Half a battery bank

[Finally Free]

Oh my a poor country boy! I was born in Magnum OK, down Altus way.

Heck everyone drives to the "City" for the cheapest barbed wire, best boots and Sunday hats. Do it then! Surely OK City has a one type of AutoZone maybe even 2.

I am lucky, my inverter/charger(IC) has a "balance mode" or boost charger built in.

My bet is one of A+B was the "snake in the barn" and bit the other.

Buying just one bank is ok if you have a bank to bank isolator or Combo switch.

I use this neat/cheap volt meter at the helm to see my battery state. Cheap and color coded LED display to tell you when to recharge.

http://www.amazon.com/gp/product/B00962CQNC?psc=1&redirect=true&ref_=oh_aui_detailpage_o06_s00

I used to have to go below to see a less informative battery state display.

That would also head off a snake problem.
Jim...

PS: Go Sooners!

I am sorry Jim but I need to strongly disagree on 1 point.

It should be Go Cowboys! (OSU grad here)

 

[dlochner]

Sorry but my drawing on a tablet sucks. But here is basically the way it should be wired.

If the diagram you drew is correct, then Finally Free is correct, your bank is wired incorrectly.

See: http://c34.org/bbs/index.php/topic,7162.0.html for a discussion on how to wire the batteries.

Essentially, the current must pass through all batteries so there is one positive and one negative connection from the bank to the charger and distribution panel.

Look for MaineSail's post on this aforementioned thread.

I don't think that you can use the 1-2-both switch accomplish the same wiring. As I respond to this I now understand how I murdered 2 batteries last year. Oh well, at least they are wired correctly now.

 

[Maine Sail]

Capta,

What are the individual battery voltages on the bad batteries? If they have rested for a few days and the voltages are equal this could have been caused by unbalanced bank wiring.

If the voltages of the dead pair of batteries are not the same then you likely had an unbalanced pair, in regards to SOC, and one died sooner than the other.

When batteries are series wired they really need to be fully charged and resting at the same voltages. Preferably they would be equalized before series wiring and the current allowed to drop to under 2A.

Every single 6V bank I wire in series or series / parallel is first balance charged. I do this by wiring all of them in parallel and then charging the paralleled 6V pack to 7.75V (this would be 15.5V for a 12V pack). This creates an even starting point for the series batteries and puts them in as perfect balance as you can do.. Parallel batteries stay in balance but series batteries can only be balanced by pushing a high enough voltage until all batteries are chock full and can take no more.

If you put two batteries in series and one is at 75% SOC and one is at 100% SOC the 75% SOC battery will be dipping deeper than the 100% SOC battery on every cycle...

 

[capta]

Capta,

What are the individual battery voltages on the bad batteries? If they have rested for a few days and the voltages are equal this could have been caused by unbalanced bank wiring.

If the voltages of the dead pair of batteries are not the same then you likely had an unbalanced pair, in regards to SOC, and one died sooner than the other.

When batteries are series wired they really need to be fully charged and resting at the same voltages. Preferably they would be equalized before series wiring and the current allowed to drop to under 2A.

Every single 6V bank I wire in series or series / parallel is first balance charged. I do this by wiring all of them in parallel and then charging the paralleled 6V pack to 7.75V (this would be 15.5V for a 12V pack). This creates an even starting point for the series batteries and puts them in as perfect balance as you can do.. Parallel batteries stay in balance but series batteries can only be balanced by pushing a high enough voltage until all batteries are chock full and can take no more.

If you put two batteries in series and one is at 75% SOC and one is at 100% SOC the 75% SOC battery will be dipping deeper than the 100% SOC battery on every cycle...

A & B boiled dry in a few hours, so I'm not even thinking of saving them. Haven't even looked at them after they cooled down.
I chose the wrong drawing; the batteries were wired correctly. Sorry all.
I would really like to do as you suggest to the new batteries, but I'll have to find someone ashore to charge them to 7.75 volts, I guess. I don't believe either one of my chargers will do 6 volts. From your description I must charge all the new 6 volt batteries as a 6 volt battery, not as a 12 volt battery, correct? What amp charger would you recommend for this balancing charging, considering The T-145 is 260ah @ 20 hr rate?
Interestingly, the Morningstar solar controller I'm using says it equalizes the batteries every 29 days. Perhaps this doesn't work too well on cloudy days and since the batteries are always being used, even with plenty of sun, it just can't equalize properly. When I get a second 500+ amp bank, I'll be able to run everything on alternate banks when equalizing, which may help.
My guess is that a couple of plates in battery B shorted out (they had always had proper water), but I don't understand why that didn't take down the whole bank down, only half.
Anyway, thanks for the input everybody, and we'll see what happens. Adding a windgen in a few weeks, so those long tropical nights shouldn't be putting such a drain on the batteries from then on.