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christian-bell avatar image
christian-bell asked

Two BP65 - one for DC loads and one for 100/50

Hi,


I have a 100Ah 24V lithium bank with a housepower bms. There are currently a couple of te connectivity relays as a failsafe, one between the battery and the dc loads, and another between the battery and the mppt 100/50.


I'm looking at replacing the relays (they use 130mA at ~26V each) with a pair of BP65s. This should be a fairly painless swap as my existing relays use M6 bolts also, I'd just need to run the negatives to the bms so it can activate the BP65s

So:

BP65 #1: Lithium battery positive to BP65 IN, then BP65 OUT to DC loads

BP65 #2 MPPT100/50's battery positive terminal to BP65 IN, then BP65 OUT to lithium battery positive


The #1 scenario seems pretty standard, just not sure about the #2 scenario. WIll this work ok?





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1 Answer
wkirby avatar image
wkirby answered ·

Are you using the VE.Direct port on the MPPT for anything? If this port is currently unused, then you could simply disable the MPPT with a signal from the BMS. Saves on having 2 BP65's and is more elegant.

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christian-bell avatar image christian-bell commented ·

Hi, Thanks for the reply.


I like the idea of disabling charging by the bms and the VE direct pin. I recently purchased the smart version of the 100/50 to replace the original one I had so I'll be using the bluetooth functionality for monitoring from now on, so the VE direct port would be free. The bms uses open collector outputs, I'd have to do some research on that, but what would happen if my bms died, wouldn't the charging be permanently enabled then?


I really still want the bms to be able to disconnect the loads and the charger from the battery if the voltage gets too low.This setup is in a location about 2 hours from where I am, and my family use it but don't really have much idea what is going on behind the scenes.


I'm happy to implement the VE direct charging disable. Just think I still need to be able to isolate everything worst case scenario? Maybe I'm overthinking it.


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