I guess I should field this. On Wed, Jul 17, 2013 at 09:11:07AM -0700, corbin dunn wrote: > Hi steve, > Can you do a capacity test of the two bad cells you took out?
One cell was shorted, probably from having been used after it's voltage went too low. The other cell had been giving me trouble and was difficult to identify with the current version of miniBMS. I took it on a trip prepared to jumper the cell out of the pack once the bad one was identified. I drove until I got alarm even with no current draw. That was about 50 miles or 100 ah. Once identified, I jumped over cell, removed the bms module from the chain and drove happily home. And waited for Steve to arrive to install replacement cells. > > How many miles did the guy get before the two cells failed? How much time? I've replaced a number of cells, maybe 10. Most probably died from mistreatment, primarily due to malfunctioning cell modules. > What is the BMS settings for min voltage (discharge) and max voltage > (charging)? I started with EVPower modules which went up to 4.0 or 4.1 volts per TS recommendation. They supplied me modules that had two different "leaking" currents. That caused a world of trouble. I eventually went to all miniBMS modules with the lower voltage. Cutoff voltage is around 3.6 as I recall. I consider 3.4 volts "charged" or "charged enough". > > What model TS cells? TS-LFP260. I've bought a total of about 110 260s in about four different buys. The pack Steve was citing may have cells from only two of those buys. Or maybe three. The oldest cells are about five years old. Irritatingly, the newer cells have smaller terminal bolts; external dimensions are the same. As Steve says, about 40k miles on most of the pack. It started with 45 cells and now has 48. I would guess 35-40 of the cells are original. Using a TBS meter when the pack was young, I determined the pack capacity about 300 ah. 6-12 months later, it was about 280 ah. Now, Steve says 260. That would be on the worst cell in the pack in each case. > > I replaced a 200ah Thundersky cell after ~20,000 miles / 2(ish) years. Its > capacity loss was about 30% (off the top of my head -- I can find the actual > number if someone wants to know) -- Willie, ONWARD! Through the fog! Ehttp://counter.li.org Linux registered user #228836 since 1995 Debian3.1/GNU/Linux system uptime 3 days 2 hours 05 minutes _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
