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Video of "Lead Free since 2003" VEVA Talk

Posted: Tue Nov 23, 2010 7:51 am
by justin_le
Hey guys, some people asked us to record and post the presentation that I gave last Wednesday at the Vancouver Electric Vehicle Association's monthly meeting on our 7 years of experience dealing with ebike battery packs. Unfortunately the video quality isn't so great and some of the slides are hard to make out, but if people are interested I can attach the original PowerPoint file to look at in parallel with the video if that helps.

Long talk, just under 2 hours, and the camcorder's lithium battery died about 5 minutes before the end:

http://www.youtube.com/watch?v=5frJlJiCS34&feature=related 1/6
http://www.youtube.com/watch?v=KHqgMec2HLU&feature=related 2/6
http://www.youtube.com/watch?v=1q5VOfYvQfw&feature=related 3/6
http://www.youtube.com/watch?v=ukfIj4Ypw8Y&feature=related 4/6
http://www.youtube.com/watch?v=WT7OPdK2ELo&feature=related 5/6
http://www.youtube.com/watch?v=T3ADCIjmnhY&feature=related 6/6

http://www.youtube.com/watch?v=s8uwkzM_GzA&feature=related 1/5
http://www.youtube.com/watch?v=xlVf4fJ8HDk&feature=related 2/5
http://www.youtube.com/watch?v=qsM_54h7GEA&feature=related 3/5
http://www.youtube.com/watch?v=ajAlu0TH8qU&feature=related 4/5
http://www.youtube.com/watch?v=vXcNthbKkNM& 5/5


-Justin

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Tue Nov 23, 2010 8:54 pm
by Ypedal
Wow... Man.... That was one radical trip down memory lane ! :o

Terrific job ! I'm gonna sticky this for a while, the video and sound quality was pretty rough but well worth watching..

Batteries are the by far the weakest link in the mass market ebike industry to be.. The 250w setups are pretty easy, but the 500w+ range of ebikes just plain need more..

I have a 1700$ paperweight sitting next to me, was supposed to be best thing since sliced bread, arrived with no BMS ( because i had been waiting for months on end for it, and it could not be hacked to work, so shipped it without one ) supposed to be good for 80 amps ( 24ah pack ) .. could not manage 20... and looked like it was assembled by a chimp.. Can't even imagine the feeling of having 50 on a pallet to deal with ...

Oh, the original eZee battery pack back from late 2007 http://ypedal.com/ezee.htm finally kicked the bucket this year, BMS and charger kept working but the cells finally swelled and are down to 5ah.. all 10 cells !!.. if they all worked like that it would be great.

About Lithium cells going to 0v and not recovering, after a whole lot of hours ( Doctorbass knows all about this too !!! ) testing defective power tool packs, and also on PSI cells, and with Turnigy lipo cells too, i've had situations that cells will either self discharge to 0v from a long trip across from china, or be discharged over a period of 3 weeks or so ( by soneil chargers none the less, plugged into the packs but not on AC )

viewtopic.php?f=14&t=22885&start=0

They sometimes survive !!! with no immediate signs of capacity or performance loss..
While some other cells die instantly below 1v ( like the 12ah prismatic lifepo4 for example )..

The nicad packs have been the longest lasting and trouble free ( other than a thermistor replacement or 2 ) .. the one's i got that are over 4 years old now are still going, higher internal resistance but giving 6 to 7 ah from an 8ah pack..

The " Best " 48v 10ah pack i have used ( and still do ) i built myself from PSI cells, no BMS, but using 16 gauge wires with anderson powerpoles.. overboard, but damn it works well..

http://ypedal.com/PSI/PSI.htm
http://ypedal.com/PSIChopper/index.htm

what is it with batteries, i lov'em so much.. but i hate them soo much too.... :lol:

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Tue Nov 23, 2010 11:55 pm
by el_walto
Nice presentation. Pretty bad luck you guys have had with battery manufatures.

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Wed Nov 24, 2010 12:19 pm
by wanders
Justin:

Excellent historical perspective on multi-cell battery packs. Any chance you could post the presentation in PDF form?

