I am interested in knowing how fast AGM deep cycle batteries charge, especially in the upper SOC range.Things to consider:- Ah Capacity of battery/bank- starting SOC or DOD, or Ah's consumed/replaced- Charge Rate, expressed as C/? (Battery Capacity divided by charging amps... i.e; 400Ah/100a = C/4 rate)- At what point do amps begin to taper?- Charge time- ???Thanks for any input you can offer.

We looked at this some time ago and the results were that with the same charger both acted pretty much the same for charging profile, time to do a 50-90, when they taper, etc.What is not addressed in that is how much more of a charging rate the AGMs could take if they had a different charger on them. With that it gets confusing because it seems different brands or styles of AGM are specified to do more or less than other AGMs

Xantrex, for "Generic AGM" shows more or less the same charge rates as flooded wet cells (I think .1 or .01 volt diference is all).LIFELINE, is the only company I have seen suggesting different (higher) rates.And even Lifeline says the Charge Wizard does a good job. So... (This is part of the reason I am a long way from sold on AGMs... There are other reasons as well)

I run 150 amps into my 3@85AH batteries. My batteries are rated for C5 charge rate - 1250+ amps. The charger starts tapering within minutes, but that is from 150 amps, they are still pulling 80-120 for quite a while. I would *guess* a 50-90 takes an hour to an hour and a half - ~125ah. I am getting solar this spring to attempt the 90-100 without running the genset.

With an algorithm appropriate for AGM rather than flooded an AGM will 50% to 100% charge in about 2/3rds the time that it takes a 5% flooded antimonial battery. Some such as Lifeline, beat that by several percentage points.A KEY the fundamental base for determining charge limit of an AGM is the rapidity of temperature rise as monitored in all cells. This sophistication is not suitable for the inexperienced. I have done a 55 amp hour replacement in my 31 Lifeline in 56 minutes. With thermocouple feedback control the AGM is a whole different animal. And no, rapid recharging is not preferred. There is little to gain and risk involved.But the AGM will continue to be measured against LiPo with a built-in handicap of a non-optimum charging protocol. I keep harping about INSTANTANEOUS achievement of max bulk charging application but I feel I'm wasting my fingers doing so.So one of the contestants continues to be a one-legged man in a butt kicking contest.

Hi Mex,What about depth of discharge? Are generic AGM's limited to 50% if you wish a large number cycle life?

AGM Charge Rates and Times | Good Sam Community

43 Replies

christopherglen
Explorer
Jan 20, 2015
I run 150 amps into my 3@85AH batteries. My batteries are rated for C5 charge rate - 1250+ amps. The charger starts tapering within minutes, but that is from 150 amps, they are still pulling 80-120 for quite a while. I would *guess* a 50-90 takes an hour to an hour and a half - ~125ah. I am getting solar this spring to attempt the 90-100 without running the genset.
wa8yxm
Explorer III
Jan 20, 2015
Xantrex, for "Generic AGM" shows more or less the same charge rates as flooded wet cells (I think .1 or .01 volt diference is all).

LIFELINE, is the only company I have seen suggesting different (higher) rates.

And even Lifeline says the Charge Wizard does a good job. So...

(This is part of the reason I am a long way from sold on AGMs... There are other reasons as well)
BFL13
Explorer II
Jan 20, 2015
We looked at this some time ago and the results were that with the same charger both acted pretty much the same for charging profile, time to do a 50-90, when they taper, etc.

What is not addressed in that is how much more of a charging rate the AGMs could take if they had a different charger on them. With that it gets confusing because it seems different brands or styles of AGM are specified to do more or less than other AGMs

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AGM Charge Rates and Times

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