On my boat, I have a multiplus inv/ch 3000. When connected to shore power, the starter battery isn’t being charged. (I checked the shore power and it works)
1- Is the battery supposed to be connected directly to the Multiplus?
2- Isn’t there supposed to be a battery charger?
(I also have solar panel system with Lilthium batteries.)
The starter battery positive needs to be connected via a fused wire to the starter battery terminal in the Multiplus. The starter battery and house battery need to share a common negative. See the manual for your specific Multiplus.
See this FAQ for more info on how it works and if it is suitable for your lithium set up.