PaulTobiasx1/9
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- Sep 24, 2007
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You may have a parasitic drain. Something is drawing current when the car is shut down and slowly running the battery flat. It's normal to have a small draw but things like incorrectly wired aftermarket radios or lights in the boot than do not switch off will draw too much.
Here is a procedure from the Guides section for chasing parasitic drains. https://www.fiatforum.com/punto-mk2...alternator-parasitic-drain-testing-guide.html
To check your alternator. At idle with no extra loads on you should have approximately 13 Volts at the battery. This should increase to about 14.4 at 2000 rpm and level off.
Thanks for response Brendan,
I don't believe it is parasitic as I did a test with multimeter (disconnected negative cable and connected from there to negative terminal, looking at the guide I'm supposed to do this with actually the positive terminal though ?). I'm pretty sure the drain was less than 50mA.
I did do a test guessing 2000 rpm (my cheap punto doesn't even have a rev counter). And I'm pretty sure the test was sort of inconclusive, if you read further back I mentioned that when I did the test the voltage did not get to anywhere near 14.4, and with electrics on (which I definitely need this time of year here in Finland) the voltage was only about 12.5V. Some people said this is normal but looking at the guide you linked me to, it said the voltage should only drop slightly. It dropped loads.
Summary,
- I don't believe anymore that it's parasitic drain but maybe I need to test between the +ve cable and terminal instead of -ve.
- Voltage at battery last time I tested properly with rpm was only about 12.v with necessary electrics on. When I tested this morning I was getting about 13.8v idle with no electics.
I have a suspicion that the alternator can't keep up under electrical load but this seems to be a point that not everyone agrees on (answers on this forum claiming 12.5 was okay under load but the linked guide for example and also haynes manual saying that voltage should drop only slightly.
Cheers,
Paul