1515 vs 1518

[phatmonk]

I have just swapped a CC 1515 2200kv for the 1518.How much longer is the 1518 rotor?My rotor on the 1518 will move in/out of the motor can 2-3mm.It always pushes back out though to line up the pinion to the spur.My 2200 also does this but very little.

[suicideneil]

http://www.castlecreations.com/produ...le_motors.html

1515 = 75.18mm
1518 = 83.50mm

Sounds like you just need one or two little brass spacers/ shims on the rotor shaft inside the motor to remove the slop- its no great biggy though.

That being the case, why wasn't the 1518 used in the Flux HP model besides cost?

[phatmonk]

I actually have some of those spacers.Thanks

[nuz69]

Originally Posted by phatmonk

I have just swapped a CC 1515 2200kv for the 1518.How much longer is the 1518 rotor?My rotor on the 1518 will move in/out of the motor can 2-3mm.It always pushes back out though to line up the pinion to the spur.My 2200 also does this but very little.

On my Castle motors I can move the rotor a little too, I push the rotor and he comes back on the front end bell. I used blue loctite in order to definitely glue the front bearing in the end bell and I add a spacer at the rear of the rotor to optimize the rotor position / stator position.

[xsmoker]

I ran my 1518 in my Losi 8T 2.0 this weekend after my 2200 decided to spin the rotor. I only had 1 tooth higher at 14/46 that I tried. It felt like it ran a little slow. I'm going to try 16-17t pinion and see what that does. 5s is not an option since I only have 4s packs to race.

[RC toy]

ERBE with 1515 2200 kv and 18.84259 : 1 total gear reduction(65t spur , 18t pinion) on 6s reaches 50 mph
If I go to 1518 1800kv then to have the same top speed I need to change spur to 54t. In chase of that I get 15.65385 : 1 total gear reduction and that's a way lower.

I can't believe that with gear reduction that low I will get beter runing times

[nuz69]

Originally Posted by RC toy

ERBE with 1515 2200 kv and 18.84259 : 1 total gear reduction(65t spur , 18t pinion) on 6s reaches 50 mph
If I go to 1518 1800kv then to have the same top speed I need to change spur to 54t. In chase of that I get 15.65385 : 1 total gear reduction and that's a way lower.

I can't believe that with gear reduction that low I will get beter runing times

Have faith ;)
The amp your motor will eat does not depend only on the gear reduction, the 1518 will produce more torque for the same amp rating, that's why it will consumme the same current for the same top speed than the 1515.
More over, the 1518 will have a better efficiency because it will handle the same power in a bigger size and at a lower RPM, so longer runtimes and lower temps ;) I warranty you the result ;)

[hemiblas]

Great discussion. So by the reasoning described above, the 1520 will be even more efficient than the 1518, and the 1717 even more efficient than both of them?

Are there any efficiency numbers on these motors that we can compare?

The larger motors also carry a weight hit. Is the small amount gained in efficiency used up carrying that extra bit of weight around?

I would strongly suggest to anyone out there that runs something a little heavier like a MT or a truggy to ditch the 1515 and go with the 1518. I just did it to my Revo thanks to the Castle Sale.

Anyway I left the gearing the same as with the 1515 2200kv motor just to see what would happen but I knew I had to gear up. 18/54 is what I ran with the 1515 but the 1518 felt very slow and uninspiring with it. To gear up to the same top speed that I had with my 1515 I moved over to mod1 gearing for the 1518. 16/40 would put me in the same ball park as the 18/54 and it made a huge difference. All the speed and power was back but the motor seemed to run a little cooler too. Not much. 4-5deg at most. Still plenty cool and I went up to 17/40 gearing. It just got more powerful but there wasn't any difference in motor temp.

The short of it is IMO it is a win-win situation going to a 1518. Everything seemed to run a little cooler so I am guessing that it should be a bit more efficient. After all heat is lost power. Less heat = less power lost.
Hard to say about run times as I mangled one of my rear drive shafts on the second run and I wasn't really paying that much attention on the first run (I was concentrating more on temps). I am sure if the same gearing was to be used the 1518 would come out tops in that comp.

Now a question time (feel free to help out here NUZ69). What can I expect if I was to stick a 1717 in the same truck and gear it for same top speed. More torque is the easy one but what about efficiency? I am going to do it soon but would like to know what I could possibly expect.

[nuz69]

I use a 1520 on 4S in my 8:scale buggy (inferno mp7.5), and I have the same runtimes with 4000mAh than my friend running a 1515 on 4S with 5000mAh . Temps were 29°C for me and 35°C for him, ambiant was 15°C (FRANCE).
For the same width and design (meaning same windings 1Y and 15 series) the longer the motor is and the more efficient it is whatever the voltage is.
==> the 1520 nomatchs the 1515 in terms of temp and efficiency.

Be carefull on the 1717 : on the one hand the rotor is heavier and larger, the motor is a lot heavier than 15 series motors, so the additional weight can drop the gain of efficiency .
On the other hand, the 1717 and 1520 motors have similar Kv, but the additional inertial rotating energy required to rotate the heavier rotor of the 1717 can drop the efficiency too, but I am not sure on the point, because larger rotor means stronger magnetic field... Maybe someone from Castle who are more qualified can confirm or deny it.
So IMO, 1520 vs 1717, same story, but I would take the 1520 for the (maybe) better ratio power handling/weight.
Hope my English is understandable ^^
Tom.

First of all you English is perfect. I wish the people I work with could write as well as you. It would certainly make my life easier. LOL.

Re. 1717 vs 1518. I pretty much had the same thoughts. I am hoping that the larger diameter rotor will help efficiency but there is going to be only one way to find out for sure so stay tuned for that one. Even if it isn't more efficient at least it will have easier time moving a big truck with huge Big Joe tires and Axial wheels.

Thanks for your help nuz69.

[xsmoker]

Ok, I geared up the 1518 and it was a strong motor now, going to check my batteries today to see how they handled, but everything was very smooth power wise.