Lead acid storage

mountainman

For 6 months I've kept my 2 golf cart 208 ah batteries on a 100 watt panel. Cc settings all on 13.6 Just sitting in the shed doing nothing. Now it's time to put them back in use. I checked the Sg today  after being unhooked 24 hrs.  b1  1.275  6.34 volts b2 1.265 6.28 volts. Is there a better way to store them for 6 months a year.

BB.

Sounds like you did good...

Did you have to add water? Were the plates exposed?

In theory, you want to exercise the batteries to less than ~75% State of charge a few times to get the plates in good condition after your 6 months of floating.

-Bill

PS: And keep the batteries cool/cold during storage (for longer life).

Tecnodave

When you store this kind of battery it is better to top off the charge every several weeks so the batteries don't discharge so far. There is no need to keep the solar charger on all the time. It's a bit harder on the batteries to charge every day when not needed. If this is a part time residence that is unoccupied for 1/2 the year then what you have done is approiate. If your charge controller is settable then I would lower the float voltage a bit and leave it connected. It appears from the voltage and s.g. readings that your batteries are in good shape. Now the only thing to do is put them to some good use.

Estragon

One thing you might want to consider if your controller has a settable auto-EQ function is to set EQ voltage to around absorb voltage (eg 14.5) and to "EQ" at that voltage for an hour say every 30 days.

Sounds like what you did worked okay though. 

mountainman

Yes this is a 6 month storage and 6 month use battery. Stored in cool cold shed in winter. Nov- april .  Water level was about half way between plates and bottom of wells. Cc is settable and us b recommends 2.17 floating. 2.26 is some how is where it was. I have read that lead acid needs to boil occasionally  (stratification) My thoughts on eq was since they were only self discharging and cc draw. That it wouldn't be worth the risk of maybe running the batteries dry unattended. Winters and fall in Virginia mountains has frequent cloudy days or even  weeks with no sun. Temps 0 f at night. And deep snows. I hung the panel vertical on a south wall.   

Estragon

I definitely wouldn't do a "real" higher voltage EQ unattended.  I was thinking more like a fake EQ at absorb voltage.  Enough to get a bit of mixing, but not the "boiling" you get at EQ voltage.  

mountainman

@Estragon so just a fizzing booster to keep the acid stirred.

BB.

Fizzing is water loss... you already lost something like 1/2 you water over 6 months. 

If you are not there to check monthly or every two months, I would avoid EQ for now...

Bill

jonr

Remember, if you don't discharge, stratification doesn't occur.  No stirring needed.   OK, just sitting there causes a very tiny discharge, but it's minimal.