My mother once sagely observed that navigation in a car is basically a process of getting lost while you try to find the right major road, then driving for a long time in a straight line, and then getting lost in the fiddly back streets of your destination town. She doesn't have sat-nav.

Sat-nav is great for ensuring that you get on that right major road and then come off it at the right exit. Then you drive, smugly, straight to a particular house on Acacia Avenue or Chestnut Street without faffing about in a maze of one-way streets and confusing urban circulatory systems. When you're running late and a bit pushed for time, it's delightful to hear a cool, female voice telling you exactly what to do and when to do it. And I enjoy my son asking, "Who's that robot lady?"

It's an amazing technology that has got much better over the last few years. However, this is not true of the humble battery. About ten minutes before my exit is usually the moment when the sat-nav's battery warning light starts to flash. I should be able to take the recharger cable out of the glove compartment, plug one end into the cigarette lighter, and the other into the teeny tiny USB port on the side of the windshield-mounted unit. This is a little bit like when planes refuel each other in flight, only slightly more dangerous when you do it at the national speed limit in driving rain.

Unfortunately, and unlike the stubble-jawed exec-u-hunks who swing around corners in most TV car ads, I don't own a brand-new, top-of-the-range status motor. My perfectly good ten-year-old Renault has everything you need to get you to where you want to go, except a working cigarette lighter. (I don't smoke. Well not much. Well only when I've had a few drinks. Oh alright you twisted my arm. Can I borrow your lighter?) As a wretched part-time three- gin-and-tonics-and-I-quite-fancy-a-Marlboro-Light-pardee-smoker I naturally don't smoke when I drive (it's so hard to manage the glass and the fag and still keep re-programming the sat-nav, especially when cornering.) So I didn't know that the cigarette lighter didn't work. The first time my sat-nav died and discovered this fact, long drive, screaming child, driving sleet, apoplectic partner) this was not much fun.

So now when I leave on a longer journey, the sat-nav unit has to be fully charged. This gives me a constant, sweaty countdown, like an episode of 24. It's what's known in the movie trade as a tick-tock, and it adds much needed drama to a Sunday afternoon visit to your cousin: we've got two hours to get to Birmingham or the car will explode. No we can't stop for coffee. Yes this is the right way. Yes I do have to drive at 120 miles per hour otherwise the robot lady will stop talking and we're all doomed.

I know that when the sat-nav dies I should just flip open my AA road map with a cruel sneer, expertly calculate routes, vectors and tangents in my brain, coolly identify churches, schools and railway lines, and navigate via dead reckoning to arrive precisely at my target location. I should. Instead I drive around for a bit, get lost, have a row, ask for directions, drive around a bit more, have another row, stop for a pee, ask for directions again, and after slowly eliminating all possible incorrect routes finally end up, beaten and exhausted, at my destination.

The sad fact is that it's another dependency. The old door-stop-pat-down, in which you check your pockets to ensure that you've got everything you need before you leave, has got longer and longer. It used to be wallet-keys-phone. Now it's wallet-keys-phone-iPod-digital-camera-and-properly-charged-and-addressed-sat-nav. Sometimes it takes several minutes to ensure that every green light is blinking properly. A wall of rechargers clutters the kitchen but none can be moved because of the risk that an important device will be bricked and useless at the vital moment.

I thought I had it under control until planning a reasonably long journey to see friends. I said we'd arrive at three, but then phoned them back to explain that actually we'd be there an hour later. Then I made a cup of tea and settled down to read a good book, waiting patiently for the sat-nav unit to recharge fully. I love the way these technologies simplify our lives and save us so much time.

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Michael Parsons, now editor of CNET.co.uk, was once European correspondent for The Red Herring magazine, and spent five years working in Silicon Valley and worrying about technology. He can be reached at michael.parsons@cnet.co.uk