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:

My question is, why would you want an RC to drive while walking/jogging, please enlighten me on what your reason for doing this is?

Since he is running (no pun intended) at jogging/hiking speeds only, why hasn't anyone suggested a MM 4600 combo? Normally, they would not be good for that size vehicle geared for ~35mph, but since we are talking about 10-15mph MAX, the load is greatly reduced. You'd have to use the largest spur and smallest pinion available to gear it low enough.

Another option to stay with more reasonable gearing is to use an outrunner motor, which typically has a lower rpm rating, yet has more than adequate torque.

14.8 to 22.2 isn't a dramatic change in voltage, but higher voltage with less amp draw results in less heat and is typically more effecient. The things you have to consider though are size of the packs and how they fit into your vehicle as well as your esc voltage limitations (not many car esc's are capable of 7s-10s operation). Funny enough in many cases a 4s 8000 config will yeild the most run time in many rc's due to battery tray limitations and where you want to be for weight. In order for a 6s lipo config to yeild longer run times than the 4s 8k you would need at least a 6s 5400mAH lipo which is pretty large but not unheard of for running.. for a 5s config to run longer than the 4s 8k setup you would need at least a 5s 6500mAH. In both cases the additional run time is marginal, but with higher voltage would create some reduction in heat. If you spend big bucks or get a deal on a car ESC capable of 10s operation a 3300mAH pack will last just a bit longer than the 4s 8k pack. (based on all options geared for the same MPH)

I'm running my 8ight Truggy w/ 5s now and almost wishing I didn't.. I got a deal on some flight power evo25 3700 packs which are nice cells but I'm only getting about 12minutes on them so they are only going to be good to run a single warm up and qualifier per pack. Thank god I have a pair of Neu 5s 4900's coming so I can keep it to just one pit in the 30+ minute a mains. I was actually surprised that the evo25 packs are only giving me 3580ish before hitting LVC, which is pretty crappy for how much they cost... I'll never buy flightpowers again.. my Elite 35c lipo's blow them away and COST LESS. Any whoo this is putting my truggies consumption at about 296mAH per minute. I'm going to recheck my times my next time at the track to be sure I didn't screw them up a bit, but it is with in a 3minute margin. I may gear down 1 tooth helping some and I am currently running some heavier proline MTR bowties and when I race I will be using the LPR's or the newer 'xxt' losi truggy tires which are really nice and light weight as well.

Save a few bucks and have a better config w/ the Traxxas Velineon combo... easily can handle it up to 35mph. He actually could gear it with a 17t pinion on the stock spur and just run it in "training mode" while walking/jogging (15mph) and then can run it regular mode for some higher speed play (35ish). Down the road if he wants an easy upgrade he can drop in a second velineon and run dual v's for rediculous speed/power.

The only trouble with a VXL combo is that the ESC doesn't give you much in the way of adjustability compared to the MM. And the MM could be used up to 4s (with BEC disabled) so future upgrades could be as simple as a new motor (XL, Neu, Medusa 60/70mm, etc). Could also go with a Novak system. Either will work though for the speeds he wants.

I just thought it was funny everyone was throwing around ideas to use the larger motors when they simply are not needed. And just spinning a motor slowly has two disadvantages: 1) as noted, there is less efficiency at less than WOT settings, and 2) there may be cogging as the motor may not be spinning fast enough to get a good rpm signal at the speeds we are talking about. No, I'd say get a combo that will allow the motor to spin fast enough and just gear down, or use an outrunner.

Basicly I want to get insane run time. I dont want to ever charge my RC CAR again.. just kidding.

I think instead of doing this to my E MAXX am going to convert my Losi LST2 Monster Truck.

Here are the packs im going to use, they are huge! I would like to stack about 6 of them on top of my lst2.

My plan for right now is to eliminate the whole transmition and run a direct drive low kv motor.

That way I would have a nice flat space on top of the lst2 to stack 6 cells for a nice 60,000 mah :P!!!


http://i4.ebayimg.com/07/i/001/17/61/a3c2_1.JPG
# Voltage: 7.4v
# Battery capacity:10000mah
# Discharge rate: 12C
# Size: 178mm (L) x 98mm (W) x 11mm ( thick)
# Weight: 530g
# Quantity：2

If I run this at 7.4v then I would have 60,000mAh @ 7.4v 720AMP<<<< Con LOL!!!!

At 60,000mAh the pack would be

7 Inch Long.
3.8 Inch Wide.
2.5 Inch High.

A very nice fit for top of the LST2, as long as I can mount the motor in the center and under. Im still trying to figure out if this will even work. I need to learn more about electricity...
All I have to do is find a nice low kv motor. Im just wondering if they make low kv motors that can run, on 7.4v. Also I am wondering how the Mamba Monster would react to a set up like this.

For weight considerations, I would maybe run 2p (not 6p) and carry the extra 2 packs in your pocket...

I like the thought of the 2 large 2s packs. I think 2x 8000MAH 2s was suggested earlier to make a 2s 16000 MAH.

If you are lucky you could have it setup for 10-15 MPH then just change a harness and get a 8000 4s pack and get some speed out of it for when you are not jogging.

highflier