Alright, first and foremost sorry for a generic topic. But I’m stuck in mind process and need additional stimula to make the right choice.
I’m moving away from my current drive train.
2x 7374 (maytech) 170kv 11/44 with a ratio of 4 with 160mm wheels.
Flat top speed ~55-57, downhill ~63-67.
Torque is very good on flat, could be better a bit uphill.
Issue, future gearing only has two options.
12/42 or 10/42.
Future motors only come in either 130 or 170kv.
Future tyres will be 175-180mm in sizes. So this gives me.
170kv X 10/42 around 60 flat and 68 downhill.
130kv X 12/42 shows the same speed I have now.
I’m moving to 7384 motors.
Thoughts I have.
I got used to the speed and would like a bit of more top end. But I also go to woods and I love just charging up hill. Don’t want to sacrifice a good torque with 170kv motors, but don’t want to loose a bit of speed for a really good torque. 140-150kv motors in this size would be best, but either long waiting times or something else, don’t see a way to chooce a better Kv, what do you think is the best outcome here?
What ESCs are you using? I’ve heard that higher KV motors, if winded just as good, heat up the same as lower KV motors at the same torque. Not current, torque. Meaning that you can go with a higher kv / gear ratio or what not to get more speed, and still have the same torque at low speeds if you can supply enough current.
Problem with this method of thinking is that I don’t know what different ESCs are rated for motor current wise. Like, could I use a cheap 4.12 vesc at 30A battery, but 80A motor?
(This is less efficient for the ESC ofc, so you’re killing your range by picking a motor + gearing that’s way too high)
If you want more torque AND more speed, the only answer is faster gearing (and/or higher kv) and more motor Amps. And if you are pushing more amps, a larger motor is going to take that with less heating than a smaller one.
Do you mean 6374 or are you actually using 73mm motors (and if so, can you drop a link to those?)? If you halve your motor KV, you double its torque per amp, but theoretically you quadruple its resistance. Heat generated is equal to current squared times resistance, so when you’re producing the same torque with both motors, you’re losing the same amount of energy to heat. In other words, torque and KV shouldn’t theoretically relate much in an ideal motor, and the peak in either case is going to be determined by stator saturation, not thermals, so size should be all you need to worry about.
@rusins now I have 80 motor, 60bat. That motor is rated to 60. @Yomiel94 what exactly do you mean by your size question? Since it’s a sealed maytech, It has a shorter stator than let’s say Tb motor would.
Hmm, not sure if I’d feel safe turning that even higher. I guess the ESCs that are rated at 100A or more would be safe to run at higher current than that. Maybe the Maytech 200A ones?
I have really crazy torque and power with 220kv 6374 closed Maytech’s on 9" with 1:6.25 gearing.The key to madness is 100A+.
I switched from 6384 on 8" to 6374 (both at 80A, same gearing) and of course the difference was there so I just gave more throttle to achieve almost the same performance (except brakes). However increasing the motor amps from 80A to 100A makes a huge difference in torque and acceleration.
Before buying bigger motors try to increase amps and have fun. With the closed Maytech at 100A I have more torque than with 6384 at 80A. And at 20° C outside temperature they don’t get hotter than 60° C.
From my experience higher kv motors plus higher gearing is the winner. 150kv closed Maytech’s on 8" with 1:5 gearing was lame compared to 200-220kv on 1:6.25. Ok there is one disadvantage, my range decreased but I have way more power.
Alright, I guess this is enough to go 170kv. Thanks for the input guys. Can’t really increase amps now, since everything is sold basically I’m ONLY mainly changing the drive, but everything else has to go with it.
190/150 = 1.26
So you would need to bump up your motor amps 26% to go back to the same torque as the 150KV, assuming the motors don’t go into saturation/overheat at that current.
Power and top speed will go up, but that wouldn’t really help with hill climbs.
I am at 80 motor amps, the maytech website says they are rated at 60amps, I don’t know how much roo. I have there. Motors get very hot but not burning hot.
basically I’m ONLY mainly changing the drive, but everything else has to go with it.
