Careful with the charger

 Most traders have a booster-box of some kind. Mine is a rather fine Clarke unit which I’ve had for well over 20 years, and despite not always getting treated with the TLC that it deserves, it’s an extremely useful piece of kit which continues to do everything asked of it. In most cases connecting it to a car battery that’s gone flat through standing is all that it takes to get the car going again.

However, it was designed and built for a different age, and needs using with care on modern cars. You also need to follow the instructions on it, especially when it comes to the fast-charge boost setting. The instructions make clear that this is only intended to be used in conjunction with starting; in other words you switch it on and then immediately try to start the car and put it straight back on to the low setting afterwards.

This of course, is the sort of ‘instruction’ that a lot of people didn’t worry about. Nowadays, however, any external power source needs using with care, as car electronics aren’t usually designed to withstand such treatment, and many won’t.

I believe Gm-type ECUS can be particularly susceptible, and I need to admit to direct personal experience of this. A few years ago, I bought in for sale a rather nice second-generation Zafira diesel auto. It hadn’t been a bargain. In fact, I had to pay top money for it, but the diesel/auto combination was rare, and I figured that with the seven-seater bit thrown in it would find a buyer without too much difficulty.

For various reasons, however, it was left standing for a month, and when I came to start it, the battery was flat. Connect booster; it cranked but still wouldn’t go. Eventually, a mobile auto-electrician diagnosed a “likely ECU fault, recommend main dealer check to confirm.” A suspended tow-in (auto, remember) later, the main dealer confirmed that the ECU was, indeed, fried. Fitting a new one, along with the necessary recoding, etc (which would have needed doing by a main dealer anyway) cost £1200. So all the profit gone, and a bit more besides!

So take care when boost-charging; these days it’s often better to wait an hour or three. Ideally, use a smart charger instead.