Lower charging current at night

Integrations OpenEVSE
1

Hello,

I have an OpenEVSE capable of 16 A - one phase.
During day or when manually overriden, 16 A is fine.

During night, when there is enough time to charge, I would like to limit the max current to 6A to take better care ot the battery (as far as I can understand, lower charge current sould be better for the battery expected life).

  1. How can I achieve this ?

  2. Is this a good idea ?
    I read in this post that lower current means lower charge effiency. Is it always the case ?

Thanks.

2

I doubt 3.6kw is considered as high current for such batteries. You will have more energy loss lowering the current also ( voltage drops through cables and the embedded ev inverter is less efficient at low current)

This won’t change nothing to your battery life

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3

AC charging isn’t fast enough to wear the battery, leaving the battery at a high state of charge for prolonged periods would be more significant problem for normal NMC lithium.

In my testing charge rates less than 15A are measurably less efficient. I think due to the fixed overheads running the car computer fans etc. These efficiencies listed below are based on mathematical expectations/ measured charge rate.
PS: edited to add more results: 6A is significantly less efficient than 10A or 15A!

Polestar 2:
6A or 1.44kw: 1.9%/h (real 1.54%/h) 80.2% efficient.
10A or 2.4kw: 3.2%/h (real 2.7%/h) 84% efficient
15A or 3.6kw: 4.8%/h (real 4.3%/h) 89.5% efficient
20A or 4.8kw: 6.4%/h (real 5.7%/h) 89% efficient
32A or 7.6kw: 10%/h (probably 9%/h)
3 phase 11kw: 14.6%/h (real 13.3%/h) 91% efficient
(Note there’s some rounding errors but 15A and higher is probably peak efficiency.)

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