Kelpie
Well-known member
Thanks Poey, my thinking was to charge the LA with the solar and mains battery charger in the usual way, and let the B2B charge the LFP? I'll check out those videos...
I am going down essentially this route, with two differences.
Firstly, I am building the battery myself using prismatic cells and a basic BMS (total cost £407, for 4x272Ah cells and a 120A BMS).
Secondly I am adding more solar panels and these will charge the new battery. This is much more efficient than using them to charge the lead-acid and then charging the lithium using the B2B.
Small update- good news, the BMS arrived. I chose the JBD, which is the hardware used by Overkill Solar who are well regarded as a basic value-for-money option. I did look at getting an Overkill but they said they wouldn't have the model I needed in stock for at least a month. Bad news, my PSU is playing up again, I caught it creeping up to 20v (I don't think the cells were seeing that- but I knew something was wrong because the current had increased). So I've stopped charging for now, and will resume once I have the BMS connected. I'm not sure what to do about top balancing now, since I no longer trust the PSU...