Battery Drain

froggy

Member
Thought it best to turn the engine over every few days while I gather the funds for my suspension repair. All I get on the dash is the airbag light dimly lit, nothing else comes on. Its just had a brand new battery, but I swapped the drivers side doors and barrel over from a donor car on purchase and have had locking issues ever since. Every couple of days I need to manually unlock the car and the keys need re-syncing, also the door locks always do a castanet rattle when turning the ignition on.

I will do a scan when the suspension gets sorted and check for drain by charging the battery, using a multi meter and pulling fuses over the next week or two, Im fairly confident its the driver door loom at this point. If you are still awake on to my question! The difference I noticed this morning was the little red led light in the door card, was still blinking even after manually unlocking with the key and opening the door. Im sure it normally goes out when the car is unlocked? ? Could this be the source of the drain and will it definitely be loom related?
 
Were the replacement electronics from roughly the same year car? Is the alarm going off and flattening the battery? Could have a door lock, door loom or CCCU issue. Battery leads and connections are all good with no corrosion and tight, including the auxiliary positive supply ( the box where it is bolted onto the positive lead and the leads inside it ). Main earth behind the left headlight and battery chassis connection in front of the left rear wheel. These all need to be clean, no lead corrosion and tight.

Your boot light is not stuck on? Nothing left switched on?
 
Were the replacement electronics from roughly the same year car? Is the alarm going off and flattening the battery? Could have a door lock, door loom or CCCU issue. Battery leads and connections are all good with no corrosion and tight, including the auxiliary positive supply ( the box where it is bolted onto the positive lead and the leads inside it ). Main earth behind the left headlight and battery chassis connection in front of the left rear wheel. These all need to be clean, no lead corrosion and tight.

Your boot light is not stuck on? Nothing left switched on?

Not sure on donor car year, but I do have the original loom, just need Tom to work his magic when the time comes. All battery connections are good and rust free. Need to work out how to disconnect the positive lead as I can’t get a spanner on the nut. I will check all the engine earth connections from memory they all seemed good.

The boot light (well the light above the rear wheel arch) is missing and the connector for it is just dangling in mid air - could that cause a drain?
 
Battery out now (brand new exide) just about to put on charge. Thinking back to last month, the car did crank with an old battery in poor condition after standing for 2 weeks. This has only been stood for 3 or 4 days with a new battery ? Only changes are air con regas, air and pollen filters. Not sure how any of that could discharge it so quickly.
 
Barrel being the door lock?
I think the vehicle systems are not going to sleep and draining your battery.
You can do a simple battery drain test with your multimeter.
Connect your meter to the battery and read the current draw.
then with your leads still connected to the battery, lock the vehicle and you should see this drop.]
If it does not then your vehicle is not switching off properly....
Someone else can advise the specifics of an A2 soon I hope...
Best wishes.
 
Battery out now (brand new exide) just about to put on charge. Thinking back to last month, the car did crank with an old battery in poor condition after standing for 2 weeks. This has only been stood for 3 or 4 days with a new battery ? Only changes are air con regas, air and pollen filters. Not sure how any of that could discharge it so quickly.
New batteries are charged at manufacture, but could be discharged by the time you buy it. So, unless you charged the new battery, before fitting it, could still be the problem.
Mac.
 
Every new battery that I have bought from Tayna Batteries has come fully charged and fully ready to use.
 
If the seller has quick stock turnover it will be, but if it's been on the shelf a while, probably not.
Mac.

I can test that theory by charging and refitting the battery, then leaving for a few days. How many times can a battery be fully discharged though, before damage is likely to occur?
 
Once unfortunately. Each time it is below about 12 volts the battery loses some of its capacity to hold a full charge, not sure exactly how much capacity is lost but even if only a few percent it does not take long for a battery to fall below limits of a good battery especially if it is left to go flat repeatedly. Make sure to note the voltage of the battery when reconnected, that way you can see how long it takes to drop from 12.5v
 
Once unfortunately. Each time it is below about 12 volts the battery loses some of its capacity to hold a full charge, not sure exactly how much capacity is lost but even if only a few percent it does not take long for a battery to fall below limits of a good battery especially if it is left to go flat repeatedly. Make sure to note the voltage of the battery when reconnected, that way you can see how long it takes to drop from 12.5v

Voltage when reconnected was fluctuating between 10.1v and 11.3. Although initially it seemed to be accepting a charge, when I checked a while later, a battery with a cross through symbol was flashing which I take to mean the battery is ruined. Is there any chance I had a dud?
 

Attachments

  • 8CCC04AB-33B2-44FA-B911-5E7AB8B7A172.jpeg
    8CCC04AB-33B2-44FA-B911-5E7AB8B7A172.jpeg
    375.4 KB · Views: 95
  • 0564F90E-B5D5-45DC-9EDA-68D96EF77F58.jpeg
    0564F90E-B5D5-45DC-9EDA-68D96EF77F58.jpeg
    312.7 KB · Views: 93
  • 192AD0AA-3B7A-472E-8A53-F8DC028AC85F.jpeg
    192AD0AA-3B7A-472E-8A53-F8DC028AC85F.jpeg
    323.4 KB · Views: 103
fully charge it then put the battery back on and reprogam the keys if need be
lock the car then try it again in 3 days
i hope you have a decent charger , if its discharged after that it may be a faulty batt
 
New batteries are charged at manufacture, but could be discharged by the time you buy it. So, unless you charged the new battery, before fitting it, could still be the problem.
Mac.
If the battery is discharged at point of sale, it will not be fit for purpose as it will be sulphated to some extent.

RAB
fully charge it then put the battery back on and reprogam the keys if need be
lock the car then try it again in 3 days
i hope you have a decent charger , if its discharged after that it may be a faulty batt
Depends on the rate of drain.

Buy a clamp meter which is able to measure down to 1mA; using a clamp meter means that you don't have to disconnect the battery. Normal drain is 40 to 50mA after switching off for a few minutes.


RAB
 
New batteries are charged at manufacture, but could be discharged by the time you buy it. So, unless you charged the new battery, before fitting it, could still be the problem.
Mac.
The basic note of caution I am trying to get over is don't buy a new battery, put it straight into the car, assuming it's fully charged and good to go, it is quite possible that it's not fully charged. I'm not suggesting a new battery is likely to be flat when purchased. It may, however not be quite up to a cold start on a cold morning. Pop it on charge for a while, just to be sure.
Mac.
 
The basic note of caution I am trying to get over is don't buy a new battery, put it straight into the car, assuming it's fully charged and good to go, it is quite possible that it's not fully charged. I'm not suggesting a new battery is likely to be flat when purchased. It may, however not be quite up to a cold start on a cold morning. Pop it on charge for a while, just to be sure.
Mac.

New battery coming tomorrow hopefully, then I can make sure it is fully charged before fitting. I will also do the multi meter test to check if there is anything causing a drain. Am I correct in thinking that I need to have all doors shut, everything off and actually be in the back of the car to test this correctly? (with the battery being in the boot)
 
re the battery check.
run some cables out through the boot.
close and lock vehicle...
then watch....
i would imagine should go to sleep before 5 mins after vehicle locked..
but please someone more familiar/knowledgeable with A2 to advise the last bit..
cheers..
 
Back
Top