question

redwood avatar image
redwood asked

Battery Protect for charging

I am currently trying to setup a Multiplus, Victron Lithium batterys, VE.BUS BMS, and a BMV712 in my RV. I have previously had a dc-dc charger and solar charger installed that does have custom settings so i can program them for the lithium battery. I do not want to have the expense of replacing them with victron chargers at this time. Can i use a battery protect inline between the chargers and the battery to stop charging in the case of over voltage? Would this battery protect be trigger with the VE.Bus BMS or for the BMV712 relay?

Battery Protect
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3 Answers
redwood avatar image
redwood answered ·

When the BP is discounted due to high battery voltage how will this affect it if the charger keeps trying to charge thru the BP?

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boekel avatar image boekel ♦ commented ·

it depends on the charger, some will keep providing the set voltage. as the connection is 'open' there will be no current flowing.

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Paul B avatar image
Paul B answered ·

I would use the VE BMS unit to trigger the BP, however make sure the "IN" connection on the PB goes to the Chargers and the "OUT" goes to the batteries. As the VE BMS would be controled by the batteries cell level BMS .

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boekel avatar image
boekel answered ·

your solar chargers might not like being disconnected from the batteries.
If they have 'remote on/of' connections, you can turn them on / off through these (don't forget to use a relay with multiple contacts if you want to switch more than one device)

You'll have to program the correct charging voltages for the lithium batteries, the remote switch should be triggered by the bms but this is only when there is an error in the battery (overvoltage in a cell, temperature to low / high, etc), during normal use the bms shouldn't have to switch the chargers.

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redwood avatar image redwood commented ·

I have check out the solar charger and it will not loss its settings when discounted from the battery bank. Is there another thing i should worry about or is this what you were talking about?

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boekel avatar image boekel ♦ redwood commented ·

If you want to be sure, check with the distributor / manufacturer of your solar chargers. Probably they will be fine, but I'd double check (if the manual says it's ok to disconnect battery while solar is connected than it's fine).

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benm avatar image benm boekel ♦ commented ·

ls it allowed to disconnect a charging Victron MPPT from the battery? I know it can be done with remote control, but I don't prefer this way off disconnecting.

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boekel avatar image boekel ♦ benm commented ·

I don't know if it can be harmful, I only disconnect for maintenance.

But you shouldn't have to disconnect! only when something is wrong with the battery. charging settings should be such that in normal conditions the BMS doesn't have to cut off.
And preferrably let the BMS also control charge voltage and current.


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benm avatar image benm boekel ♦ commented ·

Thanks: Boekel for your answer. I understand your answer. You say, you don't know or it is harmfull.

So please can Victron staff answer this question.


Will it harm the MPPT if it get disconnected from the battery at the time off charging?


@Johannes Boonstra @mvader @Guy stewart

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