Leaving your car parked while you travel: how to keep the battery alive in Abu Dhabi

Why does a car battery drain when the car is parked?

A parked car is never completely off. The alarm, the immobiliser, the keyless entry receiver, the tracker and the telematics unit that talks to the manufacturer's app all draw a small current around the clock. On a healthy car the draw is tiny, but it never stops.

Heat adds a second drain. A battery loses charge by itself with nothing connected, and it does so faster the hotter it sits, so a car on a driveway in July, when average highs are around 41 to 43°C, runs down sooner than the same car in January.

There is a longer-term cost as well. A lead-acid battery left partly discharged in heat suffers sulphation, which is a permanent loss of capacity. A long park does not only empty the battery, it ages it.

How long can a car sit before the battery dies?

For a modern car with a healthy battery, two to four weeks is typical. The table shows how that shifts with the battery's age and the car's electronics.

These are typical figures, not promises. What counts is the condition of the battery on the day you leave, so a battery test a few days before a long trip tells you more than any rule of thumb.

What should I do with my car before a long trip?

There are four realistic options, and the right one depends on how long you are away and where the car stands.

On newer European cars and anything with start-stop, the weekly drive or a maintainer is a better choice than disconnecting the battery. If you do disconnect it, first check that the mechanical key blade opens the door, because a battery in the boot behind an electric lock is a well-known trap.

What should I switch off before leaving the car?

Small loads add up over three or four weeks. A dash cam left in parking mode can draw more than the rest of the sleeping car put together.

• Switch off dash cam parking mode, or unplug the dash cam
• Unplug phone chargers, USB adapters and anything else in the 12V socket
• Remove plug-in OBD devices if you are free to do so
• Set interior lights to the door position, not permanently on
• Keep the key well away from the car so the keyless system can go to sleep
• Lock the car, since many cars only shut down fully once locked

Airport long-term parking or the villa driveway: which is harder on the battery?

Zayed International Airport is about 13 minutes from central Khalifa City, so residents tend either to leave the car in long-term parking there or to leave it at home and take a taxi. A shaded space is kinder to a battery than open tarmac, but in any public car park there is no socket for a maintainer and nobody to drive the car.

At home in Khalifa City, still Khalifa City A to many people, most cars stand on a driveway, under a carport or on the street edge in full sun. That is hotter, but you can run a maintainer from the house or leave a key with a neighbour. Residents with basement parking in an apartment compound get shade and a steadier temperature.

For a summer trip of a month or more, the car at home with a weekly drive beats the airport. For a week or ten days, either works with a healthy battery.

What do I do if I land and my car will not start?

Stop trying after the second attempt. Repeated tries drain what little charge is left, and on some cars that leaves the locks and the electric parking brake without power as well.

A jump start gets most cars going. We come to the car, in the airport car park or on your driveway, jump start it and test the battery and the charging system. The battery is replaced only if it fails the test, since one that simply ran down over three weeks usually recovers with a proper drive.

After a jump start, drive for at least 30 minutes without stopping for errands. The resting voltage next morning tells you where you stand: about 12.6V is fully charged, 12.2V is roughly half, and 12.0V or below means the battery is still flat or no longer holding charge.