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[guity]

Hey Picasso -- The batteries are yellow Thundersky 60 AH.  Actually what I am proposing to do is open up the bike and use a drill to poke holes in the two dead batteries to release the gas that is swelling them up.  I am hoping that if I "pop" them, they will shrink enough so they can be removed from the tray.  Then I am hoping there will then be enough space to put new (unswollen) batteries in their place.  My drilling operation is what EM doesn't like.  My understanding is that they don't think it is worth the risk that the new batteries will be unable to fit into the tray.  I don't think the risk is that bad, because at worst I would need to replace 4 batteries in each of the 2 trays (wish the bad batteries had been in the same tray but NOT).  It looks like EVComponents is selling them for $66 apiece, so that is a $500 risk, which doesn't seem like a daredevil risk or anything.

However, if I manage to hook up a pack of 24 working Thunderskies, I get into new problems.  If they are charged to 3.8 volts apiece they will add up to 91.2 volts.  But my 7234 Alltrax controller is set up to play dead for anything more than 90 volts.  I was kind of hoping though, that either the charger wouldn't charge the batteries beyond 90 volts or if it did, a volt or two could be drained off reasonably quickly by turning on the bike/headlight.  But again, I feel like the risk is worth it, and worst case is I am forced to buy a higher-volt controller...

[picasso]

I say dont touch it, It's up to Electric Motorsport to correct the problem. It was them who set the low volt cut off. Stay in your warranty!

If you drill make sure to drain all power out of those cells first. Chances are the other cells next to it will expand when you remove the bad one. Getting them back in might be another game.

[guity]

Well I am loath to run afoul of any advice you have to offer Picasso.  However,  I'm not sure the warranty is all that important at this stage.  The bike has been driven almost 1300 miles and shows no signs of being a lemon.  The only significant problem, with the batteries, can't/shouldn't be covered by the warranty because I abused them. (I  sort of felt bad because the Hollywood Electric techs put a lot of time-consuming labor into addressing the battery problems anyway.)  

I'm just not sure the warranty is so valuable any more.  Right now the bike's top speed is 53 mph, and as I mentioned, it can't really complete a satisfactory commute.  I charged the bike before I took the latest cycle analyst readings, so the voltage remaining reading is no good, but the latest stats show the unsatisafactory commute sucked up 30 ah instead of the usual 22 or 23.  I don't think the top speed or the over-sucking of amp hours will be helped by adjusting the lvc, but I think they might be helped by an extra battery or two.  And it looks like I would be the natural choice of candidate to perform the time-consuming labor.

If the 2 new batteries don't fit in, I'll just have to save up some money to buy enough batteries to replace all of them in the trays.  If/when I get the batteries in place, would you be able to advise me on getting them married into the pack and balanced?

[picasso]

Well I think its time to learn to work on your bike. By warranty I'd at least attempt to get parts out of them. You should never feel you abused your pack. Those guys set the limits on you, But my gut tells me you had some wonk or undercharged cells and that is what happened. Not you taking it down, had that been a balanced pack your should have been fine doing that one time. But you did take it far. Not that I did any math but just going off my gut and looking at your posted logs. And again thanks for those! I like real world numbers. Keep in mind I'm just and arm chair EV fan. I've yet to build my own bike. But have played with a few "ev" things and do way to much reading.

At this point I'd save for a BMS from elithion.
Some good reading about different BMS systems over at http://liionbms.com/php/resources.php

Next I'd get new cells that fit what you have now. And because Im crazy I'd add a controller thats over kill. I like the soliton 1 but I've yet to see many reports on its use. Zilla production is also back in swing thanks to the guys at evcomponents.com It was sad to watch others take market because the guy who made those cared so much he wanted to hand-build them himself. Got to love a man with that kind of dedication. And just dial the sucker down to what your cells can support.

I'd go headway based cells but since your bike is built out for the thunderskys you kind of stuck in the footprint and it makes getting some of the off the shelf headway configs out of the contending.


frodus is the headway nerd. I'd watch what he does with his bike. Most batt talk tends to be on this forum here http://endless-sphere.com/forums/viewforum.php?f=14

[guity]

This morning I took the bike down the hill and brought it back up with an open throttle.  It was fully charged, but had been sitting 3 days not plugged in. 

For most of the trip back up the hill the bike was drawing between 140 and 180 amps and was moving at perhaps 45 mph at most.  For the last half mile or so, the amps drawn dwindled down to the 100-120 range, and the speed dropped to around 38 mph.  I was being cut off within the first 5 miles of driving the bike!  When I got back to my house the voltage remaining popped back up to 72.9 fairly quickly, a little more than 3.3 volts per cell. 

