Firstly, sorry for the length of this!

On my way to work on Wednesday my car just cut out when changing from 5th to 4th gear (going uphill). I have done this journey many times and this has never happened before .

When the weather was really cold a really months back the car would not start at all until we managed to bump start it. All the while trying to get it going, it was making a noise like a pneumatic drill (battery?) but not starting. This was the same noise I had when trying to restart after cutting out.

Car has enough oil, is not overheating and when the AA man rescued me and restarted it the alternator and battery were reading 14. something so apparently fine. He had no idea what was going on and no codes could be found before getting it started as we had to move the car asap due to being in a dangerous place [emoji20]. No codes thrown up afterwards so he had a couple of theories but nothing set in stone saying that it would have to happen again in order to find the problem. He stated that it could be the alternator as that doesn't look like it has ever been changed (56 plate), or a connection problem from there to the battery, or the battery. Nothing definite to take to the garage though.

I'm currently using my partners *damn uncomfortable* focus and I miss my grande! Need to get it back on the road if anyone can help?

1.2 8v active if that helps! 56 plate as mentioned above.

Hi [First_Name],

I whish the AA Guy would have checked your battery ! The good way to do so is with a battery tester (see pic).

Theory:

each battery element has a voltage of 2.1 volts when fully charged and no load. Six elements give the typical 12.5 - 12.6 Volts that we can measure on a healthy battery. When the engine runs, the alternator produces electricity with 14.4 Volts (typical). The voltage difference is enough to initiate the internal chemical reaction and charge the battery.
At starting, the starter motor whitdraw a HUGE amount of current from the battery, thus creating a voltage drop. This voltage drop will be partly proportionnal to the battery health (due to internal resistance going lower on weak battery) and the 'remaining' will be used for ECU, ignition etc.
The idea of the tester is to simulate this by shunting a BIG resistor to the battery and measure the voltage at the same time, this will give a good indication of the battery status.

The noise (pneumatic drill) that you hear is the starter motor spinning with the pinion NOT engaged, possibly due to a weak battery (confirmed by the cold start issue). It seems also from other threads that starter motor are prone to failure on some GPs...

I would bring the car to an electrical pro and have the battery checked before anything else...

Regards, Bernie

If someone here helped You fix or understand your issue, hit the thanks icon, it's free !

got link of that battery tester?

A video of the sound will help a bit.
A bag ground cable will give similar symptoms.. noise when trying to crank... but engine doesn't turn over; engine sometimes dies...etc
Ground cables are prone to corroding on the GP.

Have a jump start cable go from the negative battery terminal to the gearbox (make sure it makes good electrical contact)

https://www.machinemart.co.uk/c/battery-testers/

Regards, Bernie

Bernievarian said:

https://www.machinemart.co.uk/c/battery-testers/

Regards, Bernie

Click to expand...

how accurate is this? do you have one?

Hi Fisko,

those are NOT intended to be accurate i.e. for troubleshooting electronic circuitry, but they are excellent for detecting battery/alternator car malfunction. I own one, not exactly the model shown but very similar.

You can actualy mimmic what they do if you have a standard mutlimeter:

- clamp it to the battery terminals (in DC mode !)
- check the battery voltage, ALL things OFF
- turn ignition ON, voltage should drop when the ECU, fuel pump, etc. fires up then stabilizes a few hundreds mV below initial voltage
- if it's a Diesel engine, the voltage will drop slightly while the glow plugs are ON
- once the voltage has stabilized (and pre-heat done), crank the engine and check the voltage BEFORE the engine starts running by its own. Once engine is started check the V-meter again, this will be the charging voltage.

Results of your measurements:

- all OFF : 12,5 V : battery fully charged
- ignition ON, after stabilization: above 12V: no major problem (no current leak)
- cranking : above 11V : battery is good
- cranking : betweeen 11 and 9V : battery is weakening (or too small)
- cranking : below 9V : battery is bad
- engine started : between 13,5 and 14,5V: alternator is charging

Rule of thumb : the smaller the battery, the bigger the voltage drop ; the bigger the engine (bigger starter as well), the bigger the voltage drop too ...

Regards, Bernie

Ok, so the AA guy was unable to check the battery where the car was situated due to being in a dangerous position. He placed the power pack on the battery and the car started. He stated that if he removed it and the battery was a dud then it would likely stall... It didn't. He knocked it off, restarted, off, restarted several times and it started first time every time. We moved the car to a lay-by further up the road and he put the ecu tester on and checked the voltage readings for the battery and alternator... Nothing suspect at all. Could this be the ground shifting/weakening instead? Have had 2 new starter and solenoids last year in the space of 5 months and another garage suggested it may never have been the starter but could be the flywheel which is apparently a common fault.

When I tried to start the car and heard the noise, I looked under the bonnet and everything seemed fine except that the belt was turning very, very slowly. If I hadn't been looking to see if it had snappedor eroded etc, I wouldn't have noticed it turning at all. Is this the starter again? Flywheel? Or something else?

Bernievarian said:

Hi Fisko,

those are NOT intended to be accurate i.e. for troubleshooting electronic circuitry, but they are excellent for detecting battery/alternator car malfunction. I own one, not exactly the model shown but very similar.

You can actualy mimmic what they do if you have a standard mutlimeter:

- clamp it to the battery terminals (in DC mode !)
- check the battery voltage, ALL things OFF
- turn ignition ON, voltage should drop when the ECU, fuel pump, etc. fires up then stabilizes a few hundreds mV below initial voltage
- if it's a Diesel engine, the voltage will drop slightly while the glow plugs are ON
- once the voltage has stabilized (and pre-heat done), crank the engine and check the voltage BEFORE the engine starts running by its own. Once engine is started check the V-meter again, this will be the charging voltage.

Results of your measurements:

- all OFF : 12,5 V : battery fully charged
- ignition ON, after stabilization: above 12V: no major problem (no current leak)
- cranking : above 11V : battery is good
- cranking : betweeen 11 and 9V : battery is weakening (or too small)
- cranking : below 9V : battery is bad
- engine started : between 13,5 and 14,5V: alternator is charging

Rule of thumb : the smaller the battery, the bigger the voltage drop ; the bigger the engine (bigger starter as well), the bigger the voltage drop too ...

Regards, Bernie

Click to expand...

It's a petrol engine if this changes anything

Hi Cat2 [First_Name ?],

on a petrol car there is no pre-heat glowplugs so no extra voltage drop expected here. It will drop a bit anyway at very beginning of key ON due to pumps (fuel and possibly dualogic gearbox) turning ON to reach their working pressure / fill the pressure accumulator...

The belt running very very slow : no belt slipping noise ? Is it tight ? Maybe you have the alternator blocked which is quite a common fault on UK Grandes

Regards, Bernie

These symptoms are typical of a dead battery, or a break in the earth cable. Both common issues.

Modern batteries die suddenly.

The earth cable, from battery to gearbox and on to the car body can corrode internally, as well as at the terminals. Remove it. Check the three terminals are clean, both the cable and where they attach to the car. Now flex the cable carefully along its length, feeling for any breaks or anything that feels weak or different. A resistance meter attached at each end might also help here. The cables can look fie from the outside, but the cable corrodes inside. Any doubt, replace. As said above, a quick test is to put a jumper cable from battery to gearbox. If all is then well, cable is dead.

Once sure the cable is fine, replace the battery.

I would definitely clean all the connections on the battery and the earth points especially on the gearbox.

digger58 said:

I would definitely clean all the connections on the battery and the earth points especially on the gearbox.

Click to expand...

I would check the cables too they can corrode inside the cable under the ends of the plastic cover