Sunday, June 28, 2015

Electric Bikes for Commuting in the Greater Seattle Metro Area

Last updated 25 June 2015

This document is intended as a somewhat living document to describe why electric bikes are awesome for commuting in the Greater Seattle Metro Area, and why you should consider one!

Yes, it's long.  There's a lot to be aware of.

I’ve linked to vendors and products here, but please don’t take them as the only options.  They’re just things I’ve personally used (or friends of mine have used) and am familiar with.  There are many, many valid options!

Also, please note that most of my suggestions are geared towards a daily commuter.  I'm not interested in building 60mph weekend toys.  I'm interested in boring, reliable, "daily driver" grade bikes that can get people around legally with a minimum of maintenance and drama.  This guide also assumes you want to build your own, though at the end I touch on a number of prebuilt bikes and things to consider.  Many of the same considerations apply to building your own and evaluating a prebuilt electric bike, though!

My Seattle Eastside Daily Driver

What is an electric bike?

It’s very much like a bicycle, except it’s electric!  More specifically, it’s a bicycle (with working pedals) that includes an electric (very specifically electric) motor.  Anything with a gas motor does not count here, and is legally something different.

Why are they awesome?

The hills around here suck to climb (in the majority opinion - some people love them), and traffic sucks.  In warm weather, you typically end up hot and sweaty, requiring a shower at both ends of a commute.  In cold weather, after bundling up enough for the cold and rain, you end up hot and sweaty inside the layers, requiring a shower at both ends.  With an electric motor, you have a vehicle that ranges somewhere between providing a light assist up hills (often referred to as a “hilltopper” setup), and one that is capable of hauling you the entire commute distance on motor/battery power alone.  I prefer the second type.

In addition, you're allowed to use bicycle lanes and pedestrian overpasses, so you can bypass the stopped traffic that is a frequent feature of this area.

Want to know more?  Dive on in!

Saturday, June 27, 2015

Nexus 4 Faulty Battery Behavior

I have no idea if this will help anyone else or not, but:

If you're replacing the battery (or a bunch of stuff) in a Nexus 4, and the phone does the following:
- Refuses to charge from USB/won't bring up the "charging" screen when powered off and plugged in
- Won't power on normally, but if you hold the power button for 10 seconds or so, flashes the red notification LED once when you let go
- Powers on normally with the recovery mode power/volume down sequence

Try a different battery.  I found a bad battery in a new batch that behaves like this, and while I have no idea what's wrong, the phone was perfectly happy with a different battery (and had been happy on the previous battery).

It took me an hour or so before I tried a different battery, so hopefully this saves someone some time!

Thursday, June 25, 2015

BionX 36v 9.6AH pack teardown

What's in it?

This is the starting point.  This is a 36v, 9.6AH BionX battery pack.  It clearly has a battery in there somewhere - so, this being a dead pack (there's a running theme in packs I deal with here - which is, "I don't tear apart working packs"), it's time to dive in and see what's inside it!

Keep reading for the teardown!

Sunday, June 21, 2015

2011 iZip Ultra Review

2011 Currie iZip Ultra Review

This new-to-me bike came stone dead (as far as the "electric" part of it was concerned).  It now lives with a freshly rebuilt battery pack!  So, that raises the question: How is it to ride?

There were a few issues for early owners of these bikes - broken spokes in the rear were a common complaint.  However, this isn't a problem on mine, because the previous owner replaced all the rear spokes.  He also replaced the cables to deal with some snagging issues, and I don't think it has slime in the tubes right now (apparently it solidifies if the wheels don't move for long enough).

I've been using this for potting around locally since I finished rebuilding the pack (for those not familiar, I rebuilt the 10AH stock pack as a ~14AH pack), and I think I've got a slight feel for the character and nature of the bike now.

Which is: This is really a cruiser style bike with road tires that happens to love climbing hills.

For more information and many more photos, keep reading.

Friday, June 19, 2015

Tesla Model S P85D C rate calculations

I don't know why this keeps coming up, but it does.

The Tesla Model S 85kwh battery pack has a 74P96S battery pack configuration (sets of 74 18650 cells in parallel, then 96 of these sets in series).

