[DML] Re: Jump Start & Computers (was Over revving Auto)

[Mike Substelny <msubstel@xxxx>]

Duke said:

> You're correct about the electrical surge. One thing that is
> really bad for the computer governor is jump starting the car.

Could someone elaborate on this, please? When and how does the surge
take place?

I assume this means that the tranny computer gets power even while the
ignition is turned off, and the surge occurrs when the cables make their
final circuit contact. In this case, jump starting the car will
suddenly engage the computer . . . something like a battery cutoff
switch does. Is this really dangerous?

If the computer 'boots up' when you turn the key, then the surge from
jump starting should be similar to the surge from normal starting. I do
not understand the danger. How can the computer tell the difference?

I do agree that a battery charger can be deadly to a computer. Most
chargers do not put out the steady current that a computer wants. They
put out some sort of wave, often a DC square wave, that is very
unhealthy for computers.

- Mike Substelny