Emp-6
 

Just finished my MP-6. Thanks to RCMonster Mike for the excellent motor mount! I've yet to fire it up- I hope the MMM handles the outrunner ok. It weighs 7.75 lbs. I hope I can get 20 minutes on a charge. Power is 6s A123. Don

Looks good, any chance of some closer pics of the outrunner and mount?

Sure- a little fuzzy though. Don

What is the advantage of outrunner?

I wanted to see if I could make a buggy with an outrunner replacing the center diff. They produce a lot of torque and it's low KV (600) helps keep current draw down. Now I've got to program the MMM for a 12volt cutoff and set up the Tx. Then-dirt! Don

Don't forget about the weight difference - I'm sure the buggy lost at least a few ounces after removing the center diff.

Nice work, doubt there are to many MP6 Brushless out there

Thanks, Monster Mike did a real nice job on the motor mount. Don

Interesting (light wheight) built. Which motor did you choose exactly? 600kv with 6s A123 (about 18V @ 600kv = 10800 rpm) seems to be perfect to replace an inrunner with 32000-35000rpm. Shall give you decent speed.

Report back when you fire it up. 20 minutes will be hard to reach on a track -> 2,2A x 3 = 6,6A x 18V = 118,8 Watt average. Almost 1/3 of what i used in my "heavier" buggy with 10s A123 geared for 42mph and running 13-15 minutes.

The motor is a GP Rimfire 42-60-600. IR is .029 and no load current is 2.5 amps. Maximum constant current is 40 amps and surge is 70 amps-but those figures are for an airplane propped. I wanted to set it up 8s, but the MMM will only take 7s. Your math is interesting, but I don't quite follow it? If I thought it would take off enough weight I would seriously look at getting a carbon fiber chassis made.(provided of course I didn't have to take a second mortgage on the house!) The run time is only a hope! Thanks, Don

Well ... A123 batteries should be able to constantly ouput 2.2A for 1 hour (A123 -> 2300mAh). You are looking for 20 minutes runtime: 1/3 of 60 minutes (1h). Therefore your average amp draw should not exceed 2.2A x 3 = 6.6A. Otherwise you won't run for 20 minutes.

A123 batteries will hold around 3-3.1V under a lighter load. As you are using 6 cells (3V x 6s = 18V) your average voltage will be around 18V (i would expect it to be somewhat higher). When you multiply average Amp draw with your average voltage you get your average power -> 6,6A x 18V = 118,8 Watt. As i said, that is about 1/3 of what my heavier buggy needed.

But this really depends on how hard you will drive your car, track type and so many other variables. Report back when you finished your maiden run ;-)

Ahhh-makes sense! Thanks. Don

I plugged it in, forgot I had to go through set-up-went through set up, it works!!! Now to get some decent dry weather and dirt. Don