Brushless Rock Crawler
 

I'm thinking about building a brushless powered rock crawler.

I want to use one motor.
2 or 3 cell LiPo.
I have the gearbox and axles figured out.

I need some recomendations on a motor. I see the lehner's go up to 40 turn with a very low kv rating around 700 rpm per volt. I rely don't want to spend that kind of money on a crawler. Does Feigao have an equivilant, or a BK wanderer? I can't find the specs or a list of the availble Feigao's or BK's. Other than what Mike has or carries.

Will these low rpm motors have lots of torque?
Can I get away with a lower rated speed controller?

If you want torque, you need to get a XL size of wanderer (about the same as Feigao), Mike can get them. You can gain lots of torque by gearing the truck a bit taller and use a higher KV rated motor. that XL is made till 625 rpm/v rating, they cost about 100 dollars. they are powerfull for sure.. How long do you want it to drive? gearing it higher, makes you able to drive a bit more precise

What kind of final drive ratio are you going to be running? You may want to consider a higher end motor to like the lehner. It has less cogging than the xl motors. Plus the lower(higher Numerically) you gear the less problems you have with cogging. Just a thought.

Do you think if I went with the wanderer "S" in a lower turn, like 10-15 an geared it for a top speed of 2-3 mph, I wouldn't need the torque of the XL?

I'm hoping that with the ultra low gearing, cogging won't be a problem, although most of the driving in crawling is done with the throttle bearly cracked.

A lower turn motor would be better to give me a broader rpm range to work with.

Where can I find the specs on the wanderers, Mike shows 6-12 turn. What turns do they come in?

The other option I'm keeping open is puting a High/Low range in the tranny. So I can quickly move around and position the truck then shift into granny low to crawl.

What's the least inexpensive controller I can get away with running?

if thats ALL you would do with it them i think the 7020 or the mgm 80 would be fine.

-corey

Here is the RPM information from BK Electronics for the 20 Series motors that Mike will be carrying. It's a screenshot because they don't have normal HTML or text on their site. Mike will probably only be stocking between 4 and 7 different winds, but he'll be able to get you any motor you want from BK.

<img src="http://i20.photobucket.com/albums/b239/1joeyoung/RC-Monster/BK_Wanderer_S20_RPM.jpg" alt="Image hosted by Photobucket.com">

with the gearing you have got in mind, and the speed, you can use the 7020.

Can you get a large spur?

I would go with a 380 motor if I were you and gear extremely low. 500 watts would give you well over 150 pounds of torque at the wheels and have a max speed of 3 mph. The 540 motors would just heat up since there wouldn't be much of a load on them.

Huh, What do you mean by heat up since there wouldnt be much load on them? And if someone wanted they could have put a fan on the motor, wouldnt the 380 sized motor overheat faster though?

Iwould look at maybe a 15L or higher turn. I have run a 14 l on a maxx with no problems. you put 12 cells on it with low gearing heatsink on motor it should be no worries. That would produce more torque and enough power for smooth operation. May look at someting like the lehner xl 1200 as well.

if u want the best setup, it would have to be hv-maxx! I got one if ur itnerested Very smooth accerlatiron. Much bett er then my 9l

a 14xl would kick some butt for a crawler to. have awesom power and run time.

I would not use a 380 motor. the S serie or the hvmaxx is also a good choice.

This is some good advice. The reason being that if a BL motor is undergeared, it will run inefficiently, and will heat up. So, if you have a larger motor, it will require more of a load.

The HV-Maxx on a low cell count (6 cells?) could work very well. Being sensored, you don't have to worry about cogging.

Thanks for the info.

I'll be using a planetary type transmision with stackable sections. If I want lower gears, just add another section of planetaries. It should be easy to gear the final drive to whatever motor I end up going with.

What's the Kv rating on the HVMAXX? and how big is the can compared to the "S" series?