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Klaus asked

Smart Battery Protect 12V/220A - Reverse Current

I am planning to use a Smart Battery Protect 12V/220A between a Victron Lithium Battery and my loads to disconnect those loads through ATD (allow-to-discharge) signalling.

The SBP manual states:

Caution: uncontrolled reverse current will flow through a Smart BatteryProtect if Vout > Vin. Therefore, never use a Smart BatteryProtect for battery to battery charging.

Request for clarification:

Is the uncontrolled reverse current only flowing while the SBP is in the state of ATD, or also when the SBP has disconnected the loads because of a do-not-ATD event?

My plan of action:

I would like to use this reverse current „feature“ to connect my chargers to the ATD Smart Battery Protect OUT.

Expected result:

I would expect that as soon as my chargers rise the voltage on SBP OUT above the Lithium Battery voltage on SBP IN, the batteries get charged. Whatever the state of ATD is.


Is this a recommendable/OK way of using the SBP?

Will this work as expected?

Any suggestions welcome!

Thanks and best regards,


SY Starship

Background - Why do I want to do that:

This is an installation on a sailing boat. The battery box shall hold the lithium batteries together with fuses, battery switches, BMSes and SBPs.

This box is at a distance from the main connection point for loads and chargers. The cable channel does not offer any more space for additional 50-70mm2 cables from the charge bus to the batteries, while an ATC signal cable can still be put in there.

That’s why I would like to connect all loads and chargers to the main connection point. That translates into: the chargers will be connected to the SBP OUT that protects the Lithium from discharging too deep…

Battery Protect
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1 Answer
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Klaus answered ·

Only after posting this question I found an official answer from Victron suggesting we should never do such a design, as it produces too much heat in reverse when the BP is off and even might catch fire!

See here:

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