Charging AGM batteries
I have never owned an AGM battery, but the new trailer I am getting will have 2 of them. I replaced the converter/charger in my previous RV with a PD4655V, and am thinking of installing the same i...
Forum Discussion
BFL13 wrote:
I don't know if it "overkill" to use the specified 14.5-14.9 voltage or whether they need that to get the acid up to required strength.
There seems to be one kind of AGM that specs 14.8ish and has limited spec charging amps (about 30%) while others (Lifeline eg) want lower voltage but will take huge amps during bulk. There are more types of AGMs too, like those UPS ones guys are getting, which the say you have to be careful to use their stated specs. (not as bad as GELs though, AFAIK)
I know many chargers and solar controllers that have Wet, AGM, and Gel settings have the AGM voltages set lower than the Wet settings. That seems wrong to me, since my AGMs specs batter match the Wet settings on those.
Adjustable chargers are the way to go these days.
The AGM settings are lower because that is what they need for optimal charge. A bit higher doesn't hurt and will be faster, but AGM's can take a very high current that a flooded cell just cannot due to the lower internal impedance and while they can take a higher charging current there is still a limit beyond which the heating will be destructive.
The acid chemistry is the same in all types, that is not the variable. The intimacy of contact of the plates to the acid is what varies. There are various reasons why they may be speced differently, including intended use (if it's rated less charge cycles they can rate for more abuse) if they require temperature sensing (as was mentioned some do) then they can run higher voltages when the temperature requires that and monitor for excess current etc. etc.
