Changing from 2-48v banks to one 60v

[NBBoilermaker]

Hello folks, semi newbie here. Were completely off grid in rural New Brunswick. Three years in and a few beginner mistakes, we seem to have a few batteries nearing their lifespan. We've run two banks, 8 6v batteries for most of the time. It appears after the worst 6 week run in weather We've had in 3 years, that our capacity has suffered overall. Im going to test each individual battery, and put the best ten in a 60v bank as opposed to two poorly working 48v banks. This is a temporary fix until I can replace the bad batteries with new good ones. Has anyone had to do anything similar? Our charge controller and inverter are both rated for a lager bank so not anticipating any issues there, other than learning the new values for charge percentage. Thank you for any input.

Andrew

 

[snoobler]

How can your 48V equipment work at 60V?

 

[MichaelK]

A 60V battery bank is going to need as much as 73-74VDC to fully charge. My 48V inverter has a voltage limit of 64VDC. As snoobler asks, how are you going to make it work? My Midnight controller could charge your 60V battery, but my Schneider inverter would shut down?

There's a different problem here. You have two 48V strings for your battery. What's the amphour capacity of your battery? Two popular batteries, golf carts, and L-16s have capacities of ~225Ah and 375Ah respectively. The math for the amount of solar you need would be.....

225Ah X 1/10C X 2 strings X 52V charging X 1.25 fudge factor =2925W
375Ah X 1/10C X 2 strings X 52V charging X 1.25 fudge factor =3875W

So, depending on your battery, you need between 3000 and 5000W to adequately charge your whole battery bank, depending on its size.
You can tweek each parameter slightly for your battery, your panels, and your charge rate, but those numbers are in the ballpark. These calculations are for average charging. If you want maximal charging, then substitute in 1/8C.

How many W of panels do you have? I'm guessing you don't have even 3000W. A large array will produce a bit of power even in the rain, so my 4500W primary array can limp by even on a rainy day.