Battery charging fault

[Marty762005]

Hi,
Citroen C8 2003
2.2 hdi
Diesel

Went for a drive today and the battery charging fault has appeared along with the battery light on the dash. My fist thought was alternator has gone or a bad earth to the battery, however when I put my multimeter across the battery its reading 13.90v and is the same if i meter the +ve to the body.anyone any ideas please.

[GiveMeABreak]

That looks a little low to me - but I would also put some load on the system by switching on the A/C, headlights and heated rear window / blower which should get the alternator to operate at maximum. See what happens to the reading when it is under load...

How old is the battery? - It may not be able to hold its charge if it at end of service life.

[Marty762005]

Ok just been out the car was a bit slow on the starter still metering at 13.9v , turned everything electical on and it jumps to 16.90 ???

[GiveMeABreak]

Ok, so that's probably because those items are putting quite a load on the alternator - but it shows that the alternator is generating current at a sufficient output. The question is - is the current getting to the battery - so when did you last change the battery - they really should be changed about every 5 years or so depending on use and make of course - it might be worth getting it properly tested first. You can of course check the condition of the battery terminals for rust or corrosion, check the earths and make sure these have good contact.

[white exec]

Check also the battery clamps themselves. If original lead (Pb) lumps, they can develop corrosion internally, and relax their grip on the cable strands.
A sign of the old lumps deteriorating internally is if either gets warm/hot after a bit of cranking.
Not a bad idea to replace them (now 15 years old!) if they're the originals. Brass ones something like these are a good idea:

Cut off the old lumps, and clean up the cable strands (they may have oxidised/gone black) to clean copper.

[sparksie]

Something seriously amiss here.
Check the battery in your meter, first.
If you're genuinely producing almost 17V, something expensive is going to turn into blue smoke.
The car electronics are very sensitive to voltage and anything over 15V will kill things you need to keep.
Hopefully the battery in the meter is dead and giving the wrong base level, meaning the meter is WAY out of calibration.
If that's not the case, then the alternator is not regulated.
Pretty sure your car is old enough to have an alternator with a built in reg, so popping the alt off and getting it checked would be my next move.
If it's really producing such a high voltage, ANY further testing should be done on a test bench, not on the vehicle.
Good luck

[xantiagreen]

Check also the battery clamps themselves. If original lead (Pb) lumps, they can develop corrosion internally, and relax their grip on the cable strands.
A sign of the old lumps deteriorating internally is if either gets warm/hot after a bit of cranking.
Not a bad idea to replace them (now 15 years old!) if they're the originals. Brass ones something like these are a good idea:
Battery clamp connector pr.jpg
Cut off the old lumps, and clean up the cable strands (they may have oxidised/gone black) to clean copper.

Agree with the brass clamps, it makes a battery that seems like its on its way out come back to life. I thought my banner battery nearly 8 yrs old was i need of replacement, earth lead would loosen up after a couple of months only 5 yrs later i sawed through the original lead clamp and fitted brass, ive never heard the starter motor so happy....