Hi have recently baught a 2013 plate focus titanium. 

The other day the car would not start and the battery seemed to be dead. Using a multimeter I measured the volts of the battery at 11.5V 

I had a friend jump me and I drove the car for an hour with electric use to a minimum. 

When I returned the battery read at 12V on my multimeter. Whilst the engine is running the V reads at around 14.3V and when electrics are in sue such as headlights and the AC imparticular it doros to around 11.6V 

The current measures at round 33 amps whilst running. 

Does this look like a faulty alternator to anyone a bit more experienced than myself? 

Thanks 

1 hour ago, Peter mccabe said:

Whilst the engine is running the V reads at around 14.3V and when electrics are in sue such as headlights and the AC imparticular it doros to around 11.6V

 

1 hour ago, Peter mccabe said:

Does this look like a faulty alternator to anyone a bit more experienced than myself?

Hi Peter.

Yes.  It should be reading 13.5v to 14.8v when headlights, A/c etc are on. Hope that helps 🙂

I’d say battery connect a test lamp across it and put your meter on it you’ll see the volts drop to about 8 if that happens your battery isn’t holding charge just had the same thing with the work van Engine off 

Does this alternator have a one way clutch  built into the pulley. They can fail so pulley does not grip on shaft enough

20 hours ago, Peter mccabe said:

Hi have recently baught a 2013 plate focus titanium. 

The other day the car would not start and the battery seemed to be dead. Using a multimeter I measured the volts of the battery at 11.5V 

I had a friend jump me and I drove the car for an hour with electric use to a minimum. 

When I returned the battery read at 12V on my multimeter. Whilst the engine is running the V reads at around 14.3V and when electrics are in sue such as headlights and the AC imparticular it doros to around 11.6V 

The current measures at round 33 amps whilst running. 

Does this look like a faulty alternator to anyone a bit more experienced than myself? 

Thanks 

Hi Peter,

Alternator looks good to me. You get these funny readings cause your battery voltage is low. With all other electrical loads off, alternator has enough ampacity co charge the battery, but with lights, radio, Ac on alternator supplies voltage and current to the load, leftovers to the battery. So re-charge your car battery first, than see how is the alternator voltage with and without load.

5 hours ago, Ned_Mk2_1.8tdci said:

Hi Peter,

Alternator looks good to me. You get these funny readings cause your battery voltage is low. With all other electrical loads off, alternator has enough ampacity co charge the battery, but with lights, radio, Ac on alternator supplies voltage and current to the load, leftovers to the battery. So re-charge your car battery first, than see how is the alternator voltage with and without load.

Hi thanks for the reply. I had thought of that so after the jump-start I drove the car for just over an hour in the countryside. 

 

The reading of 12.0 v was after this journey. I have been lead to belive that 12.0v is nowhere near fully charged and that the battery should be essentially fully charged after an hour of driving. 

If I'm wrong then correction is much appreciated 

If I tested battery voltage after an hour of driving (engine off, lights etc off) I would expect about 13 volts if done straightaway. Falling to 12.6v if left a while. But staying at 12.6 v and not falling further

Agree with Isetta. 

You could just drive it around for a couple of weeks and measure the battery after a few hours rest. The battery may get you through the summer, but will cause starting problems in the winter if its voltage is still low.

If it reads less than 11.8v then one cell has failed and you should change it asap.

Just get a new battery you got at least one dead cell.

On 4/9/2020 at 8:07 AM, Kevin#95 said:

Agree with Isetta. 

You could just drive it around for a couple of weeks and measure the battery after a few hours rest. The battery may get you through the summer, but will cause starting problems in the winter if its voltage is still low.

If it reads less than 11.8v then one cell has failed and you should change it asap.

Be careful about battery lasting over the summer. Battery plates are since 15 years  Lead-Calcium. Advantage is low electrolyte consumption but they are sensitive to a high temperature, hence failing more at warm season than when cold.  Peter should either charge the battery  with external charger or get a new one.