Ford Tdci Electric issues

[Dan9851]

Hi, hopefully someone can offer some advice. As soon as I turn the key to start the engine everything goes completely dead, no power at all and the battery measures 2v across the terminals. Beforehand, I have 12.4v across the terminals and everything works in the car, lights, fan etc. If you disconnect and reconnect the battery it returns to 12.4v.
I assumed it was a bad battery and when I jump started off another battery it fired up, so I changed the battery but this hasn't solved the problem. After two attempts with the new battery it did fire but then stalled after a few seconds and went back to 2v again.
When the car was running it had flickering headlights and flickering air con control screen backlights and then I found various errors codes relating to different electrical systems although seemingly not related to one another (eg turbo position and power steering). Does this point towards a bad starter or alternator (or voltage regulator)?

Car is a 2006 2.0L Tdci.

Any advice appreciated!

Dan

[Jazzy Jag]

Go cheap early and check all the heavy duty cables from battery to starter and to fuse boxes etc for condition and security.
Check both life and earth sides.

[E-bmw]

And when you have done that look for a pretty large current drain from the battery.

But before doing so, remove the battery & make sure you give it a good overnight charge first.

[Penelope Stopit]

A known good battery couldn't possibly go flat that fast

The fault could be due to dirty/oxidised battery cable terminals if you're measuring the voltage at the terminals on the ends of the cables rather than the battery lugs

[Dan9851]

Penelope Stopit said:

A known good battery couldn't possibly go flat that fast

The fault could be due to dirty/oxidised battery cable terminals if you're measuring the voltage at the terminals on the ends of the cables rather than the battery lugs

Thanks for the reply, the voltage was across the actual battery posts and I did apply copper grease. I don't think the battery is actually going that flat, it measures 2v after you try to start the engine but then if you disconnect and reconnect the battery it returns to 12.4v again. It's like there's a short when you try to turn the motor over.

[E-bmw]

Dan9851 said:

Penelope Stopit said:

A known good battery couldn't possibly go flat that fast

The fault could be due to dirty/oxidised battery cable terminals if you're measuring the voltage at the terminals on the ends of the cables rather than the battery lugs

Thanks for the reply, the voltage was across the actual battery posts and I did apply copper grease. I don't think the battery is actually going that flat, it measures 2v after you try to start the engine but then if you disconnect and reconnect the battery it returns to 12.4v again. It's like there's a short when you try to turn the motor over.

Hence why I asked you to check for a large current drain.

[Dan9851]

E-bmw said:

And when you have done that look for a pretty large current drain from the battery.

But before doing so, remove the battery & make sure you give it a good overnight charge first.

Thanks, what do you think could cause a big battery drain like that? If the alternator was faulty could an internal short cause this?

[Penelope Stopit]

Dan9851 said:

Penelope Stopit said:

A known good battery couldn't possibly go flat that fast

The fault could be due to dirty/oxidised battery cable terminals if you're measuring the voltage at the terminals on the ends of the cables rather than the battery lugs

Thanks for the reply, the voltage was across the actual battery posts and I did apply copper grease. I don't think the battery is actually going that flat, it measures 2v after you try to start the engine but then if you disconnect and reconnect the battery it returns to 12.4v again. It's like there's a short when you try to turn the motor over.

Ok then

There is nothing on the car that could possibly pull battery voltage down to 2 volts so quickly

Dead shorts on the main battery cables couldn't possibly pull the battery voltage down to 2 volts so quickly and even if they were shorting there would be plenty of smoke to be seen

Dan9851 said:

I assumed it was a bad battery and when I jump started off another battery it fired up

Tells us that the starter motor is working as it should

Does it still work with a jump start?

The second battery is definitely flat or faulty for it to drop to 2 volts so quickly

It is impossible to drop a known good battery down to 2 volts so quickly

A heavy duty starter motor might drop a good battery down to as low as 9.6 volts

Something to bear in mind though is that a high current draw such as that of a starter starter motor will drop the voltage of a faulty battery to 2 volts very quickly

A starter motor running in mesh could also pull the voltage of a faulty battery down to 2 volts very quickly, that same starter running in mesh with a good battery would burn out

Dan9851 said:

When the car was running it had flickering headlights and flickering air con control screen backlights and then I found various errors codes relating to different electrical systems although seemingly not related to one another (eg turbo position and power steering). Does this point towards a bad starter or alternator (or voltage regulator)?

One job at a time, a faulty battery could possibly be the root of all evil

Once you've solved the starting problem, check charging voltage and operation of above mentioned circuits

Edited by Penelope Stopit on Monday 17th January 08:03

[spikeyhead]

Is the new battery Lion brand? or some other cheapy?

[Penelope Stopit]

Any update on this?

[Dan9851]

It looks like I have a bad ground, I attached a jump lead between the negative connection to the battery and the engine block and it started no problem, with the old battery. I haven't been under the car yet but I guess it is a corroded connection. Maybe the additional resistance was causing the starter motor to pull a much bigger load than normal and was overloading the battery? Will have a closer look at the weekend. Thanks for all you help and suggestions.

[Jazzy Jag]

Jazzy Jag said:

Go cheap early and check all the heavy duty cables from battery to starter and to fuse boxes etc for condition and security.
Check both life and earth sides.