Help a numpty please

[tight fart]

I'm replacing the radio in my camper, the old radio would work on either the 12v supply when the ignition was on, or the leisure battery 12v supply if that was switched on.
The problem I have is I can get everything to work as it should but when I'm on the 12v from the leisure batteries it's putting 12v back into the van circuit powering up the dash lights!

Any ideas how I stop that?

[Torquey]

Also a Numpty here but isn't a relay needed? Not sure where or how it fits in though.

[tight fart]

I'm going with 2 10amp diodes one on each feed, what could go wrong?

[Alpha Omega]

Please post what you mean by dash lights, illumination or ignition/oil/handbrake etc

[tight fart]

Ignition lights etc

[Alpha Omega]

Have you got a Aux position on the key?
Are you sure the diodes are working ok and pointing the correct way?
Diodes aren't the best method for this job. A change-over relay will do a better job
Do you want a diagram for wiring in a change-over relay?

[tight fart]

No aux position on key.
I don't have any diodes yet, just trying to stop feed no 2 reverse powering feed 1.
If that makes sense?

[Alpha Omega]

Given this some more thought, we have both overlooked the obvious
The leisure battery is charged from the campers alternator and will always be above half charged and also charging when running the engine
A very easy solution is to power the stereo from the leisure battery and not the camper battery through the ignition
Bear in mind that any stereo will put a permanent drain on a battery even when switched off if it isnt wired through a switch, in your case at present the switch is the ignitition switch and you will no longer be using the ignition switch because the stereo will only be powered by the leisure battery

Wire a on/off switch in the cable that goes from the leisure battery to the stereo, you can fit the switch in the back or front of the camper
Dont forget to also wire the stereo memory wire to the leisure battery, the memory is a permanent supply and does not drain the battery when the stereo is switched off

The switch that you fit and wire must always be switched off when you are not using the stereo otherwise there will be a permanent drain on the leisure battery even when the stereo's own built in switch is turned off

[tight fart]

Yes thanks for that, i am hoping to get it working as it should not with a switch, if all else fails ill go the switch route, for now ive ordered a couple of 10amp diodes and will try that first.

[Alpha Omega]

tight fart said:

Yes thanks for that, i am hoping to get it working as it should not with a switch, if all else fails ill go the switch route, for now ive ordered a couple of 10amp diodes and will try that first.

Why?
I have already explained that there will be a permanent drain on the leasure battery if there is no switch fitted
Why ask for advice and then ignore it and carry on with your own idea that doesn't work?

Edited by Alpha Omega on Tuesday 20th June 09:51

[tight fart]

2 reasons, first is there will not be a permanent drain on the leisure battery as it's only on when when in use, most of that time is also on EHU so it's also being charged.
2nd I asked someone else and they advised a different solution.

[Penelope Stopit]

tight fart said:

2 reasons, first is there will not be a permanent drain on the leisure battery as it's only on when when in use, most of that time is also on EHU so it's also being charged.
2nd I asked someone else and they advised a different solution.

OK that's good that you have the leisure battery switched off but still charging when not in use and this set-up does overcome any current drain problem
The only other thing I am able to suggest is that a change-over relay is by far better than using 2 diodes and is very easy to wire up
Have fun whatever you decide on

Penelope Stopit alias Alpha Omega

[tight fart]

Thanks, change over relay sounds good, I'll order one and have a play.

[tight fart]

So would one of these work?
And I'm guessing 85-86 live & earth,
30 feed to the radio
87 feed from ignition
87a feed from leisure battery?

[Penelope Stopit]

85 and 86 earth and ignition
30 feed to the radio
87 feed from vehicle battery
87a feed from leisure battery

And enjoy the sounds

[tight fart]

Are you sure it's not 87 from ignition?

[Penelope Stopit]

tight fart said:

Are you sure it's not 87 from ignition?

Yes i'm sure
What you get is stereo is powered from terminal 30 and is supplied from 87a which is the leisure battery
When you switch the ignition on it will click the relay in and then what you get is stereo is powered from terminal 30 and is supplied from 87 which is the vehicle battery

Never connect switched supplies to the contacts of a relay, use the switched supply to click in the relay. In your case the ignition switched supply will click in the relay

[tight fart]

I've confused myself here as I only have 2 power feeds, both switched
1 from the ignition that is currently powering the radio
And the 2nd from the leisure battery that I switch on when required when the ignition is off.
Do I add a third permanent power feed?

[Penelope Stopit]

[tight fart]

Thanks so much for your help, you got me there in the end, all working as required. Cheers.