Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[VR4Dave]

Hi all, having a problem with a flat battery.

When I charge it up It's good for about a week (daily use) but then all seems well and the starter will turn (and sounds normal, not sluggish) but car doesn't fire.
After a few attempts battery will die, but when I connect jump leads it goes first time.

I was wondering if the alternator was the problem would I get any fault codes or other symptoms?

Battery charges well on the bench and all cells seem active, don't want to fork out for a battery if alternator playing up.

ta.

[RobG]

Read, digest, then implement
http://www.omegaowners.com/forum/YaBB.pl?num=1225724099

[VR4Dave]

Thanks, sure I will sort it from that comprehensive list. 

In my defense I did look for this but couldn't find it but then the missus does always say I look for things with my eyes shut 

[VR4Dave]

Right, I followed the guide  and am pretty sure It's battery.

Voltage across battery after charging 12.6 ok

When lights on with engine off started at 12.0 and dropped to 11.96 after a couple of mins - suspect

When turning engine over voltage dropped to 8.6 - suspect

When engine idling (no load) - 13.75 ok (with load) 13.5 ok
Engine at 2000rpm - 13.75 ok
Engine at 2000rpm - (with load) 13.6

I read these results as battery fubarred and alternator ok, could an expert please confirm this before I grease the palms of a local motor factor

[Martian]

When lights on with engine off started at 12.0 and dropped to 11.96 after a couple of mins - suspect

Acceptable

When turning engine over voltage dropped to 8.6 - suspect

Acceptable

When engine idling (no load) - 13.75 ok (with load) 13.5 ok
Engine at 2000rpm - 13.75 ok
Engine at 2000rpm - (with load) 13.6

Those voltages are right on the bottom edge of the minimum charge rate.
An acceptable charge rate is anywhere between 13.8V - 14.4V with the engine at 2000rpm and the headlights on.

I read these results as battery fubarred and alternator ok, could an expert please confirm this before I grease the palms of a local motor factor

It is possible for a duff battery to drag the alternator down, but I'd suspect the alternator first.
Test with a known good battery to confirm before splashing out.

[Lazydocker]

Check the condition of the battery cable crimps... Those figures would fit with that too

[Nick W]

It's probably worth checking the alternator output on the stud where the wiring attaches to it.

If that's what it should be(over 14 volts at idle), then you have a wiring fault.

If it isn't, then the alternator is faulty.

[VR4Dave]

Ok, so I thought I may aswell take the alternator off and clean contacts as per the guide however my alternator is different to the one in the guide 


So I couldn't clean it.
Will try and get the meter on the alternator output, but excuse me being thick what do I do with the other terminal from the meter, really don't understand electrics 

[VR4Dave]

also don't know how to post pics!!!

[Andy B]

also don't know how to post pics!!!

there's a guide somewhere, but pictures need to be hosted else where eg Photobucket or Photobox & you then link to the picture's url with the 'insert image' above. 

[VR4Dave]

[/img]

[VR4Dave]

Battery crimps seem ok, but don't really know what I'm looking for..

there is no serious corrosion and they all seem tight.

[Martian]

Will try and get the meter on the alternator output, but excuse me being thick what do I do with the other terminal from the meter, really don't understand electrics 

Red lead on meter to alternator output terminal, black lead on meter goes to ground (negative terminal on battery).

Start car, take it to 2000rpm with the headlights on and you want to see anywhere between 13.8V - 14.4V on the meter.

[VR4Dave]

It was battery that had failed, replaced and all ok now. Thanks for the help.