Car Talk - Non S2000 General Motoring and Non S2000 Car Talk

auto electrical question

Thread Tools
 
Old May 14, 2009 | 09:15 AM
  #1  
gaddafi's Avatar
Thread Starter
Banned
 
Joined: May 2002
Posts: 31,739
Likes: 69
From: Survivalist enclave
Default auto electrical question

the battery in my Omega has started draining to nothing in a few hours

I have a mulitimeter thingy in the garage

does anyone know what I need to connect it to, and what sort of reading I should be looking for, in order to check if the alternator is charging it

it's not the fanbelt - the alternator appears to run off the cambelt and looks self-tensioning

I can't see anywhere where there could be a drain when the ignition is off (any ideas?)

battery is under 4yr warranty but I'd like to know about the alternator before taking the battery back for checking/replacement

thanks
Reply
Old May 14, 2009 | 09:17 AM
  #2  
Gaspode's Avatar
 
Joined: Apr 2007
Posts: 8,905
Likes: 0
Default

Take a reading with car with nothing runninng. You should get a reading of 12.6 - 13.8V

With the car running... about 14V+

Just my 0.02
Reply
Old May 14, 2009 | 09:23 AM
  #3  
rralston's Avatar
Registered User
 
Joined: Apr 2002
Posts: 4,860
Likes: 0
From: Leeds
Default

18.8v ? That seems a lot?

It should read 12. something when the ignition is off, and late 13. something or more when running.

If it's showing 12 when running then there's an alternator problem, if it's showing 13-14 when running and it's still going flat then it's a battery issue.
Reply
Old May 14, 2009 | 09:26 AM
  #4  
Gaspode's Avatar
 
Joined: Apr 2007
Posts: 8,905
Likes: 0
Default

Originally Posted by rralston,May 14 2009, 06:23 PM
18.8v ? That seems a lot?

It should read 12. something when the ignition is off, and late 13. something or more when running.

If it's showing 12 when running then there's an alternator problem, if it's showing 13-14 when running and it's still going flat then it's a battery issue.
Twas a typo...
Reply
Old May 14, 2009 | 09:27 AM
  #5  
RUSS H's Avatar
Registered User
 
Joined: Nov 2005
Posts: 4,305
Likes: 0
From: Peshawar
Default

Touch the probes onto the battery terminals with the meter on
dc.

Post up the voltages running and not running.
( not running wait a few minutes after having say the headlights on for a minute)

Russ.
Reply
Old May 14, 2009 | 09:29 AM
  #6  
gaddafi's Avatar
Thread Starter
Banned
 
Joined: May 2002
Posts: 31,739
Likes: 69
From: Survivalist enclave
Default

Originally Posted by Gaspode,May 14 2009, 05:17 PM
Take a reading with car with nothing runninng. You should get a reading of 12.6 - 13.8V

With the car running... about 14V+

Just my 0.02
thanks

with the meter connected to each terminal?
Reply
Old May 14, 2009 | 09:31 AM
  #7  
loftust's Avatar
Registered User
 
Joined: Oct 2008
Posts: 9,234
Likes: 3
From: Fareham, Hants
Default

Originally Posted by gaddafi,May 14 2009, 05:29 PM
with the meter connected to each terminal?
Yes...it doesn't matter which way round.
Reply

Trending Topics

Old May 14, 2009 | 09:32 AM
  #8  
Gaspode's Avatar
 
Joined: Apr 2007
Posts: 8,905
Likes: 0
Default

Yes.

Set your multimeter to Volts DC.



Bear in mind a battery half flat should show around 11.8V

A flat battery is about 10-11V
Reply
Old May 14, 2009 | 09:37 AM
  #9  
gaddafi's Avatar
Thread Starter
Banned
 
Joined: May 2002
Posts: 31,739
Likes: 69
From: Survivalist enclave
Default

ok - am going to check now

look out for a large mushroom cloud in the south...........
Reply
Old May 14, 2009 | 09:37 AM
  #10  
loftust's Avatar
Registered User
 
Joined: Oct 2008
Posts: 9,234
Likes: 3
From: Fareham, Hants
Default

Originally Posted by Gaspode,May 14 2009, 05:32 PM
A flat battery is about 10-11V
Or less

If the multimeter doesn't say 'Volts DC', it'll be the range where there is a 'V' and one/two flat lines, rather than a sine wave next to it. I'm not sure how much you know about electrics, so please forgive me if I'm teaching you to suck eggs!
Reply



All times are GMT -8. The time now is 09:22 AM.