Re: Charging starter battery

I use a 7 amp 12V battery in my field box. To charge it I have used, for years, an ACE constant voltage charger, which was cheap and seems to last forever. It starts at 500 ma and as internal resistance goes up the amperage goes down, so that you can leave the battery on charge indefinitely (meaning it's not harmful, not that you should necessarily do it). The battery lasts a long time, also. I'm wondering if 4 amp is big enough for the purpose.

The wall wart I am using along with the rectifier puts out 500mA max and the voltage is limited to 14.5v. I have left batteries on this thing for weeks at a time with no apparent bad stuff. Charge current when fully charged is a dozen mA or so.

Paul,

What's the purpose/need for that regarding this subject? --

Jim Lilly - Team Z

Sounds more like a zener diode maybe... voltage limiter

Anyway.. I haven't tried the 4.5 A batt yet. I hope it is sufficient to provide the torque needed to start my engine...

Transformers turn line voltage AC into lower-voltage AC. A bridge rectifier turns the AC into pulsed DC. Capacitors smooth out the pulses to give a fairly smooth DC.

Batteries also act like capacitors. If you are just charging a battery, you don't need any extra caps.

Morris,

Thanks for that info! --

Jim Lilly - Team Z

Have you thought about getting one of these ....

You will shorten the life of the battery at the high voltage of a car charger. The high amps at the end of the charge is the biggest killer, but the high amps overall isn't good either. If you could limit the amps to about 1 amp, and put a zenier diode to reduce the voltage would help.

Or get the right charger. :-)