MY Focus won't start on pressing the Engine Start Button. It happened before and originally thought it was a flat battery, Replacing the battery seemed to cure this issue but it has reappeared again. 

 

My Current thinking is that the car isn't entering Recharge mode (it has Stop/Start and likely smart charging) but have no idea how to check if this is the case. Anyone ever have similar issues?

MY Focus won't start on pressing the Engine Start Button. It happened before and originally thought it was a flat battery, Replacing the battery seemed to cure this issue but it has reappeared again. 
 
My Current thinking is that the car isn't entering Recharge mode (it has Stop/Start and likely smart charging) but have no idea how to check if this is the case. Anyone ever have similar issues?

What is recharge mode? Is your focus a hybrid or something?


Sent from my iPhone using Tapatalk

No It's A Normal Diesal engine. Having stop start the car doesn't always go into a charge mode 

The smart charge system can vary the voltage based on the battery state of charge, engine load, battery temperature etc. I have never seen it switch off completely. Usually the charging voltage is high (around 15 volts) when the engine is cold and the voltage drops a bit (a bit over 14 volts)  when the engine warms up. Have you tried a volt meter plugged into the cigarette lighter socket to find out what voltage the alternator is putting out whilst you are driving? When you replaced the battery did you get a proper Enhanced Flooded Battery designed for stop/start systems?

No It's A Normal Diesal engine. Having stop start the car doesn't always go into a charge mode 

Yes apologies, I mis-read what you wrote. I don’t know a lot about that type of system but I do know if the voltage in the battery is low the start/stop system won’t engage, meaning the car won’t stop the engine when you sitting in traffic, basically the car detects low voltage and as a precaution won’t stop the engine incase it won’t have the power to start it again. As for not starting on the button in the first place could be low voltage. Is your battery light coming on while driving to maybe indicate an alternator problem? It could also be a less common rectifier problem. The best thing to do Is to check the voltage when the car is running as another person has suggested, this will rule out an alternator problem to start with. And may also give you an indication of a rectifier problem if the charge is higher than it should be which can over time destroy your battery either completely or enough to stop it holding charge.


Sent from my iPhone using Tapatalk

On 6/4/2019 at 8:27 AM, slim8110 said:

Yes apologies, I mis-read what you wrote. I don’t know a lot about that type of system but I do know if the voltage in the battery is low the start/stop system won’t engage, meaning the car won’t stop the engine when you sitting in traffic, basically the car detects low voltage and as a precaution won’t stop the engine incase it won’t have the power to start it again. As for not starting on the button in the first place could be low voltage. Is your battery light coming on while driving to maybe indicate an alternator problem? It could also be a less common rectifier problem. The best thing to do Is to check the voltage when the car is running as another person has suggested, this will rule out an alternator problem to start with. And may also give you an indication of a rectifier problem if the charge is higher than it should be which can over time destroy your battery either completely or enough to stop it holding charge.


Sent from my iPhone using Tapatalk

Knackered rectifiers in the alternator can also cause the battery to be drained when the car is sat/turned off for any reasonable length of time as the current is allowed back in the direction it came originally.