Battery Draining problem

If you can test the battery with a meter... You can test the alternator. It done by simply testing the battery voltage with the engine running. It's not complex and it should be the first thing you do when you have an issue with a new battery.

If you don't check the alternator voltage output as part of the fault diagnosis you are being... how do you say it.... Ahhh yes..less than smart. I've been working on cars for 45 years and have seen this more than once or twice.
 
jampudding said:
I bought the battery in May last year - but I think that the lack of driving may have hastened it's demise. I have already asked for a replacement through Amazon let's see where it goes. Also it was a Bosch S4 which I now realise have a high failure rate.

What batteries are people using these days?
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Don't Bosch batteries have a 3(4?) year guarantee? Last one I got for Boxster had. Probably need receipt though.

Thought Bosch had quite a good reputation.
 
A Cars battery has the following resting (no current) voltages to denote charge: 12.7V = 100% 12.1V = 50% 11.6V = 0%

Due to the fact the battery is draining fastest at higher voltage, it would suggest it is bad. If the car was draining it, the discharge rate should be linear. You can always check this however, by removing the negative terminal of the battery, and connecting your multimeter leads into the Amperage (e.g. 10A) sockets and connecting the leads to both the negative battery terminal and the cars negative cable. The car would need to be using over 2A for that kind of discharge rate (~35h to fully discharge a battery from full).

My car has recently been rested 4 months and drained a brand new Exide battery to 1.5V! Silly me for not disconnecting it! I hope mine hasn't gone south, the little LED hasn't re-illuminated...
 
When my battery went I was told by BMW that the number of short mileage journeys recorded on the computer was not enough to keep battery fully charged.

I only usually do 40 miles a week with 6/8 starts so I bought a small portable Solar Panel Charging unit that plugs into the cig lighter and rests on the dashboard. It has worked fine for over 2 years with the occasional mains battery charger boost in the winter when load on electrics is constantly high.

This may work for you as it saves disconnecting the battery and susequent computer reset if you are leaving your car outside for any reasonable length of time.
 
Thanks for all the help. Some very interesting postings.

I exchanged my old battery for a new battery from Eurocarparts. As I had bought my battery through Amazon they had a copy of the invoice and sent it to me so I could exchange it in store. Not sure I would have kept the old invoice for that long.

I have not connected it yet to see if it was the problem but from the various posts I assume it was. It was 10 months old and must have been fully drained easily well over 40 times. I will update when I connect the battery. Although I notice a new M steering wheel up for sale so perhaps leave it disconnected until that is decided!!
 
Have you installed the battery? Curious to see what was the real problem with the battery drain..... Bad battery ... alternator..or perhaps another issue causing a battery drain.


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I will put the battery in tomorrow as I need to use the car. I think the long term problem for me is going to be the lack of use of the car. I will be loolking to get one of the solar trickle chargers.
I will be reconnecting the bonnet sensor too. I will then report back
 
jampudding said:
I will put the battery in tomorrow as I need to use the car. I think the long term problem for me is going to be the lack of use of the car. I will be loolking to get one of the solar trickle chargers.
I will be reconnecting the bonnet sensor too. I will then report back
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I bought my Foldup Solar panel from http://www.solartechnology.co.uk and I see the price is still £25 so it's a cheap and easy solution to draining battery from low usage.
 
Is this the one you got "Foldup Solar Panel, 12v 4w" and did it connect to the car battery or just into the cigarette lighter? The blurb says you stick it in both.
 
jampudding said:
Is this the one you got "Foldup Solar Panel, 12v 4w" and did it connect to the car battery or just into the cigarette lighter? The blurb says you stick it in both.
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Yes that's the one. You get 2 wired connectors - 1 with claw clips on it for direct battery connection and 1 with standard cig lighter plug in. You can use either not both at the same time.
When plugging in make sure you keep the plug vertical and that the engine is not running as I have had a cig lighter fuse go once when I was a bit rushed to fit the unit.
I would had preferred longer leads as I wanted to put and keep the unit on the back shelf to get maximum sun but the supplier could not supply them - it still works OK as the unit charges even in low light so I just dismantle after use, fold up and store in box in passenger foot well, before I start engine and drive away.
 
As an update to this. I put the new battery in around the 12th of April and found it worked as it should. This worked for about a month. I do only about 5 miles a week and if I remember I do another 30 minute drive to keep the battery happy this is all in one day. After the month I was back in the same situation.
I bought one of those solar chargers but haven't used it yet - I will install tomorrow.
Allternator was charging at 13.97v - at idle.
I will see what the drain is like tomorrow after a charge with everything off.
Failing all of that I will be sending this battery back and gettting an S5.
 
Have you checked the alternator voltage as others have stated with a meter?

If the alternator is OK and you have a new battery, something is draining the battery.

Have you checked the basics like the interior and boot lights are not on?

Get a decent meter and put it in series with the battery - disconnect the negative lead and put the meter between the negative lead and the battery. The meter will show you the amps the car is drawing. After everything has settled down, it should be less than 0.1AMP.

If it is much higher than this, pull some fuses out until you find by a process of elimination what fuse and therefore what circuit is causing the issue and then investigate.
 
I did check the alternator the voltage was 13.97v.
Have to say I didn't check the boot light which I will tomorrow - interior lights are off.
I will check the amperage tomorrow morning in series with the battery.
 
TonyP said:
Does the light inside the cubby hole go off when the lid is shut? if not maybe the lever that should press the microswitch has broken off?
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Did you ever check this?
 
TonyP said:
TonyP said:
Does the light inside the cubby hole go off when the lid is shut? if not maybe the lever that should press the microswitch has broken off?
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Did you ever check this?
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I shall check this too as I remember fiddling around with the fuses when I had a problem with the fan. Hopefully it will stop raining soon.
 
I had a flat this morning not surprisingly.
- 40 Minute drive
- Car running voltage 13.92v
- Engine turned off voltage of battery 12.80v
Can I assume from this that the alternator is OK?

- Boot light switches off when the boot is closed.
- Centre cubby light switches off when closed.

- I did the test with the multimeter in series with the battery but it gave a very high figure. I realised afterwards that I had left the car door open when doing this and thus the reading was insanely high.
How do I perform this test - do I leave the boot open but lock the car (as in from the fob)? While the multimeter is in series with the battery? The wait for the car to settle down?

Does anybody know if the firmware of the satnav can have an effect on the battery, when the car is off?

Thanks
 
Evening all, continuing on the back of this thread rather than starting new as I have similar issues.

No recent history of battery/power/starting issues etc.

Came to the car (2004 3L) yesterday after being parked for around 2 hours. No cranking at all, large clicking from starter motor (replaced 2 years ago) Battery voltage measured 11.3v
Battery disconnected, charged for a hour, refitted and car started first time as usual, 14.4v when running, 12.5v when off.
Left overnight with the battery connected to the car, 12.1v this morning, started perfectly fine. 14.1v when running, voltage dropped momentarily when lights, radio, heaters etc were turned on, came back up to 14.1v almost straightaway (I’m taking this as the alternator being okay/providing charge)

Everything is pointing towards needing a new battery, it is at least 4 years old, just wanting a few other options before committing.

What could cause the battery voltage to have dropped to 11.3v volts so soon after being driven? I have no obvious drains, boot light and central storage compartment lights both switch off

Thanks
 
To be honest with a battery that old I'd always start with changing that first. I did when I had electrical issues and it didn't help much but at least I've got a new battery and know that isn't the issue for the next few years. Good luck
 
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