Is 12.5 volts sufficient for battery maintenance?

gperky wrote:
I have 9 batteries. 5 are on Battery Tenders that maintain at 13.2 volts. 2 are on larger automatic chargers that maintain at 13.2 volts. The last 2 are on cheap Schumacher and Harbor Freight charger/tenders that maintain at 12.5 volts. Is 12.5 volts good enough to prevent sulfation and early demise of those batteries?

Short answer ? No

12.5V is roughly 80% charged (at rest)

Not good for long term

If you start to rotate the chargers, then the battery at lower voltage will start to see some higher voltage.

Perhaps the cheap chargers will keep the battery at 13.2 but is not able to put in enough amperage to get it above 12.6?

Right now, because the 12.5 volt battery is only about 50% full, and will need something on the order of 50 amp hours to fully charge it, they will not get that no matter how 'good' the maintenance charger is, they normally only put out 0.5 - 1 amp per hour, sometimes less.

I would get a larger amp capacity charger on the discharged batterys very soon!

Fred.

Just keep in mind that 13.6VDC will start boiling out of fluids over time where 13.2VDC will not do this as much if at all...

If the batteries are already charged I would think anything above 12.6-7VDC would do the trick the maintain them...

The batteries will demand how much current they want to see depending on their charge state. The only reason to have alot of DC CURRENT available would be to be able to charge several batteries in the battery bank at the same time and try to maintain around 17-20AMPS of DC CURRENT per battery if you want to charge them then in a quick three hour time frame. Otherwise it will take longer to charge them.

My maintenance trickle charge is somewhere around 12.5-12.7 VDC and I monitor the battery charge status on a scheduled basis...

I guess what the folks on here are saying if you want the batteries to stay at 12.7-8 VDC you should have your trickle charge at that level or a tad higher...

In my case I guess they are saying my fully charged batteries will eventually drop down from their 12.7VDC level to my trickle charge level of 12.5VDC over time ???

Also alot of folks will get their batteries to a full charge state and then just disconnect them and let them set. When they drop down to 12.5VDC or so over time then re-charge them back up again and disconnect again.

I do this method as well just leaving them sit in the battery box and switch them completely out of the circuit. If they are charged-up they won't be affected by freezing temperatures.

Roy Ken

The 12 Volt Side of Life. You may find it helpful.

Have a good Turkey Day. :)

gperky wrote:
Is 12.5 volts good enough to prevent sulfation and early demise of those batteries?

NO. Any additional "discussion" is just a waste of time.

Any maintainer charger that does not hold them at 13+ volts is junk !
I guess everyone was afraid to tell you the truth !!

Not only is 12.5v not sufficient for maintenance, it is not even a fully charged battery.

trashed my Harbor freight ones and went with battery tender

Sam Spade wrote:

gperky wrote:
Is 12.5 volts good enough to prevent sulfation and early demise of those batteries?

NO. Any additional "discussion" is just a waste of time.

??????