Amp meter? (in line?)

[FyreDaug]

Is there such thing that will sense a load on a current line?

So if I put one between my alt and battery it will say how many amps are going to the battery, and one from the + of the battery to the fuse box or whatever and be able to get 2 different readings? Amperage "in" and amperage "out"?

I dont even know if such thing exists, but would this be possible?

[Swap_File]

Yes there is. First, you can simply get an inline amp meter. You unhook the wires, and place a meter in between them. Radioshack sells low amp ones similar to the picture below, but check a car place for high amp ones.

http://img213.imageshack.us/img213/8467/ampmeter8yn.jpg

Second, there are shunt type meters. You unhook the wires and place a shunt between them (the little block thing). Then you run small wires to a meter. Some people make their own shunts, but then need to calibrate them against a known current souce. Calibrated high current shunts can be expensive.

http://img290.imageshack.us/img290/9038/metershunt6ki.gif

Finally there are clamp on meters. You just clip it around the wire and it will tell you the current going through it. AC clamp meters are cheap ($10) but DC ones (like you would need for the the car) are expensive (probably starting at $100).

http://img290.imageshack.us/img290/769/ex7303wk.jpg

You could also check junkyards for old amp meters out of trucks. That would probably be the cheapest.

Edit: Here is a picture of an old truck meter:
http://img368.imageshack.us/img368/8741/5221785yk.jpg

[FyreDaug]

Shit, all of those options arent what im looking for. I wanted like a lcd screen (x2) showing the alternator output and my entire draw or something like that.

Ah well, in due time I suppose.

[1987HondaAccord]

you can get digital multi meters, but they probably won't be able to handle more than 20 amps. I'm not sure how expensive they are either, they might be a little pricy.

[Swap_File]

You can get digital displays for shunt type amp meters. Shunts are just very small calibrated resistors, so they will have a certain voltage across them for a given current. That means you can buy a low voltage meter (digital or whatever), hook it up across the shunt, and get a current reading.

Something like one of these Digital Panel Mount Backlit Voltmeters would probably work:

http://www.martelmeters.com/products.php?cat=2&action=detail&id=64

But you have to make sure the volt range properly matches up with your shunt. You could also do some tricks with an Opamp to adjust the voltage.

[1987HondaAccord]

thinking about op amps, could you use it like a current to voltage converter? i'm kinda new to electronics, so i'm not sure.

[Swap_File]

thinking about op amps, could you use it like a current to voltage converter? i'm kinda new to electronics, so i'm not sure.

It could work on a very small scale:

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/opampvar2.html#c2

To handle the large currents (like in a car system) you would basically need a shunt.

[Swap_File]

I just checked around, and I guess shunts are alot cheaper from surplus stores. Check this out on ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7557590652

You might also want to check your own local electronics surplus stores.