How to work out charge time.

 Hi there.

I am looking a purchase a 2nd hand battery set which is say 560Ah at
10hours. (flooded battery type)

My PV array will not be adequate to charge this on an ongoing basis, so
I will need to run a generator as well.

Can anyone explain how I calculate how long it would take a generator
to charge the batteries from say a 50% DOD?


I'm new to this and I'm in a bit of overload right now.

Cheers
Steve

 

franklin.sr@gmail.com wrote:

OK say 560 for 10 hours, This is the C10 rating.

If the batteries are flat you would be looking at 56 Amps for 10 Hours.

This is the theory. The reality is that you might get the battery up to
80% of it's rated capacity in 8 Hours and still need another 8 Hours to
finish off the last 20% or risk boiling the batteries dry.

This is the best info you can expect given that you have not provided
enough information on the systems use.

As for 50% DOD, well, that would be 56Amps for 5 Hours for 280Ah. The
trouble is that with second hand batteries you don't really know the
capacity.

What is the date stamp on the batteries?

 Thanks for your information...

I couldn't work out where the doubling came from but now I understand.

I don't know the date on the batteries....I'm going to ask him today.

 Steve,

You might want to look at a Real Goods catalog and read about the BZ
MPPT power point tracking charge controller (or even google for that
charge controller).  I am not saying that they have the cheapest price
for this controller and it is pricey.  It apparently charges battery
much more efficiently than other chargers.  They are claiming a 15-30%
increase in charging power from solar panels.

Of course, in the case of buying used batteries, you really don't know
how well they have been taken care of by the previous owner.

Larry