ST-Robotics R12 arm - Gecko drives and max current draw

 I got a little more insight into the current draw for the motors.

In the CD of documents provided with the robot, there is a sub-manual for the Gecko drives.  It's in Other / G203V-REV-7-MANUAL.pdf (Rev 7, January 7, 2010).

That manual says...

The G203V will accommodate motor winding currents from 0 to 7A. Use the following equation to calculate the value, (in kilo-Ohms) of the current set resistor: 

R (in kilo-ohms) = 47 * I / (7 – I) 

Use the nearest standard value 5% tolerance, 1/4W resistor for this setting.

Here are the current set resistor values for motor current in .5A increments. Round the appropriate answer to the nearest 5% resistor value.
a. 1A – 7.8K
b. 1.5A – 12.8K
c. 2A – 18.8K
d. 2.5A – 26.1K
e. 3A – 35.25K
f. 3.5A – 47K
g. 4A – 62.67K
h. 4.5A – 84.6K
i. 5A – 117.5K
j. 5.5A – 172.33K
k. 6A – 282K
l. 6.5A – 611K
m. 7A – OPEN

 Separately, there is a table on page 20 of the R12 manual (PDF manuals / R12 manual.pdf) that lays out the resistor settings and amperage for the joints.

1 WAIST 3.0 36K
2 SHOULDER 3.5 47K 
3 ELBOW 3.5 47K
4 L-HAND 2.0 18K
5 WRIST or R-HAND 1.0 8.2K
6 WRIST 5 1.2 12K

Most of these amp values match that Gecko documentation table.

Does that mean the overall current draw is the sum of the amperages of the motors, plus some for the controller?  Maybe.

Even when a stepper motor is idle, it draws current as long as the windings are powered.  The Gecko specifications also say "Auto Current Reduction: 71% of set current, 1 second after last Step Pulse", but if all motors are pulsing in a given move, it seems like it could be drawing max current during that time and until one second beyond.

If that's the case, then even for my robotic arm that is lacking a 6th joint, I'll up needing a power supply rated for 13+ Amps (!).