Car battery constantly draining, how to find out why?

Combat squirrel

Combat squirrel

Combat squirrel

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As title, I have a Punto, just a run about car. Had it around 3-4 years. Its always suffered with intermittent car battery draining, the electric warning light has always been on. In summer it doesn't really run flat (assume its the warmer weather), in winter if I do not use the car every day, the battery runs flat in 2 days :rolleyes:

I have got around this problem by carrying a spare jump starter battery which starts it but getting bored of it now.

I took it to a car electrician in stoke who had a look at it with some fancy gear and declared he couldn't find anything draining :rolleyes:

I have tried disconnecting the car stereo and leaving it out for a month. It wasn't that.

Tried using a volt metre to see if the battery is draining it is not (although it obviously is as its flat after 2 days in the cold)

I have replaced the battery with a amazing high quality high capacity battery, so good in fact that when I scrap or sell the car, I am going to keep the battery, its awesome.

But sadly, other than slightly extending the time it takes for it to run flat this didnt work either.

SO my only option now is to volt metre every damn electronic circuit in the car to find what the hell is draining the battery when its stood still - OCUK, how would I do this?

I had the idea of digging around in the fuse box, is there any way of like, wacking a volt meter on each circuit in there to find out whats pulling juice? Or am I imaging things that won't work ?

Any advice on how to do this would be great - again I took it to a professional who could find nothing wrong so its clearly some sort of intermittent issue that will require days of testing - so I need to find a way to test it myself and all I have is a volt meter.
 
turn the car off by the key. (dont try and start the car during this procedure lol)

pull off the negative battery terminal.

use a multimeter between the neg terminal on the battery and the neg cable you just removed. you should see some milliamps if something is draining.

remove fuses in turn until it shows that drain has stopped.

next step is to start investigating why that circuit is drawing. whats connected to it etc?

i believe a busted alternator can cause this too and you wont find that in the fuse box, but you gotta start somewhere!
 
If the diode has failed in the alternator that can draw current into the alternator coil and drain the battery.

Just disconnect the the positive cable from the alternator and use the diode test on your meter between the positive terminal and clean bare metal on the alternator housing. One way you should get a very low reading, swap the leads over and it should go very high. If you get similar readings both ways the diode has failed.

You could leave the alternator disconnected for a couple of days when you're not using the car and see if that helps.
 
mikeh501 said:
turn the car off by the key. (dont try and start the car during this procedure lol)

pull off the negative battery terminal.

use a multimeter between the neg terminal on the battery and the neg cable you just removed. you should see some milliamps if something is draining.

remove fuses in turn until it shows that drain has stopped.
Click to expand...

This. A voltmeter will tell you nothing, you need to measure current rather than voltage.
 
Yeah you need something that can measure in amps. I had a similar problem with my wife's S-Max battery draining after 3-4 days of not being used so was looking into this myself.

However be sure to use one beefy enough for the job. My little multimeter can only handle 250mA through it so is next to useless for this kind of thing. The S-Max battery was 80mAH so I guessed that there was a permanent draw of around 1 amp - with this the internal fuse on my multimeter would have blown straight away.
 
I've never seen a multimeter with such a low fuse! Mine is about 200ma on the one port but 10A on the other so it's been fine for doing exactly this. It was only a £6 special on eBay!

What i have found when measuring the current on some cars is you need to leave it for a while for all the alarm systems etc to go to their low power mode otherwise you can be chasing your tail with power drains.
 
Mine is clearly completely crap then :) Mine just has the one port on it and clearly states 250mA. Just going to pick up an eBay cheapie as I've found one with a 10 amp port just like yours. Will come in handy for the future.
 
I would recommend spending a bit more than i did though for an auto ranging one and i've also had to solder mine back together once already and i've only had it about a year!
 
mikeh501 said:
turn the car off by the key. (dont try and start the car during this procedure lol)

pull off the negative battery terminal.

use a multimeter between the neg terminal on the battery and the neg cable you just removed. you should see some milliamps if something is draining.

remove fuses in turn until it shows that drain has stopped.

next step is to start investigating why that circuit is drawing. whats connected to it etc?

i believe a busted alternator can cause this too and you wont find that in the fuse box, but you gotta start somewhere!
Click to expand...

nailed it!
 
Thanks guys!! This is wonderful useful info !! :D :)

Yeah am a noob, amps, got ya! checked my multimeter and indeed it does have amps on. says 200mA Max, what should I set it to for finding the drain on the battery ? What sort of ampage would you expect is being drained to run it flat in 2 days?