The cycle analyst stats for that trip showed I had driven 4.7 miles and used 10.18 AH, 637.97 watt hours, for an average of 134.7 watt-hours per mile.  It showed I had drawn a maximum amount of amps of 271.3, and had at some point sagged to a lowest voltage level of 55.2 volts (2.5 volts per cell, the danger zone).  My max speed had been 58 (that was going downhill), average speed 39.8 mph.

The fact that the bike voltage sagged down to the danger zone makes me think two things -- 1) The low voltage cutoff isn't really set too strictly, because I really don't want to hit voltage levels below 2.5 volts per cell. 2) if I shouldn't be easing off on the low voltage cutoff level, the  only other thing I can think of to get that bike up the hill without limping, is to get the 23rd and 24th batteries going

[guity]

22 batteries should not have their cumulative voltage drop below 22 * 2.5 = 55 volts.  24 batteries should not drop below 24 * 2.5 = 60 volts (all of this assumes a blanced pack).  With 22 batteries my operating voltage at 3.3 per cell is 72.6 volts .  With 24 cells it is 79.2 volts.  If the hill I live on causes a voltage sag of 18 volts from the 72.6 volts, then the cells are dipping down to the 54.6 level which would require low voltage cutoff.  But a voltage sag of 18 from 79.2 is 61.2, still above the 60 volt low cutoff voltage for 24 cells...

[guity]

This is as far as I've been able to get so far.  The most accessible tray is out, and I am working on the dead cell in the tray.  Every battery in the tray measured 3.6 volts on the multimeter, except this one measured 0.  When I first pierced it, it hissed for a bit and then started smelling.  I drilled holes in it and threaded some coathanger wire through the holes and managed to pull it up out of the box about an inch.  It doesn't seem much inclined to go any further...

Note a slight miscalculation on my part: there are 9 batteries in this case that will need to be replaced if this goes wrong, as opposed to 4!

[picasso]

Please!@ do this first. take a pic up the connection layout and take off those bus bars. Or tape the shit out of it, Never ever work with a pack connected like that. Im glad to see shrink rap on some but still one drop of a metal item and the rest of that pack is toast.
and WOW does it suck to that that lip right in the way for you to remove it that cell.


I've never let the gas out of that style cell, I would have guess it would not off gas that much. I've only ever seen the pouch style puff up.  And thats also all I've worked with cept my little headway pack.

Glad to see you are getting into the bike. My shop is always open should you wish to fab some items. But as you know Im up in SF bay. But should you need can always come up and fab. I've got a great tool collection.

[guity]

OK, so I resorted to what I usually resort to in basketball and golf -- except this time I actually had a saw...

[guity]

From straight above...

[guity]

Your tools would really come in handy becuase the main problem here is not really the batteries.  It is this fixed metal box.  There should be like a couple of plates that can be strapped and bolted into place to hold these batteries tight, but also loosened and removed when needed.

[picasso]

Craiglist should find you someone to get to weld up that box. How are the other batts on the bike? trays like that? Do you have a volt meter to check those other cells? You will have to balance your self after you get a new cell to bring them all up the same.

[guity]

Picasso I have a multimeter and it is showing the 8 other batteries in the case to be equal, all at 3.6 volts.  I bought this single cell charger for about 12 bucks off ebay for lifepo batteries that will charge a single cell to 3.65 volts.  By the time I am ready to start balancing I imagine all these batteries will be somewhere below 3.65 volts, so maybe just before I stuff them all back into the bike I can charge each battery individually to 3.65 volts to make them all equal?

[picasso]

Yes that would be a good idea.

Would not hurt to add some wires to each cells + for later when you wish to look at each cell still in the bike. A BMS will later give you this option, but for now it would be nice to have a tap to each cell to take a look now and again. You might want to hit the endless-sphere.com about your options for a cheap BMS so you can watch your cells. One that will balance is allot more $$$.

[guity]

OK, the other bad battery is now out of the bottom, least accesible case.  It came out in pretty much the same way, hacksawing through most of the corner of the case and yanking at the clothes hanger wire strung through holes drilled in the battery. 

Picasso, I don't think I want to weld those boxes back for two reasons: 1) the other batteries are still in the case and 2) I think it would be a bad idea to go back to the old system.  I would be pleased as hell to find some sort of super straps that could tighten around the case to pull it closed as much as possible, but then also be loosened and opened when needed.

I guess I should have ordered a couple of replacement batteries a long time ago.  I just placed an order with EV Components but received a message back that the guy just got out of the hospital and is swamped with orders.  So I have no idea when the replacement batteries might arrive.