Car stereo dual power feed

[MagicWagon]

I am fitting a new stereo to my wagon and was thinking of running the power feed via a 2 way switch so I can choose whether it is fed from the accessory feed (I.e first key position) or the leisure battery. I think his would give me the best of both worlds so normally it goes on and off automatically but when parked up I can run it off leisure. Is there any reason why this wouldn't work ? Also where should be the easiest place to take an accessory wire feed. The old stereo was fed off a permanent live.

[CJH]

If you just connect it to the leisure battery then you get the best of both worlds anyway, provided you have a split charge relay. The radio will work without flattening the starter battery when parked up, and when the engine's running your leisure battery will be connected to your starter battery via the relay, so it's the same as connecting the radio to the starter battery.

EDIT: Of course, you'll have to remember to turn the radio off yourself.

[MagicWagon]

But then it won't go on automatically when I turn the ignition on and turn off automatically when I leave the van. 95% of the time it's a daily runner and i`d like that convenience coupled with the ability to not use the starter battery if using it when parked up.

[CJH]

True - our posts crossed. I edited my post as you were replying.

OK, if you need that feature then the switch will work.

[Bubble Meister]

I have done it with a switch like this:
https://www.google.co.uk/search?q=doubl ... iywj41M%3A" onclick="window.open(this.href);return false;

I wired 1P as the constant positive to the stereo and 2P as the ignition live. On one 1P use one input 1T from the driver battery and other one 2T from the leisure. On 2P use 1T from the ignition live. Bridge from the other 2T across to this 2T to act as the leisure battery's ignition live.

I traced one wire from the leisure battery behind the passenger seat, under the cab mat to the switch mounted under the dash.

[marlinowner]

Does the radio keep its memory when switched as there will be a moment when there is no supply from either battery?
Otherwise power radio from leisure battery but with a relay in the switched supply, energised by ignition. Could have a 2 way switch in the radio switched supply so feed is taken either from normally off or normally on relay connections, so radio can either be switched by ignition or not.

[MagicWagon]

Marlinowner. The radio has a separate power input for keeping the settings when the main power is turned off. I was going to feed that from the existing "always on" power which fed the old radio. I better check the current draw on that I guess, but I wouldn't think that drains it much.

Bubble Meister. I'm no electrician, so I confess I haven't got my head around the wiring you describe. What would be the advantage of using one of those switches over a simple 2-way switch with leisure battery on one input and switched ignition on the other ?

All. I spent the last half hour trying to interpret the haynes manual wiring diagram. Am I right that I should be looking for a black wire to tap into to use as the "ignition switch" input ? Is there an easy place to find a suitable feed ? Can't see one so far ?
Thanks

[marlinowner]

I'm not sure how radios are wired internally, but I would worry that if the permanent supply is from one battery and the switched supply is from the other, when the radio is on then the batteries are connected together.

[MagicWagon]

Marlinowner. I hadn't thought of that. I just checked and found the following
- permanent live feed (i.e what was on the old radio) is linked to the starter battery (0 ohms between there and battery +ve when ignition is turned off. (I plan to use this as the permanent live to the radio).
- With the above lead connected to the radio, and the leisure battery connected to the yellow "Accessory" live feed on the radio, there is no circuit between the two live feeds.
Hopefully that means I can go ahead with my plan for a 2-way switch.
Still can't find an easy place to take a feed from the "ignition" live though. I guess if I take the steering column shroud off I should be able to find something in there.

[ghost123uk]

I'm not sure how radios are wired internally, but I would worry that if the permanent supply is from one battery and the switched supply is from the other, when the radio is on then the batteries are connected together.

Just popped in to say that ^^^ isn't a problem, the permanent feed is independent and just feeds 1 x I.C. only.

[Mocki]

There is no aux feed on a t25 ignition switch , first click of the key is nothing !

I powered my wireless via a 5 pin auto relay , so when the engine is running it runs from the main battery , and when the engine is off it is powered from the leisure battery . I have kill switch on the out put from the leisure battery so off this is off nothing gets power , so turning the engine off turns everything off as you exit the van .

[MagicWagon]

But if I understand that correctly, unless you flip the leisure kill switch to off, when you turn the engine off the radio will then run from the leisure battery ? If so, that is not what I'm after. I want the radio to ordinarily turn itself off when I take the keys out/stop the engine or whatever (just like in a modern), and then on the odd occasion I want to run the stereo from the leisure battery I can flick my 2 way switch.
So, if the T25 has no aux position, where would the best place/which wire would I take a feed from ? I'm happy to compromise and only have it come on when the engine is running if that's the only way.

[Mocki]

If the kill switch to the leisure battery is off then it will behave just as you want , when the engine stops the radio goes off , you remove the key and get out
You get in, start the engine, once the alternator has started charging ( alternator light gone out ) the radio comes on, like a modern car , if you want to sit in the van and listen to the radio, with out the engine running flick the kill switch on, and the radio works .....

You don't have to have the kill switch killing every feed from the leisure battery , just the radio if it suits you .
Mine is this way so nothing is powered by the main battery when the engine is not running and everything is when it is, and nothing from the leisure battery , ensuring that the leisure battery gets only a full charge when driving and the main battery is as full as when you switched the engine off when you next want to start it ........

[MagicWagon]

You don't have to have the kill switch killing every feed from the leisure battery , just the radio if it suits you .

So I guess that would be exactly like what I am trying to achieve, except my "kill" switch would be a 2-way switch which would be mounted beside or near the radio. Also, I guess having this switch up front means if I turn the engine off and am just sat in the front and still want to listen to the radio, I can easily turn the radio on again without starting the engine.
I still need somewhere to feed the radio power from when the engine is running though.
I think I may have an answer. My main split-charging relay looks like one of these http://www.autoelectricsupplies.co.uk/product/824" onclick="window.open(this.href);return false;
and from the diagram on that page it looks like terminals C2 and C3 are both connected when the engine is running. C3 on mine currently has nothing connected, so I think if I connect C3 to one input of my two way switch, and my leisure battery to the other input, then that should give me what I'm after. I'm sure there must be somewhere nearer to the radio that I could take my "engine running" feed, but I'm reluctant to go guessing at which wire to splice into, and don't trust myself enough to think I understand the haynes diagram.

[Mocki]

Depends on the age of your van , but on later fuse boxes there are some spare ignition only feeds
But the original radio wiring is already a key on supply anyway