Quote:
Owen_Dyneto wrote:
Rusty says The only way for the ammeter to read in reverse is if the battery is reversed.
There is another reason: If the ammeter reads in reverse with the battery connected as positive ground, then the ammeter leads have been reversed.
Technically you are correct. But the questioner does not mention reversing the ammeter wires. I think he would remember if he did this. He also seems to think this is a new problem, one that did not occur before changing the battery. Therefore the battery seems the likely culprit.
If you want to get real technical there is yet another way to get an ammeter to read in reverse.
It is possible to charge a battery BACKWARDS in other words, change the + to - and the - to +.
A friend had this happen years ago. He accidentally left the lights on in his Triumph TR3, killing the battery. A tow truck gave him a boost and he got in the car and drove about 50 miles.
Unknown to him the tow truck driver who was not familiar with English cars (+ ground) had connected the jumper cables wrong way round. On starting the car the generator became polarized in reverse and the flat battery charged up backwards.
He also told me if this ever happens do not try to change the battery back. You may get away with reversing the polarity once but if you try to do it again you will ruin the battery.
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