Brushless Pro's Please Help!
 

First of all Hi Every One,

I need any good advice I can get.

My Goal.

I would like to set up a stock E Maxx 3905 to take with me on trail hiking.
I would like to set it up for a walking to jogging speed.
I would like to have one set of batteries for the whole hike, I dont want to carry space batteries with me.

I need help understanding some concepts with the motor, voltage and capacity.


I would like to use the Mamba Monster ESC, because castle seems like they have a good warranty if anything break.

I would like to get TrueRC to make custom sized pack for me with the highest capacity possible to fit under the E Maxx body.

But before I order the packs I need to figure out what voltage I need to run this whole set up under.

Questions.

What would give me the longer run time.

High capacity and lower voltage or high capacity and high voltage.

What motor and pinion would you guys recommend I run in this setup?

I assume their is not going to be much load on the drive train because the car is going to be going slow, so what would be the best motor for this scenario?

Please feel free to give any additional information to me, Im new to this and anything helps.

Thank you for your time.

high voltage and high capacity will give you best run time. 6s is the most you can run on the mmm so go with that for voltage.

http://scriptasylum.com/rc_speed/_top_speed.html That is a great tool!

You should select a motor that will operate around 35,000RPMs+/- 5,000 on 22.2v and gear it for the top speed you want. Pretty much anything will handle walking-jogging speed as long as your throttle finger cooperates!. If this is going to be your first brushless build I suggest you start saving some money and do it right the first time! The MMM is a good start, select a quality motor, some good LiPos and a charger that is capable of charging them at a 1C rate.

I would go to impaktrc.com and pick up one of those tekno-neu motors they have on sale right now.. you really have a few choices;

• 1515 1.5d is great on 4s (up to 50mph) but is capable of running 5s or 6s for pure insanity (this motor gets you fastest speeds but least amount of run time of the 4)
• 1515 1y is a nice racer on 4s, but can be slow for some bashers, drop in 5s or 6s lipo and again true insanity.. expect up to 40 on 4s, 50 5s, 60 6s (about 10mph less than the 1.5d) This motor will run a little cooler than the 1.5d and have slightly longer run times depending on your gearing.
• 1515 2d is a sweet race motor on 4s or 5s, this will be more like 35mph on 4s, 45 5s, 55 6s. This motor will run cooler yet and have the longer run times; you can over gear this motor a bit but at a cost of run time and temp.
• 1515 2.5d is a touch faster than stock (tons more torque) on 4s, w/ 4s 8000mah packs it will run a REALLY long time (~32mph), nice racer on 5s (~38-40) and getting a bit giggly on 6s unless geared down. This will run the coolest of all and have the longest run times of the bunch.

The 4s 8000mAH setup will get you the longest run time of any voltage unless you buy some really big (heavy and $$$) packs. A 6s 5500mAH setup would run longer, but a 6s 5000mah will not - a 5s config would need 6500mAH or bigger packs to net a longer run time. That all said the tekno-neu 2.5d on 4s 8000mah packs will get you the speed you want with the longest possible run times & the MMM v3 is a great choice..

Umm, did everyone miss the walking/jogging pace part?

That would indicate a top speed of about 10mph ideally, so something in the 1000kv range on 4-6s lipo would be ideal. Im thinking an XL feigao as they are much more efficent at slower speeds/higher voltages, and cheap. A big fat pair of 8000mah 2s lipos would be ample, and runtimes would be pretty much doubled compared to a setup aimed at high speed running- figure about an hour or more maybe.

I did see that, they only go as fast as you tell them to though. I would expect that he will use it more than just when he's walking

Get real, he doesn't want WOT to be jogging speed.. LOL anyone can control that on the radio with very little effort :P The tekno-Neu 2.5d w/ a pair of 2s 8k lipo's (4s config) will be his best bet.

PS if he really did want jogging speed (10mph WOT).. brushless is pointless, stick w/ the water proof stock setup and get even smaller pinions and run the big 8k lipo's on them for TONS of uptime.

