battery choice
Hi, I am in analysis paralysis. I will be purchasing AGM jars. Here are my two choices: AGM L-16 Surrette 400 amp-hour six volt with 0.145 plates cost $520 plus tax and shipping Four are n...
Forum Discussion
full_mosey wrote:pianotuna wrote:
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I know a flooded battery starts to taper at 85% state of charge--12.5 amps per 100 amp-hours. Does anyone know at what voltage AGM's start to taper?
That is an interesting question.
Lifeline specs a 500% inrush limit which seems to say that a 500A charger could be used on a 100AH AGM. At what SOC% would the bulk charge end?
How long does an 80% discharged FLA stay in bulk when charged at the usual 25-33% charge rate. Is that charge rate where the 85% SOC after bulk comes from?
I would like to see a side-by-side charging test where the AGM gets a higher charge rate than the FLA allows.
HTH;
John
At a 500% charge rate, there would likely be no bulk stage... instant Vabs.
RE; an 80% dod FLA: at a 30% C-rate, at ~ 14.5Vabs, 85% efficiency, it would take 1 hr - 45 min to get a 400Ah bank to 70%soc, at which point amps would taper. The % soc at which amps taper is largely voltage related. Raise Vabs and amps taper at a higher % soc, and vice versa. Charging efficiency also plays a big role.
... A 20% C-rate would have amps taper at 80%, and a 15% C-rate would have amps taper at 85%... do you see the pattern? At the proper Vabs, amps will taper when C-Rate % = DOD %, and charging amps = Ah's depleted.
In PT's example above (12.5a/100Ah, at 85% tapering) would require a 15% C-rate (15a) @ less than the ~ 14.5Vabs. At ~ 14.5Vabs, acceptance would be 15a/100Ah, under similar conditions as stated.
... At least that's what I'm seeing, using a 10.5% C-rate. I will confirm if things hold true, regardless of C-rate, soon.
