[Snip]

The problem is the volts vs amps curve. At lower charge voltage, batteries
can take a whopping amp load... consider it sort of like the jolt they
endure when kicking over a starter for a big engine, only in reverse.
However, as the battery approaches full charge, the voltage rises and the
amperage drops. To continue trying to charge at a fixed amperage will
damage the battery as the voltage climbs towards 15 or even 16V.

A 3-stage "smart" charger will actually taper off the amperage at a fixed
voltage, and then trickle a lower voltage to maintain the full charge. It
takes a fairly sophisticated controller to do this. But it's very well
worth the extra money IMHO because the batteries will have about 25% more
electricity available (when new, if you get a smart charger and hook it up
to an old battery it could be much much more) and they will last longer.

If you are going to plug in a charger and leave the battery for a few
days, absolutely use the lowest setting. At 2A it is getting almost
50amp-hours a day, which means that in two days a big Group 31 will be
fully charged, in three or four days it will be trying to soak up a
damaging overcharge. A smaller battery will fare worse.

Fresh Breezes- Doug King


I have a question I've pondered for a while ..........

On a trickle charger, if you were to connect an IC
that limits the voltage to 12 Volts only ( LM12 ) could you
leave the charger on indefinately without damage to the battery?