Hello Chuck, Before I accept a battery pack from a dealer, I tell them I want a balance set. The battery factory use to sell a balance battery pack where the voltage of each battery or cell is in with 0.001 volt of each other. The capacity is in with 4 percent of each battery.
Make sure the manufacturer dates are all the same and not more then 30 days old from the time you received them. I inspected and test the batteries at the dealer for voltage and capacity my self. In the colder northern areas, the dealer normally received the GC batteries in the spring for the golf carts. This is the best time to purchase these type of batteries, because they ship truck loads at this time. I had to go through three pallets of 120 batteries, before I can get a match set. Batteries made back in the 70's ran hotter electrolyte, meaning the SG was mix hot at 1.340 sg and when cool, it would come down to 1.300 sg. The batteries today are now mix hot at 1.300 and cools down to 1.275 sg for large industrial batteries. The GC batteries are at 1.265 sg which we consider was 80% SOC back then. If the electrolyte looks lower than it should be, do not add distill water at this time. It is normal for the electrolyte level to change in level while it cools down. A 1.275 SG electrolyte at the initial filling will increase in temperature, thus raising the level. When cool, the level will drop. Adding water will weaken the electrolyte specific gravity. All my U.S. Batteries came about 1/4 inch below the fill neck adjusted for temperature. I just adjusted the fill spout to this level. If one or more batteries have a lower level then the others, wait until you charge it before you adjust this level because the electrolyte level will raise when charging to 100% SOC or about 2.77 SG. I charge each battery with a one of the smart chargers, that displays voltage and state of charge. The first charge normally took abut 15 minutes to get to 100% SOC. Check the electrolyte level and the specific gravity at this time. If the some cells are too low, DO NOT ADD WATER. Take several readings of the low vs high electrolyte cells. Go back to the battery dealer and pick up pre mix electrolyte for that type of battery and adjust the level. The battery manufacture did not completely fill that cell and you do not want to dilute it with water. Charge the batteries again about every two weeks when not in use. This will only take about 2 to 3 minutes at a normal charge. Even after install the battery pack in my EV, I had one battery drop in capacity twice as fast of the others. Return that battery to the dealer for another one with the same manufacturer date. This battery may check out ok at other battery dealers as a singular unit, but at my battery dealer who deals in GC batteries, know that you should have a balance set. Roland ----- Original Message ----- From: "Chuck Hursch" <[email protected]> To: "Electric Vehicle Discussion List" <[email protected]> Sent: Wednesday, January 30, 2013 3:08 PM Subject: [EVDL] cell shorts and more plus idle new packs (WAS Re: ElconPFC-2500) > On 1/28/2013 4:44 PM, Lee Hart wrote: > > On 1/28/2013 4:54 PM, Chuck Hursch wrote: > >> I think the Elcon gets set up with IUI for floodies, with perhaps even > >> a > >> fourth-stage trickle charge. > > > > The final xxI in an IUI charge cycle is generally for equalization. > > After the battery is nominally "full", it keeps charging at some low > > current until some cutoff condition is satisfied. It might be for a > > fixed time (1-2 hours), or until a particular voltage is reached, or > > some other condition. But this final xxI stage should in no case last > > more than a couple hours. > > > > A lead-acid battery should never be trickle charged. It is bound to > > overcharge it. "Trickle charge" means continuing to charge at some low > > current forever, regardless of what the battery voltage is. > > I would have to wonder how one then would handle an old pack that's got > some shorts in some of the cells, along with the fact that some cells > just don't charge as fast as others. As I mentioned about a year ago, > last March I think it was, I watched the sg in a cell in a battery that > I pulled out of the pack go from 1260-ish to 1190-1200 just sitting > there on the deck for about a week. What I've gotten into doing over > the last year or so is just float charging the entire pack w/ > variac/rectifier to the tune of an amp or two. I figure I can offset > the shorts as well as slowly equalize the pack. I'd likely be out of > the game with this pack by now if I hadn't done this. > > The other thing I'd like to hear from the battery experts is how would > they handle a new pack. My new pack, once I get it before too many more > months, is probably going to sit a lot. During the dry season in the > summer, I will be biking to work four days of the week, and drive one > day of the week, folding all my errands and grocery shopping into that > one day if I can manage it that way. I've already been working into > this mode for the last two years since the CalPark Hill tunnel has > opened making it much easier to bike to work. My car hasn't moved for > this last week, since we've had a dry spell during the rainy season in > the winter. But we get some rainy stretches, the car will be going the > majority of the time, and the bike cools its heels (this is fair-weather > biking). I'm inclined to not have the car on charge while it is > sitting. A new pack has minimal self-discharge and shorts. > Equalization once every month or two should keep the flock together. > The thing that bugs me is that a pack that sits for awhile is almost > like a green new pack, you have to kinda break it back in and keep the > amps down to avoid blowing the active material off the grid (something > I've seen Roland and Cor mention). Is that because the paste tends to > lose its structure from gravity, and then there is some sulfation? From > what I've felt of the black stuff that gets on the bottom of the caps, > it's very thick and gooey - almost like cold molasses. > > So that's kinda why I'm shooting for the fall to get a new pack. It > will be easier to swap in the new pack while it's dry outside and I > don't have to be carrying batteries up and down wet steps (after I've > processed them on the deck - grind the lifting tabs off of eight batts > to fit under those front racks, for one thing). And then shortly it > will be rainy season and I'll be using the car more. Let the old pack > sit during this summer. > > > [snip] > _______________________________________________ > 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)
