voltage vs efficiency?? - RC-Monster Forums

01:01 AM

Motors with lower kv and higher voltage will have higher efficiency?
Virtually I can get efficiency near 100% if I get 100 kv and 350 volt, for instance?
In the other way, Neu 2200kv with 4s and 1500kv with 6s both have 90+% efficiency?

suicideneil · 10.17.2009, 06:18 AM

Efficiency isnt just reliant on high voltage and low kv, the motor, esc, and batts all play a part, as do the laws of thermodynamics... In short, you would need the most pure of pure copper wire and solder for the efficiency to climb over about 90%.

Using high voltage & low kv means you use less current to make the same amount of power as a lower voltage & higher kv setup, so that does lower the energy lost as heat, but you are still limited by the materials and contstruction methods of the components in the system.

For the typical racer or basher, a 6s lipo & ~1700kv setup is about as good as you can get; something like 12s & 800kv is better for 1/5 scale models that suck current like... yeah...

lutach · 10.17.2009, 11:00 AM

I'm loving my truggy's set up. I use 8S lipos (2 4S ranging from 3200-3700mAh), a Neu 1515/2Y (1100Kv) and nothing gets to 120F degrees.

bdebde · 10.17.2009, 02:10 PM

It is not so much efficiency numbers, it is more about current (amps). It takes a given amount of watts to move a vehicle a given speed (varies with every set up). Say it takes 1000 watts to move the car, you could use 10 volts which would draw 100 amps and things would get hot, or you could use 100 volts and only draw 10 amps and everything runs cool. More heat in the components can cause efficiency to go down as well as more power wasted to heat.

Motor efficiency doesn't change much no matter what the kv but y winds are often more efficient (lower kv than the d counterpart). My lehner 1930/8 is rated at 90% efficiency as d wind but when reconfigured to y wind it is rated at 92% for example.

stum · 09:26 PM

8s 3700mAH is sick huge, you race w/ a brick like that on your truggy? Even a 3200 8s is a monster pack, bigger than I want on my race trucks. What is the weight of your packs? Got some picks of this beat all put together? 800g for cheap lipo's up to about 1000g for pricey 8s setups good thing you don't need 35c lipo's at that voltage the Hyperion vx 35c's would be like 1400g

lutach · 10.17.2009, 09:51 PM

Quote:

Originally Posted by stum

8s 3700mAH is sick huge, you race w/ a brick like that on your truggy? Even a 3200 8s is a monster pack, bigger than I want on my race trucks. What is the weight of your packs? Got some picks of this beat all put together? 800g for cheap lipo's up to about 1000g for pricey 8s setups

stum · 10:53 PM

I've been running 5s 5k packs this year that weighed in at about 665 grams on my 1515 2.5d/f in my 8ight-t, but this next year I'm stepping to a 4s 6500 35c hyperion pack (685g) for most races w/ a Castle 2200. I'll use my SMC 4s pack (842grams) for those few Sunday a-mains when I need to race for 30-45min against nitro's; this will keep me at one battery swap, giving me a chance to stay near the top.

18.5*5k=92500
14.8*6.5k=96200
14.8*9k=133200

59.2v*3200=189440 (pushing 2x as much run time as my normal setup)

SpEEdyBL · 12:14 AM

My Tekin 1900 on 6s, for instance, runs a good 10-15 degrees cooler than my 2650 on 4s. It also seems a lot more powerful, almost like the 2650 on 5s.

Btw, for 6s i use a 35C 3300mAh Hyperion G3 pack (529g) and for 4s i use a 25C 5000 mAh Zippy pack (497g).