Over charging AGM battery?

[Rbertalotto]

I built a portable generator using a 100Ah AGM battery. I recently bought a portable refrigerator and wanted to do some testring for an article on my web site. I took the battery down to 75% during one of these tests. Usually I'd use my portable solar panel to recharge the battery, but there has been no sun for days up here in New England

A few years ago, a whole bunch of us RVers were buying and using a Black And Decker "Smart" charger that was the "Cats A**" back then. It offers multiple stages of charge and you can set the bulk amp stage.

To bring the battery back up to 100% for the next phase of testing, I used this battery charger set at 40A. The battery was back up to 95% within 20 minutes! I then set it to 20A and brought it up to 100%....From there it went to trickle charge at 1A

My question is.......Is it bad to dump 40A into a battery at this state of discharge?

My understanding is you should only charge an AGM battery at 20% of capacity (in this case, 20 amps?)

Any comments would be appreciated.....

 

[Ped]

After the battery reaches saturation voltage 14.4, 14.6, etc youre supposed to switch to constant voltage variable current mode. Supposed to hold voltage and taper amps to under 1 then go into float. Forcing 20A at 95%+ can dry an AGM and ruin it.

You shouldve noticed it getting warm, no?

 

[Rbertalotto]

Thank You.......Let's hope it didn't do to much damage.