Bmv-712 and MPPT 100/50 conflicting settings

DIY
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1

I seem to have a different value for ‘tail current’.
BMV-712 is set to 2% which it has been since installing.
The same setting for the MPPT 100/50 is greyed out which is a preset value from the LiFePo4.
Any suggestions please?

2

They are not conflicting settings as they do different things.

Ideally the value in the BMV should be slightly higher than the value in the MPPT so that the BMV synchronises to 100% before the MPPT goes to float. A 4% value may be better for lithium. The Charged Voltage setting in the BMV should be 0.2V lower than the absorption setting in the MPPT.

I do not know if the tail current setting can be altered if you choose the expert option. The default for the Victron Smart Lithium batteries is fixed absorption time. It may also depends if you have a GX device and managed batteries.

2 Likes
3

Thanks for that, what would be the effect of increasing the 'tail current '?

4

Increasing the tail current on the BMV will get it to synchronise to 100% a bit sooner. Increasing it on the MPPT will stop charging a little sooner and reduce the risk of voltage spikes towards the end of charge.

5

Great, I’ll make a change and monitor the result.