question

getwilde Are you using a BMS with the lithium?

When the inverter starts it will pull several time its operating current the BP220 is rated for 600A for 30sec and similar with the fridge.

getwilde In some respects lithiums are very fragile and run without a BMS leaves them vulnerable - also using some of the signals from for example the Victron BMS you can control things better, I was looking for a better way to do what you are trying to do with the Battery Protect. My gut is telling me your problem is things are drawing too much current on start up and that is why the Battery protect is shutting down.

I would not dream of installing lithiums without a BMS and if that was what the client required for whatever reason I would not do it, it is not safe over all, sorry

I just wish this Victron BP would work as expected. Is anyone else on this forum using a BP220 with LiFePO4 to power an inverter, or a 12v fridge? With any surge, mine shuts off all power to the load. There's no way I'm drawing 220a surge... so perhaps mine is defective?

Our charge controller is programmed to stop charging at 90%. And the BP was intended to protect me from over-discharge (had it worked). I bottom-balanced upfront, and they've remained within 15mv of one another through numerous charge cycles thus far. If they go out-of-balance, I'll bottom-balance them again. If necessary, I'll invest in a BMS.

getwilde I use them in all my Lithium designs but do tend to use the Cyrix Li Load for inverters. In Lithium mode the BPs operate slightly differently and both need a BMS even the mini BMS would do for what you are doing. https://www.victronenergy.com/upload/documents/Datasheet-miniBMS-EN.pdf

I us the BMV high voltage relay to stop charging via the BMS charge signal. They need to get to 14V/14.2V for the Balancing to automatically work. Also I understand that a V Lithium brought up to 14.2V is about at 95%

@Graham. I really do appreciate your responses. Maybe my problem is that I wasn't running it in "lithium mode"... I can give that a try.

From what I've read, the Victron BMS(s) are only designed to work with Victron-branded batteries. Perhaps I should have mentioned in my first post that my battery bank is not Victron, and perhaps that's part of my problem (although I haven't seen any mention that the Victron BP is only compatible with Victron batteries). As I understand it, LiFePO4 have a unique charge profile... and sounds like it doesn't match Victron's lithium. On my batteries, 14.2 is essentially 100%, but 13.6v is also very near 100%. 13.4v is 99% and 13.3v is 90%.

@getwilde I'm going to echo what @Graham is saying. A battery protect is also no substitute for a BMS, no matter if you top or bottom balance. You should be using a BMS, period.

I wouldn't suggest running an inverter through the BP as you're going to have super high inrush currents at power on and that will most likely shut off the BP or damage it over time. And if this is an inverter/charger, the charger will damage the BP. You should have a BMS that will turn off the inverter in the case of a low voltage event. However depending on model of inverter, you may not have a remote port (though most do).

I too have a battery bank that is DIY. Check out electrodacus SBMS0. It's a cheap solution that you can use to disconnect your loads and disconnect your chargers (as long as they support a remote disconnect) or you can run your charge sources through a second battery protect like I'm doing an let the BMS disconnect the BP in lithium mode.

@nebulight: thanks for your response. I'll look into BMS (and probably return the BP). I hadnt heard of that electrodacus previously but it looks promising, especially for the price. Thanks again everyone.

I was having the same issue and saw the thread linked below. It says you should not have the BOP between Inverter and Batteries as I had done. Anyway, read though.
https://community.victronenergy.com/comments/18261/view.html