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trougnouf avatar image
trougnouf asked

BatteryProtect needed with smart LifePO4 battery?

Is the BatteryProtect needed/useful with the smart LifePO4 battery?

Does the battery itself stop sending current when its voltage is too low?

The battery itself has an "Allowed-To-Discharge cell voltage" setting, the manual says "As soon as one of the cells reaches this voltage, the BMS will disable all loads by sending a signal to the load or to the load disconnection device.".

I don't understand if the battery is smart enough to stop sending power to devices once that voltage is reached, or it (and the VE.Bus BMS) needs a "load disconnection device" that acts like a switch between the battery and the load.

A standard load wouldn't care about a stop signal, unless that signal was a complete lack of current.

I often see the BatteryProtect in schematics but it seems the battery with the (VE.BUS BMS which is directly recommended) may already be equipped to protect against under/over voltage.

Lithium BatteryBattery Protectve.bus bms
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3 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

I guess you mean the Victron Smart lithium batteries. For those you need ab external BMS.

https://www.victronenergy.com/battery-management-systems

The BMS will give you a "charge disconnect" and "load disconnect" signal. The battery itself will not cut-off.

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trougnouf avatar image trougnouf commented ·
Yes, but I then also need something between the battery and the load which takes the "load disconnect" signal from the BMS, like the "BatteryProtect", right?
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trougnouf avatar image
trougnouf answered ·

From reading the VE.BUS BMS manual it seems that the feature is indeed only meant for devices that obey the disconnect signal, so I do need to put a BatteryProtect between the battery and the "dumb" loads.

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drlbradley avatar image
drlbradley answered ·

Still building mine, but I have a VE.Bus BMS, and then a Battery Protect on the load side, and a Cyrix Li-charge (CYR0101240430)on the charge side of my system, both of those taking their disconnect signal from the VE.Bus BMS.

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Related Resources

Victron BatteryProtect product page

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Battery Compatibility

Did You Know - How to create a battery profile for non-Victron batteries?

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