

Saturday, May 23, 2015

"Cree 2000 Lumen Bike Light" Disassembly and Testing

If you've gone shopping for bike lights, you've probably run into the Cree 2000 Lumen Bike Light.

They look like this, more or less:

They cost about $20 with a battery (quad 18650s in 2S2P, usually), you can get them from an endless supply of vendors (eBay, Amazon, and plenty of others), and they have a surprisingly tight beam.

But what if you want to run them on ebike pack voltage?

I couldn't get anyone to give me an answer, so I set out to find out.

Click through to see what I found!  And, if you just care about the answer, it's "No."  They're 8v lights, and by 12-14v, components on the board are smoking.

Thursday, May 21, 2015

iZip Ultra Pack Rebuild 3/3

Rebuilding the Pack for the iZip Ultra

The actual pack rebuild process went smoothly at first, then took forever while I repaired the welder, then smoothly again after I got the welder repaired.

I started with 50 Samsung ICR18650-32A batteries and a lot of parts, and ended up with a new battery pack!

Continue for an awful lot of photos of rebuilding a battery pack.

If you're here because you have an iZip battery pack you want rebuilt, please go here for information on my pack rebuilds.

Tuesday, May 19, 2015

iZip Ultra 2011 Battery Pack Rebuild 2/3 - The Parts

After deciding to rebuild the battery pack for the 2011 iZip Ultra, I got the pack torn apart.  After I knew what was in it (50 Samsung 18650s), I had to figure out what I needed to rebuild it.  I'm starting from ground zero here - I've never rebuilt a battery pack before.  Usefully for you, I had to do all the research myself to figure it out, so I can share some of that to help people who may find themselves in the same position.

If you find yourself interested, read on!

Friday, May 15, 2015

Sunkko 788+ Welder failure and repair

I have a Sunkko 788+ Spot Welder.  It failed on me rather quickly, either from a faulty triac, or from overheating the triac due to an aggressive duty cycle (I'd say I exceeded the rated duty cycle, but that would imply there was enough documentation to determine this, which... not so much).

The quality customer support on eBay was at least nice enough to suggest I replace the triac.  They did imply that this was about the only support I was going to get, so... well, in I go.

This might be part of the problem...

Failure Behavior

I was welding away at a battery pack, happily popping nickel strip onto batteries.  I stepped away for a bit to get the next part of the pack assembled, and when I came back, the unit wouldn't power on.  Well, I'm smart enough to know that if a unit comes with spare fuses in the box, blowing a fuse is somewhat common.  Annoying, but common enough.  I removed the fuse holder, dumped out the shattered remains of a fuse (it apparently crumbled when the holder was turned), and replaced the fuse.  Excellent.

I plug it back in, hit the power switch, and... BANG.  Something inside the unit fails, hard.

The unit still powers on, but it won't weld anymore. shows it's behavior after the failure, if anyone is curious.

Well.  Time to dig in. Read on for the photos.

Overview of a Sunkko 788+ Welder

Power 788+ Battery Spot Welder

So, you find yourself needing to spot weld a battery pack (or something else) together.  And, spot welders are expensive, and most people end up building DIY devices, but there's this little gizmo (and it's siblings) all over the internet.  Alibaba, eBay, Amazon... it's a common item that claims to be a decent spot welder. It runs about $200 shipped to the US.  Be sure you get the 110v one - most of them run on 220v (unless you have 220v power, of course).

But what is it?  What makes it tick?  Why is it so much cheaper than every other spot welder out there except ones that are very obviously related to it?

Well, as it so happens, I've gotten very friendly with one (details in a separate post), and will happily share some of my insights with you.

Let's dive in.

Thursday, May 14, 2015

iZip Ultra 2011 Battery Pack Teardown 1/3

2011 iZip Ultra Battery Pack Rebuild

Someone at work was getting rid of an ebike they were sick of.  It didn't work.  One of my flaws is that I'm a sucker for free stuff I'm interested in, especially if it originally sold for a lot of money.  Please ignore the stack of phones and tablets on my desk that I need to fix or strip for parts...

A quick trip to pick it up, and I had the following sitting in my garage:

It's a 2011 Currie iZip Ultra.  This is a 500W geared rear hub motor, pedal assist ebike, with a 36v, 10AH pack.  Of note are the very small, high pressure tires - it's supposedly quite efficient as far as power use goes, even on a higher assist setting.

Unfortunately, this one wasn't going to do any assisting at all.  The battery pack was stone dead.  I got a back story involving the charger, a power outage, and the pack dying, so perhaps the charger drained it after the power outage, but whatever the case, it was dead.  Really, really dead.

