When did a 'simple' battery change become a two-hour ordeal?

A few weeks ago I had a Land Rover Defender on test. Despite its 1940s driving position, I loved its character and the fact that the new engine, from the Freelander, gave it a bit of modern engineering to go with the ancient body.

However it was not all progress. Charging its flat battery was an ordeal that would have horrified anyone used to the mechanical simplicity of an early Land Rover. I flattened the battery by leaving the lights on – or rather by putting the lights on without realising it. Parking in daylight, I must have knocked the lever for the headlights, which is next to the ignition key.
When I discovered that the battery was flat I did momentarily think of calling the AA, but then thought that would be a pathetic cop out – surely I could sort it in 10 minutes? I found a new-shape Ford Focus and a set of jump leads, so I just had to find the two batteries.

The Defender hides its battery under the front passenger seat (not a stupid place to put it, but not the first place you would look), but the Focus was the one with the real challenge. All engine components are now hidden under plastic covers (are we so squeamish that we cannot bear to look at bare mechanicals anymore?), so first you have to find the right plastic cover.

The first one I tried was the fuse box, then one at the back of the engine compartment. And there was the battery – or rather half of it. The other half, with the negative terminal, was hidden under the windscreen. Attaching the jump lead to the hidden terminal was out of the question, but a bit of wiggling got it attached (just) to the bolt attached to the terminal.

Having started the Defender, I was a bit concerned that the immobiliser warning light was on, so I drove around for a couple of miles to charge it up and then found a non-residential road to stop - it was now 8pm, so families would not appreciate the ear-splitting alarm going off.

Sure enough, the immobiliser would not allow the Defender to restart – every turn of the key just triggered the alarm. The handbook's procedure for rebooting the immobiliser had exactly the same effect. Now there really was no alternative but to call out the AA.

The nice man from the AA had a world-weary air. "Oh yes, we know about these," he said. Apparently the rolling code immobiliser, which generates a new code each time the engine starts, can get too far out of sync when the battery goes flat and cannot reset itself. The trick, apparently, is to disconnect the battery, wait a few minutes, reset the immobiliser, then start the engine. Silly me for not realising.

So, what used to be a 10 minute job to start a car with a flat battery turned into a two-hour adventure. No wonder so many people now regard a car's engine compartment as a sealed unit, and would no more interfere with it than they would try re-plumbing a nuclear power station.

The Defender feels indestructible in every other way, but can you imagine being stuck in the middle of the outback because the council-estate-proof immobiliser has thrown a wobbly?
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