Thanks for the replies. The MPP unit hasn't arrived but I wanted to know if the lithium batteries would be compatible with the MPP unit. I noticed You Tube Will Prowse is using a lithium battery for his unit. When the unit shows up I'll try the things suggested. I wanted to get ahead of the game that's why I posted my dilemma. The batteries are Renogy Lithium with Reliable BMS System, the state-of-the-art battery management system (BMS) with high-performance dual-processors provides short circuit, over charging and over-temperature protection while maintaining a balanced voltage across all cells................. Flash!!!!!! Just received a message from the seller, Maximumsolar_US:
This is OK.
"Voltage Range:10~14.8 V" -- this tells you the min voltage is 10v so you set low volt cut off = 40V and 14.8v is the max charging voltage so you want to set bulk/float voltage as 14.8*4=59.2v