Radio back up.

[ericmark]

There was already a hole for radio so I bought a cheap car radio to fit hole. As with most car radios there are two live supplies, one permanent the other when engine switched on, but with caravan only one feed so both wires connected together.

This was not a problem, some one had by-passed the master switch, so only if battery was removed did radio loose supply. However that has been fixed, so master switch now turns off radio, also when car power is connected as the relay changes over there is a short loss of supply, this results in the radio auto switching on and going into demo mode, it takes some time to start playing so you don't notice what has happened some times, and you return to caravan with radio running quite loud.

I am sure I can make a back-up battery for it, but before I re-invent the wheel, is there a ready made back-up system for car radios fitted into caravans?

 

[Woodentop]

I have replied to you on the same question in the Caravan Talk Forum - if anyone else is also interested.

 

[audiorob]

Unless I misread your posting I would only expect the radio to run from the caravan 12v system when the master switch is on, and the only feed I would expect from the car when towing is for the fridge. Can you not insulate the 'spare wires' and leave it at that?

 

[ericmark]

There are two independent supplies from the car, until this week the relays were by passed and the tow car is not wired to S socket, however I have every intention of swapping tow car so decided I should correct faults on caravan and return it to standard.

I had a 7Ah 12 volt VRLA battery I was using to emulate a tow car to help fault find, I found two faults, one a poor connection on fuse, and two a blown fuse, both faults had been pre owned by me bypassed which made fault finding harder.

However during this I found when the relay is activated it removes and reinstated power to radio, this means even if the radio is turned off, it auto turns on at a default volume on demo mode which delays sound coming from radio so one can walk away unaware the radio has turned on and one returns to find it blaring away.

The radio has two feeds which I have linked together, one ignition and one perment, as yet not measured my normal meter is a clamp on and only measures A.C. current, so I need to get the AVO Mk8 set up to measure current. I hope the non ignition supply requirement is very low, but as said not measured,

So it seems three likely methods, one is a 9 volt battery to non ignition supply and accept it will need changing every so so often, same but with a rechargeable battery diode and resistor so it recharges when there is power, and third is a capacitor with diode will not last as long as battery, but would be long enough to stop the radio switching on every time car is plugged in.

However I don't think my problem is unique, so I would guess there is a ready made device, hence the post, much easier to buy it ready made, specially with demise of Maplin so harder to buy parts I need.