On Sat, 7 Jan 2006 13:28:28 -0500, "D Duddles"
wrote:

The lighter outlet will probably be fused at somewhere between 10 and 20
amps in the car's fuse block, depending on if it's actually a lighter outlet
or an Aux. Power Outlet (same size, but the Aux. Power Outlets sometimes
have higher fuse ratings and heavier gage wiring to power external devices,
and also may not have the clips at the bottom to retain the lighter element
when it's pushed in). In any case, make sure you either use wires that are
large enough to support the maximum fuse rating of the outlet, or put in a
smaller fuse to prevent turning your "extension" wires into a heater
(especially if there is an internal short in the drill that destroyed the
original battery). There's not much danger of a hydrogen explosion of the
car battery, since the car's fuse will blow before you can draw that much
current from it.

The risk of explosion is low, but not for that reason, It doesn't
take a large amount of current to cause a hydrogen explosion, and if
there is a 10 amp fuse, 9 amps is a plenty large current if it isn't
in the wire.

If the current is in the wire, a far larger current is not sufficient
to cause an explosion. Consider the hundreds of amps used by the
starter motor when the car is started.

Any tiny spark can cause a hydrogen explosion, far less than one amp.

Why you don't see many is that hydrogen is only generated when the
battery is charging, not when it is being drained** and in this case
the guy using the drill probably won't need to run the engine to run
the drill. And a hydrogen molecule is the lightest of all molecules,
and they float away as soon as they escape from the battery. Since
they are generated under the battery caps, and I think, not sure,
that maybe only escape rather slowly, that they tend to build up
under the battery caps, and if a spark, from a loosely connected
drill, for example, ignites the small amount of hydrogen outside the
battery, the burning can spread to the larger amount inside, and that
is the explosion.


**Although since one would drive the car to where the drill was going
to be used, it would have been charging recently.

The draining, the discharging of the battery, requires hydrogen, but
it takes it out of the sulfuric acid in the battery, because the acid
is the electrolyte,, and I don't think will normally take it from the
gas above the acid.

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