question

dthomson avatar image
dthomson asked

Unrealistic charging history

I have a Victron SmartShunt I use with 2 100AHr Lithium batteries. I've gone through the manual and configured it and have used it for a few weeks. It seems to work, more or less. But sometimes I don't believe what it is telling me. See below for today's charge history. It had dropped to 50% over a few cloudy days, and was charging up this morning. Then around noon, it shot up to 100% in a few minutes. Any idea what could be going on here?



screenshot-20230706-1953192.jpg





battery charging
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·
Show us your settings, I guess they are not correct.
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Alexandra avatar image Alexandra ♦ Matthias Lange - DE ♦ commented ·

Yep, the full is being triggered too easily

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4 Answers
dthomson avatar image
dthomson answered ·

Here are my settings.

I went through the manual and attempted to set these correctly for my batteries, which are LiFePo4 from Ampere Time (now Lithium Time).

screenshot-20230706-2350591.jpg


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dthomson avatar image
dthomson answered ·

Ah... The "Charged Voltage" parameter is set to 13.2. Which I got from Page 10 of the manual. But I didn't see the text there that says that that table is for Lead Acid batteries! The jump was right when the battery voltage reached that value, as per the graph below.

So the question is, what is an appropriate "Charged Voltage" for a LiFePo4 battery?

screenshot-20230706-2357331.jpg


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dthomson avatar image
dthomson answered ·

I've put it at 14.5V for now. I'll try to sync it soon and see how things work.

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·
I would recommend to set it 0.1V below the absorption voltage of the charger.
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dthomson avatar image
dthomson answered ·

Thanks. I was hoping for recommendations on the value!

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