more torque? sure?

[ED66677]

I've heared many times people saying a 10XL has more torque than a 8XL and a 12XL has more than a 10XL!
Has anyone tryied to figure out what the torque of a Feigao is?

[marker]

Ed
The torque for the XL 's calculated at their rated max amps is,

8 XL 51.61 oz inch
10 XL 51.74 oz inch
12 XL 51.9 oz inch

So allowing for rounding errors all the XL produce the same torque.
Mark

[ED66677]

That's what I wanted to hear, I made some calculation and got to the same result... but in Nm more or less 0.36
I was just confuse when reading that a 10XL has more torque than a 8XL and a 12XL has more than a 10XL
I also guess some people are running their 10 or 12 XL high above the max rated amp so the torque is obviously higher!

[andym]

Mate torque is more important than KV take a 9xl feigao and run against say a Nue 1515 2.5d. The feigao has approx 1850 kv and the new 1700 but run them both on say 4s and the nue will spin a larger prop faster with less heat and with a bit of timing advance not be to far behind on the KV front either. The extra toorque of the nue will win hands down any day. The feigao has .616 inoz/amp the Nue .841 inoz/amp. The nue will pull less amps for more HP and less heat. Here is a great explanation from AndrewG
Dyno tests show the Feigao making 0.616 inoz/amp torque

The 1515/2.5D will make 0.841 inoz/amp



SO it has more torque to turn a prop faster



Lets assume you current motor is running 70 amps at top speed ie 26732rpm ie about 86% of free running rpm

Its efficiency is a maximum of 78 percent so its output is 17*70*.78 = 928w and torque output is 43.12 inoz



Lets say the Neu is turning the prop with 43.12in/oz of torque. The Neu makes the same torque at 52 amps. This means the pack is running at about 17.4v rather than the 17at 70 amps, so the Neu runs at 26632 100 rpm less than the 1820 9XL with an output of 811 watts



So you are doing 100 rpm less for 18 amps less. Add a little advance the motor will gain the rpm and more.



And it will use maybe 5 amps to do it – you are way ahead the pack is getting an easier ride especially at part throttle say between 20 and 40 amps the Neu will make 30-20% more power than the Feigao from the same amp draw so heating isn’t going to be an issue.



By the time you add a little cup and timing to the current draw to the same amp draw as the Feigao you will have ½ the heat, 37% more torque, and 17% more power



The boat will go harder or harder and longer



Andrew Gilchrist

https://www.fastelectrics.com

[ED66677]

I understand that Neu motors are much better than Feigao, I guess any other brand is better!
I was originaly trying to calculate myself the torque of Feigao's and got to the same result as Marker! I was just confuse!

[andym]

Yeah it was just an explination how a lower kv can be faster with the same amps due to an increase in torque. For saws runs you would want more KV and torque but for oval ,torque is a real weapon if used correctly.

[ED66677]

I think this is certainly the most difficult thing to understand when you start in FE boat, KV, power and torque, what is the right choice!!!

[andym]

A balance my friend a balance. I would take torque with higher volts over high KV and lower volts any day.

[ReddyWatts]

I learned from the beginning that I liked the higher voltage BL setups for reliability. High amps will have a lot higher failure rate than High volts. I have not had any unexplained controller failures for years since I went to the High volt setups. Well only one actually and that was because i got the controller wet.

[ED66677]

that's exactly my point of view ReddyWatts, on my mono with the Feigao8XL, I started with 12cells, and now I'm running 18cells with gear, the 8XL already tend to drain lot of amp with a small prop but can basicaly provide 50% more power than a 12XL with same torque, using a 1:2 gear ratio, I double the torque, under 18cells (21.6V) it is spinning 45K rpm so the prop spins at 22k rpm, and at 70 amp that's around 500watts extra... not bad!
BTW, what HV controler do you use ReddyWatts?

[ReddyWatts]

I am using the Jeti advanced 77 amp and the OEMRC 100 amp controllers.

[ED66677]

yeah the OEMRC seems to be the one for a budget, I currently have the Hex120 and plan to get one of these!

[Eodman]

Good morning ED -- Question for you guys .... Is there a marine version of the OEMRC 100 amp controller? Or do i just order their 100 amp controller?

[ED66677]

Nope! but it seems not to be necessary, don't know what about you ReddyWatts but I think I read that this baby doens't heat too much

[properchopper]

Thanks all, for a very informative thread, I just learned some really good info from it. One comment on having more torque and thus being able to swing a larger prop : I've found that too big a prop does induce some torque roll/prop walk problems and possibly may contribute to chine-wobble at higher speeds when a deep-vee is riding on the very bottom of the vee. I've just re-fit two of my monos to place the motor far back, allowing the batteries to be placed on the keel centerline , raised the struts, and will try a three-blade prop for the first time tomorrow. Anyway, thanks again & keep the good info flowing !