[AlanQS]

Single driveway, the BMW is facing out, wife's Clio facing in, so bonnet to bonnet. BMW hasn't moved in two weeks, every second day I run the engine for 10 minutes to try and keep the battery in reasonable condition since low car usage over a period of months means it's not in tip-top shape.

I go to use the Clio this afternoon and the engine turns slowly and won't start, - it is -14 C which might have something to do with it. O.K. start the BMW and jumpstart the Clio.

Er, no. The heater sign comes up in the dash for quite a long time and the engine turns - but it won't start. It turns quite healthily but will not start.

I have a fancy charger which automatically switches from charge to a trickle/maintenance flow. On both cars, the charging light goes off after about a minute and it switches to trickle/maintenance. What a pain. It's clear that neither battery is 100% though both turn the engines quite strongly and yet I cannot give them a decent charge.

Is it just the temperature? I thought diesel didn't freeze until much lower than -14c. Anyone got any info on that?

[creepy coupe]

Glow plugs knackered?

[jinjur]

^ this, definately.

ITS FRENCH FFS.

[Shadow]

Originally Posted by AlanQS

Is it just the temperature? I thought diesel didn't freeze until much lower than -14c. Anyone got any info on that?

I think the UK EN standard for winter diesel is down to -15C only. Northern European spec is -25C. It doesn't freeze, but it goes cloudy with wax crystals - these can block the fuel filter (especially if there's already ice crystals floating about).

Typically British to have skimped on the spec... And today Edinburgh Council was toying with getting the army in to deal with the snow they should have cleared before it froze solid.

[doughboy]

Originally Posted by AlanQS

every second day I run the engine for 10 minutes to try and keep the battery in reasonable condition since low car usage over a period of months means it's not in tip-top shape.

This doesn't work too well as alternators don't produce much output at idle speed, also you might just be filling your crankcase with condensation and fuel that doesn't get evaporated off.

Er, no. The heater sign comes up in the dash for quite a long time and the engine turns - but it won't start. It turns quite healthily but will not start.

I have a fancy charger which automatically switches from charge to a trickle/maintenance flow. On both cars, the charging light goes off after about a minute and it switches to trickle/maintenance. What a pain. It's clear that neither battery is 100% though both turn the engines quite strongly and yet I cannot give them a decent charge.

Is it just the temperature? I thought diesel didn't freeze until much lower than -14c. Anyone got any info on that?

I'm sure its not the diesel.

If the starters are turning well then the batteries are providing the necessary current, so yes, it seems they are ok. Although you did say the Clio turned slowly which could indicate a problem. However, if during cranking a poor battery causes the voltage to drop too far, there may not be sufficient voltage level to drive the engine electronics - although the starter motor, being pureley mechanical, will keep turning once the initial momentum is gained.

Battery conditioner / chargers are flawed in that they rely on the battery voltage to indicate condition (as do car alternators). When lead acid batteries begin to fail (or at low temps too) they still charge up, but their internal impedance can increase so you can't draw off as much current, so a lead acid battery can be completely shot but still show a 'fully charged' healty 12 volts or so, but when any current is drawn off the voltage will collapse.

So your charger says it fine, your voltmeter says its fine but it could be shagged.

You need to use a voltmeter across the battery terminals during cranking an see how much the voltage drops by. Try between the cars to see the difference, a good battery should only drop a volt or two at most during starting.

[NFS]

Originally Posted by AlanQS

Is it just the temperature? I thought diesel didn't freeze until much lower than -14c. Anyone got any info on that?

I think that you need to start using additives with diesel motors once you are a couple of degrees below freezing.

It starts to thicken rather than freeze, but this is enought to screw up bus engines and construction site generators etc.

If that car has stood through this weather it could well be the diesel temp.

[creepy coupe]

If i were the fuel, most of the country would have problems.

[doughboy]

+1 - If its the fuel, why aren't all the soot chuckers all waxed up?

-20 in some areas.

You see truckers in Siberia lighting fires under their fuel tanks, but that's when it -50 odd.

[creepy coupe]

My Missus had a 106 derv burner years ago, the glow plugs needed changing on it. Anything over 5-6 seconds for the light to go out and I'd say their in need of changing.

[AlanQS]

Well, temperature has got up to +1 c so far so I thought I would try starting the car. It caught reasonably quickly but immediately started hunting, then stopped. Started it again, the glow plug light came back on followed by car on a ramp sign followed by a big yellow exclamation mark as a horrible screech started up, under the bonnet - so I switched it off. It will be warmer later on today so I will try it once more - if still no good, it's phone the dealer time.

[AlanQS]

Tried again at 3.30pm. It started, complete with whine but the minute I tried to apply some throttle it slowly faltered and stopped - complete with yellow engine block sign.

It is now deceased.

[milesr3]

It seems highly likely that you've completely drained your battery.

Starting a car takes far more charge out than 10 minutes of idling could ever put back in. Especially in sub-zero temperatures.

Recharge the battery (if you haven't completely killed it) and don't start it unless you can drive it far enough to warm up properly.

[AlanQS]

That's my problem. Previously when I put the charger on it automatically switched over from charge to trickle/maintenance after 30 seconds. When I put it on the charger this time, it charged for about 3 minutes and then switched over to trickle again -which is where it stayed for the last hour.

By the way, thanks for the comments and suggestions gentlemen.

[creepy coupe]

Sounds like a loose alternator drive belt might not be helping.