Alternator (charging Problem)

[scottharvey]

I have just put another alternator in my car and this one as well seems to not be charging the battery while running. The old alternator was reading 11.70 volts and the latest one was reading 13.10 and climbing and just checked this morning and now its reading 12.40 and dropping it cuts while driving on the way to work, when demister etc. is on could it be a dud alternator or something else??

[rslegy]

It will b a dud mate as it should be reading about 14 volts while the car in running

[scottharvey]

That\'s what I was thinking could it anyway link to my battery being the problem tho??

[Guest]

 scottharvey said:

That\'s what I was thinking could it anyway link to my battery being the problem tho??

Unlikely. Even if your battery was shagged, the Alternator itself should still output ~14v.

Mine went a few months back, got a brand new one & chucked it in, 6 days later it failed. Was a faulty unit & is apparently quite uncommon, but is definitely a possibility.

[scottharvey]

OK then cheers I\'ll get my new n old alternators tested

[scottharvey]

Just got another one and still reading low voltage this is the third one now could this now point to it being a battery problem it is reading 12.45

[Rosssub]

 scottharvey said:

Just got another one and still reading low voltage this is the third one now could this now point to it being a battery problem it is reading 12.45

Is it showing 12.45v at idle?

Edit: What voltage does it show at 4000rpm?

[scottharvey]

It drops when revved

[Rosssub]

 scottharvey said:

It drops when revved

:-\

I\'d be checking all Earths over thoroughly. Remove them, clean them, sand them bare then reinstall.

Then do the same to all Positive/Power connections, at the Battery/Alternator and Starter Motor.

Something must be loose/dirty or shorting?

Any CEL at all? Is your Starter Motor working normally?

Double check all Charge/Alt Fuses in the Engine Bay and Cabin too?

[scottharvey]

Starter hasn\'t been great since I had the car but hardly plays up

I didn\'t think there was fuses for charge and alternator are they in engine bay??

Not showing any cel either

[Rosssub]

 scottharvey said:

Starter hasn\'t been great since I had the car but hardly plays up

Which year/model car is it?

[scottharvey]

Bg5 94 legacy gt

[Rosssub]

Something\'s loose or shorting somewhere, Battery/Alternator/Starter.

 Rosssub said:

I\'d be checking all Earths over thoroughly. Remove them, clean them, sand them bare then reinstall.

Then do the same to all Positive/Power connections, at the Battery/Alternator and Starter Motor.

Something must be loose/dirty or shorting?

Double check all Charge/Alt Fuses in the Engine Bay and Cabin too?

[scottharvey]

So I shouldn\'t change battery yet

[Rosssub]

 scottharvey said:

So I shouldn\'t change battery yet

No, I wouldn\'t.

Even with no battery at all the Alternator should still be putting out 14.5v at idle. :-\

Edit: Which makes me think that all your Amps/Juice, is getting drained through a Short. Or being lost due to a bad Earth.

[scottharvey]

Yippee sounds like fun the car wasn\'t like it when I got it it has started since putting a sub n amp now that I think of it like when driving in rain the other day up the bombays I had demister on wipers, music and headlights and it kept cutting out o turned off denister and it stopped cutting

[Rosssub]

 scottharvey said:

it has started since putting a sub n amp

[scottharvey]

So may have blown when installed I guess

[Rosssub]

 scottharvey said:

So may have blown when installed I guess

Something you\'ve installed is shorting or draining Amps, big time.

Unplug the power cables from your new sub and amp. Then test Alternator voltage at Idle, see if it goes back to normal (14.5v).

[scottharvey]

OK I\'ll pm you tomorrow after having a look at work

[Rosssub]

 scottharvey said:

OK I\'ll pm you tomorrow after having a look at work

Sweet, will be something simple.

Plus you\'ve got a few Alternators for sale...

[Kiwi_Fozze]

if voltage is still dropping, check your earths.

[scottharvey]

OK I have checked my fuses and removed the power to my amp and the volts went up to 13.10 and fan turned on then dropped to 12.80 still way too low

[Rosssub]

 Rosssub']

I\'d be checking all Earths over thoroughly. Remove them, clean them, sand them bare then reinstall.

[quote name='kwi_fozze said:

if voltage is still dropping, check your earths.

Go through all engine earth straps.

[scottharvey]

Where are you located easier if you check it would out