Hello all, new poster just hoping someone may be able to answer a problem we seem to be encountering with our 2012 S-Max.

We have only had the car for around a month but already had a flat battery 5 times. I’ve had the battery tested at the local garage and there appears to be no problems with it.

At first it seemed like an intermittent fault and the first couple of times it happened we assumed we’d left something on being a new car and all... 

However we have now realised that the flat battery seems to follow when we have loaded or unloaded the car without the engine running that the battery just drains almost instantaneously. 

I confirmed this by testing the theory today after a 5 hour drive from Devon. I turned the heater and stereo off, unplugged the sat nav and then stopped the engine. 

We then spent the next 5-10 minutes (no more than 10) unloading the car with the boot open and a couple of doors open, and it went flat straight away (this was straight after a 5 hour journey so I’d expect some charge in the battery!) 

Is anyone able to offer any advice please? Surely it shouldn’t drain this quickly? 

all help / suggestions greatly received! 

Thanks for reading! 

5 hours ago, Mule said:

We then spent the next 5-10 minutes (no more than 10) unloading the car with the boot open and a couple of doors open, and it went flat straight away (this was straight after a 5 hour journey so I’d expect some charge in the battery!) 

Is anyone able to offer any advice please? Surely it shouldn’t drain this quickly? 

It physically can not drain that quickly!

A 70AH battery would need a 420 Amp load to drain it in 10 minutes. That load, and any wires to it, would be red or white hot, and the battery would be boiling.

It suggests the alternator is not charging the battery, so it has hardly any charge in it when you stop. Alternator faults can be very hard to diagnose without special equipment.

Checking the battery terminal voltage would give some clues, it should be over 14v while charging,  then dropping very slowly (over say 30 minutes) to about 12.6v with no charge and no load. Even with headlights on and engine off, it should hold at about 12v.