Brushless Pro's Please Help! - Page 2 - RC-Monster Forums

11.04.2008, 09:28 AM

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?

BrianG · 11.04.2008, 10:54 AM

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.

stum · 11:15 AM

Quote:

Originally Posted by skyler

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.

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.

stum · 11:14 AM

Quote:

Originally Posted by BrianG

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.

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.

BrianG · 11.04.2008, 11:20 AM

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.

vokus · 01:18 PM

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!!!

# 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.

BrianG · 11.04.2008, 01:17 PM

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

highflier · 11.05.2008, 11:47 PM

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