Charging a florklift battery with a GC2 bank

jedon

I have an older bank of 16 GC2'a I want to use as a reserve for my forklift battery. When the forklift battery voltage gets low can I use a DC SSR + Diode to hook the GC2 bank to the forklift battery to charge it?

BB.

You can try it and see how it works.. 

Your resting charged bank is resting at 12.7/25.4/etc. volts and your discharged bank is strong 12.0/24.0 volts.

You may get some charging, but real charging is around 14.8/29.6 volts.

You might just parallel the two banks for charging and discharging (assuming the charge set point voltages are similar) and see how it works.

I am not a big fan of paralleling battery banks, but if you already have them and monitor voltages & specific gravity... Why not.

If the batteries are different types (flooded cell vs AGM as an example), you should use the lower AGM charging voltage.

If the two banks are very different regarding capacity (if smaller back is 20% or less of large capacity back), then it will be very difficult to even measure the added capacity of the smaller back.... And possibly not worth the effort.

Bill

jedon

Ahh good point about the charging voltages, they are both 48V banks, one is 16 GC2'a and the other is a 56kWh forklift battery so very different capacities although they are both FLA. 

littleharbor2

Isn't there a danger of explosion or generally bad things happening if there is a large difference in soc between battery banks when connecting them together?

mike95490

littleharbor2 said:

Isn't there a danger of explosion or generally bad things happening if there is a large difference in soc between battery banks when connecting them together?

Only if you let uncontrolled current flow.   Hundreds of amps even with small banks - one car battery can supply 300A to the starter motor in a car.

BB.

Nominally, you should only be looking at 12.0 volts low battery bank vs 12.7 volts for "charged" battery bank (or 48.0 vs 50.8 volts @ 48 volt bank)... Should not be a lot of current flow for an FLA battery to FLA battery (if this was Li Ion--Probably a different issue).

-Bill

jedon

It would be maybe 50.4 (GC2) to 48.7 (forklift), I suppose I could PWM the DC SSR to limit current.