Hi Guy's.

I've got a 2007 transit connect and having a strange battery drain problem.

 

When the weather is mild (warm) and left overnight it starts perfect, however when the outside temperature is cold, it drains the battery.

I've done a battery drain test in the day and all seems to be OK, however I can't stay up all night to keep testing the battery..

 

I would appreciate any help or advice.

 

Ash 

1 hour ago, _ASH_ said:

When the weather is mild (warm) and left overnight it starts perfect, however when the outside temperature is cold, it drains the battery.

It can be very hard to separate battery problems from battery drain.

As the temperature drops, the terminal voltage of any car battery will drop, and its internal resistance (ability to supply current) will get worse. This happens even with a brand new battery, the cranking current (CCA) is specified at a low temperature for that reason. But as a battery ages, or a fault develops in it, these effects will get much more noticeable.

Add in the extra glowplug current (60A quite possibly), and more effort needed to turn over a cold engine, then a cold morning start really stresses the battery.

Doing a voltage test on the battery before starting would separate the extra effort of a cold start, but would not separate drain from the effects of temperature on the battery. You would probably have to leave the battery disconnected overnight to do that, which is a nuisance as everything, including ECU adaptions, gets reset. Unless you could leave the car connected to a charger, with the battery disconnected. Then there would be no drain on the battery, just the temperature effect.

A voltage test would be: Volts immediately after unlocking, nothing else switched on. This should be over 12v (ideally 12.4 to 12.6v, but the unlocking will knock it down a bit). Then ign & headlights on for about 15 sec, and re-measure the voltage. If below about 11.5v, it is probably a bad or discharged battery, but voltage tests will not separate the two. A good proprietary battery tester (expensive) might separate the two effects, but even that is not certain.