Robert Bruninga via EV wrote:
what is the "load dump" problem?
In automotive parlance, the dreaded "load dump" occurs when the
alternator (or DC/DC) is charging at a high rate, and something causes a
sudden drop in load current. It could be a loose or corroded battery
cable, or a cracked or intermittent connection inside the battery, or a
momentary short somewhere in the wiring (like hooking up jumper cables
backwards) that pushes the alternator (or DC/DC) to its maximum
output... and then suddenly that load goes away.
The voltage then skyrockets to 30v, 50v, even 100v or more; until
*something* absorbs the current (Bang!), or the alternator or DC/DC
detects the loss of load, and backs off.
Here's an example that happened to a friend of mine. The car was
running, and he reached up under the dash wearing his wrist watch with a
metal band. It shorted +12v to GND. The voltage sagged, and the
alternator went to full power. The wristwatch band melted off his wrist
(YOW!) Now the load was suddenly removed. And then... every light in the
car that was on flashed and burned out. It also blew a number of uses,
but luckily the electronics were either well enough protected, or off at
the time.
Lee
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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