Battery Charger

I will try to attach the Electrical Schematics for the Hymer - if it dosent attach - PM me and i will send to you.

I can't see a fuse on the PCB - this is a 1990 B544 Hymer

(First time poster - Hi all & apologies for resurrecting an old thread!)

Bought our first Hymer couple of weeks ago - it's a 1992 Hymer Camp 56 LHD German imported at some stage.
Am still familiarising myself with its systems and tracking back over years of mods/add ons going over how stuff works & what doesn't work.
The leisure battery mains charger is a Elektromatic LA110K & was not outputting any voltage at all.
A very quick look today I found the internal transformer fuse blown - replaced it & still no output.

Is it worth getting this charger repaired? I know it is the original as fitted.
But I have to replace the ~10yr old leisure battery anyway as it is only charging to 10.6V; would I be better to fit a more modern multistage battery charger at the same time to maintain the new battery(s) in prime condition (with perhaps an integrated solar PWM controller to give future options)? While solar is not a pressing need for as, there already is a (non working ~3V) solar panel fitted on the roof. This solar panel seems to have been wired directly to the output terminals of the LA110K???? - The charger says Solar on the front plate & there are 2 sets of +/- terminals; one set going to leisure battery, one set direct to the solar panel.
Is this a common setup on these?
Also, I am considering 2x Trojan 105Ah in parallel; is this overkill? Would the old Fiat 2.5D alternator handle charging them?There was another 45aH general battery added in parallel to the 96Ah leisure battery at some stage (2010); can't see that setup having worked very well.

Any advice you guys can give would be greatly appreciated & may save early mistakes in choosing something unsuitable.

Also if anyone had the electrical drawings of the Hymer Camp from this date or something similar.

Thanks

Thanks insider.

Lots of questions I know!

I am thinking the primary charge for the Trojans will be the mains battery charger from EHU onsite & regular EHU when parked at home. Supplemented by the alternator when traveling to/from - as you say, I suppose this wont give much really to the leisure battery by the time the starter battery is topped up. Then eventually the system be supplemented by solar panel which I will replace in time (more a trickle charge topup).

The existing solar panel seems to be shot - I disconnected the cabling coming from the panel into the LA110K & I am only measuring ~3Vdc on the wires in (somewhat cloudy) daylight.

As we are new to the van, we are obviously still guessing how we will use it exactly - I would like to do a little bit off grid; maybe a couple nights parked up without EHU or starting the engine & mix this with campsites with EHU - I am in the process of replacing all the non working incandescent and fluorescent habitation light fittings with LED fittings, so the biggest 12V draw I can see would be the blown air fan (max 30mins operation/day) followed by the water pump (occasional use). Couple of USB chargers 12v-5v won't be a big load. Fridge & cooking & heat source will be on gas.

So I wonder am I going overkill with 220Ah capacity? Bigger battery bank obviously more power when required, but takes longer to charge up again.
What are others experience on this?

All suggestions are greatly appreciated; no advice is bad advice at all - I will do my homework on all suggestions made thanks again!