Wanders

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Mon Nov 29, 2010 8:52 am
by justin_le
wanders wrote:Justin:

Excellent historical perspective on multi-cell battery packs. Any chance you could post the presentation in PDF form?

Wanders


Hey sure thing. The file is too large to attach to the ES message but I've uploaded it to our website here:

http://www.ebikes.ca/images/Lead_Free_Talk.pdf

20MB of battery carnage for your perusal. -Justin

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Mon Nov 29, 2010 9:12 am
by justin_le
Ypedal wrote:Wow... Man.... That was one radical trip down memory lane ! :o


Hey Gaston, yeah for me it was an almost therapeutic experience to get all that off my chest too! It gave some closure to this whole chapter of trying to work out custom ebike packs with all the various Chinese cell and pack assembly companies. From now on it'll be just eZee batteries with Samsung / Sanyo / Panasonic cells and programmable O2micro BMS circuit. Don't care what's the price at this point. Just want reliability.

Terrific job ! I'm gonna sticky this for a while, the video and sound quality was pretty rough but well worth watching..


The original video file isn't too bad, it lost a lot on the compression for the youtube upload. Is there a chance that someone on this list might be interested in taking the original video and editing it to include the actual powerpoint slides at appropriate times so that the images come through crystal clear? Then we could upload the whole thing as a single file to google video with better resolution.

If so, send me a PM and we'll work something out.

-Justin

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Mon Nov 29, 2010 11:26 pm
by Zoot Katz
That was a good talk. I learned a lot about the mechanisms by which batteries can head south.
Your presentation exposed a regular trail of tears encountered on your quest for quality suppliers.
Your ongoing experiments in order to provide us with reliable energy for our bikes bespeaks your commitment.
I certainly, and selfishly, hope you finally have some well deserved luck with your current choice of E-Zee packs.
Thank you Justin.

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Tue Nov 30, 2010 3:45 am
by jonescg
Just went through the pdf. Great presentation Justin! I'm a little concerned about any battery I buy now :?

So what's the solution? Are ANY batteries any good these days? reduced life cycle is one thing, burning your house down is another :shock:

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Tue Nov 30, 2010 8:10 am
by docnjoj
PDF was excellent and scary! Thanks Justin. Are present batteries any better?
otherDoc

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Tue Nov 30, 2010 10:59 am
by liveforphysics
Outstanding as always Justin.

I loved every second of your vids.

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Wed Dec 01, 2010 5:38 am
by justin_le
jonescg wrote:Just went through the pdf. Great presentation Justin! I'm a little concerned about any battery I buy now :?

So what's the solution? Are ANY batteries any good these days? reduced life cycle is one thing, burning your house down is another :shock:


My own personal feeling is that unless the cells are coming from a long standing big company with years and years of expertize and R&D and internal know-how in battery manufacturing, then they're not going to come close to the standards needed for a consumer industry. Almost all the new companies eagerly selling larger format EV batteries fall way short of this category. I mean we got 4 sample 48V headway packs earlier this year, and have already had to do cell replacements in two of them. A hobbyist can put up with those kind of statistics, an industry can't.

BionX was smart and used Sony cells in their lithium packs. Much as some might begrudge them charging $1200 for a replacement 36V 9Ah lithium pack, at least their users almost always get 3-4 years of regular use from the batteries before they start to wear down, and virtually never have cell problems. Sony can't afford the risk associated with their cells having problems. In hindsight I would have so happily paid twice as much for our packs to have those kinds of statistics, and at the end of the day our customers (assuming they weren't put off by sticker shock) probably would have too.

For now, we're taking a gamble on Samsung being able to deliver a reliable LiMn ebike cell, and they are assembled into packs for eZee at the same facility that does the BionX pack assembly. It's only been 6 months that we've been dealing with them though, so too early to say if that typical lifespan will be 12-18 months or 3-4 years. I'm sure hoping it's the latter because ebike users really deserve it.

