That "got'cha" pertains more to German cars but it's true, you will lose most computers' memory, however, that will be relearned as you drive, usually within a few miles. There are more problems related to anti-theft systems locking you out of your own car. With the newer silly "throttle-by-wire" systems the engine MIGHT start and idle but it won't increase speed when you press the gas pedal and it won't come out of park. That is very common with Volkswagens. They must be dragged to the dealer to have the computer reprogrammed, and you know they won't charge much for that!
To avoid those possibilities, and to avoid the inconvenience of having to reset my customers' radio presets and clock, I connect a small battery charger to the positive battery cable or stud in the fuse box, and the negative cable to the engine block, and I set it on the lowest charge rate while I have the battery disconnected. Jumper cables and a third battery works even better. You just have to watch that the jumper / charger cables don't fall off, and the positive battery cable must not touch anything metal on the vehicle.
They also make little "memory savers" you can plug into the cigarette lighter and use a 9 volt battery, but a lot of cars need the ignition switch turned on for the lighter socket to work. Turning on the ignition switch means running the fuel pump and many computers on the car. A 9 volt transistor battery can't handle that.
Wednesday, March 2nd, 2011 AT 3:57 PM