#Random battery question: does anyone know how to calculate how long to charge a battery?
Have a 190Ah battery bank (AGM, 12v) being pushed by a 13V 6A charger (plus some solar panels) at 50% charge per voltage. I should remember this math LOL.
95Ah/6A, or is it 2x because Lead Acid?
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AI6YR Ben
In response to this post16 hours? 32 hours?
@ai6yr i wager the best way would be to measure its voltage, and the rate at which its voltage is going up, and then to calculate how much time, at that rate, it will take to get to its target voltage
by Viss ;
@ai6yr This calls for Middle Aged Man!
Tonight's episode: How long to charge a battery
https://www.youtube.com/watch?v=pzo73jYl3Ew
by FreddyB Aviation Photography ;
@ai6yr 1 meeeeelion hours?
by cetan ;
Charging voltage chart from random website... note that a heck of a lot of AI crap there TOO. Egads. I believe my charger is underpowered, and the 300W of panels in winter isn't getting nearly enough amps in there. (hoping: charger + panel = enough amps to catch up).
by AI6YR Ben ;
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GreenDotGuy
In response to this post@ai6yr you can measure your own results periodically and base things off that, but I don't think there's going to be one good safe solid answer besides "Don't push more voltage than the batteries can take, and use a charge controller that safely stops when they hit their capacity". The batteries are going to offer varying levels of resistance between production runs, brands, lifetime, and temperature conditions.
(I should note that I'm new to this, but those are my findings from measuring times and watt-hours needed to charge my 18650s up)
@DarcMoughty Thanks. This is normally maintained very well by a very good solar charge controller, it's just been poor solar conditions (winter + smoke)...
by AI6YR Ben ;
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Anne Ominous
In response to this post@ai6yr 20.6 hours according to this handy calculator that i have no idea if it's reliable
https://footprinthero.com/battery-charge-time-calculator
@rustoleumlove Thanks! Seems reasonable! Looks like I need to keep this plugged in until tonight (don't want to leave it), unless the solar panels are contributing more charging capacity than I thought.
by AI6YR Ben ;
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jeffluszcz
In response to this post@ai6yr With my SLA and AGMs I figured out the final resting voltage that showed state of charge to confirm my battery charger was doing the right thing.
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Michael Busch
In response to this post@ai6yr Don't lead acid batteries have widely varying efficiency?
Making charge times hard to predict.
@michael_w_busch @ai6yr yeah and it changes based on how fast you charge it thanks to Puekert's Equation, aka, MATHEMATICAL PROOF THAT THESE BATTERIES SUUUUUUCK. Oh um hi
by vxo ;
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Artemesia
In response to this post@ai6yr
I don't have a straight-up answer, especially since it's lead acid and most of my experience is with lithium ion or nickel metal hydride. I'll say that 6 amps is more amperage than I would go with for a simple lithium battery. Rough rule of thumb, assuming appropriate voltage and amperage for that battery, check the power consumption of your charger and figure around 80% of that ends up as battery charge. So, a 600 Watt-hour battery being charged by a 120 watt consuming charger would need about 6.25 hours of charging. But...some chargers will taper the charge when the battery gets near full, dropping the amperage to a trickle for the last hour. So that takes longer.
I suggest looking at batteryuniversity.com , which will have more than you want to know about it.
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