12volt parallel batteries

brucemayer · Jun 5, 2023

12volt parallel batteries. Picture below is my first round at a DIY solar generator with three lion energy UT700 batteries and a Renogy 3k inverter. System works great .....looking to sanitize the wiring a bit on the next build and reduce number of connections.

Are the circuit breakers I used in the picture below necessary to keep this system safe when paralleling batteries in case one of them fails and goes south.
Upcoming bill this week will have three smaller lion energy 250 batteries in parallel and a 1K inverter to make a more portable setup.
Thanks for any input

SamDeleted · Jun 5, 2023

Although it's a little messy , it's not actually a bad job , it's wired up quite well

I know people don't rate those DC breakers,

Supervstech · Jun 5, 2023

Think about this…
The leads to the loads from the battery look larger than the links between the batteries. Why?
You are building in resistance between them. Don’t do that.

The bussbars you chose are brass cheapies. As long as you limit to below 100A they work, but they are wasting your energy.
The breaker is a cheap knockoff of the bussman breaker… don’t trust it to protect anything. Only useful as a disconnect switch… get fuses rated for the amp loads.

I like the shunt. It should show you state of charge, and provide more accurate load usage.

brucemayer · Jun 5, 2023

Supervstech said:
Think about this…
The leads to the loads from the battery look larger than the links between the batteries. Why?
You are building in resistance between them. Don’t do that.

The bussbars you chose are brass cheapies. As long as you limit to below 100A they work, but they are wasting your energy.
The breaker is a cheap knockoff of the bussman breaker… don’t trust it to protect anything. Only useful as a disconnect switch… get fuses rated for the amp loads.

I like the shunt. It should show you state of charge, and provide more accurate load usage.

Thanks for the feedback I appreciate your time

brucemayer · Jun 5, 2023

SamG340 said:
Although it's a little messy , it's not actually a bad job , it's wired up quite well

I know people don't rate those DC breakers,

Thanks!

mikefitz · Jun 6, 2023

Those low cost breakers have issues, the trip point is not reliable, they have high volt drops and overheat, the connection studs overheat, melting the plastic, useless junk. As suggested, fuses, MRBF in Blue sea holders or ANL high quality, not eBay /Amazon.
Fitting overcurrent protection on each of the batteries is best practice, but very often is not implemented, your choice.

Mike

HRTKD · Jun 6, 2023

No, that's not how I would wire up three parallel batteries. Take a look at the thread linked below. Your batteries are likely to be out of balance before too long.

If it was my setup, I would create equal length cables and run them from each battery to a set of common bus bars (not the ones you have now, as pointed out by Supervstech). Then connect your shunt to the negative bus bar.

Calculation of parallel string battery currents

Hi, everybody! I'm a retired EE. I didn't want my EE skills to fade away after retirment, so I exercise them when I can. Whenever I see a non-trivial circuit analysis problem on one of various forums I frequent, I challenge myself to solve it. Recently I watched Will's video about current...

diysolarforum.com

Brett V · Jun 6, 2023

The battery in the middle will be underutilized. Since you invested in bus bars, you should connect all 3 negatives and all 3 positives to their respective bus bars with exactly equal lengths of cable. Then make your load connections from there.

brucemayer · Jul 27, 2023

brucemayer said:
12volt parallel batteries. Picture below is my first round at a DIY solar generator with three lion energy UT700 batteries and a Renogy 3k inverter. System works great .....looking to sanitize the wiring a bit on the next build and reduce number of connections.

Are the circuit breakers I used in the picture below necessary to keep this system safe when paralleling batteries in case one of them fails and goes south.
Upcoming bill this week will have three smaller lion energy 250 batteries in parallel and a 1K inverter to make a more portable setup.
Thanks for any input

New build (smaller) with three Lion Energy

brucemayer said:
12volt parallel batteries. Picture below is my first round at a DIY solar generator with three lion energy UT700 batteries and a Renogy 3k inverter. System works great .....looking to sanitize the wiring a bit on the next build and reduce number of connections.

Are the circuit breakers I used in the picture below necessary to keep this system safe when paralleling batteries in case one of them fails and goes south.
Upcoming bill this week will have three smaller lion energy 250 batteries in parallel and a 1K inverter to make a more portable setup.
Thanks for any input

New smaller build with Lion Energy UT250's and a Renogy 1k inverter.

brucemayer · Jul 27, 2023

brucemayer said:
12volt parallel batteries. Picture below is my first round at a DIY solar generator with three lion energy UT700 batteries and a Renogy 3k inverter. System works great .....looking to sanitize the wiring a bit on the next build and reduce number of connections.

brucemayer said:

12volt parallel batteries. Picture below is my first round at a DIY solar generator with three lion energy UT700 batteries and a Renogy 3k inverter. System works great .....looking to sanitize the wiring a bit on the next build and reduce number of connections.

Are the circuit breakers I used in the picture below necessary to keep this system safe when paralleling batteries in case one of them fails and goes south.
Upcoming bill this week will have three smaller lion energy 250 batteries in parallel and a 1K inverter to make a more portable setup.
Thanks for any input

Click to expand...

Are the circuit breakers I used in the picture below necessary to keep this system safe when paralleling batteries in case one of them fails and goes south.
Upcoming bill this week will have three smaller lion energy 250 batteries in parallel and a 1K inverter to make a more portable setup.
Thanks for any input

12volt parallel batteries

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