Charging 3 battery banks

[Wanderingmac]

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.

 

[autorouter]

Installing 350w solar - would this be overkill for leisure battery?

Not really, you'd need that much to run a compressor fridge for example. Maybe in the summer the batteries would be full by 9AM, but in the winter they would struggle even with that amount of solar. Once the batteries are full the controller dials back and doesn't generate any more power, so no problem.

1. how would I then connect all these 4 batteries to mains charger?

If the extra bank of 2 batteries was separate, you could have a separate mains charger - a multistage intelligent charger with settable charging profiles so you can match it to the battery type. With a lithium profile for future upgrades.

 

[autorouter]

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?

Use a Battery-to-Battery charger (B2B), which is a charger that takes power from the alternator and sends out the correct amps and volts to charge a battery. Again they have settable charging profiles. There are a range of outputs available, from a small 20A to a big 70A, or even larger. Also called a charge booster or DC-DC charger.

In theory you could use a second split charge relay, triggered by the D+ signal, that connects the two extra batteries to the existing starter and leisure batteries while the engine is running, and disconnects when it stops. But I think a B2B is better.

 

[RogerIvy]

How big is the space where your leisure battery is?

 

[mitzimad]

wiring a second battery to the existing even under the bonnet shouldnt be that difficult as the wiring would go under the vehicle and up through the floor where the second battery is situated keep it towards the front as a crafter is a long run back to front

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[RogerIvy]

If your battery bay is 190mm wide, 367mm long and 240mm high you can fit a 304AH LifePO4 battery in there.
I don't know what your electrics are ... so don't know what would need to be changed.