Hi there

 

This morning in heavy frost, I started my 2003 VW Polo 1.4TDI 9n and let it tick over for about 20 mins on my drive, with heater and windscreen fan on full.  I did start it without revving the engine and just let it tick over, without lights, as I have done before and come back to a toasty defrosted car.

Today I noticed that it wasn't particularly warm inside, the power steering light was on and it hadn't fully defrosted.  I turned the engine off thinking it may need a restart and it wouldn't restart, as the battery was dead flat.

After about ten mins it had regained a little power but not enough to start the engine.  I have had to use my partners car to get to work and will return to it later with jump leads.

 

What caused this problem?  Lack of a quick engine blip on starting or is it deeper than that?  

 

Do I need a new battery?  It has been getting a touch slow in the colder weather but has never failed to start the car before.

 

Thanks for any suggestions

 

sounds like a charging problem ...get it running again and have the alternator tested

Thanks for the reply.  

 

It jump started just fine and the charger gave the battery a clean bill of health.  I have given it a good run and fingers crossed it appears to be an anomaly, but will be keeping a close eye on it from now on.

 

Cheers

 

 

Cold weather is generally a 'killer' for batteries that are getting past their best.

Is the auxiliary drive belt in good condition and correctly tensioned?

With the engine on a fast idle, you should get something like 14 volts at the battery terminals - If you do, repeat the test, but with a good electrical load switched 'on' (headlights, rear screen demister) Take the revs up a little, and it should still produce at least 13.5 volts.

If the idle speed was very low when you left it to idle with the blower etc switched 'on', it could well be that you were taking more out of the battery than the alternator could put back at that low speed.

A good test for the battery, is to leave the car standing (overnight say) Connect a voltmeter (multimeter set to 'volts' and have an assistant operate the starter - Battery should hold at a minimum voltage of 9.5 (assuming that it was fully charged before you left the car to stand)

 

If the battery fails this test, disconnect the battery negative (-) terminal before leaving the car yo stand (overnight) Re-connect the battery and repeat the above test - If the voltage stays appreciably higher than before, and the engine turns over on the starter quicker, there may well be a parasitic  drain on the battery, which would need to be investigated. (a common cause of this is the boot light staying 'on')

 

Regards

Thanks once again for the reply.

 

I rather think it was the idle speed too low, as the battery has performed well ever since, however, I will test it as recommended.

 

I may try it again, having given the engine a good 'rev' before leaving it to idle and see what happens.

 

Cheers