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Only 13volts

Mark996

Mark996

PCGB Member
Member
Hi.
My 2005 C4s will only show 13volts at the battery and after using it with lights and heated seats one the battery will not start the car.
The battery is new the alternator was swapped for a new on but that only showed 12.9volts so we swapped it back.
Help please.
 
Lead acid batteries have 6 cells, each with a voltage of 2.1, so a fully charged car battery has 12.6 volts.

At 12.4 volts, a car battery is 75% charged while at 12.2 volts it's 50% charged.
You don't provide much information for a diagnosis.

But work through all the usual electrical tests and this should reveal the fault. Check for any loose or damaged connections (ensure the engine earth is sound), check the heavy duty cabling from battery to alternator and starter and confirm the alternator is actually charging the battery. Check the starter motor.

If the battery is new, it should be OK, but if all else fails have this tested for heavy discharge as it could be faulty.
Regards,

Clive
 
Hi Clive.
Thanks you for the advice, I will work through what you have said and fingers crossed fix it.

Kr
Mark
 
With the age of your car, I would suspect a faulty starter motor. May be eligible for replacement under extended warranty.
Regards,

Clive
 
Ask your local garage to check the voltage at various points from the battery to starter. I had to have the main lead changed as it had corroded and caused a power drop. Once changed all fine....
 
Hi All.
Thank you all for your help.
My car is now fixed.
As suggested the starter was lazy dragging a lot of power along with the main cable crimps being iffy.
New starter and my ends re crimped with the addition of an extra cable to assist the oe main cable and all looks good.
Now if you could fix Covid19 I can enjoy the car.
Thanks again and stay safe everyone, see you on the roads asap.
Mark
 
Mark,
It's always good to hear of a satisfactory outcome, so thanks for coming back on this.
My lawn mower has just started to display similar symptoms, so I guess I'm now going to have to follow my own advice. [:mad:] [:D]

Regards,

Clive

 
May be stale fuel, but a blocked jet would be my guess, Paul.
Suggest you refill the tank with fresh fuel, pull the top off the carb and blast it with an air hose.
See how that goes.

Regards,

Clive
 
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