Is this correct and a good design for 12v battery bank of 8 6v batteries

patpat

Is this design correct and appropriate for using eight 6v batteries for a 12v system battery bank?
I want to make sure the loading is balanced and my amp hours are correct.
Attachment not found.

Charge controller and inverter will attach at the buss bars.

Thanks

inetdog

Re: Is this correct and a good design for 12v battery bank of 8 6v batteries

patpat wrote: »

Is this design correct and appropriate for using eight 6v batteries for a 12v system battery bank?
I want to make sure the loading is balanced and my amp hours are correct.


Charge controller and inverter will attach at the buss bars.

Thanks

Your numbers and your wiring method seem to be acceptable. Some would suggest that as long as you are using a bus for + and - you bring each battery pair to it individually instead of combining via diagonal connection. That would make it easier to disconnect and work with a single pair of batteries.
However, there are also those who would suggest that you go with 4V or 2V batteries instead to allow you to use a single string or at most two strings to get your 1740AH capacity.

Also are you committed to using 12V instead of 24V for your system?

Cariboocoot

Re: Is this correct and a good design for 12v battery bank of 8 6v batteries

Welcome to the forum.

Two things: first, avoid using a 12 Volt system if at all possible. The same batteries can supply the same power @ 24 Volts with less current and fewer current sharing problems. Second, if you must connect four in parallel each string should have its own connections to the bus bars. Here is a drawing of four parallel connections on a 24 Volt system. Merely halve the number of batteries per string for 12 Volts. The long vertical red and black lines would be the bus bars; the wires from each battery string to them would be equal length. Ideally each string would have its own fuse.

patpat

Re: Is this correct and a good design for 12v battery bank of 8 6v batteries

Thanks for the feedback
This is a retrofit to an existing 12v system, and the (new) 6v batteries are already purchased and installed, so I can’t change those parameters.
I suppose I could look at taking each pair to the bus - I will have to see if I have enough 2/0 cable. Will using it as-built for a time be hard on the batteries?
(The original design had 20 6v golf cart batteries connected as 10 12v series connected in one long parallel run with the inverter and charge controller all connected at one end. It magically lasted 9 summers, albeit a lot of generator usage the last two)

solar_dave

Re: Is this correct and a good design for 12v battery bank of 8 6v batteries

patpat wrote: »

Thanks for the feedback
This is a retrofit to an existing 12v system, and the (new) 6v batteries are already purchased and installed, so I can’t change those parameters.
I suppose I could look at taking each pair to the bus - I will have to see if I have enough 2/0 cable. Will using it as-built for a time be hard on the batteries?
(The original design had 20 6v golf cart batteries connected as 10 12v series connected in one long parallel run with the inverter and charge controller all connected at one end. It magically lasted 9 summers, albeit a lot of generator usage the last two)

Hopefully they are ALL new batteries.

patpat

Re: Is this correct and a good design for 12v battery bank of 8 6v batteries

Yes - all $new$ trojan L16P's

Cariboocoot

Re: Is this correct and a good design for 12v battery bank of 8 6v batteries

As-is will not be too bad for them, especially if you keep a close eye on the SG's.

Four parallel strings of L16P's? Those things are 420 Amp hours bringing the total to 1680 Amp hours. That's 20kW hours of stored power. Why so much?

Plus you need two big charge controllers (Classics as you should be slightly over 80 Amps peak current) and over 2600 Watts of PV to properly charge these. If you really need that kind of stored power it really should be a 48 Volt system.

I think I'd be reevaluating the power requirements.

patpat

Re: Is this correct and a good design for 12v battery bank of 8 6v batteries

That is good advice as well. It's is a classic real-world stop-trying-to-make-sense situation. System was 'suppose' to provide X was was designed as Y. So too much battery, not enough PV, resulting in a lot of generator propane.

Thanks again for the advice and fresh perspective.