BFL13 wrote:
I have never quite understood the notion of "how many amps does it take to support the voltage"
YEs you do. Your powermax puts out 65 amps or whatever its rating, until the batteries get near the set absorption voltage. Constant Current, then the charger, as to not exceed this voltage, the amps required to hold that voltage decline. Constant Voltage.
Constant current until a chosen setpoint, then constant voltage for a period of time. Our manual adjustable voltage charging sources give us much better control on how long we keep the constant current stage by the voltage we choose. But the battery is the overlord. If it takes 100 amps to get it to absorption voltage instantly, then amps are going to start tapering practically instantly too. If the battery only needs 27 amps to maintain 14.7v, then so be it. In 20 minutes it might only require 22 amps to hold 14.7v
NOw having too thin and too long of copper is like having a rubber band, The Vbatt is far different than Vsource. The source shooting for 14.8, the batteries at 12.4, and a voltmeter placed in between will read somewhere in between. and it will change as the battery acceptance rate changes. I just push my voltage higher than ultimately desired so amps start tapering later.
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My wanting a potentiometer for adjusting amps is unneeded, but there was one time charging a healthy 12v battery which was brought to 9.2 volts that even when I lowered the voltage as far as it would go, 20 amps were still flowing and the battery was heating rapidly, so it would have been nice to limit amps then, but otherwise it is a feature not really needed in my usage, but it would still be neat to have.
https://www.youtube.com/watch?v=8_T1WhErEew&list=UUoPqTkOluQsuu3RpGnxVwFw&index=26That small Odyssey AGMbattery in the video is requiring more current to maintain float voltage than my significantly larger AGM Northstar does. Mine drops to 0.049 or less of an amp to maintain 13.6v, and when this full, it will also take somewhere under .049amps to maintain 14.7 though it will exceed this briefly in order to get up to that higher voltage.
My battery monitor just reads the voltage +0.0amps when this AGM battery is chock full.
The Screwy31 always required significantly more current to be maintained/floated at any voltage, and the higher the voltage the more amperage required.
Change voltage, watch amp flow change. Great learning tool that allows one to gain perspective on the battery's character and personality, even if one cannot test specific gravity.
I'm not doing a KW out vs an KW in for this AGM as Mex recommends. I consider full whenever it takes less than 0.42 amps to maintain 14.46 to 14.7v, but the amps will taper below this level too if I leave the charging source on at absorption voltage, or float voltage.
Sometimes my battery monitor agrees and reads 0 from full right when it only requires 0.42 amps to maintain 14.46, some other times it will read 0AH from full when it still is taking 1.4 amps, and some other times it will read 3 or 4AH from full when it is accepting 0.3a @14.46.
Not perfect, but close enough that I place trust in it, and if it is more than 10AH out of Whack, I reset it that night when the sun is down.
I judge how happy the battery is by how long it takes amps to taper from ~8 to 0.42 at 14.46 to 14.7 depending on temperature. Sometimes this takes much longer than other times, and this primarily happens with multiple solar only low and slow recharges, and is guaranteed to happen if I only get to 95% day after day.
My observations with this battery is the higher the charge rate, the more it likes it, so in many ways I approach charging it like I am on a generator. A 90AH battery getting 40 Meanwell amps, and I can parallel the schumacher for 65 amps into it.
Achieving a high charge rate allows one to easier to see what the limitations of the battery, acceptance wise, are.
But only if one is interested in the first place.
So many are like RJ, and just don't really care and place full confidence in an automatic product to do it all while chanting their JUST FINE mantra.
Completely different approaches and the two will never see eye to eye.
Us curious types need tools to change the variables and measuring devices to measure them, and some way to judge performance.
My battery monitor as at my right hand as I type this. I press a button often with expectations of voltage and AH from 0 and loading at the present moment, and see how far off I am. IT is Easy to see when something is not right or the battery capacity is dropping quickly.
I really can't imagine not having an Amp +/- readout. I just wish its resolution was more precise than 0.1 of an amp.