Originally Posted by motion30
If starting with fully charged batteries and then using a total of 100 amps, how many amps would the charge source need to put back to fully charge the batteries again. In other words What are the losses?
Well, I happen to be sitting over at Catalina Island charging
batteries at the moment and asked the BMV702s what they claim for the total number of kWh of energy removed from the batteries over the last 20 cycles vs the total amount of energy used to charge them. Note that there are periodic equalization
cycles included in these numbers, a charge to completely charged at the dock
, periodic acceptance charging when sitting at the dock
. The batteries have been installed for about 18 months now (2 seasons) and are a bank of 6V golf cart batteries in two banks of 24V and are generally paralleled
Bank 1: 156 kWh total consumption
/ 191 kWh total charge = 81.7% efficient
Bank 2: 153 kWh total consumption
/ 197 kWh total charge = 77.7% efficient
Note that bank 2 has required a bit of additional care and feeding as it has one cell which had trouble coming into balance initially. I have been continuing to monitor
but that gives two banks basically getting run in parallel almost all of the time.
So, I would expect somewhere between 20% and 30% additional charge being needed in my installation
, so take out 100ah you will need to return between 120ah and 130ah to charge the battery.