Proper Battery Charging Voltage

[12VoltMan]

On the "Fishing Show" thread I mentioned that one of my favorite shows is "Ship Shape TV". Well, if you'd been waching this morning's program you would have learned about the most common mistake we all are probable guitly of and that's not using the proper "voltage" when chargeing our deep cycle batteries. If you think the proper voltage to charge a 12-volt battery is 12 volts, you're wrong; the actual voltage should be 13.5 - 15 volts. After learning this on "Ship Shape TV" this morning, I researched my own Optima batteries and found they too recommend charge a 12 volt battery at 13.5 - 15 volts. If you're using a 12 volt output charger, you're not completly charging your batteries.

[Duayne]

A healthy battery will measure over 12 volts at rest (with no load), usually in the 12.6-13 volt range. Any 12 volt charger should be cabable of charging to a slightly greater level than 12 volts. Most trickle chargers operate by "pumping" current versus a higher voltage charge. In those cases, you probably won't even measure a voltage level on the charger with it off the battery. The charger is able to sense the battery level and trickle current to it until it reaches the chargers set potential. You can get an idea of the chargers potential by measuring during a charge, but a drained battery won't always show the capability of the charger until the charge is complete.

The only way to check the potential of a trickle charger is to measure a known good battery after a full charge. if you measure 12.6 or slightly better, your charger is doing its job.

[coombro]

I believe the rule of thumb when measuring voltage is 10% high or low. 10.8 or 13.2 is adaquet voltage to operate properly. Don't hold me to this on dc voltage as I'm not sure although it pertains to ac currrent for sure.

[brucehampton]

During this same SSTV episode they referred to a battery conditioning product called
INOX mx2.......this conditioner pledges to extend the life of marine batteries 2-3 times longer. Has anyone tried this product ...and if so did you notice positive results?

[Duayne]

I believe the rule of thumb when measuring voltage is 10% high or low. 10.8 or 13.2 is adaquet voltage to operate properly. Don't hold me to this on dc voltage as I'm not sure although it pertains to ac currrent for sure.

Many 12v DC devices can operate at a higher or lower voltage than 12, although it isn't advisable. A charged 12 volt battery at rest should rate higher than 12 volts. If it doesn't, it either needs service or needs replacing. Under a load a battery can drop it's measured voltage. Too much of a drop and the battery is not cabable of supplying the requested current. (That's usually close to the cranking amperage values you see listed on batteries).

When dealing with AC (or anything that deals with an equal positive and negative value with a base of zero), there is an RMS factor. That's a measure of the usable voltage. In the US, the standard home AC is 120 volts. The peak for that measures around 170 volts, and that might be what you are thinking of..

[Embrey]

never seen a battery charger that just puts out 12V....if it does its broken

[DJD]

never seen a battery charger that just puts out 12V....if it does its broken

I agree and was gonna post that until I got to your post. Same thing for some of the chargers we use in our systems integration. They read 13 -13.5 vdc.

[12VoltMan]

never seen a battery charger that just puts out 12V....if it does its broken

So are you saying that the charger should be putting out more or less than 12 volts?

[Embrey]

So are you saying that the charger should be putting out more or less than 12 volts?

mmm, more. how could it possibly charge up if it never reached 12 or more?should be showing around 13-13.7 approx. just like an alternator