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BMS vs Smart Battery Protect

Barold

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Oct 11, 2019
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103
I think I understand the purposes of each (BMS - Low voltage disconnect would disconnect if a cell voltage drops below a certain value) and Victron's Smart Battery Protect would disconnect the loads (no inverted in my setup) if the battery voltage drops below a threshold.

Would the SBP and BMS be considered redundant (which is usually good on a boat)? Are there othe benefits to adding the SBP that I am not considering here (rest of the components are Victron - MPPT, Orion DC to DC, BMV)
 
Hi @Barold, they're more complimentary than redundant - the SBP is best used as a device to disconnect non-critical loads well before the BMS shuts the batteries down, thus prioritizing your critical loads. So, if you consider (for a random example) a fridge to be critical but your exterior lighting to be non-critical, you would connect your fridge to the battery and the lighting to the SBP; then you'd set your SBP to shut down at, say, 12.4v while the fridge will keep going until whatever v your BMS is set to shut down.

Worth noting here, since this has been an ongoing battle on multiple fronts, that the SBP is unidirectional in operation only, so it must not be used to control a circuit in which current will be flowing in two directions, and also note that the SBP must not be used to directly disconnect the main DC line of an inverter; I know you mention you don't have an inverter, but just in case you were thinking of adding one in the future, you would not put an SBP in between it and the batteries.
 
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Thanks Justin. I think on my boat I have a single distribution to DC loads so there is no separation of critical and non-critical loads. I'll have to trace whether my bilge pump is wired direct but I doubt it.
 
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