Sounds like problem connections, if all the cells are an even 2.12 v. I wouldn't solder 4/0 connections, the solder can run back up the cable stranding, and make the cables too stiff to fully connect with the battery terminal. I had a battery terminal meltdown due to this. We quit using thick bussbars, soldered cables, and stiff (THHN) cables at battery terminals. Also if not soldered properly, you can actually create more resistance in the connection due to oxidation and pockets of flux. Cables from the manufacturers (HUP, Outback, Trace) are not soldered BTW. Its possible that heating the terminals when soldered (with a torch?) may have created a layer of oxidation that is causing the resistance (internally or externally) Sand the contact surfaces, and see if that helps.
Get an infrared thermometer (fairly cheap these days at Sears or automotive store) and check all the connections under load. Also, check the voltage drops on your cables under load, you should be able to find where all that voltage is going, and it should match your infrared readings. I'd also take out another set of cables to see what that does. R. Walters r...@solarray.com Solar Engineer On Apr 20, 2011, at 1:15 PM, Bob-O Schultze wrote: > Rich, > It sounds like you've got a rotter or two. Given the short age of the pack, > that's my suspicion. Try checking the individual battery voltages when under > load and fairly well discharged. I've seen a new battery bank all show good > SG and individual voltages while resting but one or more batteries tank badly > under load. Poor manufacturing QC is the cause. > good luck, Bob-O > > On Apr 20, 2011, at 12:03 PM, Rich Nicol wrote: > > RE Wrenches > My question regards a system (installed by homeowner / friend) where they > recently upgraded their t105 battery bank to Trojan RE series L16 2 volt > cells. The battery bank consists of 6 batteries in series for a 12 volt > system. The interconnects are 12” long 4/0 cables with crimped and soldered > lugs. Main cables are 6’ long 4/0 cables. > The first issue is high terminal temperature during periods of heavy draw > (~100 amps @ 12v when water pump is on). Due to the issue the owner has been > only running the water pump when charging the batteries with his generator > since the transfer switch on the Outback inverter has transferred his > household circuits from the battery bank to the generator. Obviously this is > an inconvenience. Before the end of life on his T105’s he had no issues with > the 6 volt cells in series/parallel using only #2 AWG interconnects. > Most recently he’s experienced an issue where the inverter will not come on > at all and when attempted to come by switching on his main DC breaker the > voltage at the batteries sags from 12.5 to ~5V! This issue is not with the > inverter since I loaned him a back up Trace DR I keep around as a loaner but > it too would not come on and voltage sagged as well. This sag is with no > demand since it sags immediately when the DC breaker is switched on when > connected to the inverter even though the inverter has not been switched on. > I stopped by this AM to check out the situation, specific gravity of all > cells is good, open circuit voltage on each cell is matched at 2.12 volts. > The battery bank is only about 4 months old. > Any insight would be greatly appreciated. > > Battery specs: > 2 volt, Rated Capacity @ 5 Hr rate=909 AH, 20 hr rate = 1110 AH, 100 hr rate > = 1235. > > Thanks for your help! > Rich > > > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org >
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