Yesterday came to start up but engine didn't fire, and the battery flattened in the process. Temp yesterday was about -10°C or so.

I charged the battery overnight with a crappy charger and got the wife's hair dryer on the fuel filter.

Engine started first time.

Battery voltages:
12.4V engine off.
14.9V running under load

The battery voltage seems a bit low, but I don't how much it will vary with temperature. It isn't as cold today, but probably between 0 to -5

The charging voltage seems a bit high compared to what I'd expect from googling about car batteries - any thoughts?

I'm going away for 2 nights, and the wife is worried she'll end up stuck somewhere. Any ideas how not to get me into trouble???

sorry for long post!!!

cheers in advance.....

sorry, the point of my thread is, do you think it was the cold temp or the battery at fault?
Because I changed 2 things (charged battery and warmed filter), I can't figure out what the problem is.

Combination of temperature, partially discharged or weak battery, thick engine oil, etc. How long had the motor been standing since it was last started? Voltages seem about right.

Carry some decent boost cables, put a gallon of unleaded in your tank when you fill up with diesel, let the glows operate until the light goes out before cranking (the glows will still be powered by the ECU until it decides they are not needed), dip the clutch while cranking, turn off everything else including the radio, heater fan, and any lights until the engine is running.

This weather is hard on batteries especially when cranking a cold diesel engine.

Sounds like battery to me, i had the same problem, a sub par battery will lack cranking ampage even if volts are in the good zone. 12.9V is low tbh, i'd be looking at near 14V on a good battery overnight from previous journey.

yer batteries knackered

cheers chaps, sunds like a mixture of things, will get a new battery from santa....