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Our BMV 712 loses data after our lithium battery dischages. Then when we initiate recharging, the BMV shows no data on the SOC, no Consumed ah, and Time remaining shows "nanm", etc.
We depend on solar charge only and we rarely reach the 100% SOC in order to sync the BMV.
To put it simple: - How can we know how many amps are in the battery after a charging session that have charge the battery only partly?
The 712 should not be turning off. What voltage are you discharging to? The 712 will stop working at 6.5v, if you are taking your lithium all the way down to that you are/have killed them.
its possible your lithium are disconnecting their cells in a protection mode (you might be taking them down to 10 or 11v, whatever their cut off is and they then disconnect completly giving zero volts to the BMV. Either way, you shouldn't be discharging that low.
Hi dazey77 thank you for your reply.
Yes the battery disconnects at 11v. But this does not happen very often, but often enough to be annoying as we dont know the SOC of the battery - because of the BMV losing data.
If we could avoid the BMV losing data, we could also avoid emptying the battery.
Is there a way to (can you think of a workaround) to avoid having the BMV lose the data when the battery disconnects?
thanks in advance
I would suggest adding a Smart Battery Protect to the system to disconnect the loads gracefully at something like 12v. They are one way devices so the MPPT and any loads you don't want to disconnect (e.g. the BMV) should be connected battery side.
By the time a lithium gets down to 12v there is very little power left.
Your bmv is on the wrong side on the LV disconnect, place the bmv power lead directly to the battery, if your relying on an internal Lithium battery bms LV disconnect then purchase a programmable LV disconnect (like victron smart battery protect) and program it to open at 11.2v, place your bmv positive cable on the battery side of that disconnect. I hope this helps
Yes it is impossible for us to put the 712 before the LV disconnect. Should have an internal battery maybe :)
If we swap our Lithium for one with a Bluetooth BMS, then we should not need the BMV 712 right?
Swapping the battery is about the same price as installing yet another device like victron smart battery protect.
Do I understand it right or do we lose anything by using an internal battery bluetooth instead of the Victron BMV 712?
