8, 6 VOLT SURRETES

ingoldsby · January 2018

Hi everybody I have a question if anyone could give me advice I have had a problem with #2 batteries on end of string I have . #8 ,6volt BATTERIES hooked in series, one end of the series call it last 2 batts never charge up like rest of string I have charged those 2 separately then put them back into service sg,1265 have also did eq still doing same thing those 2 batts at end of string are always lower after 5 hours of absorb at 60.4 temp 64 farenheit 5 hour float 54.4 I then went and got 2 new SURRETES put them in service with other 6 batts never guess.... same thing ,,, oh forgot I even went as far as changing pos and neg on string still those #2 new batts are low in sg please if anybody has a clue , love to hear from you cheers ,,,,,

BB. · January 2018

Try swapping the two weak batteries with batteries at the other end of the string.

For otherwise good battery installations, a few people here have rotated their batteries every few years because the batteries at one end of the string had low charging SG readings over time.

I don't understand why, but it works for them.

Bill

ingoldsby · January 2018

Hi Bill my name name is Dennis and I am glad you have answered my pleas again you are a man of knowledge I do appreciate it as a you were saying to change end batts I did I put 2 new batts and still they dropped in sg and voltage
I even changed both end cables other ones were fine but thought for 40 bucks for new cables would maybe fix problem was wrong but have two new cables at least lol any other thing you could think of Bill *

BB. · January 2018

Denmis,

Did you put the new batteries, for example, failed batteries1+2 to location 7+8, and move the existing good batteries to location 1+2 where the failing batteries were? (Swap locations)?

The only reason i think this could help is if batteries 1+2 average 10-20F hotter than the test of bank (poor ventilation, bad terminal connection getting hot, breast sunny window, etc.).

Otherwise, are you equalizing the battery bank? This overcharged some cells to bring up weak/low sg cells.

Some surrett batteries are known for needing quite a bit of equalization. Charging at 60-62 volts (especially in cooler climates). You are looking for roughly 5% rate of charging current (ex: 400 ah bank, 20 amps equalization). Can take many hours or several 1/2 day sessions (don't overheat the bank).

Watch cells, and if the sg stops rising after 1 hour on all cells, log the temperature corrected sg for each cell. That is now 100% charged.

Bill

mcgivor · January 2018

It does seem strange that the two batteries in a specific location would always be at a lower state of charge in a series string, do you perhaps have a 12V load tapped off those batteries as this would definitely cause such a phenomenon, long shot but a common mistake made.

ingoldsby · January 2018

Hi Bill again thanks for replying I replaced the 2 batts with new which were 1265 sg , thinking they would stay up in sg they dont ,,,, I will charge them separate tomorrow and then do absorb then start eq batts never get below 59 farenheit right now at 62 f can improper torque values cause this type of problem?

ingoldsby · January 2018

Hi McGivor thanks also for your reply there is no load connected to those batts I have a b.m.k kit and arc remote wire to the bank i am stumped I also replaced those 2 cables connecting the 2 new batts and still low sg on both batts . fyi ,,,they are always at the same sg and voltage ie. Lower than the other full six batts

BB. · January 2018

Improper torque could, in theory, cause a battery to run hotter--If you run high current (loading or charging) for a while, then use an IR Thermometer or even your hand, and see if any of the terminals/wiring is hot (or warmer than others).

But if the terminals are clean and reasonably tight, it should not be a major contributor to this issue.

Note, we are talking about a "hot battery" (10-20F or higher than the rest of the bank) having higher self discharge than the rest of the bank.

Is this your issue--I have no idea--It just has been seen by several long time members that "rotating" the batteries (say once a year) in a single series string helped keep the batteries happy overall.

If you had "dirty battery tops (and/or corrosion on the battery) can also cause leakage current. And as McGiver asked--If you have "tapped" 12 volts for some local DC loads from a 24 or 48 volt battery bank will also cause charging imbalance too.

-Bill

ingoldsby · January 2018

Hi Bill I charge those 2 batts separately from series got them up in sg then introduced them back to series then charged absorb til all sg were up then followed with eq all seems well I 'll no more as day go by I guess any way ,checked for hot cables none hot temp of batts roughly same ,top of batts clean I am going to by a torque wrench to to batts I will keep you posted ,, again thank you guys for your input Bill have a good night cheers,,,,,

8, 6 VOLT SURRETES

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