Motor and Battery Caclulations... am I doing them right?

[DanL]

One of my team-members approached me with a little question...

He decided he wants to use the window motors (specs and curves) as drive motors (worm gear, yeah, he knows, but he doesn't really care) for a little mini-bot he's making. The battery that he's using is a 12v battery rated at 4amp-hours. The question is how long will it take for those motors to drain all the juice out of that battery.

It's a small bot that just has to move, so I figured there isn't going to be a lot of torque on the thing - maybe .5 to 2 Nm. From the curves, I figured that to be 5 to 8 amps per motor. Together, thats a total of 10 to 16 amps of current thats going to be drawn by those motors.

So with a 4 amp-hour battery, how long is it going to last? I figured:
4 amphours / 10 amps = .4 hours, or 24 minutes
4 amphours / 16 amps = .25 hours, or 15 minutes
So basically, I told him theoretically, 15 to 24 minutes, depending on the load. I want to know did I do these calculations right, or did I miss something.


He also said the battery's "initial current with cyclic use" is 1amp. What exactly does that mean? Is that the max current that the battery can supply at one time, or something else?