C5 Mk1 Flat battery problems.

[hawaiianblue]

Does anyone have problems with the C5 2.2HDI (mk1) having flat battery problems.

My mums will start fine with a fully charged battery and will drive around (mostly short trips) for about a month. But after about a month of use if it's left for a few days the battery will be dead. Take the battery off and put it on a mains charger over night and it'll be good for well over a month again.

When you jump start it and get it running again there are a good 14odd volts at the battery. You can then take it for a run and it will start fine after that. A long run will put the battery back to full charge and a 20min run will put enough charge in the battery to last a day or so if the car is stood.

The battery is good and of the correct size, there is no abnormal current draw from the car when in standby. Working it out from the current draw and battery capacity a full battery will last the calculated time of about a month if not charged, and it does that. The earths are all good, I've cleaned them and checked them for tightness. Alternator has a good connection.

The only thing I can think of is the alternator is 'weak' as if it's stopping charging when the battery gets to a certain level. But then from a jump start a short run appears to bring the battery back up pretty quickly, albeit not to full charge. All the googling I've done suggests that an alternator that gives out 14 volts is healthy.

So this one has got me stumped, there's no obvious drain and it appears to be charging when you put a test meter on it! is there some sort of electronic charge controller on these?

[Peter.N.]

The voltage across the battery with the engine running should be about 14.4 volts, much less than that and you have an alternator problem. If it does show that, check it periodically and make sure its always at that voltage, there may be an intermittent fault.

All the while the car is running the battery should be fully charged as the alternator takes all the load on a full battery. It should charge at a very high current when you first start the car and should be nearly full in about 10 minutes.

Peter

[waynedance]

Take it to a decent garage and they should for free or small charge do a battery and charging test.

[hawaiianblue]

The voltage across the battery with the engine running should be about 14.4 volts, much less than that and you have an alternator problem. If it does show that, check it periodically and make sure its always at that voltage, there may be an intermittent fault.

All the while the car is running the battery should be fully charged as the alternator takes all the load on a full battery. It should charge at a very high current when you first start the car and should be nearly full in about 10 minutes.

Peter

Yeah I see what you're saying, I might connect up the multimeter and log the voltage as I drive, in case it's not charging at a particular engine speed/load. I wonder if perhaps the alternator is charging the battery at idle, but failing under load.

My omitec battery tester says the battery is fine, and passes the alternator check (I think this just tests the voltage is above 14v)

[Peter.N.]

Yes, good idea, connecting the meter to your cigar lighter socket should do the job.

Peter

[wheeler]

, there is no abnormal current draw from the car when in standby.

What is the actual current draw figure you are getting ? A top spec (with alarm & satnav) mk1 C5 should have a maximum current draw of 0.06amps after 3-4 minutes of the engine switching off.

[hawaiianblue]

I'll have to retest it, and come back, as it was some time ago that I checked the current draw. It really wasn't much though. 300 mili amps springs to mind.

[sparksie]

Ok, 300mA sounds rather a lot for standby.
I'd have expected 30mA would be more likely.
If it's actually 300mA then you probably have a bulb staying lit in the boot, or maybe the glove box, or perhaps under the bonnet.
My Xantia hasn't got an engine light, but SWMBOs Spacestar has. I imagine higher spec Xantias probably have them too.
Another thing to consider is your declared short journeys. A good rule of thumb is it takes about ten minutes to replace the power used to start the car, following a trouble free start. Only after this are you gaining anything in the battery department. So, if your trips are ten minute runs, your net situation will be marginal, at best.
The combination of higher than usual standby current and short runs will certainly cause problems such as those you describe.

[hawaiianblue]

I'll have to double check the current draw, it was about 6 months ago I checked it.

Short journeys are obviously going to be bad, but then my mum borrowed on of my other cars for a couple of months and that was fine.

There's no bonnet light on my mums C5, the boot lights definitely go out, i'll check out the glovebox light though.

[Deanxm]

When the battery charges on the mains charger does the draw drop to practicaly nothing as it charges or does it always seem to draw a lot of amps even though the voltage of the battery is up to what it should be.

D

[hawaiianblue]

Hi, yes it starts off towards the top of the gauge and gradually drops down to zero as it charges.

[Deanxm]

The battery should be fine then, must be something using the juice. Ive just had to sort the same problem on a MK1 C5, even with a new battery i found it needed a lexia session to clear all the silly little temp faults before it stopped draining the battery, even though the new battery had been fitted.

D

[hawaiianblue]

What sort of temp faults did yours show?

I cleared a load on my mums the other week, but the problem is when the battery gets low and the car fails to start it flags up loads more.

[Hell Razor5543]

The problem could be that the C5 is VERY sensitive electrically. What could be worth a try is a BSi reset. This link is how you do that;

http://www.frenchcarforum.co.uk/forum/v ... 11&t=40407" onclick="window.open(this.href);return false;

[Deanxm]

It showed lots of temp over/under voltage faults on the injection, plus immobiliser issues, bulb failures. mostly on the BSI detecting issues with the brakes (failure) and dispay faults, once removed it stopped running the battery down in a random fashion, it seems when it gets upset by a flat or sick battery it doesnt fully shut down the bsi when the car is unused, this car was turning its stereo on during the night and completely flattening the battery.

The BSI reset procedure didnt work for me, it was the clearing of all the temp codes that cracked it.

D