Hi,
Best to think about it in watts, rather then amps (and volts).
Watts is volts by amps.
12v at 1 amp is 12w of power, same as 6v at 2amps.
Both provide the same amount of power.
So charging to 8.4v at 6 amps is 8.4 x 6 = 50.4w
So you charger is supplying 50w to the pack, your supply, will need (ideally) to supply 50w to the charger, in reality it will be more due to losses.
So for some headroom take charger needs 60w to supply 50w.
So 60w at 12v ~ 60/12 = You need a supply giving out 5a at 12v.
So if you want to charge at 10a (8.4x10 = 84w)
You'll need a supply to give 7.5a (at 12v)(90/12)
A 15 to 20a supply with give you lots to play with.
A 20a supply will give you 240w at 12v.
This will allow you to charge at 27a at 8.4v (230/8.4)
You can also use the above to see how many chargers you can run off your supply.
(Always safe to assume there will be some loss in conversation, mains to 12v to charger.)
MiCk B. :-)
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