Maximum Battery Charging Amperage

[Cantari]

Hi all,

I am trying to determine what is the maximum number of amps I can charge 4 batteries that are in parallel and series ( 4x12V batteries) to produce 24 volts.

I have the specs on the batteries and everything but can not seem to determine how many amps they can handle when being charged? I even talked to the distributor and he kinda just told me "Yah, you should be fine", but couldn't provide me with any kind of calculations or limitations on the batteries.

They are charged at 28 (+ or - 1) volts and sometimes spike at ~150 amps.

Thanks for any help.

 

[dlgoff]

I'm assuming you are considering lead-acid batteries (deep cycle perhaps)? Battery charging current is very dependent on their temperature. I'm surprised your specifications don't mention this. Anyway, I'm not endorsing this paper but from my experiences with maintaining a UPS battery bank consisting of 10 in series, this sounds correct:

Improper Charging



Battery manufacturers specify a voltage range for their various cells that must be adhered to. If the voltage on a given cell is allowed to go either higher or lower than the recommended value, it will have a detrimental effect on the life of the battery. It should also be noted that the specified voltage range is very temperature dependent. The right voltage for a battery at 77°F would be too high if the battery was operated in an ambient temperature of 90°F. It is important for a user to understand the interaction between voltage and temperature.



Low float voltage (Undercharging) – Undercharging causes sulfate crystals to form on the plate surfaces, since there is not enough current flowing to keep the battery fully charged. Sulfate crystals that harden over a long period of time will not go back in solution when proper voltage is applied and, therefore, result in a permanent loss of capacity. Extended undercharging will also cause a loss of active material from the negative plates.



High float voltage (Overcharging) – Overcharging causes excessive gassing of hydrogen and oxygen. This leads to loss of water in flooded cells and dryout in VRLA cells. High float voltage also causes higher float current, which in turn causes accelerated corrosion and shedding of active material from positive plates. The recombination of gases to form water in VRLA cells generates heat, and heat causes higher float currents. Therefore, excessive gassing in VRLA cells can lead to thermal runaway.

More here:

http://www.powerengineer.com/Reliable%20Battery%20Systems.htm