battery or alternator
Hi guys how can i tell if my battery or alternator is knackered?
My car wouldnt start the other day, the Battery was flat.
Jump started the car and it run all day even cheers starting after work, but the next day it was flat again.
Now i know the alternator can drain the battery if its knackered i also know there is a way to test which one is knackered but cant remember how.
Any help guys
measure the voltage across the batter posts with the ignition on but engine not running. if the battery is healthy it should be between 12.5 and 13v (approx)
now start the engine and give it a high idle. measure the voltage across the battery now. if the alternator is charging, the voltage should between 14.5-15v (approx) and shouldnt really get any higher with RPMs
the figures arent important, but it is important that there is a noticeable increased step change in the voltage when the engine is running.
The alternater is charging ok, i think this may be a case where the alternator is draining the battery when the car aint running
the alternator cant drain the battery, there is nothing on it to drain with!
Check that no interior lights or anything are staying on (radio too)
After you have checked the above, stick a new battery on it. I think thats your problem. As silly as it sounds, the cold weather doesnt help if you have a dodgy battery.
My Rebuild
They're over there with their new toys. Someone brought them in. No idea who bought them though.....
who needs the RAC with these guys
If the alternator is charging (approx 14v) then the battery is dead next morning, is probably the battery unless somthings draining it (glovebox light stay on??)
Right i have found out the if the regulator on the alternater is on its way out it will drain the batt.
Anyway it was the battery, it failed the dump test
if the ignition is still live to the excitor coils, then yes the alternator could drain your battery with the ignition off. but i feel this is an unlikely cause of your misfortune.
if it happens again, you could try a tong-tester on the battery to see how much drain is placed on it while the ignition is off. then pull fuses until the load is isolated. this will then determine the circuit at fault, and steps can be taken to fix the fault.
sounds like brake pads to me
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