Jammin X1-CR HV conversion

It will be interesting to see how mine works out. I will be running 10S so my current draw should stay below 40A. I wish I had purchased a 1907 instead of this 1912. I'm 90% certain 1912 will be way overkill, and a 1907 is 100g lighter (and cheaper of course).

My biggest concern so far is my gearing setup and the fact that these Neu 1900s cog quite heavily. The cogging might be a bad thing for coasting and I suspect might cause startup issues.

Hi

I started experimenting with replacing steel fastners with aluminium ones. It looks like I won't save 100g as hoped, but 40-50g I will. Not sure it's worth it TBH. Alu screws aren't cheap, and I'm only able to get them in one length so there's a lot of manual resizing that I have to do.

Well I got half way with it today before running out of alu screws. I might as well finish it though so will buy more next week and replace the second half. Photos below show today's weight saving.

Small update in my blog.

Hi

My X1-CR is finally running! I don't have a painted canopy yet, and still a couple details to sort out, but I gave it a maiden run this afternoon and am rather impressed.

Video here (XviD encoded, 42MB)

Gearing is a bit noisey and Jazz 55-10-32 throttle takes a bit of getting used to, but so far it's been good. I'll have more data to post in a couple weeks when I get my DPR back from a friend.

Enjoy. :)

[starscream]

I was looking at the Kontronik controllers but I don't know anyone using them. What driving adjustments did you have to make in regards to throttle?

[lutach]

Originally Posted by starscream

I was looking at the Kontronik controllers but I don't know anyone using them. What driving adjustments did you have to make in regards to throttle?

I have used almost all the kontronik line of ESC. They are great. Pricey, but great.

[othello]

@aragon
Great to see that you finally maidened her. She definitively seemed to be too fast for your driving spot ;-) More than enough starting and braking power with this setup and no cogging at all. I'm looking forward to see some DPR data.

@starscream
I do use those Kontronik ESC too since they are very popular in Europe but normally you will find them in helicopter applications. But they do have 2 car programs with proportional braking and reverse and served me well in a 1:8 buggy and now in a 1:8 truggy conversion. They certainly are underrated as my Jazz 55-10-32 is listed with a max short burst of 65A and i have some eagletree graphs with up to 95A peaks and 2275 watts.

run 1 on a big open tarmac place: eagletree graph

run 2 on grass: Eagletree graph

When you use it at this power levels a small heatsink could be needed during summer time (in my lighter buggy i never used one during summer but the power level was somewhat lower max 1.7Kw). As for now i never had thermalling with a complete shut down.

I made some video clips of my maiden with the truggy and the Jazz55 in this thread. And you can see the jazz 55 in action in my buggy when you look at the videos i'm linking to in my signature.

starscream, I find the car doesn't coast freely when the throttle is released suddenly. Looks like it brakes for a split second and then lets go again. I'm guessing it is specific to my motor and this firmware as I have a Jazz 40-6-18 and Hacker C40 in another car and it runs great.

I'm going to be putting a Crowdpleazer body on this car, so it will eventually be run without much ventilation (no fuel cap and engine openings). With the stock body installed the ESC gets slightly warm - maybe 35 celcius? The motor gets hotter, but cold enough to keep two fingers on it - I would guess about 50 celcius. Will try take more accurate measurements soon.

There are still other things I still need to do. Most important is sealing the motor. I'd like to run it on the track sometime against some nitros. :)

These Jazz ESCs are actually well priced IMHO. If you look at what the alternatives cost (MGM, Schulze, etc.), they're dirt cheap. I wish they were more popular in cars - that might give Kontronik reason to extend their car firmware support. Personally I'd like some improvements made to the forward/reverse program.

[lutach]

It seems that the more voltage you add the more power the braking has. Try and set your EPA to see if that helps. The first video I made you can actually see how strong the brake is: http://www.youtube.com/watch?v=-yrzb2EYsug. I adjusted my EPA and it was working really good.

Oh, I've got plenty of braking power! Don't need more. :D

The Jazz's onboard LED lights up when throttle is at neutral, full open, and full brake.

Looks like your truck has plenty braking too. ;)

Othello, your buggy looks awesome. I remember seeing that vid the other day. Your setup looks very well balanced too. I think mine might have a bit too much forward weight as it tends to understeer.

[othello]

>I find the car doesn't coast freely when the throttle is released suddenly. Looks like it brakes for a split second and then lets go again

well ... you are not the only one experiencing this phenomenon. 95% of my driving is on a rather loose and dusty surface where i didn't noticed it. But when i drove my buggy on tarmac i noticed it too. Not every time when i released the throttle but from time to time. This also comes in to play when you are jumping since this short braking phenomenon will let your nose dive as you release the throttle. I even made a small video where you can see this split second brake (my comments are in german though): video clip. Look close at the front suspension.

gas loslassen = release throttle
bremsen = braking

Thanks for sharing. Glad I'm not alone!

Maybe we should both take this up with Kontronik? Would be nice to get a fix from them. :) I would guess it's just a firmware issue...

What firmware version are you running btw? 8 over here...

[lutach]

It might just be the torque the magnets make. I might be wrong.