Thread: AGM Battery: Charging Question

The graph seems to show a charge rate over hours. With the charge rate set at a low amperage..

If connected to to a larger charge like 50amp the graph would show say

50amp for an hour and then a drop off as charge reached 100%. or 14.4volts.

An AGM will reach close to 100% charge in 2hrs if you can keep the amps up to it,,,

Hope this helps.

P.s Throw out the graph..

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That graph is for a smallet capacity battery in a "standby use" scenario for example a 7Ah in a home alarm system. if you look at the charge voltage you will see it is steady at 13.8v (or whatever), but is lower at the start due to current limiting at 0.1(ish)amps (100ma). All these figures are quite low which to me suggests a small capacity battery with a very small charger circut with 100ma max current and voltage limited to 13.8 (or 13.7) volts.

Would everyone agree?

Fraser

Hi isuzu110, for a starter, I’m with fraser130 in that the figures do seem to relate a small battery.

Next, unless there has been a major redesign of Fullriver batteries, the maximum charge current that be applied to any Fullriver AGM battery is 20% of the battery’s maximum A/H.

In your case, with a 100 A/H battery, the maximum charge current is 20 amps and NOT 50 amps.

The problem with most AGM batteries is that they will take high charge currents but they can not tolerate them and doing so on a regular will shorten the battery’s operating life.

isuzu110 check out the Fullriver web site, there is some excellent info there and it will help to explain the correct charging rates.

Cheers

http://www.fullriver.com/

Thanks for the feedback

According to the Ritar site, my battery is a 100AH AGM (agrees with the label on the battery). Unfortunately the Ritar site appears to be down right now.

However, if I go to the Fullriver site, they have similar charge curves



Note this time the CA peaks at 0.4. Still a mighty low number.

Even if this is for a single cell, aren't there 6 cells in a 12V battery so multiplying 0.4 by 6 is still a small charging current.

I must be missing something obvious. Please tell me what it is so i can go *doh of course*

Originally Posted by isuzu110

Thanks for the feedback

According to the Ritar site, my battery is a 100AH AGM (agrees with the label on the battery). Unfortunately the Ritar site appears to be down right now.

However, if I go to the Fullriver site, they have similar charge curves



Note this time the CA peaks at 0.4. Still a mighty low number.

Even if this is for a single cell, aren't there 6 cells in a 12V battery so multiplying 0.4 by 6 is still a small charging current.

I must be missing something obvious. Please tell me what it is so i can go *doh of course*

The chart you have there is for a 2.3 A/H 12v battery.

What info are you actually after?

Cheers.

Yes, the Fullriver site you posted seems to only publish these curves for individual cells, not the 12V battery as a whole. Unless you can find better info on their site for 100AH AGM batteries ?

So back to my question again, if a 12V battery has 6 x 2.x volt cells, why does the charging current not exceed 400mA ?

Even if I use your 20% rule, I'd expect 20A charge rate for a 100AH battery.

Is the CA abbreviation on the scale something other than Amps ?

If nobody knows the answer, that's OK. Just thought someone here might know.

Not sure how it would equate but the standard unit symbol C relates to Coulombs and A is amps...

from memory A = C/sec ie unit charge passing a point per second is the measure of current.... but a CA equates to some weird and wonderful squared unit of charge per second???? doesnt really compute...

Could it be a typo and they mean k as in kA
not a common measure but would bring your 400mA up to 4A per cell which would be 24A
max charge current?????

Steve