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what voltage is lower limit for stored battery? - Page 2

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Posted by jack on August 27, 2009, 4:20 pm

how about my original (in subject) question?

is the lower limit 13 v, 12 v or something else?

is the limit different form AGM vs lead-acid type?

Posted by Paul on August 27, 2009, 5:14 pm

jack wrote:

The lower limit is zero.
Not sure what you are looking for though.

Posted by jack on August 27, 2009, 6:22 pm

dont think a lead-acid can be at zero and still successfully brought back to
13.5 v or better

same with AGM type

could be wrong on both counts, thus am asking.

Posted by Scott Dorsey on August 27, 2009, 6:45 pm

If you care about the battery, don't let it ever drop below 13.5V at all.
Every second that it spends at less than full charge is wearing the battery
out faster than the same second spent at full charge.  That is why battery
tenders exist.
"C'est un Nagra.  C'est suisse, et tres, tres precis."

Posted by RamRod Sword of Baal on August 27, 2009, 8:41 pm

I do not profess to be an expert of battery charging but have a set of deep
cycle flooded lead acid batteries (4 x 6 volts) Trojan T 105 which in series
is 24 volts. The batteries are 250 ampere hours.

I do not float charge them but allow the voltage to drop to 25.2 (or 12.6
volts for a 12 volt system) and the charge them.

I charge them up to around 30 volts that allows around 1.5 amps to trickle
in. More often than not I will begin the recharging when they get down to
25.3 volts

In essence I charge them around once every 2 weeks and for around 10 hours
at a fairly low amperage. They start charging around 5 or 6 amps tapering
off to the 1.5 amps.

Last time I ran the charger was a week ago and the now have a voltage of
25.6 volts. There is no power being drawn from them.

A fully charged battery is around 12.7 volts for a 12 volt system and around
25. 4 for a 24 volts system with no charger running and allowing time for
the batteries to stabilize after a charging

My charger is a 24 volt 40 amp simple charger, just a transformer and
rectifiers. Yes I know there are automatic chargers, I had one and it broke
down and the cost is considerable to replace it. This one just lasts and

The batteries are there for emergencies to supply 240 volts via the
inverter. They are hardly ever used and have never been run down to even 1/2
their charge.

They are at least 2 years old. I noticed yesterday some corrosion on the
terminal so looks like I need to clean them. It is also about time I checked
the water levels.

I hope this is of some small help to you.

In general terms is seem that  sulfation takes place once the battery is
less than fully charged, and the lower the charge the more sulfation takes
place and that is what ruins many batteries, hence I attempt to keep my
batteries near fully charged.

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