C5 Battery Draining Very Quickly

[Jamesblack1608]

Hoping for help..I have a 05 Citroen c5 2.0 and the battery drains very quickly if the car isn't used for a few days at a time, I've had 3 new batteries in 6 months. I've tried lowering the suspension, not leaving the auto lights on and turning the interior light off but still have the same problem. I've also noticed if I turn the engine off and just sit in the car I can hear a clicking/buzzing coming from the boot and after exploring I think l it's coming from the wiring or wire box behind the plastic covering in the boot under the left hand boot window. By the looks of it, it's the wiring loom for the boot lock, boot interior light and 12v socket. I've unplugged it and the noise is still there. I think this is killing the battery maybe a short there but not sure. Can any help. Thanks in advance. Edited December 19, 2014 by Jamesblack1608

[paul.h]

Welcome to the forum.

 

I think that under the rear left wing is the alarm and I vaguely remember (but I could be wrong) that if its battery is no good then it may cause the main battery to go flat as it tries to charge it - the parts diagrams though do not show a separate battery for it. A dealer could do a diagnostic check on it to see if it has a fault. The handbook for our 2007 C5 does not list the alarm fuses but in the RTA French manual it lists the dash fuse box fuses F4 20 amp  includes the alarm, F5 15 amp does the alarm siren and tyre pressures, F7 15 amp does an after production alarm - however these could be wrong. You could try removing these to see if it makes a difference or remove each fuse and connect an ammeter in place to see what current is being drawn. As a guide, our C5 uses about 15 mA with nothing awake, plus the same again if the tow bar electrics fuses are in place - combined these are enough to flatten the battery in about 3 weeks if the car is not used.

 

If not done already, it may help to find the fault if the boot inner wing plastic trim is removed and then have a good look around and also check any earth points are tight and there are no loose/damaged wires that may be touching the metal body and shorting out.

 

If you have a tow bar you can also try removing its fuses in case that has a fault. The electrics for our tow bar are located in the left side of the boot behind the plastic panel and include smart relays.

 

If you have a mobile phone or sat nav connected these can also help to flatten the battery.

 

When you park the car leave the front wheels pointing ahead since if to one side it could cause the suspension to go up and down and run the pump.

[pikesrelaybus]

Paul.h has hit the nail on the head. Diagnosing electrics can be a nightmare but breaking things down makes it much easier. A ammeter in series with the battery terminal gives you a starting point. Connect the ammeter up on a fairly high range before removing the battery lug, the meter will then show you the current flowing. Pulling fuses one at a time isolates any potential faulty circuit, a circuit diagram detailing items on each circuit definately helps. One point that might be mentioned elsewhere but I'll just say it here, a typical cranking battery will loose "life", whereby a life of a battery could typically be 5 years, if it's allowed to discharge below 10.8volts and then recharged quickly, like when you jump start a car. If your battery goes flat, charge it at 10% it's A/hr rate. ie 70A/Hr battery, no more than 7 amps. I've one of those smart chargers with just under 4A maximum output, my OEM battery is now 6 years old despite some recovery driver ignoring my plea's to stop starting it with the battery in it's current condition. Battery's also like to be charged - all the time. Until to isolate your problem I'd suggest leaving a small charger connected to maintain the battery voltage while your car is inactive.

[kirkie]

I have a similar problem. Totally out of the blue my car wouldn't start. I had the local garage come down to get it started and they fitted a new battery as they said the other one was U/S. After around 48 hours the new battery was dead. The car has now been in the garage for 3 days and they are trying to find out the problem.

[coastline taxis]

In theory the car should enter economy mode to save enough power to start the car. a couple of quick checks that can be done are multi meter on battery voltage should be12ish volts then start engine and u should be getting 14.4 to 14.7. next put the live probe onto the main wire (always bolted on) from the alternator  and do the same two checks and compare the readings and post here