New hi-speed project

[lutach]

Originally Posted by BrianG

Even better! I'll keep those in mind if I decide to go higher V. And I don't mind the Koolflight's size really. I have TONS of room on this thing!

Ok. Keeps us posted with pictures and a video of your beast running.

[Arct1k]

Couldn't you just use a 2cell 1200mah lipo reciever pack with the UBEC... That shouldn't weight more than a few Ozs I would have thought...

[BrianG]

Yeah, I could. I try to stay away from using an Rx pack altogether though as it's just one more thing to charge. Not to mention creating some type of LVC - but I've already designed a circuit for that.

[Arct1k]

Oh how about a123 2s1p - You'd hardly ever have to charge it and wouldn't need a LVC or a UBEC...

6.6v is a little high but doable no? The Spektrum will take the volts will the servo?

[BrianG]

Yeah, that would be ok too. 6.6v is a tad on the high side, but do-able considering that 6 NiMH cells is usually around 6.4ish volts.

[lutach]

Originally Posted by BrianG

Yeah, that would be ok too. 6.6v is a tad on the high side, but do-able considering that 6 NiMH cells is usually around 6.4ish volts.

I've seen my 5cells Rx packs come out of the charger sometimes at over 7V. I think most servos can handle 7.2 volts and I've seen some digital one even list it.

[jhautz]

2s a123 would be 7.2V off the charger. A littel on the high side, but I have considered doing the same thing in the past for my nitros. They only reason Ididnt was the dang battery boxes on the nitros were just a touch to small to fit the length of the a123s.

I wound up using 2 of the 1200mah LiFePo4 cells in seriies though with no isses. Same voltages as the a123, just smaller size and capacity.

[Mod Man]

I have a couple VHVBECs and love them! I would move you in that direction. I have had very good success with them.

That 1515 should rock! I run my 1515/3DF on 12S and it is absolutely gear strippingly wicked!

Matt

[BrianG]

Well, since I got the 1515 2.5d(f) already (1700kv), I'm pretty much limited to something under 40v anyway, so the Koolflight will be fine. At 9s, that makes 56,610rpm, which is the max I want the Neu to spin. And, 9s maxes out at 37.8v right off the charger, so it works for the UBEC too. Perfect!

I don't know if I'll be able to hit the high speeds I was hoping for, but I hope 90-100mph is doable and would be fun! And when I just want to play, I can simply reduce the pinion for more manageable speeds.

The "only" things I need now are lipos, ESC, motor mount, and a bunch of fabbing. Ugg, this hobby is expensive!

[Mod Man]

You should be good for an easy 90mph (well, easy relatively speaking).

Above 80mph aerodynamics become a huge issue.

Oh, Nic Case called me and we spoke for 45 minutes yesterday (He had engineering questions). He is tooling up for this year's event! There should be some good cars this year.

Matt

[Big House]

Motor - Mega Motor ACn22/35/1E (2550 Kv)
ESC - MM
Battery - 2 A123 3S1P 9.9 in series (19.8V)
CC UBEC
Geared to run 60+ mph (however I do that)

Any other suggestions, I am open to all facts and opinions.

[BrianG]

OK, I've settled on either 8s or 9s lipo, probably 9s for more power. So, now I'm looking at some HV ESC options:

• MGM 12032.
  • Doesn't seem to be in stock right now
  • Kinda expensive at $450
  • Support/warranty would be a PITA
  • Highest current HV option they have. Don't think I'll need/want more but you never know.
  • Does have brake/reverse if I decide to use electrical brakes in the future. Probably not, but the option is there.
  • Looks to be my best bet so far as far as working out of the box.
  
  
• CC Hydra HV-120.
  • Not much information about this so don't know if it will work with a pistol radio for sure
  • Availability?
  • Need to swap out the water cooling for air cooling
  • Cheaper than the MGM at $345
  • Has the 180A and 240A options if I want to get crazy.
  • Support/warranty is definitely a plus.
  
  
• CC Phoenix HV-110.
  • I know I'd need a pistix adaptor
  • Highest current HV option they have. Don't think I'll need/want more but you never know.
  • Cheapest option at $270
  • Support/warranty is definitely a plus.

Decisions, decisions!

Kontronik Jazz 55-10-32? No need for pistix adapter.

[BrianG]

55A is too low current. I want at least 4-5HP. Thanks for looking though. They DO have an aircraft 120A 63v model, but it probably needs that adaptor...

They have just released a new range of controllers called the Jive. Biggest is 80HV rated to 12S and 80A continuous with onboard 5A switching BEC. No word yet on whether or not it'll have the car modes that the Jazzes have though...