Alternator output. Battery dying - Page 3

SD1too · 25th November 2019, 17:14

Quote:

Originally Posted by COLVERT

If the voltage at the battery terminals is around 14 volts ( tickover. ) the regulator is just fine.

Quote:

Originally Posted by pletevl

My alternator is pushing out 14.6 volts.

I expressed my concern at the beginning about your charging voltage.

Simon

pletevl · 25th November 2019, 18:21

Too high?
I don't understand why it's goi g flat in around 10 days.

COLVERT · 25th November 2019, 20:44

Quote:

Originally Posted by pletevl

Too high?
I don't understand why it's going flat in around 10 days.

There are, really, only two answers.

1/ The battery is a dud.

2/ You have a serious drain down to earth somewhere.

You have a good voltage at the battery terminals on tick-over so it is almost certainly not the charging system.

pletevl · 25th November 2019, 21:21

It's not the battery either. The old one is charged up and is holding its charge fine.

Comfortably Numb · 26th November 2019, 22:12

Pletevl, re-read my earlier post about the battery draining back through failed rectifier diodes in the alternator. If you disconnect the alternator wires (admittedly fiddly) and that stops the battery draining, you know where the fault lies!

Lee T · 26th November 2019, 23:04

Quote:

Originally Posted by Comfortably Numb

Pletevl, re-read my earlier post about the battery draining back through failed rectifier diodes in the alternator. If you disconnect the alternator wires (admittedly fiddly) and that stops the battery draining, you know where the fault lies!

I had a Rover 800 that did the same thing, but would flatten the battery in under 24 hours. A new alternator solved that, so well worth pulling the plug on it even if only to eliminate it as the cause.

pletevl · 27th November 2019, 05:16

Can a diode leak be tested with a multi meter or does it not show up?
And how fiddly is fiddly?

Mines not going flat overnight. It takes just over a week if the cars not used at all to loose about one volt.

Pete.

Lee T · 27th November 2019, 05:34

The plug can be removed with 1 finger and a screwdriver to push the clip down easily enough, getting it back on is the fiddly part. My battery drain was on a petrol 800 Rover and I'm assuming here but Mabey mine was a few diodes at fault and yours is just the 1, hence the quicker drain on mine. Either way Comfortably numbs suggestion is still worth exploring IMO.

pletevl · 2nd December 2019, 12:53

Hi all,

so, the battery has been off the car for just over a week, I charged it up and it hasn't dropped a volt in a week, it's still giving 12.7 volts. So, for me, the battery is fine.

Can an alternator give out 14 odd volts and NOT charge the battery ?????

Pete.

Lee T · 2nd December 2019, 13:05

Quote:

Originally Posted by pletevl

Hi all,

so, the battery has been off the car for just over a week, I charged it up and it hasn't dropped a volt in a week, it's still giving 12.7 volts. So, for me, the battery is fine.

Can an alternator give out 14 odd volts and NOT charge the battery ?????

Pete.

That's not something I've ever heard of happening, simple conclusive way to test that would be to start the car and switch on all lights, heaters on Max rear screen heater and anything else that uses power and see if lights are still bright. If they are then alternator is providing the power it's showing, but that won't explain why it's draining the battery when stood still and locked. Have you tried the suggested removal of the plug on the alternator?

27th November 2019, 05:34	#28
Lee T Gets stuck in MG ZT Join Date: Jul 2014 Location: Liverpool Posts: 851 Thanks: 180 Thanked 248 Times in 189 Posts	The plug can be removed with 1 finger and a screwdriver to push the clip down easily enough, getting it back on is the fiddly part. My battery drain was on a petrol 800 Rover and I'm assuming here but Mabey mine was a few diodes at fault and yours is just the 1, hence the quicker drain on mine. Either way Comfortably numbs suggestion is still worth exploring IMO. __________________ [SIGPIC][/SIGPIC]

25th November 2019, 18:21	#22
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	Too high? I don't understand why it's goi g flat in around 10 days.

25th November 2019, 21:21	#24
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	It's not the battery either. The old one is charged up and is holding its charge fine.

26th November 2019, 22:12	#25
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	Pletevl, re-read my earlier post about the battery draining back through failed rectifier diodes in the alternator. If you disconnect the alternator wires (admittedly fiddly) and that stops the battery draining, you know where the fault lies!

27th November 2019, 05:16	#27
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	Can a diode leak be tested with a multi meter or does it not show up? And how fiddly is fiddly? Mines not going flat overnight. It takes just over a week if the cars not used at all to loose about one volt. Pete.

2nd December 2019, 12:53	#29
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	Hi all, so, the battery has been off the car for just over a week, I charged it up and it hasn't dropped a volt in a week, it's still giving 12.7 volts. So, for me, the battery is fine. Can an alternator give out 14 odd volts and NOT charge the battery ????? Pete.