Alternator output. Battery dying - Page 4

pletevl · 2nd December 2019, 13:09

No, I haven't tried anything yet, not had the battery on the car. And it's ruddy cold here :-)

Lee T · 2nd December 2019, 13:15

Quote:

Originally Posted by pletevl

No, I haven't tried anything yet, not had the battery on the car. And it's ruddy cold here :-)

Haha isn't it just! I've just washed my car so you don't have to tell me, I'm typing with semi frozen fingers and not the fish type either. Until you try comfortably numbs suggestion there's not much else to add that I can think of, but I'm not the best with auto electrical issues.

Comfortably Numb · 2nd December 2019, 23:10

As explained before, the alternator can continue to produce 14V, but if there's a leak, it drains out of the battery, via the diodes. Diodes are only supposed to allow current to pass one way, like a one-way valve, that is how they rectify the alternating current (AC) to Direct Current (DC) for the battery to store. Once you switch off the engine, and the alternator, the full battery slowly drains back through the faulty diode(s).

pletevl · 3rd December 2019, 05:23

Thanks. But surely I would be able to measure that with my amp meter.
All locked up, the car is drawi g around 18 milamperes (if I remember correctly) I'll recheck this weekend.
This is why I'm wondering if the battery is not being charged.
The first time it happened was after a 600 mile run to the UK. The battery was dead the next day.

Pete.

2nd December 2019, 13:09	#31
pletevl Posted a thing or two rover 75 cdti(rhd), MG ZR(lhd), MG TF(lhd), MG TF(rhd), mini mpi (lhd), Renault megane III (awful) Join Date: Mar 2014 Location: East of France Posts: 1,282 Thanks: 124 Thanked 114 Times in 93 Posts	No, I haven't tried anything yet, not had the battery on the car. And it's ruddy cold here :-)

2nd December 2019, 23:10	#33
Comfortably Numb Posted a thing or two Rover 75 Saloon Join Date: Dec 2017 Location: Penrith Posts: 1,336 Thanks: 165 Thanked 303 Times in 241 Posts	As explained before, the alternator can continue to produce 14V, but if there's a leak, it drains out of the battery, via the diodes. Diodes are only supposed to allow current to pass one way, like a one-way valve, that is how they rectify the alternating current (AC) to Direct Current (DC) for the battery to store. Once you switch off the engine, and the alternator, the full battery slowly drains back through the faulty diode(s).

3rd December 2019, 05:23	#34
pletevl Posted a thing or two rover 75 cdti(rhd), MG ZR(lhd), MG TF(lhd), MG TF(rhd), mini mpi (lhd), Renault megane III (awful) Join Date: Mar 2014 Location: East of France Posts: 1,282 Thanks: 124 Thanked 114 Times in 93 Posts	Thanks. But surely I would be able to measure that with my amp meter. All locked up, the car is drawi g around 18 milamperes (if I remember correctly) I'll recheck this weekend. This is why I'm wondering if the battery is not being charged. The first time it happened was after a 600 mile run to the UK. The battery was dead the next day. Pete.