question

ww2bar avatar image
ww2bar asked

Why is Compact Multi plus 2000 charging over set parameters.

I installed the unit and used software VE config to change setting for my SOK lithium profile. 40 Amps max, 14.6 charge volt max as well 13.8 float. Charging began in Bulk mod for 3 to for hours at 13+ volts at what looked like 33 amps. When it switched to absorption mode I saw voltage fluctuates but goes to 14.75 and 14.8. It only goes there for a few seconds as it cycles up and down. I don't want to damage the battery, I plan on changing the max voltage to 14.4. Any ideas.

Multiplus-II
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3 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Did you selected the Lithium charging profile first?
If not maybe the temperature compensation is still activated.

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ww2bar avatar image ww2bar commented ·

I did select the lithium profile first and then made some manual changes as per SOK. I did have the victron temp sensor installed but not connect. I read after the fact it is not needed for lithium. Should I disconnect the leads or can I just go into the software an deactivate?

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kevgermany avatar image
kevgermany answered ·

Could be normal behaviour. Up to the limit of the 40A you set, the battery/BMS will control charge current. If it decides current is too high and shuts it off, a voltage overshoot may occur. Lowering your max charge voltage may help.

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ww2bar avatar image ww2bar commented ·

I think I will look to lower to 14.4.

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Trevor Bird avatar image
Trevor Bird answered ·

@ww2bar hello, I have experienced this type of voltage variation when the battery BMS becomes active because of cell voltage imbalance. To prove this try reducing the absorption voltage to say, 14.1Volts and see if you have the same DC voltage fluctuation.

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ww2bar avatar image ww2bar commented ·
Thanks do you think changing it to 14.4 or go to the 14.1 you recommended?
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