ph2t
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hey Aaron, just found it! 🙂
cool! looks like it might be a go’er! My only concern is that they mioght be a bit too big, ie: I don’t want to have issues with shorting out the power/signal wires. I mean, it should be OK and the whole adhesive setup is definately a sweetner!
And I was just at jaycar on Sat too! bugger! must be a new product….
@jollyboss, a heatsink on the motor is not related to the heatsink on the nelly. but in such high current configurations, more heatsinks the better! lol…I’m using ETEC 450mAh 3S packs for the 3S combo and ETEC 700mAh Cells for the 2S setup. you can get both at http://www.allerc.com and some at http://www.aircraft-world.com (I think).
Yes, all my Nelly turbos retain the break function. 🙂
cheers,
ph2t.
ok, got the parts, only now had some time to sit on my arse and play around with them….
the atomic motor mount is cool, bloody light!!!
the only bugger is that only the ATOMIC bb can fits in this motor mount!!!! something they neglected to say in the product brief, argh…..
no big deal for me, but might be for other people….
here’s some pics, the area’s circled in yellow point out where the space doesn’t exist for a regular bb can to sit, hence why you need to use the ATOMIC can.
I’ll know more when I mount the thing…..it DOES sit the motor uber low AND you get these spacers that mount the diff shaft at 1 of three heights….so that’s another cool option….
ph2t.
great to hear the feedback hachi, it’s always appreciated…
As for the Nelly EVO turbo, you may be interested in something like this:
This venture into 3S lipoly territory has made me think a lot about cooling, nelly and the motor. Did a bit of searching for some heatsinks and found one that fits with a bit of cutting, it’s not too much work….
I’m trying to get a combination that works well enough to provide some cooling but without infringing on too much space. Even the one above may be a bit too high, depends on the shell. Also, mounting the nelly a little bit but into the centre of the chassis will allow for more head room under the shell….
more testing to come, still gotta figure out how to hold the heatsink down onto the MOSFETS….
ph2t.
UPDATE:
OK, I put it all together and installed the pn anima motor. The ESC has no problems handeling this 33 turn motor in terms of current, the GWS GS-100E ESC is rated at up to 8A.
Unfortunately it didn’t run well. If I applied the throttle too hard the whole car would stutter and the steering would go crazy. It seems that the ESC is dumping all the current to the motor and therefore the supply voltage is dipping too low to run the RX and Servo properly.
Given this I tried to add several capacitors to the voltage rail to help smooth this out. In the picture below you can see the ghetto setup of several capacitors in parallel (it’s all I had available at the time) totaling approx 900uF.
Even with the caps the ESC would still dump too much voltage. It did lessen the effect, but over time it got worse as the batts started draining.
In the end for the first racetrack test I just put a stock xmod stage 2 armature into an ATOMIC bb can. With this setup there was no issues at all. The car ran smoothly and had no twitches under acceleration….Mind you it was no match for betty’s mr02/nelly/S04 combo!
But it didn’t stop there…. 🙂
I bought a PN Saber motor from the ausmicro shop and installed that instead. The PN Saber is a 35 turn motor (ie: 2 turns “less hot” than the PN Anima). It’s basically an S04 with a fat commutator.
This motor ran fine in the car. No issues with the ESC dumping at all. Not until the very end of the batt’s charge. I tested this and found that when the car did start dumping the current, it was near the end of the batts charge anyway. I drain one set and they only had 22mA left in them, so given that I find this acceptable.
So to be on the safe side and to get the greatest amount of smooth, “non-dumping” runtime I installed a 330uF 6.3V capacitor across the voltage supply on the RX. This capacitor now supply’s the RX and Servo directly. It’s a balance between how much uF (capacity) I can get vs. the space I have to install it in.
So, with the swap to the Pn Saber motor and the addition of the 330uF capacitor, I can say now that this setup runs really well and I’m very happy with it. I am pretty much limited to the 35 turn motor, as I said, not because the ESC can’t handle the current of lower turn motors, but because the ESC doesn’t handle the current draw very well in terms of keeping power up for the RX and Servo electronics…
Maybe this is because I am running this setup on the lower limit of 4 cells (4.8V). It is a 4 – 6 cell ESC. I think what’s happening is the 5V regulator on the ESC is the cause of the problem. This 5V regulator is the “BEC” portion on the ESC that drives the servo and RX and a constant 4.8 – 5.0V. If the supply into the regulator isn’t high enough (ie: just like a 4 cell supply may be) then this “dumping” effect may be the outcome of this limitation. I may eventually put a 6 cell or 2S (7.2V) li-ion combo in just to test….
Still, why stop there???? lol…
I noticed on the ESC the MOSFETs are layed out in a nice, “please modify me” sorta way, lol….
Since this is a FWD only ESC it doesn’t have the traditional h-bridge design. The setup is 2 n-chan MOSFETS that are wired in parallel (ie: 2×1) for the main FWD drive and 1 p-chan MOSFET that is used to create the break function.
So I replaced the main FWD drive MOSFETS with some more efficient MOSFETS. 🙂
Comparing MOSFET specs.
Stock MOSFET (4410) = Rds(on) @ 4.8V = 0.017 Ohms
New MOSFET (IRF7456) = Rds(on) @ 4.8V = 0.0057 OhmsSo the new MOSFET is ONE THIRD the resistance of the stock MOSFET. On paper anyways, but still, the difference in the end result is VERY noticeable…
So with all that now done, here’s the curernt setup. Looking a lot cleaner than before….. haha..
Now that’s I’ve had some time to run with this chassis I thought i’d list some pros/cons I’ve found.
PROS:
-FM design, more range, no freq clashes with competing Z’s.
-Cost of electronics is equal (if not just a bit cheaper) to the cost of a Kyosho PCB.
-ESC can handle hot motors with the need to upgrade the MOSFETS.
-Can support 2S li-ion or 2S li-poly install natively.
-Steering strong, ESC powerband very smooth.
-4 Channels!! (I may do a headlight mod…).CONS:
-FWD only. ie: a track only type setup. (I myself don’t find this a big issue).
-Tricky to install.
-ESC dumping issue with < 34 turn motors.
I’ll try and get some video of this chassis in action soon!ph2t.
