Rewiring interior lights to secondary battery

[ImaginePineapples]

Hey guys

Not sure if what Im wanting to do is possible but worth a shot. Im doing a camper conversion on my 2002 bongo. It has two interior lights that run off the starter battery, going through the fuse box under the steering wheel. I would like to rewire this to not run off the starter battery but my secondary battery so I can use the lights already installed without draining the starter battery. I have looked at the fuse box and have identified the right fuse, labelled 'ROOM'. There is only one whire wire going into the back of the fuse (is this + or - ?). would it be possible to just cut this wire going into the fuse box, and re run it to the possitive terminal of the secondary battery (installing an inline fuse possibly). In this case, what would go to the negetive terminal of the seconday battery? This solution seemed too good to be true.

I am awfully confused, any help would be appreciated.

Thank you!!!

Heres is an image of the back of the fuse box. The white wire runs to the ROOM fuse:
https://ibb.co/gZkDJtL

[Doone]

Geoff posted a wiring diagram in his reply to this post, it may help you. viewtopic.php?f=3&t=72649&p=p681864

[g8dhe]

Its normal to just use a "Swap loom" this moves across up to 4 circuits that are likely to be used when the vehicle is static, it also doesn't require any wire cutting or alterations to the existing wiring. You can make your own or buy a kit along with a Split Charge Relay https://www.ebay.co.uk/sch/bespokeautoe ... pg=&_from=
The swap loom plugs into the lower of the two two fuses connections for each circuit and the fuse is transferred to an new fuse block fed from the lB itself. this way no wire cutting or loom breaking is involved.

[Roy748]

Hello
As g8dhe mentions it best to fit a split charge relay, mine is a 2001 model so has the same configuration as yours I believe. There is a great YouTube video on installing a split charge relay which should help you fit and achieve what you are looking for.

[Rickster]

This is quite simple to do, assuming the fuse box is wired the same as a 99 van.
You may find the radio itself connected to the interior lights, if this is the case, either leave it wired to the engine battery or migrate it to the other side, a lot of house stuff, radio included, has been migrated on mine.
Behind the fuse box is a maze of wires, start by pulling fuses out one at a time on the top set, the middle & bottom fuses are for other stuff, usually switched via the key.
The wiring for the lights is branched, this cannot be seen without taking apart the loom sheath.
Bringing in another fused wire from the LB would go to the wires for the lights, the ground is something to forget about, the LB itself should be chassis grounded.
If all this sounds too complex, just get the conversion loom instead, it might be easier.
Hope this helps in some way.
Stay safe, Rick.