He would have to answer that question himself, but I personally wouldnt wouldnt turn down the throttle EPA or only hold 1/4 throttle all the time, as thats a great way to fry an esc; they are most efficient at full throttle (think old tamiya mechancial speed controller and you'll know exactly what Im getting at). Using a motor that will only give 10-15mph at wot would be much more efficient. I would agree though, this sounds more like a 35-55turn lathe motor or two would be best- cool temps, ample torque and 1-2 hour runtimes on a pair of big lipos....

This set up is going to be purely for hiking jogging speed.

I will have a brushless revo for all round bashing when it comes out.

I would like to set this up for about 10 - 15 MPH Max with the most possible run time and best realibility.

So what motors and pinion would you guys suggest?

by the way, I dont really have the EVX and the titans any more, sold them on ebay.

stock motors w/ 13t should slow it up enough.. just get the true-rc 2s 8k packs and you may want a LVC on each lipo. Sick run time..

I dont have the stock motors of EVX.

Anyway, thanks for all the info ppl.

Like everyone has said I think that 4s 8000mah is a good place to start...

I would go for a high torque outrunner in the 800-1000kv range...

Check with john but this might be the ticket.

http://holmeshobbies.com/product.php...&cat=19&page=1

http://holmeshobbies.com/files/d_60.jpg

or

http://holmeshobbies.com/product.php...&cat=19&page=1

http://holmeshobbies.com/files/d_45.jpg

Thank you.

Sorry I thought low voltage and high amp will give the best run times. Not high voltage and high amps. Could be wrong, just something I remember some years ago.

I figured power = voltage * current

It is easier to reach a desired power output with a high voltage and a high current, if your voltage is lower, then the current has to increase to achieve the same power output. At least that's what I think.

So if you are using less current then your runtimes will increase.

ok...

I'll take a stab at it....

I'm gonna suggest the following;

For the ESC, The MM or the MMM....possibly a UBEC.
For the motor, A feigao 12XL
For batteries two TRC 2s 15c 8000mAh run parallel. Thats right...7.4v 16000mAh.
Gearing 68/16

Differential Ratio: 2.8461538461538462
Transmission Ratio: 1.7222222222222223
Other Ratio: 1
Spur Tooth Count: 68
Pinion Tooth Count: 16
Total Voltage: 7.4
Motor KV: 1390
Tire Diameter (inches): 5.9
Tire Ballooning (inches): 0
Motor Current Draw: 90
Motor coil Ω: 0.0164
Spur/Pinion Ratio: 4.25 : 1
Total Ratio: 20.83226 : 1
Tire Circumference (inches): 18.54 inches (470.8 mm)
Total Motor Speed: 8234.36 RPM
Vehicle Speed: 6.94 mph (11.14 km/h)
Estimated Adjusted Speed: 7 mph (11 km/h) - 1% loss
Effective KV Value: 1112.75
KT constant: 0.97 oz-in/A
Motor Torque: 0.46 ft-lbs
Final Torque: 9.5 ft-lbs
Final Power: 666 watts (0.9 HP)


if its too slow...you got tons of gearing options to go upto;

this is 54/24

Differential Ratio: 2.8461538461538462
Transmission Ratio: 1.7222222222222223
Other Ratio: 1
Spur Tooth Count: 54
Pinion Tooth Count: 24
Total Voltage: 7.4
Motor KV: 1390
Tire Diameter (inches): 5.9
Tire Ballooning (inches): 0
Motor Current Draw: 90
Motor coil Ω: 0.0164
Spur/Pinion Ratio: 2.25 : 1
Total Ratio: 11.02885 : 1
Tire Circumference (inches): 18.54 inches (470.8 mm)
Total Motor Speed: 8234.36 RPM
Vehicle Speed: 13.11 mph (21.05 km/h)
Estimated Adjusted Speed: 13 mph (21 km/h) - 2% loss
Effective KV Value: 1112.75
KT constant: 0.97 oz-in/A
Motor Torque: 0.46 ft-lbs
Final Torque: 5.03 ft-lbs
Final Power: 666 watts (0.9 HP)

just a guess.

just be careful....the devil is in the wattage.... :diablo: