Does spark mean a short?

[hrosenthal]

When I connect my battery, I get a spark when connecting the negative terminal (positive is connected). It's only when the cable first makes contact with the battery -- it doesn't continue sparking after the contact is made.

Is that normal, or does it mean there is a short in the system?

I don't have any experience with hooking up batteries or even jump starting cars for that matter, but sparks make me nervous.

[FFinisher]

Not necessarily, what drivetrain, engine combo?

[Bob Cowan]

That means there's some sort of electrical draw in the system. A stock computer needs power all the time. So do things like clocks, and radio's with memory preset buttons. Or it could be a short.

[Jeff Kleiner]

What Ron and Bob said. A tiny spark would not be abnormal if you have accessories which are powered all the time such as those that Bob mentioned. With the battery cable off set a digital VOM to the 10 amp range then touch one probe to the battery post and the other to the cable. I'd expect you'll see <1 amp.

Jeff

[skullandbones]

http://ts1.mm.bing.net/th?&id=HN.607997584994009550&w=300&h=300&c=0&pid=1.9&rs=0&p=0

Now that's a short! But seriously if it goes "pow" or scares the crap out of you especially if you are in a tight spot causing you to hit your head, something is touching that shouldn't. The little ones are just a reminder that you're live.

Good luck, WEK.:cool::cool:

[Oppenheimer]

A 'short' means there is a shortcut path for electricity to travel other than the normal, proper path. Like wires touching that aren't supposed to. Typically that shortcut path means more current can flow than normally should (lots more), and all the heat from all that current beyond what wires and such were designed for is what makes things melt and burn, the kinds of things that make short circuits dangerous. The opposite of a short is an open, a broken connection that does not allow any current to pass.

Like others mentioned, a spark on battery wire connection just means current is being drawn by something at the time of connection. If your motor has an ECU, or your radio has presets, or any other components uses juice even when the key is out and everything is off, then this spark is probably normal.

Unless it was big scary sparks, it was probably just the radio or something like that.

[Tocoti]

You can find out what it is if you want. Take the pos cable off the battery. Hook a test light between the post and the cable. Start pulling fuses until the light goes out.

[hrosenthal]

A 'short' means there is a shortcut path for electricity to travel other than the normal, proper path. Like wires touching that aren't supposed to. Typically that shortcut path means more current can flow than normally should (lots more), and all the heat from all that current beyond what wires and such were designed for is what makes things melt and burn, the kinds of things that make short circuits dangerous. The opposite of a short is an open, a broken connection that does not allow any current to pass.

Like others mentioned, a spark on battery wire connection just means current is being drawn by something at the time of connection. If your motor has an ECU, or your radio has presets, or any other components uses juice even when the key is out and everything is off, then this spark is probably normal.

Unless it was big scary sparks, it was probably just the radio or something like that.


I've been told there are no stupid questions, so I'll ask this...

In a carburetor, isn't there always fuel vapor present? In which case, wouldn't a spark present a serious risk?

H

[Bob Cowan]

Yes, there is always fuel vapor present.

But, no, it's not generally dangerous. In order to ignite, the fuel vapor has to be in a high enough concentration to ignite. If the fuel is hot (boiling), and the spark is right next to the carb, it might happen. But that's pretty rare. You almost have to have liquid fuel near the spark to get ignition in an open space like that.