Battery charging advice

September 1, 2017 | By Staff


I have a series 24 agm (absorbent glass-mat) battery known as a green cap in my Cuda. During the winter I put it on a maintainer and that has worked well. But during the spring, summer and early fall I go to shows weekly. Should I put it back on a maintainer until the next weekend during that time? What’s your take?


The simple answer is no. You do not need a maintenance trickle charger to top up your battery if the car is being driven normally every week or so. Actually the inexpensive float chargers can even overcharge an agm battery, though that is not likely to occur unless you are charging an already fully charged battery.

On the other hand, when you are going to store a car for long periods, the most important consideration with either a flooded (conventional) battery or an agm type is to make sure the voltage doesn’t drop below 12.4 volts. To do that it is preferable to use a fully automatic or multi-step charger that can monitor the battery and charge it as necessary.

Multistage maintainers will charge at varying voltages and amperages as required (rarely exceeding two amps). Some of these multi-step chargers can also be used as regular battery chargers as well, and are capable of putting out seven amps or more. A cheap battery maintainer is OK for long-term storage, but they are less than optimal. That’s because ordinary float chargers provide constant voltage with tapering amperage to the battery even when it is fully charged. For float charging, one amp maximum and 13.2-13.8 volts is what you want.