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I have a 12v scissor jack that is meant to plug in to a car cigarette lighter, which I believe is around 10 amps. However, I want to hook this jack directly up to a 12V battery, which is rated at about 345 amps. How do I reduce the amps? I see some reducers on ebay but they seem to be for 24v to 12v.. I'm not sure what to call what I am looking for so I am not finding it. How is this done on a car?

lucky.expert
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  • Current is not really pushed through something like that, current is more the result of a voltage (think, pressure) pushing on something which may have holes in it (is a conductor), and depending how large the hole is (resistance) allows a certain amount of current to go through it. – KyranF Apr 24 '15 at 00:12

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The current (in Amps) is determined by the scissor jack. As long as you provide it with the correct voltage (12V), it will only take the current that it needs.

This is similar to how you can plug in a small light bulb into the same socket that could power an power-hungry hair dryer. The current flow is determined by the properties of the load.

Here is a good (much more detailed) explanation of how this works.

Community
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bitsmack
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  • Thanks, that is a very good explanation. The reason I got confused is, the jack has an inline switch, and once I hooked up the jack to the battery, there was just a clicking noise in the swtich when I flipped it on. I assumed this must be an amp problem, but I guess not. I'll have to bypass the switch and see what happens. – lucky.expert Apr 24 '15 at 01:37
  • @lucky.expert You're welcome! There's something important to consider, especially since their's an electrical problem happening. If you plug into the lighter, then your circuit is protected by a fuse in the car. If you hook up directly to the battery, you lose this protection. Unless the jack has a built-in fuse, that is! – bitsmack Apr 24 '15 at 03:31
  • @lucky.expert If you have no fuse, and your get a short-circuit somehow, then your wires become the fuse! I've fried an entire extension cord before, and melted plastic insulation is hard to get out of carpet :) – bitsmack Apr 24 '15 at 03:43