Using a C+C pm-129a to measure current

[auriuman78]

I am new to the site, hello everyone. So i just bought two pm-129a meters to monitor a 12v battery system. The applications listed include voltmeter and ammeter but the data sheet included only show voltmeter applications. How do I monitor a dc current level with this? Here's my max current level also, which is throwing monkey wrenches at me left and right... up to 100A @11-14vdc. So with meter sensitivity 0-200mV, I basically need to drop 0.001v for every amp flowing putting me around 1mOhm for a shunt. Do they make resists that low? I know using a diff opamp measuring voltage drop across a shunt resistor is the basic idea but the size of resistor for 200A has to handle 40w(?). Wow. So since I'll never exceed 100A, I can scale down to 10w but where do you get a 10w 1mOhm resistor? There's got to be a better way to do this, and please don't say analog meter. Any help would be appreciated! Thanks in advance.

Panel meter info: ".web-tronics.com/led9vingrpam.html" it's just w-w-w in the front, i'm not yet allowed to paste links yet.

 

[crutschow]

They do indeed make 1mΩ, 10W resistors for the very purpose of measuring current. They're called current shunts. Current shunts are commonly made with a 50mV or 100mV drop, and 100mV types are available in 100A versions.

For example, a Google search found http://store.altenergystore.com/Meters-Communications-Site-Analysis/Shunts/100A-100Mv-Shunt/p4637/ and http://www.galco.com/scripts/cgiip.exe/wa/wcat/itemdtl.htm?pnum=FN-100-100-CMI among others. Those will give you 1mV per amp for a direct ampere readout on your meter.