Saturday, Jan 02, 2010 at 23:05
Richard,
I'd do the following:
check the manual of your new charger for boost voltage and float voltage specs for the three types of batteries.
Your AGM battery most likely will be happy with a boost/float setting of 14.7V/13.6V @ 20 to 25 degrees, so select the closest setting on your charger - go for the lower one if none matches perfectly.
If you charger has temp compensation, use it!
If not, select boost/float voltage 0.25V lower per 10 degrees above 25, and the opposite in winter.
Ensure that the charger never goes into equalisation (in the flooded setting) as this voltage will likely exceed your AGM battery's maximum boost charge voltage (which can cause loss of electrolyte).
Also,
check that the max charge current isn't higher than 25 to 30 percent of the Ah rating (e.g. 25A for a 100Ah battery).
The crucial point to remember when matching a multistage charger to any battery is the charger's ability to automatically switch from boost back to float once the battery charge approaches 100%.
This switch over is usually governed by the charge current dropping off to about 10% of the maximum charger current.
If things go wrong, this switch over never happens, and the battery could be overcharged.
Factors determining this switch over are: battery temperature: if too high (non temp compensated charger on a battery sitting at >30 degrees), the boost charging current won't taper off far enough to trip the switch over.
Similar thing can happen if concurrent load currents fool the charger into thinking the battery still sucks in charging current at higher than the 10% trip point.
Good chargers have an overriding timer for the boost charge cycle built in which forces the boost/float change over as soon as the pre-settable time limit is reached.
thx pop for the pat on the shoulder :)
Best regards, batterymeister
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