question

trp-racing avatar image
trp-racing asked

Use of excess solar power when batteries are full

Hello,


This may be asked before but in this case there may be some specialities.

System:

Off grid

MPPT 150/35

Multiplus 24/3000

BMV-712

Venus GX

PV power 2,5kw

Leaf- lithium battery set, round 10kW, 32V with BMS which are not connected to Venus

System starts to use battery energy when charger goes to float mode. I setup float voltage 0,5V (SOC round 85%) below absorption voltage to prevent micro charging. I think there is no way to prevent this? Normally my batteries are full at the afternoon during summertime and I loose 5-8 hours of solar power.

I will add dump load for system later but I assume that situation will be the same: It just use current from batteries until it's hit float voltage.

Any ideas?


thanks

Pentti


MPPT SmartSolar
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2 Answers
klim8skeptic avatar image
klim8skeptic answered ·

System starts to use battery energy when charger goes to float mode.

Surely there is a resting cell voltage for leaf cells? A (float?) voltage where a decent SOC can be maintained, without undue degradation?

Use the search function, and look for leaf..

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trp-racing avatar image
trp-racing answered ·

Problem is more how to prevent micro charging. If I put float voltage to same as absorbion, I will get micro charging after the situation where solar power is less than usage/needed power. I am not sure how harm full micro charging is for the battery life.

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