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Old 12-15-2018, 03:51 AM
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ilandtan ilandtan is offline
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Join Date: Oct 2014
Posts: 311
Originally Posted by luc2010 View Post

i am trying to charge my 12v 70AH dead battery! using capacitor charger
with 1.28A

the battery voltage gos up to 15.4 v on the meter and i stop it
we can see the voltage run down to 13.6 v or something?? i dont know why

where we should stop the charging process?

best regards
That seems like a curveball right away. What do you mean dead; Does that mean acceptably discharged, or discharged beyond recommended recovery levels? I'm not an expert on battery charging, but I can give my useless advice.

A battery is a chemical device, so when you say it's dead, your telling me something is failing in the battery's ability to retain charge. Depending on the makeup of the plates, it's sulfation, the specific gravity of the electrolytes all contribute to the battery capacity, which is usually reflected by the voltage if all the baseline levels of the reaction are possible. However, you can't use voltage alone as the indicator of how many amps it can produce over a specified time.

If you take a brand new AGM battery, I think it will be above 14V, but a used one will charge to somewhere around 13.5V. There are sites that have all this information, but the fact is that it's better to have a "smart" charger, because it varies the charge rate by where the battery in its charge leve.. i.e., bulk, absorption, and float. If you are leaving it on 1.28A charge rate, that is a low rate, but you can't leave it indefinitely because it will cook the battery.

I have heard that radiant charges destroy batteries and make them more like capacitors, which we know doesn't work the same way as a battery. If you are using capacitors to charge a battery you can deliver high bursts of currents, but if you deliver too much it can damage the components. Heat is bad for AGMs, I've read. I recently bought a 5aHr battery and solar charged it with a 15W panel, in a month the battery slowly lost capacity because I had it out in the sun charging. I measured the voltage and everything worked as described, but the battery sides started to warp, and my charge controller started pulsing the load after an hour.

If the battery is "bad" it could mean different things so. I have probably given as much useless information as anyone can tolerate. You might ask Turion, he breaths batteries because his 3B device revolves upon the charging of batteries.

Last edited by ilandtan; 12-15-2018 at 04:17 AM.
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