Battery Not Charging?

The battery in the 2003 C3 1.4 8V would not charge and it had me stumped. What I normally do is google search and normally a fix is found so I checked through all the various forums and threads as there would surely be a fix for this issue out there? What I found was a lot of threads with people with the same issues and not one answer to them so I thought I'd dig a little deeper and hopefully find a cure for everyone. Or if it only helped one person it would be worth it.

The symptoms.

Firstly the symptoms were the car would not start one morning so assumed the battery was duff so fitted a new one. The car ran fine for a week before the same thing happened again.

I then checked the voltage across the battery to discover only 12.5V across it when the car was running when it should be 14.5V and assumed the alternator was goosed so I replaced it with a 2nd hand unit. However after fitting the new alternator I was still only getting 12.5V across the battery when running.

This is where most of the threads peter out and no one seems to be able to resolve it so I made it my aim to find the root cause and hopefully find a fix for it. I also noted a few threads where cars were having electrical issues after clutch changes which I think is related to this issue as well.

My investigation went as follows. With the car running and using a multimeter I checked the voltage direct from the alternator output to an earth point nearby. I used the top left securing bolt (16mm Spanner required) that secures the alternator to the engine block and found I was getting a little over 14.5V. Using the same earth point I checked the voltage to the battery live and it too was 14.5V. However checking the voltage across the battery it was still 12.5V so I was losing 2 Volts somewhere.

I then switched off the car and removed the battery to measure resistances of the cable work. To gain access to the main earth point I mention below you will need to remove the air box. This is quite simply done by loosening the clamp from the air box to the throttle body, removing the air feed from the front of the airbox and in my case removing a tyrap which I assume has taken the place of the original securing clip. Once removed the airbox can be angle out and placed out of the way.

I then measured the resistance from the alternator earth point I’d used previously to the main earth point which returned a value of 36.5ohms when it should be zero. The main earth point is connected directly to the negative terminal of the battery and starter motor through a single crimp connection and the resistance therefore should be zero however I was getting 3ohms. I then went to remove the bolt used to secure the main cable from the battery to the engine to find it was loose and I could remove it with my fingers. Not good.

On inspection of the bolt it had a fair bit of corrosion on it so took some sand paper and gave it a good clean. Inspection of the body earth point also showed a fair bit of corrosion and it was the same for the main cable crimp so I also cleaned up these items with sand paper.

The next step I took was to run a 6mm earth cable from the main earth point which required a yellow insulated ring crimp with an 8mm hole up to the earth point for the coil pack and connected using a yellow insulated ring crimp with a 6mm hole. I then ran another earth cable using another ring crimp from the coil pack earth point to the alternator. I removed the top left securing bolt I used for the earth point mentioned previously sand papered the metal surface and connected the cable using another yellow insulated ring crimp but this time with 10mm hole.

A quick check of the cabling and I now had zero resistance from all points to the main earth.

I replaced the airbox and battery, started the car and measured the voltage across the battery and was delighted to find just over 14.5V across the battery. JOB DONE.

I think it is also worth mentioning the main cables from the battery and starter motor weren’t in the best of conditions and may require further attention in the future, but hopefully they should be fine for the foreseeable future.

For those that experienced electrical issues following a clutch change I would check the main earth point is still secure. I believe they would need to remove the earthing cable when changing the clutch so it could be that they have not secured it properly when putting everything back together. Whilst checking the security of the earth connection I would also check there is no corrosion on the connectors and that your cables are still in good condition. If there is still an issue you might also want to try running a separate earth to the alternator as detailed above.

Hopefully this will be helpful.

Thank you for this in depth information. I am sure it will move to the tips about a C3 before long.