question

markwinship avatar image
markwinship asked

Blue Smart IP22 charging a 200Ah Lithium battery exhibiting strange behavior

The Lithium battery seems to be charging correctly and gets to Storage Mode. My BMV-700 shows 100% SOC but then slowly, under load, drops to somewhere like 90% SOC before recharging (positive amps) restarts. The IP22 is in Li-ION mode and the BMV-700 is all factory defaults except Charge Efficiency is set to 99% and the Peukert's exponent is set to 1.05.

Lithium Battery
2 |3000

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1 Answer
Justin Cook avatar image
Justin Cook answered ·

@mark.winship@hotmail.com, this appears to be entirely normal behavior. Your IP22 charger is looking at voltage, not SOC, and your lithiums maintain a high voltage for longer than a flooded bank. Your lithiums aren't dropping to a low enough voltage to trigger the charger until they reach 90% SOC or lower... which is fine, and normal.

Keep in mind that 90% SOC isn't very significant on a lithium bank considering that you can safely discharge to 20%, unlike a flooded bank that you could only discharge to 50% at most. So your 90% SOC on a lithium bank is far less significant than a 90% SOC on a flooded bank.

Good news: everything appears to operating completely normally.

2 comments
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markwinship avatar image markwinship commented ·

Excellent answer; many thanks; I am still getting used to Lithium batteries!

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Justin Cook avatar image Justin Cook ♦♦ markwinship commented ·

No worries... we're all so used to being able to only use half our bank capacity at most that it takes some time to wrap our heads around being able to actually use our capacity.

Happy travels/sailing/boondocking/whatever it is you're doing!

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