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chrisryan43 avatar image

VE.Bus BMS functionality

Could somebody confirm if a BMS used in conjunction with a Smart LiFePO4 battery will shut down the output of the battery when required. The wording on the pamphlet says 'The BMS will shut down or disconnect loads in case of imminent cell under voltage' but i get the impression it will only control a separate relay (purchased separately) to disconnect the load rather than doing it in the battery itself.

Lithium BatteryBMS
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Simo Hassi avatar image
Simo Hassi answered ·

Additional question: VE.Bus BMS manual has wiring diagrams where a "System on/off switch" is located in the wire going to Battery + terminal of the BMS. What does this switch actually turn on and off? Will a MultiPlus in the system turn on and off through this switch?

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hello Chrisyryan,

There is no switching device inside this battery, or BMS itself.

The VEBus BMS can only signal to switch things off.

We have some diagrams that have the BatteryProtect instead of a relay. See here:

https://www.victronenergy.com/upload/documents/Manual-Additional-Li-ion-battery-circuit-suggestions-EN.pdf

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Boekel avatar image
Boekel answered ·
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I did (first place i looked in fact) and it says

'The BMS will: - shut down or disconnect loads in case of imminent cell under voltage, - reduce charge current in case of imminent cell overvoltage or over temperature (VE.Bus products, see below), and - shut down or disconnect battery chargers in case of imminent cell overvoltage or over temperature.'


Which would suggest the BMS will shutdown the battery but if that was the case i would expect the battery to switch off when the BMS isnt connected (for safety) but that isnt the case. Which leads me to think the wording is a bit misleading and it should say:


'The BMS will (in conjunction with an external relay eg Battery Protect or Cyrix-Li-Load) - shut down or disconnect loads in case of imminent cell under voltage

Yes, it states that those can be used to control relays but the original description suggests that the controller itself will disconnect the load