dc to dc battery charger

Hi , am considering fitting a lithium battery to my kingham as the leisure battery getting a bit tired .am aware that I will need to fit a dc to dc battery charger to get the correct charge from the alternator , wondering if anybody else has done this as need information on what to do regarding the the split charging relay , any advise would be helpful on this

Interested in the wiring set up not about the cost!!

Now sorted , Seargent electrical very helpful and gave me the information required

I'm interested in doing the same, any chance you could share the info from Seargent?
Cheers

I spoke to a chap called Andy at sergeant technical, very helpful and emailed me all the wiring diagrams for there equipment ,it is straightforward but a relay is required to isolated the vehicle battery when the ignition/engine is started , it is normally closed and opened( disconnect ) on energising.The relay is fitted on the vehicle battery positive OUT on the EM 40 and relay is activated by ignition or D+ on the alternator , I have not fitted the relay yet but I disconnected the vehicle battery out plug on the EM40 on start up to simulate a relay disconnect and the fridge auto switched to battery feed as normal so all appeared to function ok on that side