Hi All, I bought a 2015 Focus Zetec 1.5 TDCi six weeks ago and have the following issue. When inspecting car prior to purchase, I noticed battery was 11.8v but car starting and driving very well with no electrical issues other than auto stop/start would only occasionally work. I thought I’d just buy a new battery as I was getting car for a good price anyway.

So, I got a battery of same spec and it was 12.6 before I installed it and 12.4 as reported by the Torque OBD app.  When driving, the voltage stays within a range of 12.0 – 12.3 all the time and rises to 13.5 when deaccelerating. I know batteries should be around 14.2 when driving so it was suggested the alternator was bad and it did look very old.

So, I put new alternator in, but the voltage issues remain the same and no electrical related issues other than auto start/stop not working. After I installed new alternator, I now have a ‘engine service now’ notification appears every time when starting the car. No codes on my basic OBD scan tool and none reported by the garage’s high spec scan tool. Car is driving fine and not in limp mode but it’s driving me nuts not knowing what it is.

A mechanic suggested that the low voltage might be normal for Ford cars and their trickle charge system, but he couldn’t confirm if that was the case. Another thing I noticed is the dashboard auto stop/start icon is missing since installing new alternator, but icon was there beforehand.  Any advice appreciated!

Did you carry out the full reset of the battery charging monitor after you fitted the new battery ? If not then the car thinks it still has the old battery and will not increase the charge voltage for the new battery.

Yeah I did the rear fog light/hazard light method a while back

You can do the reset at any time:

Try this to see if it the reset for your car:

Registered

1. Get in to the car and do all from points 2 to 4 within 10 seconds.
2. Turn on ignition with engine off (key in position II) .
3. Turn on and off 5 times rear fog light switch .
4. Turn on and of 3 times hazard light switch .
5. If everything goes OK battery light will flash 3 times on cluster within next 15 seconds.

Yeah i did that a while ago makes no difference to voltage readings 

The major problem now is engine will only intermittently turn over.

Have to crank it 4-5 times and have to press accelerator otherwise it won't start and the 'engine service now' notice comes up before attempting to start car.

Have you cleaned up any of the connections with some scotch brite and a bit of grease?

It was a snapped connection on the starter motor. £25 garage repair job 🙂