UK Advice needed on narrow boat battery charging circuits please.

[Bernardo]

I've been asked by a keen DIYer friend to to advise on how to wire his boat batteries when he has three potential inputs. 1. Shore mains feed 2. Boat engine 3. Two solar panels.
I've drawn what I think would work but it's not my field, so advice would be appreciated.
I've advised him to get a specialist in but funds are limited and he's keen to give it a go. I've told him at least to get it checked / tested before he goes live.
I've attached some details of the equipment he has ready to go, he hasn't got a split charge unit yet and would like to buy Lithium batteries on the leisure side.
Thanks in advance, Bernardo

 

[davesparks]

You need a galvanic isolator in the earth coming from the shore power.

If using lithium batteries you will probably need a dc-dc charger to charge them from the alternator otherwise they won't charge properly.

You should check the requirements of the BSS (boat safety scheme) there are requirements for isolators, fusing, how and when connections to the hull should be made etc.

You need to make sure the chargers are compatible with lithium batteries, or that the lithium batteries are compatible with that type of charger.

You've shown the two batteries linked but also connected to two separate battery terminals on the charger, I'd expect this to be one or the other but not both.

Check the manual and connection diagram for the batteries carefully, the way you have drawn it would not be correct for some.