Fully charged, the Model S pack is right around 400v.  At 4.2v/cell, this should be 403v, so I'm happy to call "fully charged" 4.2v.

Nominal voltage on the cells will be around 3.7v/cell, or 355v.

The cells are each ~3AH (3000mah).

At highway cruise speeds, a Model S manages roughly 300WH/mi at 70mph - or 21kW.  For a fully charged pack, this is 52A, and at nominal voltage, 59A.  This correspond to 0.7A or 0.8A per cell, for a C rate of ~0.25C.

Peak power consumption on the P85D is about 470kW.  This corresponds to full/nominal amperages of 1175A/1324A, for a per cell current of 15.8A/17.9A, for a C-rate of 5.25C/6C (briefly - the car will hit max speed in a hurry).

The normal P85 cannot sink so much power, so peak C-rates are lower.

Ludicrous mode seems to peak around 570kW (based on Wikipedia).  This requires the 90kwh pack (or roughly 3.2AH individual cells, assuming the same pack configuration).  This corresponds to full/nominal amperages of 1415A/1605A (though I understand it's limited to 1500A).

1500A out of the P90 pack works out to a per-cell current of 20.3A, for a C-rate (on the 3.2AH cells) of 6.35C - so slightly more than the existing pack, but not by much.

Talking to some Tesla owners, the cars only accelerate "at their best" when fully charged - so the amperage being limited and acceleration being slightly worse when drained sounds like that's actually how things work.  This being, of course, utterly opposite from an internal combustion vehicle, which will accelerate best with a nearly empty tank (less weight).

Still very, very impressive!

Thursday, June 18, 2015

An open letter to Toshiba and Schwinn regarding the Tailwind Electric Bicycle

To whom it may concern:

In 2008, Toshiba and Schwinn partnered together to create one of the first lithium powered electric bikes, the Schwinn Tailwind.  Right now, many of them are sitting, waiting to be scrapped, because of dead batteries.

An advanced, pedal assist electric bike with a very fast charging lithium battery was revolutionary at the time.  Toshiba used their new SCiB technology, and Schwinn, a long recognized name in bicycles, designed the bike.

Seven years later, in 2015, there are a large number of Tailwinds sitting in garages with dead batteries, and an advanced, undocumented battery management system that nobody will admit to knowing anything about.  I've personally received calls from many people who have dead packs, and know of many additional dead packs that could be revived with the right information.

Schwinn support won't help but suggests talking to the battery manufacturer, and Toshiba suggests calling Schwinn.  The corporate finger pointing doesn't help customers who own one of these bikes and would just like to use their electric bicycle again.

There are diagnostic ports on the battery management circuit board, but nobody knows anything about interfacing with them, despite Schwinn documentation talking about how this advance will make diagnosing bad batteries easy.

If you genuinely care about sustainability, the environment, and keeping bicycles and batteries from being scrapped long before they should be, please provide information about these battery packs so those who have the packs and bikes can keep them running and repair the batteries and bicycle.

I'm currently serving as a source of information for these batteries, so please contact me about how these bikes can be kept out of the scrap heap.

Chromebook Pixel LS vs Chromebook Pixel

I've had the original Chromebook Pixel for a while.  It's been my favorite little piece of hardware, for quite a few reasons:

The keyboard is excellent.  The trackpad is excellent.  The screen is excellent.  And the overall build quality is superb.

It did, however, have a few issues.  Mostly, only 4GB of RAM.  And the heat/battery life from a somewhat older processor than it probably should have used.  That didn't stop me from carting it all over, using crouton, developing on it, and generally enjoying it immensely.

As all 15 people who use Pixels now know, Google released a new version!  And the high end version (the Pixel LS, for Ludicrous Speed) is very nice indeed.  It's fitted with a Broadwell i7 2.4ghz processor, 16GB (!!!) of RAM, and is otherwise almost identical to the first generation.

The keyboard is also different.  It's slightly softer and less crisp, but is in no way more difficult to type on.  And there are separators between the "F-key" row at the top instead of one long row.  Those are noticeably quieter and less "clicky."

The speakers, though. :/  Ouch.  What a downgrade.  They're muted and muffled.

But for a Linux development laptop (using Crouton)?  There's nothing else like it.  It's worth every penny.

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.