Alex Robbins is contributing editor at Telegraph Cars where, as well as responding to readers’ queries, he also contributes reviews of new and used cars, together with articles on buying and selling. 

His knowledge of the used car market informs his many buying guides relating to the best buys in particular sectors, with an emphasis on value for money. Every week he will answer your questions on buying and selling, as well as solving your car problems, whether consumer or mechanical.

Do you have a motoring dilemma you’d like our expert to solve? For consumer and used car advice, or car faults, email CarsAdvice@telegraph.co.uk and include your subscriber number. This week’s question… 

Dear Alex, 

My 2013 Ford Mondeo Titanium X was fine when I used it at the weekend, but by the following Friday morning the battery was so flat that my garage had to remove it and charge it overnight. The car is now fine, although I’ve lost confidence that if left for a few days the problem will not recur. The battery is only a year old. My garage is proposing to check the electrics for a current drain. Is this model of Mondeo susceptible to this sort of problem – and is it likely to be easily diagnosed and remedied?

– CD

Dear CD,

With the battery being so new it is unlikely to be the cause of the problem and, given that the issue cropped up after the car had been left for a few days, it’s understandable that the garage thinks a battery drain is at fault.

However, it could also be a faulty alternator – it may be that the car was charging enough to get you to your destination and back at the weekend, but it left so little juice in the battery that by the time you came to start the car again on the Friday it was flat.

I wouldn’t say battery drains are common on Mk4 Mondeos, but there are a couple of unusual issues they have that can cause them. For example, if your car has a Bluetooth stereo (which I think it will, given it’s a top-spec, late-model car), the Bluetooth module can become faulty and stay active even when the ignition is switched off.

This might not sound like much of a drain, but the problem is the way the car is wired; the instrument panel lighting and the screen between the dials won’t shut off if the Bluetooth module is still active. If they stay on permanently, that’s a fairly significant drain on the battery that would lead to the sort of flattening you describe.

There is an easy way to check whether this is indeed the fault you’re experiencing. Switch off the ignition, lock the car and leave it for a couple of hours. After that time, the instrument panel lighting and screen should have turned off.

If they haven’t, I’d say that’s the probable source of the battery going flat. Otherwise, get your garage to test the alternator first to eliminate it as the culprit.

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