Charging issue under load
Discussion
I have a TVR S3, so Ford Granada 2.9 mechanicals, so nice and simple electrics. When I put the lights on the voltage drops below the required 12v, side lights drops a little, dipped beam a bit more, then with the indicators on the voltmeter goes up and down with the indicators. Without the lights on, everything is fine. Am I looking at a tired battery or tired alternator? I don't want to replace both if only one needs replacing.
grumpynuts said:
I have a TVR S3, so Ford Granada 2.9 mechanicals, so nice and simple electrics. When I put the lights on the voltage drops below the required 12v, side lights drops a little, dipped beam a bit more, then with the indicators on the voltmeter goes up and down with the indicators. Without the lights on, everything is fine. Am I looking at a tired battery or tired alternator? I don't want to replace both if only one needs replacing.
Or a crappy Earth. Our TVRs have always had the habit of cooking alternators into early retirement but you can do a very simplistic initial test by revving the engine up and seeing if the voltmeter goes up.
Re the battery, you'll know how old it is and how Much of a beating it's had.
Can you get hold of a voltmeter to check both and their currents etc?
But the other thing to consider is that TVRs had rubbish earths to start with and they deteriorate over time and all too often low voltage and current issues are a result of an Earth cable needing replacing.
The other thing with cars like this is that the noise the starter motor makes tends to tell you a lot.
When we've owned older cars for a long period we instinctively know when firing them up whether the starter is getting a full kick from the battery or something less than normal. You kind of develop a sixth sense for when it's more likely to be the alternator or the battery/earth.
When we've owned older cars for a long period we instinctively know when firing them up whether the starter is getting a full kick from the battery or something less than normal. You kind of develop a sixth sense for when it's more likely to be the alternator or the battery/earth.
Thanks guys, I have a voltmeter, I will try it out, I did wonder about a poor earth. I've only had the car since April and have no evidence of the battery being replaced recently, but the alternator was changed not long ago, but can't determine whether it was a new or recon one. It starts well and the battery seems strong, but you never know what lurks within the electrics of an old car, especially a TVR.
It is very normal to have voltage drops in the wiring of these cars.
Before you worry yourself too much, measure the voltage directly at the battery. I wouldn't be surprised if you've got a drop of a volt or so by the time you get to the lights, and that's enough to be very noticeable.
Before you worry yourself too much, measure the voltage directly at the battery. I wouldn't be surprised if you've got a drop of a volt or so by the time you get to the lights, and that's enough to be very noticeable.
grumpynuts said:
I have a TVR S3, so Ford Granada 2.9 mechanicals, so nice and simple electrics. When I put the lights on the voltage drops below the required 12v, side lights drops a little, dipped beam a bit more, then with the indicators on the voltmeter goes up and down with the indicators. Without the lights on, everything is fine. Am I looking at a tired battery or tired alternator? I don't want to replace both if only one needs replacing.
I think you might be worrying about nothing, volt meters in cars are never that accurate, is it starting ok? is the battery going flat? if not its just a quirk .The wiring on older tvr's was never the best, if in dought put an extra earth or two on, and make sure the ones there are clean.
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