Currently the car battery is not in the car as its charging off the wall (says running it flat for to long can damage it), but I can wire up my spare to run current through the car to test it - following mikeh501's advice.

Thanks guys its massively appreciated!

EDIT:

This is my EXACT multimeter, what do I want to set it to to find a drain ? (am I right in thinking the '7 o clock' position of 20k ? - lower left) or is it the other side at 3 o clock 20m under the A section, resistance, amps, uggh,lol

How_to_measure_resistance_using_XIOLE_XL830L.gif


Thanks
 
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Could you not pull fuses systematically until the culprit is found?

Had something similar on an old A3 - constant draw of 1A all the time was flattening the battery overnight to the point that not even the central locking worked. Turned out to be the bluetooth module.
 
AshD93 said:
10A. Green next to hFE.

Also you need to use the 10A socket on the left.
Click to expand...

Yup. The drain is going to be higher than 200mA to flatten a battery in a couple of days, and even if it wasn't the initial current surge when you first connect the battery is several amps which would blow the 200mA range fuse instantly.
 
Vertigo1 said:
Could you not pull fuses systematically until the culprit is found?

Had something similar on an old A3 - constant draw of 1A all the time was flattening the battery overnight to the point that not even the central locking worked. Turned out to be the bluetooth module.
Click to expand...

Exactly what it turned out to be on my wife's S-Max. I'd removed the Ford head unit and replaced it with a Pioneer thing. It was only after this that the battery started draining and I read of people who had issues with their Bluetooth module causing battery drain. Since the Bluetooth module was no longer required as the Pioneer HU has it built in I had to take various bits of trim and the glove box out to get to the BT module to unplug it. No battery drain since then :D

Alas this likely won't help the OP.
 
mikeh501 said:
turn the car off by the key. (dont try and start the car during this procedure lol)

pull off the negative battery terminal.

use a multimeter between the neg terminal on the battery and the neg cable you just removed. you should see some milliamps if something is draining.

remove fuses in turn until it shows that drain has stopped.

next step is to start investigating why that circuit is drawing. whats connected to it etc?

i believe a busted alternator can cause this too and you wont find that in the fuse box, but you gotta start somewhere!
Click to expand...

This sounds a great method.
 
Phemo said:
Exactly what it turned out to be on my wife's S-Max. I'd removed the Ford head unit and replaced it with a Pioneer thing. It was only after this that the battery started draining and I read of people who had issues with their Bluetooth module causing battery drain. Since the Bluetooth module was no longer required as the Pioneer HU has it built in I had to take various bits of trim and the glove box out to get to the BT module to unplug it. No battery drain since then :D

Alas this likely won't help the OP.
Click to expand...

Mine was a nightmare as I ended up calling out Audi recovery who couldn't stop the current draw, no matter what they tried or what fuses they pulled. In the end they got enough charge into it to start it and I then drove around for 20 mins to get as much charge into the battery as possible. I then came home and had to disconnect the battery overnight so there was enough juice in the morning to get it to the dealer.

Oh and a comical design flaw - when the battery is disconnected it's not possible to lock the car without the alarm going off! I thus had to empty it of everything and leave it unlocked on the drive all night.
 
Have you gone through the usual process of checking that the alternator is charging the battery? driving during winter always puts more load on the battery for various reasons, and this could explain why it's not so much of an issue in the summer, plus got better once you changed the battery but didn't totally fix it.

With the car left overnight have you then measured the battery voltage? Repeat the measurement with the battery negative terminal disconnected for 5 minutes. If the car has a current draw these figures will be different, the higher reading being with the battery disconnected. It's not possible to accurately quantify the drain from that measurement but indicates one to be present. Think from memory one example I tested had drop of 0.4V with 1.5A drain measured with a clamp meter.

Also, what voltage are you measuring on the battery? should be over 12.5V with voltage stabilised overnight and engine not run. If it's under 12.5V the battery could be goosed, especially if the alternator hasn't been charging as every time the voltage drops below 12.5V the battery suffers from a process called sulphation which gradually reduces it's capacity.
 
The alternator works as if I drive it for abit it will then start and have power for a couple of days - I used to have a van with a broken alternator and that simply didnt work once it was flat - this does.

Ok I just did what mikeh501 said using a backup battery to put power in the circuits - HOWEVER, the car has had no battery in it for 24 hours now - the meter read 0 current draw, I feel I will have to leave the battery charging, reinstall it, run the car for a couple of days and try again but use a spare backup battery to keep the circuit 'live' when I disconnect the main battery and then put the meter in series to see if there is any current draw
 
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