Higher voltage and efficiency

[nuz69]

Originally Posted by BIG-block

Also I can swear that my motor runs cooler too. I remember my CC 1515 1Y getting rather toasty on 6S but my 1520 geared for some speed runs much cooler. Maybe because the can is bigger and can dissipate more heat?????

Totally normal, the longer motor has less magnetic losses because it spins at lower RPM and the can is longer so it dissipates more... This is not the compairison we talking about, here it is :

1515/1Y 2200Kv on 4S
1515/2Y 1100Kv on 8S

2 motors of same length and weight. I don't know the neu specs but I am pretty sure that the internal resistance of the 2Y will be ~4*more than the 1Y

You try the both setup, geared for the same speed, you will find ~ same temps for both motor, although the ESC will be cooler.
To keep the runtime equal, you need for example to run 4S 5000mAh and 8S 2500mAh, 2 batteries of same weight and price.
So the battery discharging rate is also divided by 2 ==> the 8S will operate at ~ same temp too.
That's why I said earlier that the efficiency gain in HV setup will be mainly in the wires and the ESC, not necessarily in battery and motor...
Just my 2$