Common port Daly and Morningstar MPPT....Possible solution?

MorningStar documentation warns that if the BMS drops off charging connection while PV is producing voltage, it will damage the controller (TriStar MPPT specifically). They even go so far as to say that to remedy the situation with a relay to cut of PV from charger likely wouldn't happen fast enough to avoid damage. True or not? Too expensive to test their theory.

I have some 25Ah lifepo4 cells lying around and I thought that maybe I could use those to maintain the power to the controller should the BMS disconnect it.

Do you see any reason why this wouldn't work? It has been suggested to just connect the charger directly to batteries but I'm not comfortable doing that. I mean eventually something will go wrong with the charger and the battery no longer has any protection.

Frankly, If that is what MorningStar is saying, I would not use it. I would rather spend the money to get a controller built for LiFePO4 than to try to kludge the MorningStar into place.

(BTW: Even if the Morningstart has a LiFePO setting, if it has this restriction I do not consider it built for LiFePO).

I already have the controller. Four years now. It doesn't have a lithium profile

I agree with the points you make and not sure why it is designed that way. Irregardless of the battery type, that is not acceptable.