I've long wondered whether there was a phenomenon whereby the end battery/cell cooks more during charging for some reason. I saw this pretty consistently with the lead-acid batteries on my 1920 Milburn Electric car which has 14 T-105's in series. OTOH, I do know that 2 of the lugs that connect to the 2 half-packs can get hot when going up hills. I had thought this to be a factor in why those batteries lost water more than the others, but I'm becoming inclined to believe there's something about being the first batteries/cells in the string…
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com]
Sent: Tuesday, April 11, 2017 8:47 AM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Re: Battery rotation in 48V string of 6V GC2s
The terminal connections are probably not the issue as I frequently check them with an infrared thermometer and service any terminals that are even the least bit warmer which only happened once or twice.
I have a 24V string of the Sam's 6V GC2s on a micro power system on my work trailer and so far they are working well. I'm planning on using them on the Arc next time when the T-125s die. Hopefully that won't be for a while but considering the abuse I've put them through it will likely be sooner than later.
On Monday, April 10, 2017 10:15 AM, king_of_neworleans <no_reply@yahoogroups.com> wrote:
I use Sams Club Eveready GC-2 6v batteries in series for 48v 220ah. I have not noticed any battery or batteries in the string being more thirsty than the rest. But in your case, since you do notice this, maybe the problem is not cleaning the battery tops and sides enough? You may have a very high resistance ground from the battery terminals, which would manifest itself more strongly toward the positive terminal of the bank. Just guessing. I have gotten somewhat anal over keeping mine clean and the terminals coated with vaseline. Maybe I pay more attention to them than what is strictly needed, I don't know, but I am pretty pleased that they are still going so strongly after 3 years, even though they are so cheap.
Anyway another possible factor is my shore power charger is a 4 bank 12v charger. I charge 2 batteries with each pair of charge leads. I really don't think that assuming good wiring and connections, that it would make a difference vs charging the string at 48v nominal, but electricity seems to me to have an element of chance, fate and sorcery to it so who knows.
Your Trojans are holding up well. Sounds like they have taken a licking in their 4-1/2 years of use. Here's to another 5-1/2 years!
As for rotating them periodically, I certainly don't see what it would hurt. Just a couple hour's work a couple times a year. I can't point to any definite benefit, though, from my own modest knowledge base. Anyway it would make an interesting experiment. Swap the end ones in reverse order and see if the previous positive end batteries are still as thirsty when moved to the negative end of the string. I for one would be interested in your findings. Before you do it, you might try to record empirical data in great detail, even data that you presently don't think is important. You never know what comparisons you might later want to make. When I do stuff like that I never make enough notes, and a year later I don't understand what I recorded, or how.
Posted by: "Myles Twete" <matwete@comcast.net>
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