Battery extensions

[Zoltan Doka]

Hi. I have an existing 3x100 Ah Winston LIFePO4 battery bank on our catamaran. They are 3 years old. I want to extend my capacity to 600 AH. Can I just add an other 3 X 100 Ah? Or is there any concern to do so?
Thanks for any feedback.
Zoltan SV iCat

 

[740GLE]

Your doing this for added load or added run time between filling charging?

 

[Zoltan Doka]

For adding run time.

 

[rmaddy]

Adding more LiFePO₄ batteries in parallel with your existing LiFePO₄ batteries should not be an issue. The trick is to properly wire all 6 in parallel to ensure the batteries are used in a balanced fashion. And make sure all 6 are fully charged before connecting them together in parallel. Hooking LiFePO₄ in parallel when there is too much voltage difference can result in a lot of current between the batteries until it all balances out. You want to avoid that.

Victron's "Wiring Unlimited" has a whole section on batteries in parallel. Read chapter 3 of the following:

Wiring Unlimited

Wiring Unlimited is a great resource that covers many many common topics and questions relevant to DIYers. It is a free E-book from Victron Written by Margreet Leeftink. Check it out! Download

diysolarforum.com

 

[740GLE]

What’s the peak current demand you expect?

If current is low it’s easier on the banks to share current and remain balanced

 

[Zoltan Doka]

What’s the peak current demand you expect?

If current is low it’s easier on the banks to share current and remain balanced

As we live on a sailboat, it's about energy storage. I have a Victron 3000 Watt Inverter, which covers all the need we have on board.

 

[Zoltan Doka]

Adding more LiFePO₄ batteries in parallel with your existing LiFePO₄ batteries should not be an issue. The trick is to properly wire all 6 in parallel to ensure the batteries are used in a balanced fashion. And make sure all 6 are fully charged before connecting them together in parallel. Hooking LiFePO₄ in parallel when there is too much voltage difference can result in a lot of current between the batteries until it all balances out. You want to avoid that.

Victron's "Wiring Unlimited" has a whole section on batteries in parallel. Read chapter 3 of the following:

Wiring Unlimited

Wiring Unlimited is a great resource that covers many many common topics and questions relevant to DIYers. It is a free E-book from Victron Written by Margreet Leeftink. Check it out! Download

diysolarforum.com

Thank you for your input and the interesting link.

 

[rmaddy]

I have a Victron 3000 Watt Inverter

FYI - it's a 3000VA inverter which is 2400W.

 

[joanna_lannie]

That's OK. In most cases of mixed batteries, it is only necessary to ensure that the voltages are equal (that is, in parallel), so it is good to expand the batteries. Also, I'm curious about one thing, why to 600Ah? Wouldn't it be better to raise the voltage a bit?