Not wrecking the van electrics when upgrading the leisure electrics

[AlBundy]

Hi everyone,

I have a 1986 t25, LHD bilbo conversion. The electrics are old and have been advised to update them to the Sargent EC155 PSU and peripherals as this is the easiest DIY option, and it gives a lot of functionality that I don't have I.e. charge batteries from mains, install solar etc.

My main concern is not actually fitting the new kit, it's removing the old kit without wrecking the van electrics.

I know I need a new battery, as the current leisure battery is actually in the engine bay running the vehicle, but what I need is some guidance on whether I can remove the fuse board, relay, switches etc without destroying the van electrics.

All advice welcome.

Pictures are of the current setup.

.

[AlBundy]

I should add that I do have do have basic wiring diagrams as below.

[AngeloEvs]

I’m a bit confused regards your current battery set up.  You say that your leisure battery is in the engine bay running the vehicle and needs renewing.  Do you only have a single battery that provides 12v for both engine, lighting, etc and the leisure electrical system?

You also show pictures of the main vehicle fuse/relay board which should not be removed if that is what you mean by interfering with the vehicle electrical system.     Most conversions have a dual battery system comprising of a normal starter battery for the vehicle and a second deep discharge leisure battery for the habitation electrical equipment.   A relay is the only item that brings both batteries and the electrical systems together and is energised once the engine has been started and is running in order to charge the leisure battery.  There is no need to interfere with the vehicle electrical system and it should be left alone.  I would advise fitting a deep discharge leisure battery and connecting your new distribution/charge system to that.  

[Oldiebut goodie]

Presumably a diesel.
Pics show one battery in engine bay and one under seat. So far fairly normal.

[AngeloEvs]

Ha, Oldiebut goodie, I missed the battery under the seat.  In the first post it states the leisure battery is in the engine bay and it runs the vehicle which got me a bit confused.  I can now see it’s a twin battery setup and the wiring sketch.  

[AlBundy]

Yes, someone switched them at some point before I owned it, I guess because the vehicle battery is no longer charging.

Thanks for guidance on the fuse box, was initially confused as a wire from the leisure fuse board went to the car fuse board, but on closer inspection it just goes behind it to some interior lights.

Will post up some pictures of the new setup when I get to it.

Thanks again!