# Solenoid circuit current draw doesn't match calculations

I have a circuit of 6 solenoids connected to Darlington Array (http://www.ti.com/lit/ds/symlink/uln2803a.pdf) and driven by 18V (2x9V batteries) as can be seen below:

From what I understand, each load should draw 200mA (18V/88Ohm) and when all of them are switched on at the same time, the total draw should be 1.2A. They are all in the active state for a brief moment (20ms).

I wanted to confirm my calculations by measuring the total current draw with a multimeter connecting it in series with the current source.

The measurements showed a maximum of 47mA draw instead of 1.2A.

What could be the reason why the actual measurement does not match the theoretical?

• Is the voltage still 18 V with all six solenoids turned on? You will find that your batteries have internal resistance. The terminal voltage will drop as current increases. Commented Jan 28, 2018 at 10:35
• @Transistor you are also correct! Goes down to 16V Commented Jan 28, 2018 at 10:50