This is probably a dumb question, but I spent 10 grand on this large lead acid forklift 1000 amp hour battery, that has no charge rate specifications. The manufacturer the battery simply says get the charge rate off the vehicle it is installed in, obviously it's not installed in a vehicle, anyway 20% I assume is 200 amps, does that seem correct to you? I read that 20% is a good charge rate but I am not sure how amp hours and amps going into the battery relate to each other. It sure seems like a lot of power going into that battery. This forum has helped me a lot, thank you very much for the help.
Charge rate1,000 amp hour battery
- Thread starter tylarson
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MisterSandals
Participation Medalist
20% seems reasonable (200A)
200A x 5h charging = 1000Ah
If the battery is half full (needs 500Ah), it would take 2.5h at a 200A charge rate.
If the battery is half full and you charge at 100A, it will take 5 hours.
To a point, a slower charge will generally put higher quality charge on the battery.
But you will soon come to know this, 200A is a LOT of amps and will require some very thick cables and at least a 250A breaker or fuse.
mikefitz
Solar Wizard
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A lead acid battery will not charge that quickly.
Assuming we need to charge a 1000 Ah battery from 50% SOC to full , getting from 500Ah to 800 Ah , 80%SOC, will will take 3 hours to reach absorbtion volts. The absorbtion stage will take sometime. Using the formula given by Rolls batteries, T = 0.4 x C/I,
Charging at 100 amps, absorbe time = 0.4 x 1000/ 100 = 4 hours.
Total charge time = bulk 3 hours plus absorbtion 4 hours, total 7 hours.
Charging at 200 amps, bulk = 1.5 hours, absorbtion = 2 hours, total 3.5hours
This is approximate, the bulk period is a best guess , the often used 80% SOC , as the start of the absorbtion period, is a variable depending on battery health and charge current.
My guess is that, regardless of charge current, it will take 6 hours minimum to charge from 50% to full.
Without guidance from the manufacturer, using typical charge guidelines, charging at initially 0.15C with a total charge time of 8 hours, would seem a safe strategy.
Carring out SG readings and having an equilisation charge at regular intervals will help battery life.
Warpspeed
Solar Wizard
Fork lifts and their batteries are basically designed for an eight hour working shift, and to be then plugged into a charger and recharge overnight for the remaining sixteen hours.
Agree with the above ^^^ probably bulk charge for about 8 hours at roughly 0.15C sounds about right (150 amps max rated charger).
Also agree with Mr Sandals, to a point, a slower charge will generally put higher quality charge on the battery.
A really big charger will certainly bring the voltage up much faster initially, but that will not give you a full recharge. You still need to let the current taper right down to zero over many more hours to reach anything like full charge.
A slightly less powerful charger takes longer, but not as much longer as you might expect.
Agree with the above ^^^ probably bulk charge for about 8 hours at roughly 0.15C sounds about right (150 amps max rated charger).
Also agree with Mr Sandals, to a point, a slower charge will generally put higher quality charge on the battery.
A really big charger will certainly bring the voltage up much faster initially, but that will not give you a full recharge. You still need to let the current taper right down to zero over many more hours to reach anything like full charge.
A slightly less powerful charger takes longer, but not as much longer as you might expect.
So do amps really matter when charging a lead acid battery besides the speed at which it charges? As long as you get a good rolling bubble going in the battery, are amps that important? My research says no. You have to give it enough amps to stir the electrolyte, but beyond that it's just a desire for quick charging. Is that incorrect?
Exactly what I needed, thank you
Symbioquine
Solar Enthusiast
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Yes (er... I mean that's correct), and to @Warpspeed's point, you're only cutting down the time for the very first part of the bulk charging. Once you get into the tapering charge current where the battery is the limiting factor, a larger charger won't make any difference speed-wise either. (Though there are edge cases to consider with very large batteries or very small chargers where the battery might never really get full or where the charger might wear out prematurely due to exceeding its intended duty cycle.)
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