Speed_Freak_039

iTrader: (10)

Does anyone use this combo and how do you like it? I am thinking of putting this in a 8ight.

Now as the voltage goes up and the KV goes down does the motor get more snap?

Edumakated

iTrader: (19)

You could use that on 6s. The motor will not have more snap though. People use higher voltage because it runs more efficient - longer run times (gas mileage basically). Generally, the higher voltages run cooler on the ESC and batteries. This is why the battery mah goes down as voltage goes up.

4s 5000 = 5s 4000 = 6s 3300 All three of these batteries will give you 18-20 minutes of run time.

You want to match the KV of the motor to the voltage you plan to use considering what type of RPM makes sense for your application. If you are racing, you want to keep your RPMs around 30-37,000 typically. Anything more will start to get a little uncontrollable on the track. If you are bashing on the street for speed runs you can push the motors up to about 55-60,000rpm.


Typical Track setups:
2050-2650kv for 4s (4s 5000 battery)
1700-2000kv for 5s (5s 4000 battery)
1400-1700kv for 6s (6s 3300 battery)

All three will feel exactly the same and yield between 18-20 minutes of run time in most situations.

Speed_Freak_039

iTrader: (10)

Hey your back on, lol. Im thinking I could get the 3D and if its not enough on 5S I could go 6S as a backup plan. I am looking at the Neu charts for specs on the batteries. They are missing dimension for the 3300EP 6s.

Personally, you know our track would it be too much on 6S?

Also, If I got the 3D with 5S 4300 pack and its not fast enough for me would you be interested in buying the battery from me so I can go 6S or do you not need any more of them?

Fastelectrics

Going to a higher voltage will let you shorten your gearing and get more torque ie snap

ALso if the motor is operating at low levels of amps the extra voltage may push it up to a more efficient amp level where efficiency is higher. Both of these will give you more snap

Or all three might happen.

markhat250

iTrader: (65)

Now that we're on the subject....

I had a 4S 5000 on a 2000kv Medusa and it was decent untill I tried my buddies 6S 4000 on a 1300kv Medusa.

The 6S definitley had more snap (i'de call it sheer balls more than "snap" though). But the top end sufferd a bit due to the lo spinning kv.

My question is:

Can I just keep up'ing the pinion to get the top end I want? It for sure has bottom to spare. But it seems brushless (at least the Novak 1/10 stuff) has a sweet spot. You can over gear to a point with good results, but anything over the "sweet spot" and you don't really gain much other than an overworked system. I wonder if the same applies to these NON-sensored bigger motors.

Any thoughts?

RBMike

I run a 1512 3/D/F in a HB D8 with Thunderpower 6S 2600Mah packs. It's perfect at the indoor track I go to but I had to gear up a couple on the pinion in order to pass up the nitro guys at the end of the straight on our local outdoor track (145 ft long). I felts 5S was not enough with this motor. Keep in mind my D8 is on the heavy side even with these light packs (8lbs, 2oz).

macchi

Hi guys, slightly off topic but might be helpful to others as well....

RBMike, I also have a D8 that I am electrifying and was curious as to what tooth pinion you are running with the 1512 D? I am assuming you are running the stock spur and that the 1512D is 1700kV?
I have a Medusa 2000 and am trying to figure out if I can run it with a small pinion and 6S batteries.
Thanks,

Freddy

Speed_Freak_039

iTrader: (10)

I would like to bump this thread up before I order some 6S packs. Any of you guys using this setup on 6S and what Mah packs you using?

Im almost thinking of squeezing in the 3900 6S instead of the 32-3300 range. its 50g lighter but still light than any of those zippy packs. Im getting probably right at 20 mins on the 5S 4300 and I dont want to lose my runtime.

Or does anyone run any packs that weigh around 595? The 6S 3900 is 595 and my current 5S 4300 is 552. Im more worried about the wieght being to much to cause a balance problem is my question.

Speed_Freak_039

iTrader: (10)

Anyone else have this setup and like to pitch in on runtime and pack size? Performance over 5s? Or their burn rate on 6s?

chip cross

iTrader: (2)

In my SC8 I am using a Monster Max with a Neu 1515 2.5 D F can motor on a 6S 6000 mah Polyquest. The runtimes are great and the temps are super low just how I like it. This is a link to the build http://www.rctech.net/forum/electric...5512-sc8e.html

Speed_Freak_039

iTrader: (10)

My burn rate when I checked it once with 5S was 193mah/min. So 17.5 min on a 4300 5S. I dont want less than 15 min on a 6S. Will my burn rate drop that much? with a 180 burn rate on the 3300 is only 14 min at 80%. Very hard decision.

shurcooL

Speed Freak, you can think of potential energy a battery can store as the product of its mah rating by the number of cells.

So, your 4300 mAh 5S can hold only 8.6% more energy than the 3300 mAh 6S lipo (4300*5 / (3300*6) = 1.086 = 8.6% more).


Also, the 1512/3D/F motor + 5S or even 6S Lipo has always been my dream setup for an 1:8 scale buggy. I like the better efficiency potential of a higher voltage system, and the 3D name of the motor just sounds cool to me hehe.

As far as the top end speed and stuff goes, you can always control that with your gear ratio. The is no such thing as more or less snap with different voltage setups, as long as you change the gear ratio to compensate for different kV.

Speed_Freak_039

iTrader: (10)

Thats a good way to look at it. So I figured I use 193 burn rate at 5S last time I checked. So round up to 200 incase. The 4300 5S gets me 17 at 80%. so then I take your 17min and subtract 8.6% that leaves me with 15.5 min of runtime at 200. but with 6S I will be less of a burn rate so more run time. Does the extra rpm come free then and its still more effecent?

shurcooL

The only thing that comes free is the cheese in a mousetrap.

Here's how I would redo your calculation to make it more accurate:

The 6s lipo will give you a 20% higher voltage (6/5) over 5S. So everything else being equal (i.e. assuming same power output of your car's wheels), your amp draw should be 17% lower (1/1.2).

So take your 5s burn rate (I'm assuming you mean that many mAh gone per minute) of 193 mAh/min and subtract 17%, you get 161 mAh/min amp-hour usage.

Since your 6s lipo has 2640 mAh if you only use 20% of its energy (as to not to damage it), 2640/161 = 16.4 mins of runtime.

Keep in mind, I said "everything else being equal" above. That means if you want the above calculation to work, you have to gear 17% lower to compensate for 20% higher kV (same motor kV * 1 cell higher battery voltage).

Ok, I hope I didn't confuse you too much... and maybe it helps somehow.

Now for some good news. In theory, a higher voltage setup might be more efficient. So you might get a burn rate of less than 161 mAh/min on 6S. That way, you'll get slightly more than 16.4 min of runtime. The extent of this increase is unknown to me, however. It might be 0.1% more efficiency, or perhaps up to 5%+. And yes, this extra efficiency does come for free (in the sense, you're wasting less energy on unwanted stuff like generating heat).