question

Brian Scott avatar image
Brian Scott asked

Should I be at 14.4 volts or 13.6v?

Hello,

Everything I read says a full charge is 14.4 volts for my 400ah LIPO bank. My system never goes above the float voltage of 13.6. On shore power I watched it fully charge to 14.4 once and hold it for just a few seconds, then it immediately dropped off back to 13.6.

The system is 2 months old, smart networked, and I have the following Victron components:

Multiplus 2000/12, Smart solar 150/35, BVM 712, Battery Protect









battery charging
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3 Answers
rickp avatar image
rickp answered ·

You may be confusing charging voltage suggestions with the static charge of your battery after charging. It requires more voltage than the “fully charged” state to reach that level. This would be the 14.4 - 14.8 (or thereabouts) your charger is utilizing. I think 13.8 or so is fully charged for a 12V LiFeP04 battery, so that drop back would be normal.

As long as the discharge curve is as expected, it doesn’t sound like anything to worry over.

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Brian Scott avatar image Brian Scott commented ·
Thank you so much. The only thing odd I have noticed about the discharge curve so far is when I dropped down to around 11.8 volts once, it started rapidly dropping. The alarm went off early in the morning, so I was a little groggy, but I don't recall much running at the time. Maybe the refrigerator. I just need to learn more. Really appreciate the validation.
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Brian Scott avatar image
Brian Scott answered ·

Does anyone know the answer to this? I know it is simple, but I want to make sure what I am seeing is correct and understand why the voltage hits 14.4 then drops quickly back to float voltage instead of slowly draining back down to it.

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kaeser-sosae avatar image
kaeser-sosae answered ·

Hi Brian,

Just confirming, is your battery bank definitely LiPo, not LiFePO4? The cell voltages are different between the two. I’m guessing it’s LiFePO4.

With LiFePO4, it is normal for this chemistry that the voltage ‘settles’ back to 13.6 volts or so. The cells won’t hold 3.6v each for very long.

Remember with the discharge curve of this chemistry that it most of it’s usable capacity will be a pretty flat voltage, and at either end, it very quickly drops and rises. So once you get under 12v you will see very fast drops in voltages. While you might still get some capacity at that voltage, it will be minimal as a percentage of your total capacity so you may as well consider it pretty flat.

Hope this helps a little bit.

Cheers

Gavin

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