battery going flat over night

colin machin · Post by **colin machin** » 19 Dec 2013, 21:03

HI C5 2007 HDI BATTERY GOING FLAT OVER NIGHT ONLY WHEN ITS A COLD NIGHT WHEN TEMPERATURE IS UP ITS FINE
(IT AS A NEW BATTERY FITTED ) ANY IDEAS .......C MACHIN

Post by **Peter.N.** » 20 Dec 2013, 00:02

Does it go completely flat or just low? Don't really know your car as mine is a Mk1 but anything that upsets the main ECU can flatten the battery. Connect an amp meter in series with the battery, remove one connection, connect that to one meter lead and the other one to the battery, with everything turned off it shouldn't read much more than about 50ma, if it does, remove one fuse at a time until it drops, see what circuit it powers and that will be your problem.

Peter

qprdude · Post by **qprdude** » 20 Dec 2013, 10:38

Peter, I have to say, that is a very clear method of checking. To those of us who are not electrically aware, instructions like, " chuck a meter on it and check the current drop" is pretty meaningless.
Giving advice should always be as clear as this.

Mandrake · Post by **Mandrake** » 20 Dec 2013, 11:23

I would add that on a modern car if you disconnect the battery then reconnect it (as would be the case when trying to insert an amp meter in series) that some ECU's will "wake up" and start drawing more current for a period of time - so once the amp meter is connected leave it in place for at least 15 minutes for the various ECU's to go into low power mode. Don't be alarmed if the reading is initially too high.

Also remember to close all doors, check interior lights etc are off as even a single interior light such as a glove box or vanity mirror light will draw much more than 50mA by itself.

colin machin · Post by **colin machin** » 20 Dec 2013, 13:24

taken on board your suggestions but bare in mind it only happens when its very cold and the battery goes very low but not drained as soon as the weather gets milder its ok thanks for suggestions

Stickyfinger · Post by **Stickyfinger** » 20 Dec 2013, 14:30

Battery needs replacing, he has problems

You could also make sure its in good charge, disconnect it and store inside one night, take it out in a cold morning and see.....my bet is that it is failing and needs replacing

qprdude · Post by **qprdude** » 20 Dec 2013, 14:35

stickyfinger wrote:You could also make sure its in good charge, disconnect it and store inside one night, take it out in a cold morning and see.....my bet is that it is failing and needs replacing

Would be strange, as the OP say's it's a new battery.
More to the point would be, is it the CORRECT battery.

Stickyfinger · Post by **Stickyfinger** » 20 Dec 2013, 14:47

qprdude wrote:You could also make sure its in good charge, disconnect it and store inside one night, take it out in a cold morning and see.....my bet is that it is failing and needs replacing

qprdude wrote:Would be strange, as the OP say's it's a new battery.
More to the point would be, is it the CORRECT battery.

Why cant a new battery have a problem ? (the symptoms are after all pointing to the battery even if it is new), and I did say do a check. What systems on the car say to themselves, "ah its cold, I will switch on now" ?

Agree worth checking if it is the correct battery.

?? to OP .............Do your journeys give the battery time to charge ? How old is the battery ?...brand new ? 1 year ? 3 months ?

qprdude · Post by **qprdude** » 20 Dec 2013, 15:18

Cold temperatures affect the chemical process inside the battery that produces and stores electricity, effectively slowing it down and reducing the battery’s ability to hold the charge. Older, weaker batteries will typically already have reduced performance and cold temperatures will often drastically reduce this further, to the point where the battery will discharge or go flat very quickly.
Lots of short journeys in winter, with Heated screen, rear screen, heated seats, lights etc will have a huge effect on the charging. What you don't even notice in summer, will be very obvious in winter.
Oil will also be thicker in cold temperatures so it is important to have the correct viscosity.
Nothing like winter weather to highlight all the little problems that are not evident in mild weather.
My journeys are mainly local, and I try to use the minimum accessories to help the battery recover as much as possible. Never have the radio/sat nav on when going to the shops. Minimum use of heated screen and seats. Switch off DRL and auto headlights. (disconnect wife's ejector seat).
You won't know if the battery is low when you get back home from a short winter journey but you will know in the morning.
It could ,of course, be a duff battery, or a wrong one,
Has it been fitted because the old one was failing? Is it a like for like?

Mandrake · Post by **Mandrake** » 20 Dec 2013, 16:17

colin machin wrote:taken on board your suggestions but bare in mind it only happens when its very cold and the battery goes very low but not drained as soon as the weather gets milder its ok thanks for suggestions

Yes but the issue is whether or not there is an excessive drain when the car is parked, and that will be independent of temperature so can be tested any time.

The difference with the cold temperatures is that battery capacity drops dramatically with cold temperatures even on a good battery, causing the excessive drain to become an issue where you might get away with it in warmer temperatures.

Reduced battery capacity due to cold temperatures + excessive drain = problem.

Another possible issue is incorrect charging voltage - if the charging voltage is too low the battery will never fully charge. With the engine idling for at least a few minutes measure the voltage at the battery posts - it should be between 14.0 to 14.4 volts, ideally 14.2 volts. If it's anything less than 14.0 volts you have a charging system problem and the battery will not be getting fully charged, combined with the reduced battery capacity in cold temperatures you will have problems.

Battery problems are not rocket science - it will be either faulty battery, (not likely if its been replaced) faulty charging system, or an excessive drain when the car is parked, and a few simple voltage and current measurements will reveal the culprit.

colin machin · Post by **colin machin** » 03 Jan 2014, 16:16

re battery going flat new battery .disconnect over night when i connect the earth connection i get a large spark and theirs a clicking sound from behind the engine in the area of the turbo

Mandrake · Post by **Mandrake** » 03 Jan 2014, 16:55

Its normal to get a spark and maybe some relays clicking when you reconnect a battery as various ECU's will re-initialise when the battery is first connected and temporarily draw more current.

As I said earlier, its the amount of current drawn after a wait period of 5-10 minutes that matters for battery drain issues, not what is drawn immediately after the battery is connected.

You need to connect an ammeter in series with the battery (on 10 amp mode) and monitor the current drain over a 10-15 minute period, with all the doors shut and just the bonnet open. Have you tried that yet ? Otherwise you can only guess.

If there is an excessive drain after 10-15 minutes (more than about 0.1 amps) then you need to remove fuses one at a time while watching the ammeter to find the culprit. Unfortunately a bit of elbow grease is needed to track down this kind of problem...

colin machin · Post by **colin machin** » 03 Jan 2014, 17:19

2007 c5 hdi disconnect battery when i reconnect in the morning when i connect the earth lead i get a large spark and i hear a clicking sound from the rear of the engine near the turbo area as if some thing is turned on if i leave the battery connected over night it gets pulled down and nearly flat any ideas

colin machin · Post by **colin machin** » 04 Jan 2014, 08:33

thanks mandrake for info will try later and see the results

colin machin · Post by **colin machin** » 04 Jan 2014, 08:47

i also have a 2002 c5 hdi and that one as stated to play up the problem seems to be developing first the lights came on on there own whilst not switched on and now the speedo and rev counter needles go past zero right to the bottom of the dials both work but read low ie 40mph reads 20 and rev counter reads 0 when engine running both work but read low only started yesterday ive had 2 xm and 2 c 5 only problems have been electrical and one suspension ram fault very pleased with the cars

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