Help me read my Multi Meter for Amperage

Gang, I'm fairly handy with a multimeter but I've never measured DC current draw with it. The instruction manual is long gone and the tutorials online that I've found are generic, with every MM being a little different in one way or another. I'm trying to figure out how much of a parasitic draw I have on the car battery of my project/commuter car (1995 525i). I disconnected the negative cable from the battery and bridged it to the battery with my MM, with the settings below. The book says 100ma or less is acceptable, and with the settings below I get 00.05 on the readout. I believe that is 50ma, putting me in tolerance. Am I right?

Yes, I believe the right hand side is 10A and the left is for ma. I noticed that after I did this. I think each side is just fused differently. That's probably why I'm getting 00.05 instead of 50.00 but I just want to make sure. I don't want to buy a new battery, then kill it with this car.

What is the rest of the lettering in the green DC section, the plugs are blocking something.

Thanks Pete. HW, I think the black plug is hiding a green "10". Unfortunately Autozone carries the BEST cheap BMW battery ever, the Duralast 49DL so I'm going to have to make the trip, unfortch. The current battery is a AAA brand battery which is still under warranty (and probably also made by JC) but I believe the warranty is only for the original purchaser.

Yeah then switch the red lead (to mA), and set the dial to 200 you'll most likely see ~050.0 displayed.

Right now you are reading 20 A max, so .05/1000 = 50 mA

Tim stayed at a Holiday Inn last night.

M3Fan wrote: How can a load (resistance) "draw" power? Isn't the battery the "engine" that is pushing electrons through the circuit? Thus how can something "pull" down the line? Why can mini xmas lights have such a small gauge wire (bonus question)?

Youre thinking about it backwards. The battery doesnt "push"; the load "pulls", if you will. While you can think of any load as an equivalent resistance in a circuit, you can also think of a load in terms of how much power it consumes (remember, power = voltage x current). A battery wont "push" power anywhere- if you dont attach it to anything it just sits there, its not trying to "expel" anything at a certain rate. It needs to have a load attached to it for current to flow- and how much current is dependant on what you hook up to it.

Bonus: Christmas lights generally consume about 25 watts of power for a typical 50 light strand. Plug them into 110VAC and that means each strand only draws 220mA. The selected wire size is dictated by the amount of current expected to flow through it... and it doesnt take a very big wire to handle 220mA. Check this chart (AWG vs. Max amps for chassis wiring) for a guide:

http://www.powerstream.com/Wire_Size.htm

Another example: This is the same principal that allows you to use a much smaller gauge wire to hook up an appliance if you run it on 220VAC instead of 110VAC. By using a larger supply voltage, you essentially cut the current flowing through the wire in half (the power consumption of the appliance remains constant).

tullfooter wrote: The other easy way to think about current is with the word potential. The battery has the potential to send current from the positive side to the negative side.

... and electrical potential is voltage.

Put the new battery and took the same measurement- sure enough, current draw is lower. About 30ma. Go physics.