question

afrikii avatar image
afrikii asked

Battery over heating?

I am on a sailboat in the Caribbean. This week I had 4x 200ah Victron lithium batteries installed professionally with a bms, bmv712, battery protect, mppt 100 solar chargers x 3. Everything seems to work well except the temperature on one of them was 52C and the others were in the high 40s. Is this normal?

Lithium Battery
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2 Answers
tozz avatar image
tozz answered ·

If this is normal depends.. If there is a lot of active equipment running in a confined space, perhaps heated by the sun? Then it could be normal.

Nevertheless 52 degrees is uncomfortably hot for li-ion batteries. Ideal is somewhere between 20 and 25 C


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afrikii avatar image afrikii commented ·
The temperature offset was at 6C on the batteries (I think the installer put them there) and I now have it at 0C. The temperature of one of the batteries goes quickly from around 40C to 48C (the other 3 are within 6C lower) during the absorption phase at 100% soc. Then, after 2 hours, the float stage kicks in and the temp quickly drops back down to the thirties. Victron says the charge temp safe parameters are between 5C-50C so 48C is still “safe” but seemingly excessively high.

Is this a problem?
What can I do to change it?

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nickdb avatar image nickdb ♦♦ afrikii commented ·
What is the ambient temperature of the area?

Start there. If it is hot, the batteries will be hot so then rather consider improving ventilation, perhaps with some extraction.

Electrical gear does not perform well at high temps, so if your inverter is also hot you will be losing performance.

Space should be left around all the components so there is reasonable airflow.

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marekp avatar image marekp afrikii commented ·
@nickdb

Lower the charge current.

I was told that using LFP batteries in 40C halves their lifespan.

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kevgermany avatar image
kevgermany answered ·

If the batteries are all in the same place/compartment and equally cooled, wired to share the load, you may have a faulty temp sensor. Installer should test.

Guessing the plus 6 setting was to trigger load reduction early and keep temps down/help battery life.

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