Hi everyone, hoping someone may be able to shed some light or possibly have experienced this themselves and found a solution…

 

I have a Focus ST-2 2007 2.5 and overnight the battery is draining. At first, the alarm would sound every couple of minutes and the only way to stop it was leaving the car unlocked until the battery eventually died. There are no obvious lights left on (including the boot and glove compartment). 
 

The car seems to have an exact sequence it goes through:

1. Jump start, steering assist failure comes up 

2. ESP dash comes on (esp button not lit up

3. Both heated windscreen buttons light up (without being pressed ‘on’

4. ESP dash light goes off but the button then lights up 

4. handbrake light on although handbrake is off then goes off a few seconds after 

4. battery light on then goes off 

5. steering assist failure pops up

6. Finally - all lights go off as normal, steering assist goes away therefore I have steering now but 20 seconds after the whole process starts again in the exact same sequence 

I had a mobile mechanic out and he tested the alternator off the battery and said it was fine so definitely the battery as it was draining instantly. Replaced battery yesterday, car dead again today no lights on at all and no crank. 
 

We did notice an earth cable was corroded near the battery and de attached so we replaced that, car seemed totally fine - steering was back and no lights up on dash until of course the following morning it had died and back to square one again! 
 

sorry for the long post - I’m losing the plot 😀

You need to do a parasitic draw test.

Get a multimeter, remove the negative terminal and put one lead on the battery terminal and the other lead on the negative cable. Set your multimeter to amps and check how much current you have. My guess is you'll have a draw above 200mA if your battery keeps going flat.

Start removing fuses 1 by 1 till the current drops off, then you've identified the circuit at fault.

When you do the test, make sure the doors are locked, all lights etc. are switched off and you've left the car for half an hour ish. You'll get a false reading if you don't, as some of the modules will be awake and drawing current.

Unless you do this test you're just guessing as to what's at fault.

3 hours ago, Luke4efc said:

You need to do a parasitic draw test.

Get a multimeter, remove the negative terminal and put one lead on the battery terminal and the other lead on the negative cable. Set your multimeter to amps and check how much current you have. My guess is you'll have a draw above 200mA if your battery keeps going flat.

Start removing fuses 1 by 1 till the current drops off, then you've identified the circuit at fault.

When you do the test, make sure the doors are locked, all lights etc. are switched off and you've left the car for half an hour ish. You'll get a false reading if you don't, as some of the modules will be awake and drawing current.

Unless you do this test you're just guessing as to what's at fault.

Thanks Luke, I’ll give it a bash this week when I get a chance and hopefully find the culprit.