My battery keeps going flat - why..?!

[Andy Mc]

I'm at a lost as to why this keeps happening. I first noticed something not quite right last wednesday, the car started up fine to go to work at 8am, enroute I had to pick someone up 10 minutes up the road, as it was cold, I sat with the engine running to keep the interior fan going. After a few mins, my mate hadn't arrived so I turned the engine off. 2 minutes later he appeared and when I turned the key my motor struggled a little but fired up. It was at this point I noticed the clock had reset its self.

I left the car all day whilst at work (about 8 hours) and when I tired to start the first 2 attempts nothing, on the 3rd, she fired up. After a short 5 mile journey home, I cut and restarted the engine no probs.

...Anyway, I went away for the weekend and this morning the battery was flat (after being standing for 5 days) so I got a jump and off on my way and again this evening, after work she wouldn't start, nor would she be bumped so I ended getting another jump. Before I first turned the key this evening the clock was ok (since starting this morning) and was still past the first few clicks of the ignition, but on the final click, she wouldn't start and the clock again reset its self.

I have no idea why this is happening, the car has never been left wiv an interior or exterior light on, nor does the battery light glow (or faintly glow) when driving.

Does anybody have ideas as to why this is happening.....? I mangeded to re-start her after standing for about 30 after my drive home from work but I know she'll be dead in the morning.

The cars a mk2, thanks..!
 

[Mr Blue]

sounds like you need a new battery. 

[richandhazel]

The fact that this has happened now that the temperature is colder does tend to point to the battery. They have to work a lot harder as it gets colder for a number of reasons. Verify that your alternator is working (stick a voltmeter across the terminals prior to starting, check the voltage, start the car and make sure the voltage has increased to around 13 to 14V). If thats ok, try disconnecting the battery overnight. If you're still having trouble when you reconnect in the morning then battery is looking favourite.

Bear in mind though, if you're only doing short runs, you may not be puting back into the battery what you have taken out. It takes a hell of a lot out of a battery to start the car and the alternator needs a good run to replenish the battery. This is made even worse, at this time of the year, as you'll probably be running your heater, windscreen demist, lights etc.

[Andy Mc]

Thanks for the responses..!

I must admit, I have only been doing short runs recently (mainly to and from work, 5 miles each way) and during these runs, basically all electrical items have been used for best part of these trips, lights, heater, rear demister, wipers, stereo).

I do have a new battery which I can take a jump off to get her started today and I'm going to be out the country for a few days so the run upto Gatwick from Southampton mite do her some good (about 80 miles or so).

[Tucker]

Mine was doing the same mate, was fine then starting having probs with it I used to do 50 mile round trips a day tho so would be ok for a few days then nothing. As richandhazel said, the cold does amke it work harder and takes a lots out of it. I wacked on  new one and not had a problem since

[druid]

Ive been having teh same problems.

I realised my problem was down to the ignition.
When i take the keys out of the ig. the switch lights (elec window switch and headlight switch) stay on.
Its only a dull glow but it has been permanantly running my power down.

I would check you dont have any electrical devises staying on.

I would also try charging the battery and see if you still have the same prob.
It could be the battery is on its way out

[kniterider]

get in your car, shut the door and keep the igniton/lights off (best done at night), pull the rear seats down and just check wether your boot light is on? common prob mate, the switches can knacker up and the longer you leave it the flatter it gets.... not saying you dont need a new battery etc, just saying check this 1st ive had this prob on varios cars aged from 20 to 4 years old!!!

kid

[richandhazel]

Its all about process of ellimination, hence the sequence I suggested. Make sure you're alternator is charging the battery, if thats ok, disconnect the battery overnight. If its ok in the morning then you move on to find out what is draining it overnight. If its still f**ked in the morning after being disconnected all night then its the battery unless, as I've already said, you're not puting enough into it during your day to day driving.

[rubjonny]

If you take it to Halfords they'll test the battery for free.
To check for voltage leaks, set your multi meter to measure amps and take off the negative battery terminal. using one lead touch the - battery terminal and with the other lead touch the - terminal wire. Do this with the igniton off and make sure the doors & boot are closed.

[richandhazel]

Thats a good point, I forgot Halfords did that^^^^^^^ That could save you a lot of time and grief.