question

bjorn-madsen avatar image
bjorn-madsen asked

Are battery balancers overkill for 24v series of 12v lithium batteries?

I have a battery bank configured like this:

1606386195352.png

Where the batteries are TN 54Ah Lithium Iron Phosphate (LiFePO4) Battery. The batteries have internal cell balancing, and built-in automatic protection for over-charge, over discharge, over current and over temperature. These are NOT Victron batteries.


From what I understand from the educational document "Wiring Unlimited", I infer that the battery balancer, performs the actual balancing by adding a small resistance to either side (left/right) of the series of batteries, and thereby skew the current in either side:

1606386400657.png

If the Left side shows higher voltage, add minor resistance on Left to increase the current delivered to the Right. And of course vice versa.

Question 1: Is my understanding of the way that a battery balancer works correct?


Despite that lithium batteries, have internal cell balancing, and built-in automatic protection for over-charge, over discharge, over current and over temperature, the theory of battery balancing still applies for Lithium batteries because of the resistance in the circuit of batteries, so battery balancers are NOT overkill.

Question 2: Is it correct that battery balancers remain an essential element in the long term maintenance of the circuit?


Kind regards

Bjorn


Lithium Battery
1606386195352.png (32.3 KiB)
1606386400657.png (28.6 KiB)
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klim8skeptic avatar image klim8skeptic ♦ commented ·

Have you already purchased those batteries?

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bjorn-madsen avatar image bjorn-madsen klim8skeptic ♦ commented ·

No. Why?

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bjorn-madsen avatar image bjorn-madsen klim8skeptic ♦ commented ·

Why x2?

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2 Answers
bjorn-madsen avatar image
bjorn-madsen answered ·

Got an answer from victron sales:

> Battery balancers are not required for Lithium as that kind of batteries has their own system.

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jwfrary avatar image
jwfrary answered ·

The best solution is to buy 24volt version of the batteries, this entirely removes the problem your thinking of and simplifies your wiring. - You just have to find somewhere to put it! The only model available at the moment is a 25.6 v 200 ah.

Generally due to the lower internal resistance of lithium battery's balancers aren't used.


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bjorn-madsen avatar image bjorn-madsen commented ·

Thank you for your opinion, but it doesn't answer my question. Please see Q1 and Q2.

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