Hi Steve, Excellent write-up. Thank you.
Do you have a source for the TS cells as you describe? I have a pack of 100Ah cells and I would like to have some spares. I don't currently have any and I have a couple of cells I suspect won't last as long as the others. My cells are also the yellow cells with the blue/red button. The conversion has been on the road for more than 3 years, so mine are likely the same rough age as the ones you describe. Mike > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Steve Clunn > Sent: Thursday, July 18, 2013 6:56 AM > To: [email protected] > Subject: [EVDL] TS li-ion batters capacty test 5th year > > From: corbin dunn <[email protected]> > > Hi steve, > <Can you do a capacity test of the two bad cells you took out?> One is totally > zero. and the other, according to the customer, was dropping out at about > 230ah, I believe this is I heard. The other problem is... this one would turn > OFF the Charger. An interesting thing happened when I was charging the > two replacement batteries. I had them in Parallel, trickle charging them at > 3amps for days. When I put them in the car, and charged the pack, including > the new ones, one of the new ones did not come up to 3.6V which is where > the regulators have the red and green light ON. So I hooked my little power > supply up to the one battery and it took 2 days for him to come up to the > 3.65V that the regulators show those lights ON. This means, that even > though the 2 batteries were charged in Parallel, for days, one was > approximately 50ah behind the other. > > > <How many miles did the guy get before the two cells failed?> almost > 40,000. these are not the first cells to have failed. I believe there were 2 > others the years before. Of course when we say "failed" here, we are talking > about under 260ah. > > <How much time?> > 5 years. > > <What is the BMS settings for min voltage (discharge) and max voltage > (charging)?> > > Min. buzzer is: 2.7v and Max red/green lights lit: 3.6v I believe the charger is > told to shut OFF at 3.7V > > <What model TS cells?> > These are the yellow with the Blue / red button in the center. > Probably what ever was popular 5 years ago. > > Originally, the charger was set for 45 cells. My customer decided to put 3 > extra cells in, to cut back on the aggressive charging. The Charger now will sit > at .2amps and not have the regulators force the charger to stop charging. > The process of leaving the charger ON until all red/green lights on > the mini BMS is lit is done about once a month, I believe. He has a > collection of charger, which when all are plugged in, put out about 70amps. > After doing the capacity test, I charged the pack back with the small 12amp > charger. I will check today to see that all red/green lights come ON. > I would like to do one more capacity test while I am here ( off the clock). To > see if there is any difference. > > The more opportunity I get to play with these batteries, the more that I am > seeing that they are not like Lead Acid Batteries. One problem with them > that I see, is that if you have ONE cell whose resistance is higher than the > others, the BMS will start shunting current on that one cell, giving him less ah. > As this process continues cycle after cycle, that one cell ends up with less ah > than the rest. Which means on the discharge, he is that much closer to the > critical area than the rest. So he starts to heat up more than the others. This > in turn, makes his two friends on either side of him... > a little warmer. It seems that the cells usually go out in pairs or in 3's.. And > my guess is that the Center one is the stinker and the two on either side take > the heat. > > Steve Clunn > > 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) > > corbin > > > -- > Steve Clunn > Merging the best of the past with > the best of the future. > www.Greenshedconversions.com > _______________________________________________ > 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) _______________________________________________ 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)
