Charge 3 battery banks advice

[wanderinmac]

Hoping to start converting new Crafter with factory fit leisure battery. Installing 350w solar - would this be overkill for leisure battery? Could add additional leisure battery but this may prove difficult as I understand leisure battery is in engine bay. Think perhaps it would be simpler to add extra bank with 2 matching leisure batteries and connect these to solar panel.
1. how would I then connect all these 4 batteries to mains charger? 2. Also how could I charge both starter battery and factory fit leisure battery from solar panel as well as charging new battery bank? 3. Both starter battery and factory fit leisure battery would be charged from alternator whilst driving. Is there any way of also trickle charging new battery bank also?
Lot of detail here and probably very confusing but any advice greatly appreciated.

 

[Pauly]

Having 3 separate battery systems on the go will complicate things and limit what products you can find, there are various charging/voltage converting devices out there that are designed to interface with 2 separate batteries but 3 ?? and even the ones that do 2 will generally prioritise one output (the leisure batt/s) and then switch to the other output when its done (the engine batt)

I personally would consider either making the factory aux battery linked to any additional ones you are thinking of putting in (this may mean replacing it) or scrapping the factory one in place of a couple new ones ?

Consider if they were all separate what equipment would run from what battery bank and why
If you are intending to fit reasonable size solar then you have a good chance of keeping them healthy and running even if you go off grid for periods

I always think the best way to design these situations is to start from the end and work back, have a think about what equipment you are wanting to run and how long you are wanting to run it for in situations with no charging ie off grid and no sun, this info will help you decode what battery capacity you will need, once you know what rough size you are planning to install then you can think about charge rates etc but that will largely depend on if you intend to be mostly in campsites with hookup (so mains chargers would be more important) or off grid roaming away from electricity (where solar would be more important)

Im sure others will have different views but the more info/decision you give about intended use etc the more you can narrow it down