The bike uses lithium cells - ICR (LiCoO2) cells to be specific.  Lithium cells are great in terms of power density and energy density, but they require some specialized care and feeding.  They must exist in a voltage range between about 2.7 and 4.3 volts per cell (and spend most of their life in the upper 3v region).

Discharging a lithium cell below 2.7 volts tends to do physical damage to the cell if it's left there (and, really, you shouldn't ever have them below 3v/cell for any length of time).  Skipping to the punch line, this is a 10S pack.  That means the pack should live between 30v and 43v.  Maybe down to 27v, briefly.

10 volts for the whole pack is right out.  That's "bad."  That voltage, combined with the time sitting, means the pack is physically damaged, recharging the batteries is not a good idea, and even if it will take a charge, it's very likely significantly short on capacity.  Individual cells were between about 0.6v and 1.2v.  Neither is 2.7v or greater...

A replacement OEM pack is $600.  A bit of research indicates that I can do a lot better.  So, of course, I tried to.

Continue for lots of interesting teardown pictures...

Tuesday, May 12, 2015

My Second Ebike: A properly good build!

After spending a year commuting on my first ebike, it finally failed on me - I overheated the motor too many times, and it quit for good.  There was a lot of other stuff starting to go wrong as well, and I'd learned a lot more about what I wanted and what worked, so I built myself a new one in October 2014!

This bike is built with everything I've learned from my previous ebike, and is built as a robust, rugged commuter designed for my 10 mile daily round trip commute.  I'm not a fan of fixing my daily driver, so it's built with this in mind.  As may be obvious from the pictures, I'm not a huge fan of washing it, either.

It's built on a used 2007 Specialized Hardrock frame with 26" wheels, uses my existing battery pack, is driven by an HPC Thunderbolt motor/controller combination, and is built to be rock solid reliable.  So far, so good!

Features I wanted when building this bike:
  • More power.  The 600-700W output of my previous build just wasn't enough for the hills I deal with and my desired level of "e-motorcycle" behavior.
  • Disc brakes.  The rim brakes on the previous build were better at grinding the wheels into dust than stopping the bike, especially when wet.  Paired with Seattle traffic, this was quite terrifying on multiple occasions.
  • Better fenders.  The mountain bike style fenders didn't keep me dry in the rain.

The frame and basic donor bike were purchased on Craigslist.  However, I'm not sure that purchasing a donor bike was the right option for this build.  I ended up replacing most of the hardware that came with it to get it to where I wanted it, and I'm thinking it might have been slightly cheaper to go with a frame-up build.

Read on for more details...

Saturday, May 9, 2015

My first ebike: Lessons Learned

Sometime around November 2013, I became tired of biking to work and being sweaty at both ends of the trip.  I'd been motorcycling, but traffic was terrible and getting worse - my record of "45 minutes to get 5 miles home" was not something I cared to continue with.

I've known about electric bikes for a while, but never knew anyone with one.  I knew of the BionX kit, but didn't want to spend the money on that for something I had no idea if I'd like (and it requires a bit of work on an existing bicycle, which I wasn't sure I wanted to do).

So, where does one go for something along these lines but Craigslist?  A few listings later, I'd found a $400 ebike that ran, test rode it briefly, and brought it home.

It looked something like this (though this is a slightly later version of it - note the adequate size wiring).

It was some year of MGX D50i, it had a 24v Heinzmann geared motor (brushed) in the rear wheel, a Chinese 36v brushed motor controller, and 3 12v/8AH lead acid batteries for 36v of overvolted fury.  A thumb throttle provided power on demand.

I had an ebike!  *whirrrr*

Wednesday, May 6, 2015

House fan for vertical windows: DIY Version with 120mm fans!

I had a problem.  I solved a problem.  In extreme overkill form, as is right and proper.

The problem was that my office ran too hot in the summer.  It's on the southwest corner of the house, and has both a good southern exposure and a good western exposure.  Also, it's on the second floor.  And, finally, the house is poorly insulated.

Prevailing winds get me a bit of ventilation, but the direction of the wind will force the hot air from the office into the rest of the upstairs, and generally make the rest of the upstairs hot and miserable to be in.  This is not a good solution.

The last few summers, this led to the office being more or less uninhabitable in the afternoons.  Several times a year, I have to shut down computers because they've tripped thermal alarm setpoints and are beeping loudly about the heat.  I've lived with this, but this year, the ferrets are in the office, and they don't deal with high heat.  So, I set about finding a new solution.

The solution was to find a way to exhaust hot air from the office, against the prevailing winds (yes, I know, this is terrible, but... it was either that or move the office, so, I'm just fighting nature).

So I fought nature.  And, so far, am winning.