I have 13 Sears PM1, 12v 100 ah AGM batteries in series.
Sometimes one or two of my individual modular chargers flake out and shut off. Typically when I restart a charger that has shut down it will then say that the battery is fully charged and thus it enters its 13.5 volt float mode.
Will applying the 13.5 Volts for long enough time, fully charge the battery? If so how long is "long enough"?
Re: Will float voltage ever fully charge a battery?
A float voltage is use to maintain the battery at 100 percent State of
Charge. A 6 volt battery is consider to be 100% SOC at 6.37v or 12 volt at
12.74v. A battery may be self discharging with no load, or in case of a 12
volt accessory battery that has a small continuous load, like a E-meter and
motor controller, the battery charger will supplied the current while
keeping the battery at 100% SOC.
You can charge a battery that is below 100% SOC voltage at 13.5 volts which
is over 13.5-12.74 = 0.76 volts. Now lets say the battery needs only 0.1
more ampere hour to get to 100% SOC and the battery charger float charge is
0.1 amp, then it will take about 0.1/0.1 = 1 hour to charge the battery to
I am using a on board Schumacher 12 volt smart charger which may charge the
12 volt accessory battery which only takes less than one minute and than it
will go to a float charge at a voltage between 13.3 to 13.5 volts.
I do not like to use the IOTA DC-DC converter for this application, because
I would have to change the voltage from 14.5 to 13.5 volts every time I park
This on board 12 volt charger now has been maintaining my accessory Trojan
deep cycle battery since 2002 at 20 to 22 hours a day at a voltage of 13.3
to 13.4 volts with no problems.
----- Original Message -----
From: "David Delman" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, May 05, 2011 6:56 AM
Subject: [EVDL] Will float voltage ever fully charge a battery?
On 5/5/2011 7:56 AM, David Delman wrote:
> Will applying the 13.5 Volts for long enough time, fully charge the
> battery? If so how long is "long enough"?
Yes. A 13.5v float voltage will take a couple days to reach "full".
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