Theoritcal CC Motor Gearing Questions - RC-Monster Forums

Bmr4life · **Theoritcal CC Motor Gearing Questions -** 09.29.2010, 03:11 PM

Alright. Lets talk motors and gearing.

For all examples, the battery is 4S 30C 5000mah.

Vehicle weighs ~14lbs.

Stock motor and esc is a CC MMM 2200kv combo.

Stock gearing hits 40mph with a 20t pinion.

If one were to purchase a 1518, 1520, or 1717 motor, what would happen if the vehicle were geared to still hit its 40mph top speed while using the same battery?

Table: Motor and Pinion required to hit stock 40mph top speed.

1515 1Y 2200kv motor 20T pinion

1518 1Y 1800kv motor ~25T pinion

1520 1Y 1600kv motor ~28T pinion

1717 1580kv motor ~28T pinion

The three choices all have significantly more torque than the 1515, but will they be able to over come the added strain.

Will they pull more amps to do so?

Will they over heat?

Thanks

pinkpanda3310 · 09.29.2010, 03:17 PM

I saw Bondo recently say the 1717 is an amp hog. Given that I would say the 1520 would be the most efficient. Longer motors generally run cooler geared for the same speed.

thzero · 09.29.2010, 07:28 PM

I'm switching to a 1518 in my truggy and a 1520 in my Savage 5T. I'll be running on 5S/6S.

Bmr4life · 09.29.2010, 07:45 PM

I'm switching to 1518 in my truggy also. Either a 1520 or 1717 in my DB17.

Still wondering about what would happen on 4s geared up.

nuz69 · 09.30.2010, 04:50 AM

Well, bigger pinion on bigger motor means nothing in terms of "extra gearing".
The longer motor produce more torque for the same current, so geared for the same speed the current will be theoritically the same.
In the reality, the current will be a little smaller in the longer motor, as it's run more efficient (less magnetic losses as it spins slower, less heat as it handle the same power in a longer can...).
But this is true if the widings are the same, which the case between all of thoses motors (1 turn star widings).
So don't be worry using bigger pinions on longer motor ;)

10.03.2010, 07:19 PM

Quote:

Originally Posted by Bmr4life

Alright. Lets talk motors and gearing.

For all examples, the battery is 4S 30C 5000mah.

Vehicle weighs ~14lbs.

Stock motor and esc is a CC MMM 2200kv combo.

Stock gearing hits 40mph with a 20t pinion.

If one were to purchase a 1518, 1520, or 1717 motor, what would happen if the vehicle were geared to still hit its 40mph top speed while using the same battery?

Table: Motor and Pinion required to hit stock 40mph top speed.

1515 1Y 2200kv motor 20T pinion

1518 1Y 1800kv motor ~25T pinion

1520 1Y 1600kv motor ~28T pinion

1717 1580kv motor ~28T pinion

The three choices all have significantly more torque than the 1515, but will they be able to over come the added strain.

Will they pull more amps to do so?

Will they over heat?

Thanks

Hello
I didn't want to start a new thread in the same subject. I am wondering about the same question, but not from the theoretical point of view:
Did someone actually try the 1717 or the 1518 geared up for about 40MPH with 4S 5000 mph (or so) Lipo in his truggy ? any conclusions? (amp draw, run time, temperatures ?)
Thanks
Billy

Bmr4life · 10.03.2010, 07:20 PM

Once mine gets here, I'll be able to comment on my own question. :)

nuz69 · 10.04.2010, 06:04 PM

I try a 1520 on 4S in my buggy instead of a 1515 on 4S. I have lower temps and a little more run time, which is logical, the longer motor provides better efficiency (same windings and design).
The 1515 was about 42°C at run end, and 1520 was about 34°C...

Bmr4life · 10.04.2010, 06:27 PM

Quote:

Originally Posted by nuz69

I try a 1520 on 4S in my buggy instead of a 1515 on 4S. I have lower temps and a little more run time, which is logical, the longer motor provides better efficiency (same windings and design).
The 1515 was about 42°C at run end, and 1520 was about 34°C...

Both were geared to hit the same top speed?

nuz69 · 10.04.2010, 06:47 PM

Of course ;) 13/46 vs 18/46

Bmr4life · 06:59 PM

Thank you very much. That is the exact kind of info I wanted to hear. Maybe I won't have to run 5s in my truggy. Only needs to hit 40mph for racing. I planed on running the 1518 in it, but I may trying out my 1520 also.

The 1717 will still be going in the Flux.

10.05.2010, 01:53 PM

I Will try my 1717 when it comes. I am very curious to see what will be the temps, the amps draw and run time if geared to hit 40 mph (about 19/46) with my 4S Lipos on the rc8t-e. I anyone here have any news to me also - I would like to hear

nuz69 · 10.05.2010, 02:42 PM

Don't forget that the 1717 is a lot heavier than the 1515, 424g vs 570g, the efficiency gain can be therefore minimal.

Bmr4life · 10.05.2010, 03:20 PM

Quote:

Originally Posted by nuz69

Don't forget that the 1717 is a lot heavier than the 1515, 424g vs 570g, the efficiency gain can be therefore minimal.

But how much more power does the 1717 make versus the 1515?

Maybe it can't be geared up even more due to it having more torque.

nuz69 · 10.05.2010, 03:35 PM

Yes, but if you gear more in an heavy vehicle, that's the ESC which will suffer a little more. The danger is that your motor temps will be colder than the 1515, so you will want to gear it up a lot...
Anyway, nothing replace the test, with checking the motor and ESC temps every minutes the first run