question

chrisgreci avatar image
chrisgreci asked

Battery Protect - battery banks in parallel

I have a system that conforms to the Victron recommended schematic for two battery protects. One to isolate the charging current, one to isolate the discharge.


However, for redundancy, I have two of these systems in parallel, and when the battery banks are out of balance, there is a potential for a small reverse current to flow ~5 amps, quickly settling down to <1Amp, then zero between the batteries until they balance. This happens until the battery banks balance between the two, then it stops, and the voltage difference we're talking is also small, <1V reverse bias across the battery protect.


There is no way to prevent this (aside from only using one battery bank at a time). Should I be worried about ~5amps flowing reverse through the battery protect for a short amount of time?

Also, when the battery protect is off, is it also preventing current in the reverse direction? Or does this device only provide isolation in forward bias?

From an engineer's point of view, I wonder why the battery protect datasheet is so lacking of information.

Battery Protect
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1 Answer
Paul B avatar image
Paul B answered ·

Hi Chris, I have had a few of these fail on me but only when reverse flow occurs and thats when 50 amps or so flows the wrong way when they are switched off, I would suspect that as long as you keep the total wattage down to under 20 to 30 watts then I dont think you will have any problems.

I am not part of victron so this is not advise from them.

the lower the wattage the better, heat is the killer when they are getting reverse current.

and 5 amps at 1 volt is that large

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