Robitronic Mantis HV truggy with 10s A123
 

After getting a little bored with my buggy i started a new project. It's a lesser known truggy a Robitronic Mantis.

I used the same setup like in my Buggy: pic1 , pic2

The electric components:
. ESC: Jazz 55/10/32 (55A cont, 65A peak)
. motor: Neu 1512/2Y (1400 kv)
. Batteries: 10s A123 (33V)

After sorting out my pinion problem i made my 2nd maiden run yesterday. Those are a few clips shot with my digital cam: clip1, clip2, clip3, clip4, clip5, clip6,

This is how she looked after this rather wet run:

http://bt2007.braintrust.at/ds/rc/ma...rd_4th_run.jpg

This is the eagletree graph from this run:

http://bt2007.braintrust.at/ds/rc/ma...graph_run1.gif

And a second one from a run with my second battery pack (driven on wet forest soil)

http://bt2007.braintrust.at/ds/rc/ma...graph_run2.gif

. The neu 1512 has more than enough torque to power this 4.9Kg (10.8) truggy. I never expected wheelies with a center diff.
. Outside temperature was a low 10°C (50°F). The motor never exceeded 37°C (99°F). Batteries and ESC were warm to the touch.
. Max recorded Ampere 63A (1700 Watt). No cogging.
. Average Amps were at 15A (400 Watt). I never exceeded 350 Watt with my buggy.
. When pushed hard a battery pack is good for 10-12 minutes

Dude, that looks awesome - nice work!! I love the videos too - thanks for posting!!

Question for you Othello, do you use the stock mechanical brake system or use the motor for breaking?

Very nice. What size pinion/spur are you using?

@david lamontagn
I only use motor brakes because i do not need brake bias and the brakes are powerfull enough for my driving profile.

@lutach
Pinion is 13 and spur is 52.

pinion:spur: 13:52 = 4
Diff gearing: 10:42 = 4,2
total ratio: 16,8
Tire diameter: 140mm (5.51in)
Max Motor RPM: 38000-41000rpm

If i did my maths correctly, top speed should be between 60 to 65kmh (37-40mph). And she does feel a little bit slower than the buggy. I will make a run on this big open place where i shot one of my buggy videos to get the true max rpm value to get a more precise estimate of her top speed. I'm also eager to see how much watt she needs when full speed is reached.

Your truck might be faster then 40MPH.

ver nice conversion and impressive startup on the jazz.

wow that thing was flying about like a panther.

I assume your using a plastic spur is it mod 1 as it was very quite are the diffs metal or are they plastic?

also i think that is the best balanced converted truggy i have seen it was almost gliding across the surface.

Really nice! Gotta love high voltage. I would think that 55A wouldn't be enough for it, but when you're running 30v+ I guess the draw's not too bad!

Good work!

Thanx for all your nice words.

@lutach
Yeah could be. With this much tire spin i really can not tell if those recorded RPM peaks do come from the front tires unloading or from straight line speed itself. I will definitively shoot a video similar to my buggy videos. At least then it will be clear from where those 38000-41000 rpm spikes do come.

@chilledoutuk
After seeing the Jazz ESCs abilities in my buggy i really hoped that it also could handle the heavier truggy. The Amp spike at 63A is nearly at its rated peak Amp of 65A. But after looking through some eagletree curves of some heli guy putting around 100A through his Jazz i'm quite sure the jazz is able to provide more than 65A peak. Under normal driving conditions peaks between 40-50A will be the max i will see. On those runs captured with my cam i really tried to push the truggy as hard as i could to see if the Jazz will do the job. As i never experienced some kind of cogging and temperatures remained safe i can again recommend it for HV car purposes.

I tried to use a plastic spur but the mantis spur is too different to the plastic spur i used in my buggy. So i had to use the metal spur. On my first run i used a non hardened steel pinion which lasted only for 3 minutes (i expected this to happen). As i heard from a guy that those hardened pinions could be tougher than the spur gear (and started to grind his spur) i decided to use the gear from the clutch bell that comes mounted on the nitro motor. A nice guy from germany established a contact to a brushless shop that soon will open near my place which already has some kind of adapters to fit those cut of gears to the 5mm motor shaft. Those are some pics (from Josi) of an early version of his adapter and how it is mounted on the motor: pic1, pic2. It doesn't look as clean as a hardened pinion but it's an easy way to fit those cut off clutch bell gears which assumably are hardened the same way as the spur gear.

Thanks for your nice words. As i never have driven a nitro truggy i can not make a comparision between them. The setup can not be done way different with those bulky A123 cells without having a huge imbalance. Both packs together wheigh around 800gr (1.76lb). This is hard to compensate when put on one side. As to front/rear balance it seems to be a bit heavier on the rear axle but it is nearly 50/50%. This setup also worked good in my buggy and i didn't wanted to start from scratch with the truggy. As i never drive at races i guess i will never find out how good or bad this setup really is but for my bashing needs it does the trick.

EDIT
The spur is mod 1 and the diffs are metal too. I too am surprised how relatively quite this truggy is.

High Voltage is the way to go. I was hoping my controllers would get done a month or so ago, but at this moment I have to wait. I'm talking with 2 companies that seems to have a HV controller for cars. I have to wait and see if they can send me samples to test. I'll also be making my own chassis (For truggy and buggy) as soon as I find the right place (cost wise) to do some CNC work for me.

Cool video... I like it.. a lot... but that area is way too small for you....

@lutach
It sure is the right way. I really am happy that it cured all my heat issues i had with my 4s setup. Seeing all those very creative modded mamba max or Quark ESC just tells me this can not be the ultimate way to get it done. The upcoming monster max will be a step in the right direction but i can understand why you asked Castle to get those HV boat ESC fitted with a car software. I also think this would have been an easier approach and would have provided a broader choice of ESCs and voltage options. But i'm no engineer so i sure think castle had enough good reasons to go the monster max way.

I hope you will get your ESCs done. Plane, heli and now even boat guys do use those HV ESC for quite some time and it sure is time to have a better choice in the car segment. I will stay with the kontronik ones.

@aqwut
Thanks ... those videos were only meant to show that my setup indeed works even in a truggy. This area is only a 5 minute drive from my place and thus ideal for testing purposes, but truly it's to small to get some good high speed passes. Now that i know that everything works out i will unleash her on those wider places :smile:

I'm just fed up with all the good stuff coming out for air and water. The major companies here in the US needs to wake up. Most HV controllers for cars are coming out of Europe. I hope to get a little peice of the car market and make the big guys play catch up. It should be fun LOL.

Lutach... I'm really counting on you man... but you know, it's not too bad using the air/water esc witht he PiStix... though it would be nice to have reverse...