For all the talk of LiFePO4 lasting 5-10 years and thousands of cycles, we've yet to see anything firsthand that comes close to consistently delivering this in practice with the ebike grade LiFePO4. I'm sure A123's are up to the task, but I have sincere doubts about all the other manufacturers.

As for the house burning down at the end of the slides (video cutoff just before I got here), that occurred to my very close friend just this summer. She happened to have a battery pack that had all the EU ebike certifications, including the stringent UN38.3 shipping tests, with a UL/CSA certified charger. Went to walk the dog for 15 minutes with the battery charging by her door and came back to the suite in flames, with the battery pack and charger (which had been beside her coat rack and a wicker basket) right at the epicenter. The fire investigation that followed was inconclusive at determining the exact cause or event sequence that lead the pack to do this.

Just 4 months before that I was actually on a tour of this very battery facility and saw the test rooms where they drive nails through the cells, heat them up to 100oC, charge them to 10V, pound them with a sledge hammer, etc. and in all cases the cells wouldn't fail with flames. So what happened that would cause a 2 year old battery that hadn't shown a single sign of strange behaviour to suddenly burn down a house? I have no idea.

-Justin

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Wed Dec 01, 2010 6:12 am
by johnrobholmes
Maybe it was just a charger failure?

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Wed Dec 01, 2010 2:04 pm
by el_walto
justin_le wrote:
Ypedal wrote:Wow... Man.... That was one radical trip down memory lane ! :o


Is there a chance that someone on this list might be interested in taking the original video and editing it to include the actual powerpoint slides at appropriate times so that the images come through crystal clear? Then we could upload the whole thing as a single file to google video with better resolution.

If so, send me a PM and we'll work something out.

-Justin


I haven't done this before, but I'll give this a try.

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Thu Dec 02, 2010 5:27 am
by justin_le
johnrobholmes wrote:Maybe it was just a charger failure?


That's a possibility. The charger is one of the aluminum High Power models which have very good safety records (especially compared to other brands). The main fire investigator had a strong inclination to think it was a wiring related origin but I think that's in part because it's what he's mostly familiar with. The heat of the fire did melt the electrical cords going to the outlet and tripped the breaker.

I didn't get to see the actual damaged battery pack, but from the descriptions the plastic casing was 100% disintigrated, nothing left to see, all the cells were exposed and massively ballooned and had burst through the stainless steel strapping band that holds them together. I did see a piece of the BMS circuitboard which was fried to a crisp.

It could have been a situation similar to this one in the presentation:
DLM Burnt, Wiring Removed.jpg
DLM Burnt, Wiring Removed.jpg (113.09 KiB) Viewed 767 times


Where for whatever reasons there was heat which melted the insulation and caused a short circuit across the BMS lead wires, which in turn shorted out the cells. In the above case (which happened to me) it didn't result in any cells going up as the short circuit current vaporized the lead wires. But if that didn't happen and the current kept flowing, then there would be a lot of cell energy to reckon with.

The description of the smell of the white smoke from the tenants upstairs and the neighbors also really matched my own experience of a venting lithium cell, so it definitely seems like the cells were not just bystanders in this case.

-Justin

Re: Video of "Lead Free since 2003" VEVA Talk

Posted: Sat Dec 04, 2010 11:53 pm
by Biodiversivist
That was a great presentation, Justin. Very informative. I was hoping for a happy ending but I guess batteries remain the weakest link. I'm one of the first guys to put Dewalt A123 packs on a bike in a 72 volt configuration. I was aware of all of these battery problems from the start and have managed to keep my batteries going strong since about May 2007. I bypass the BMS when I string the packs in series/parallel but use your wonderful Cycleanalyst to monitor amp hours. I stay away from that part of the discharge curve where the cell voltages start to plummet to protect any weak cells. I also put them in Dewalt chargers every night to get each cell balanced. I always put the same two packs together in series.

Maybe I've just been lucky but these packs are still serving me very well.

I have a bunch of A123 cells laying around in my shop from fixing other bikes in town. Would it be dangerous to try to spot weld these batteries? I talked to a guy at a battery store who replaces bad nickel based cells in power tool batteries and it is against company policy for them to mess with lithium.