Do I need an inverter precharge circuit for a MultiPlus II?

[Gomez38]

Good. That may mean your Inverter capacitors are not so big, and/or (probably related) the current drops quickly enough that the fuse doesn't blow.

Edit to add: As most of us design and build our systems, we try and identify and address theoretical risks. The whole pre-charge thing is to address a theoretical risk. I'm not sure I've seen ANYONE report any sort of catastrophe because they didn't do a pre-charge. Your real world data is actually very nice to have. Doesn't mean that people don't need to do a pre-charge, but it is a valid rea world data point.

Good point. It would be interesting to know whether any manufacturers recommend it, they must be testing units all the time either with some precharge action, or it doesn’t matter.

 

[corn18]

Good point. It would be interesting to know whether any manufacturers recommend it, they must be testing units all the time either with some precharge action, or it doesn’t matter.

I am leaning this direction as well, especially with Victron stuff. This is what Victron says about connecting a MultiPlus:



So they know it will spark, and I assume they know why, but they don't say anything about a precharge. Doesn't mean it hurts to precharge, but I am inclined to trust that if Victron doesn't require it, then it isn't required.

 

[toms]

Good. That may mean your Inverter capacitors are not so big, and/or (probably related) the current drops quickly enough that the fuse doesn't blow.

Edit to add: As most of us design and build our systems, we try and identify and address theoretical risks. The whole pre-charge thing is to address a theoretical risk. I'm not sure I've seen ANYONE report any sort of catastrophe because they didn't do a pre-charge. Your real world data is actually very nice to have. Doesn't mean that people don't need to do a pre-charge, but it is a valid rea world data point.

I’ve seen a real world system where the lack of using a precharge caused the LVD contactor to be welded closed. Cells were damaged later because the BMS couldn’t disconnect the load.

 

[1pt21GigaWatts]

I was just reading the Victron Lynx manuals, and apparently they include a precharge circuit in their Lynx SmartBMS.

So, they know it is an important feature, you just have to have the full Victron stack to get it.