garethgb21 Posted March 31, 2015 Share Posted March 31, 2015 Hi, We recently bought a TV online for out German made 1991 camper . It works fine on 240 volt, but won't work on 12 volt. It tries, flashes then goes off again. Frustratingly, it worked just once today, then stopped again. The seller re sent me a replacement 12 volt adapter, but this says 15 volt on it, but the seller assures me she has never had an issue with the adapters. Has anyone got any ideas? Link to comment Share on other sites More sharing options...
PeteH Posted April 1, 2015 Share Posted April 1, 2015 Hi Check your Habitation battery voltage. Especially if it is not new it could be showing 12+V but drop under load (the T-V, water pumps, lights, etc;), to much less. Also often the sign of a cell going down. Charge the Battery, take the battery OFF charge and disconnect the earth lead. and let it Stand for at least an hour then check the voltage (Use a digital meter if you have access to one). That should show about 12.5V for a battery in good condition unconnected to any circuitry. You can also test the "old fashioned" way with a Hydrometer, the actual readings are not too critical but the comparison between each cell will tell you if you have a "weak" cell. Virtually all these T-V`s have a voltage below which they will not work and if it`s 10V (sometimes even higher!) or less Forget it!. Also CABLE size is important, Voltage drop is proportional to the length and Cross section of the conductor. bigger dia and shorter is best. Long thin leads (and `van cable runs!!) can seriously reduce the voltage at the Consumer (in this case the T-V.). Less sophisticated Adapters are less tolerant to battery voltage fluctuation but 15V is probably the rated input. supplying it with 12V should`nt make a big difference. There are also complications with mains Voltage settings, which less sophisticated adapters will not cope with. Pete Link to comment Share on other sites More sharing options...
StuartO Posted April 1, 2015 Share Posted April 1, 2015 I have a similar problem. I chose a domestic TV which used a transformer, nominally 12 v output, and installed it for use in the MH connected to the 12v supply. Some of these TVs are very voltage sensitive and the bare 12 volts supplied by a MH system (because there will inevitably be some voltage drop from the battery as the cabling meanders towards the TV) will be barely enough (and perhaps not enough) to run the TV. Try plugging the TV's transformer into the mains and measuring the output voltage - you will probably find it is significantly above the nominal 12 volts. Our domestic TV is slow to come on when running on 12 volts and the sound takes even longer to materialise than the picture. But as long as the leisure battery is well up, it works satisfactorily once it has started up, so maybe it needs a bit of extra voltage to get going. If the leisure battery is low however it might struggle to get going and if we watch it until the leisure is getting substantially discharged the sound goes off. It sounds like your TV might be designed to run on 15 volts rather than 12, in which case it might run while your MH engine is running (when the alternator is producing 14.3 volts) but not just on the leisure battery at 12.6 or less. Try it and find out. The remedy is of course to buy a proper, purpose designed 12 volt TV from a camping shop - but they cost more. Link to comment Share on other sites More sharing options...
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