Optimal AGM Battery Charging

I think that the charging voltage needs to be quite high (14.7V) during the ‘absorption/equalisation’ stage, which is similar but slightly higher than that for Wet batteries and much higher than for Gel. For the prolonged ‘float’ stage the voltage should
be 13.5V, which is somewhere between the profile for Wet and Gel.

I’d find out what the manufacturer of your AGM battery recommends for charging and then compare that with the two options from your charger. I don’t think all AGM batteries are the same. If in doubt, I’d plump for the ‘Wet’ setting on your charger and, rather
than leaving on float for extended periods, restart the charging cycle once in a while.

This goes to show how easily confused we can get. I have just looked at the manual for CBE 516 and the information is perplexing. As Dave says, the maintenance (float) voltage is 13.8V or 13.5V for Gel or Wet, but suggests it’s 14.3V or only 14.1V for charging Gel or Wet. I rather think that the 14.1V should read 14.7V to fit with what I was expecting. It’ll be worthwhile checking.

I have also found <this link> which refers to the different phases for charging a 12V battery (according to which I appear to have used the term “equalisation” incorrectly). If the information here is correct (not everything on the interweb is reliable) the graph shows the ideal charging voltage for AGM being higher than Lead-Acid but Lead-Acid then falls below the ideal for AGM when in the float stage. The important conclusion from the graph displayed is that the conventional Lead-Acid (Flooded) profile suits AGM better than the Gel one.