There are numerous threads on this subject. Search on "battery drain". The only problem is there are about 20 different ideas on how to do it. Inductive definitely will not work for DC. The usual approach is to put a 10 ohm resistor in series with the battery during the test and measure the voltage across it. Using Ohm's law, you will get 1 volt for every 100 mA, .1V for every 10 mA etc. You could also use a 1 ohm and then you get 1V per Amp , 1mV per mA etc. Technically you can use a multi-meter to measure current directly, but many people find that hard to set up so the resistor method is more straightforward. If you are looking for really small currents then the 10 ohm will probably work better since it will yield 10x the voltage for a given current.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra