Ten Steps Forward, Two Steps Back

posted May 12, 2011, 12:47 PM by Lewis Baumstark   [ updated May 13, 2011, 1:12 PM ]

Current Status

Current weight: 2.57 pounds (measured with the scale at work).  Only thing missing from that calculation is the back plate, some bits of wire, and a little bit of mounting hardware for the electronics.

Everything is in place except the battery (more on this in a minute), the weapon ESC, and a rear armor plate to protect the electronics.  You may notice the layout has changed a bit -- I re-designed and re-built it all yesterday.  This design is simpler, likely more combat-durable and, best of all, I think it's a bit lighter!

Drive ESC & Rx Shock Mount

I wanted to mount the drive ESC on PCB stand-offs but I also wanted to shock-mount them.  Here is what I came up with:

The stand-offs are mounted to a piece of plastic I scavenged from the junk bin.  That in turn is layered on top of some mouse pad foam (left over from my Electric Funkatron project).  The whole thing mounts to the 'bot's case with Velcro.  It may not be clear from the pic, but the Rx is tucked immediately underneath the ESC, giving it, too, the benefit of the foam.

Safety Block

I wanted some way to mechanically keep the spinner from spinning up when not in the arena.  So a $0.71 piece of 8-32 threaded rod, two wingnuts, and a couple of holes later: voila!

Battery Power (this is the 2 steps back part...)

I goofed selecting my battery.  There is no way the ones I bought will do the job, so back to the drawing (and ordering board).

The math:

Current (amps)
Max Burst Current (amps) 
 Beetle B62 gearmotors (2x)*0.4 x2 = 0.8 4.3 x2 = 8.6
 EFL-200 Six-Series 2700 kV brushless motor34 42
 Rx 0.030 0.030
 Total 34.83 50.63

*Using the 12V values, which are WAY too big for the max burst current, since I'm running them at 7.4 V.

I think what happened is I spec'd my batteries for an older weapon design (yeah, that's my story and I'm stickin' to it).  The max current available to the batteries I now have is 25-A.  I probaby need something in the 36+ volt range.