OK, I've had a lot of success with the Stacked Nelly turbo. I never realised so many people want to run < 20 turn motors!! You're all crazy! haha...
What I've found is that whilst stacking the MOSFETS on top of each other was the
easy way to go, there's a few design challenges.
1) If a MOSFET fries, it can be tricky to repair (given the stacked setup) and I may need to destroy a perfectly good MOSFET to get to the fried one.
2) Heating in the stack is additive, ie: MOSFET on top of MOSFET, not MOSFET -> air. Whilst heating isn't a huge issue (ie: 'cause of high current rating of the turbo), some people run some crazy hot setups (3S lipo + 20turn or 2S lipo + 15 turn, etc, etc...) and I gotta account for that.
3) Stacking MOFSETs is essentially quite a messy job. Takes time to do and time to "tweak". You need to bend MOSFET pins and the labour (from my point of view) is just too much....
4) I found on a 3S lipoly + 27 turn (plasmatomic) setup that I acutally fried one the copper tracks on the Nelly PCB!!! Yes, a solid 2-3mm copper track just fried under the current load in a 3S lipo + plasmatomic setup (in an AWD EVO running around a parking lot...).
So I've now just simply increased the size of the PCB and layed all the MOSFETS out flat!!! A simple change that has increased the size of the Nelly PCB, but it's still under half the size of the V2.x .
Here's a pic showing the changes to the PCB. The new Stacked Nelly EVO PCB is on the left, the original Nelly EVO PCB is on the RIGHT.
Notice that the high current copper tracks are a lock thicker in the new design. To do this I had to remove the motor solder pads off the end of the EVO PCB, but that's no big a deal. As you can see this setup is really intended for all the nutter's out there with low turn motors, lol...
Here's another picture showing the orientation of the power wires and the typical 4 signal wires that goto the xmod/mini-z/iwaver RX PCB.
I'm still undecided on the final wiring layout. This will do for now, since I still need to cover the Nelly in the clear heatshrink that Ilike to use, so the wires need to be able to come out each side for this....I'm also experimenting with some custom heatsinks as well...
And here's a closeup of the Stacked Nelly PCB itself...
Sweeeeeeeeet......
Operating Limits:
Max current: 30A
Max Voltage: 20V (Actual true limit dictated by RX, eg kyosho PCB 7.4V, EVO PCB 11.1V)
This has been tested on a 11.1V 3S Lipoy setup running the MinizWorkshop 15t Motor(running no load). Ran cool with no problems. I will be testing this setup in an EVO chassis soon. Just don't have time at the moment....
Will be avilable to purchase from my site and others soon!
ph2t.