Fordmods Logo

Battery Goes Flat, Volts Low but Alternator and battery fine 

 

Page 1 of 2 [ 18 posts ] Go to page 1, 2  Next

 
 Post subject: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 9:26 am 
Stock as a Rock
Offline

Age: 38

Posts: 160

Joined: 28th Mar 2005

Ride: EF Falcon Futura

Location: Brisbane
QLD, Australia

Hi All,

I know immediately you think this is either alternator or battery, but it is not as I have replaced both!!!

Ok, start the car and the volt gauge sits just below 12, and the multimeter across the terminals shows about 12.5. Once something like headlights, thermo fan or similar goes on, this drops to about 11, and keeps dropping until the battery is flat.

The funny thing is, if I disconnect the battery, the reading across the terminals goes up to 13.7 (normal). And I can turn on headlights and so on, and the alternator takes this charge.

I have checked all fuses and wires, and I am STUMPED! Earths seem good ??

Car is a 1991 Ford Capri COnvertable.

Any suggestions?
Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 9:32 am 
Technical Contributor
Offline
User avatar

Age: 44

Posts: 4093

Joined: 20th Mar 2005

Gallery: 2 images

Ride: 2.0 Turbo VW

Power: 142 rwkw

Location: Seaford State:
VIC, Australia

Something must be draining when it shouldn't be!

What auxiliaries have you got?

My old alarm was draining 3ah on arm, which made my battery go low in the morning.
Check amps, alarm, boot light, anything!

 

_________________

Carefree, we may not be number one, but we're up there.

Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 9:35 am 
Stock as a Rock
Offline

Age: 38

Posts: 160

Joined: 28th Mar 2005

Ride: EF Falcon Futura

Location: Brisbane
QLD, Australia

I have gradually taken out all auxilary fuses and nothing seems to be it. It doesnt have any amps or anything as its my mothers car.

I just dont understand how it sits at 13.7V and can run all accessories without the battery plugged in, but when its plugged in it dies ??
Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 9:42 am 
Getting Side Ways
Offline

Posts: 2464

Joined: 5th Nov 2004

Gallery: 7 images

Location: Brisbane
QLD, Australia

Are you sure the battery isnt just stuffed????
Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 9:43 am 
Stock as a Rock
Offline

Age: 38

Posts: 160

Joined: 28th Mar 2005

Ride: EF Falcon Futura

Location: Brisbane
QLD, Australia

Replaced it with one out of another car, and THEN purchased a brand new battery.

Also replaced the alternator and same symptoms.
Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 10:24 am 
Tyre Shredder
Offline
User avatar

Age: 37

Posts: 317

Joined: 22nd Aug 2008

Gallery: 4 images

Ride: EB

Location: Wellington
New Zealand

Hey I had a similar problem, the plug that went on to the top of my alternator was full of crap, gave it a good clean with crc and a wire brush and has been good as since. Had water dripping on it from a leaking expansion tank :roll:

 

_________________

1989 EA Falcon column shift - SOLD
1990 EAII, BBM, EL ECU, T5, LSD - SOLD
1993 EBII Fairmont Ghia V8 - SOLD
2006 BF Fairlane Ghia 6C

Huge thanks to BenJ, TROYMAN, fiend and XR-Lane. The E-series knowledge/motivation pool.

Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 10:38 am 
Moderator
Offline

Posts: 14489

Joined: 7th Nov 2004

Ride: AU XR8

Location: a shit suburb in sydney
NSW, Australia

was the alternator a new one or a secondhand one??

if its secondhand it might be stuffed aswell..
Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 10:52 am 
Stock as a Rock
Offline

Age: 38

Posts: 160

Joined: 28th Mar 2005

Ride: EF Falcon Futura

Location: Brisbane
QLD, Australia

It has gone through 3 alternators in 2 months, so there is definately something wrong.

The alternator that was in there was brand new, but I replaced this alternator with one that was Known working 2nd hand.
Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 10:56 am 
Stock as a Rock
Offline

Age: 38

Posts: 160

Joined: 28th Mar 2005

Ride: EF Falcon Futura

Location: Brisbane
QLD, Australia

Forgot to add, The battery Light is NOT on??
Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 1:45 pm 
Getting Side Ways
Offline

Posts: 631

Joined: 27th Jan 2007

Ride: Supercharged BA XL ute

Location: Gordonvale
QLD, Australia

EF_STOCKO wrote:
I have gradually taken out all auxilary fuses and nothing seems to be it. It doesnt have any amps or anything as its my mothers car.

