Jammin X1-CR HV conversion

[Kraeuterbutter]

hmm. don´t think you realy need the mod Ulrich Röhr did to the Jazz55..

imagine: he flies the Jazz55 in his Factor (heli with 1.8m rotordiameger)
with 10s2p Kokam3200 !! (so 6400mAh)
with peaks up to 110A
(so over 3000Watt Power, look here for onboard-diagramm: http://www.ulrich-roehr.de/hubi/e-power18/factor2b.gif)

that are reagions you will not (and want not) reach in a 1:8 buggy

count with around 1000Watt-1200Watt peak max on track
and not more than 2000Watt for speed-runs..

i think you will stay with peaks under the continouse-amp-rating of the JAZZ55 (=55A)

(someone here has an 1:8er with 5s Lipo and 120A peaks running 65mph.. and when you watch the video: thats too fast :D seriously ;) )

oh:
10s 2100mah-Batts..
considering you have 30C peaks
--> that are 60A max (you don´t want more for batterie-life-reasons)

Hey Kraeuterbutter :)

I think you are right. Initially I'll be getting 16T, 20T, and 24T pinions for my conversion. This will allow me to adjust top speed between 30 and 50 MPH depending on desire. I think with 16T for track racing your 1000-1200W prediction will be correct.

2100 cells are the smallest I will use. I chose the 2100s for low weight and their dimensions that should fit my chassis like a glove. I might increase to 3000 or 4000 mAh later.

I think 50 MPH will be the highest speed I attempt. :)

[Kraeuterbutter]

my setup is 5s and 4400mAh batts..

here a diagramm of my power-consumption..
motor-rpm-max is around 30.000rpm
--> speed (calculated from the gear-reduction) should be around 55-60km/h which is already nearly too fast for my driving skills on our relativly small track





on that graph i got way too much motor-temperature :013:
was running at hot summer-day without cooling finns or fan on grass
(that has been changed and now no problem)
i use a smaller motor than you will (only 230g weighting Lehner 1930)
so this should be of no problem for you

oh: i use around 2000mAh-2200mah in 10min
more measured datas (also with 4s, 3s and 2s) here:
http://www.kraeuterbutter.at/Bilder2...ono_Messwerte/

instead of increasing capacity on your batts, i would buy another set and change after 15min driving..
its like on helis.. don´t carry too much weight with you ;)

This is very useful information. It is making me wonder if I shouldn't rather get a smaller motor like a Neu 1910 or 1907 to save weight. I have not yet ordered one because Neu don't have stock of the 1912 I requested.

On the other hand, a 1912 might be big enough to not need cooling...

Thank you for posting your data.

I agree with you about batteries, but I've heard there are race segments here that last 30 minutes. It would be a big plus to be able to run non stop for 30 minutes in those races. Talk about nitro spanking. :)

I think I got my spur sorted out. Ended up redrilling it myself and managed to get it mounted more accurately with my $70 drill press. It's now a couple 100th's out instead of a few 10th's! Should mesh ok like this.

Unfortunately the countersink screws can't go more flush than they are. Hardened steel is very difficult to cut.

Assembled the center diff and mounted it all to the chassis. Will be a while still before I get the power system and radio components, but wanted to double check fit. Pics on my Blog.

Hey I was wondering... has anyone considered swapping out some of the steel fastners for aluminium fastners? I think one could save over 100g by swapping to alu. Alot of steel fastners are used for screwing into plastic parts, and in a lot of cases it seems like overkill to use steel there.

[coolhandcountry]

That is pretty cool idea.

Long long LONG overdue update on my blog.

:)

[rschoi_75]

damn that's clean.

[jhautz]

Looks great. Really looking forward to seeing how it runs.

Only one suggestion, I would look into getting a better pinion gear. That skinny pinion is only touching half of the width of the spur and with that motor on 10s its gonna pack some serious torque. I can see that stripping your spur very easily. And since the spur isn't exactly an off the shelf item it investing $15 in a better pinion might save you allot of hassle.

Thanks. I'll post some more detailed photos when it's completed. :)

Jhautz, yea it has me worried too. I purchased my pinions on the specification from the seller of a 7mm face width, but they turned out to be 5mm wide when I got them. I'm going to try it anyway and see what happens. The spur gear is actually deformed so I'm going to be getting more made anyway - the guys who made this one refunded me for their bad work luckily. It feels like Nylon despite me requesting Delrin, so I suspect it won't last!

[lutach]

Originally Posted by Aragon

Hey. I found this Jazz modification from a while ago that some heli guys in Germany are doing with their Jazz 55 controllers. This might be the key to avoiding thermals...

That is a very nice heat sink layout. I should try that on my Jazz 55s.

Do you find you need it, lutach?

[othello]

From my perspective i don't think you will need this complex heatsink design, because you won't push the Jazz to the same powerlevels (up to 4KW) as he does with his big heli.

I found this graph of a heli guy using a jazz 55 with a Neu 1910/1Y using 8s lipos. Power levels up to 2.3KW and an average amp draw of 42A. On your car i would expect your highest bursts between 1.2-2.5KW but your average amp draw will not be even close to 42A. I think it would be more in the range of 8-15A.

The only thing i did is mount the ESC upside down and removed the heatshrink where the cooling plate is (this improves heat dissipation). After a hard continouus run the cooling plate feels only warm to the touch (This is with power levels up to 1.7KW and 10s1p A123 in a 9lb 1:8 buggy geared to 67km/h (42mph)).

Very clean layout ... looking forward to read about your maiden run.

[lutach]

I have one with a small heat sink and it does help. The one I used with the Align didn't overheat, but it stopped working. I will probably make heat sinks for all my Kontroniks.