I just dont understand how it sits at 13.7V and can run all accessories without the battery plugged in, but when its plugged in it dies ??

There's your answer right there.

 

_________________

BA XL ute.
P'maker headers',Hi flow cat,3" sports sytem,
Raptor V-clutched lightweight not intercooled,no tranny cooler,no worries.

Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 1:47 pm 
Stock as a Rock
Offline

Age: 38

Posts: 160

Joined: 28th Mar 2005

Ride: EF Falcon Futura

Location: Brisbane
QLD, Australia

Ive tried multiple batteries?
Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 9:09 pm 
Getting Side Ways
Offline
User avatar

Age: 36

Posts: 3737

Joined: 22nd May 2006

Ride: BF F6 Tornado - #0077

Location: Bendigo
VIC, Australia

did you put an EL alt in to an ef? i think they have different amperage outputs or something

 

_________________

** For Sale ** http://www.fordmods.com/ford-parts-for-sale-f17/assorted-e-series-parts-t124697.html

F6 Tornado 2006 Build

Is it about sex? The engine in my car? Or a cure for cancer?
No?

Then f**k off

Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 9:17 pm 
Stock as a Rock
Offline

Age: 38

Posts: 160

Joined: 28th Mar 2005

Ride: EF Falcon Futura

Location: Brisbane
QLD, Australia

This is a 91 Ford Capri.

Alternator before this one was a genuine one from Ford, installed by ford ($380 later).

The one in now is from a wreck which was known working.

Cheers
Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Wed Mar 04, 2009 9:42 pm 
Getting Side Ways
Offline
User avatar

Age: 36

Posts: 3737

Joined: 22nd May 2006

Ride: BF F6 Tornado - #0077

Location: Bendigo
VIC, Australia

ah soz.

have a quick look over the connections. SUPER RIDICULOUS bad earthing, regulator f**k itself major too

 

_________________

** For Sale ** http://www.fordmods.com/ford-parts-for-sale-f17/assorted-e-series-parts-t124697.html

F6 Tornado 2006 Build

Is it about sex? The engine in my car? Or a cure for cancer?
No?

Then f**k off

Top
 Profile  
 
 
 Post subject: Re: Battery Goes Flat, Volts Low but Alternator and battery fine
Posted: Thu Mar 05, 2009 11:00 pm 
Smokin em up
Offline

Posts: 258

Joined: 30th Dec 2007

Location: cairns
QLD, Australia

DO NOT RUN THE CAR WITH THE BATTERY DISCONNECTED.If you do this you will either [a] blow up alternator by destroying the rectifier and /or [b] blow the fusible link which supplies power to the alternator.So how many alternators have you f$^&*?The days of disconnecting the battery to test the generator went out when the alternator was introduced.So stop doing it,ok?Do not disconnect the twin plug which goes to the alt. while vehicle is running.To test your charge rate 1st.Buy a multimeter and learn how to use it2nd.Buy a testlight and learn how to use it.Now turn on ignition and make sure you have a warning light which looks like a battery.If you don't disconnect the twin plug and use your testlight to make sure you have 1[12 volts dc and the other if you use the testlight to earth it out should make the warning light turn on.If you do have a w/light then start the car.Use the multimeter to see what volts you have at the battery and at the B+ on your alt.13.6 to 14.4 volts is ok Rev the engine and recheck volts .Turn on a/c and headlights and check volts ,rev and check.if there is more than .3 v difference then either your battery needs charging or you need to fit another wire 6mm between alt and battery .ANY Q's ?
Top
 Profile  
 
Display posts from previous:
Sort by  
 Page 1 of 2  [ 18 posts ]  Go to page 1, 2  Next

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

 

 

It is currently Fri Apr 26, 2024 3:55 am All times are UTC + 11 hours

 

 

(c)2014 Total Web Solutions Australia - Australian Web Hosting and Domain Names