ORIGINAL: Matthew007
Well, you know how much power you want, but what you don't know is what to gear it so that when you UP the voltage, the final result, Power (watts), stays the same
This is so wrong. Power=Torque x RPM and P=V x I Up the voltage : more power regardless of gearing. Gearing changes the ratio of torque and rpm, either up/down or down/up respectively.
To understand better, maybe knowing how a
Prony Brake works will help.
Infact you can easily make the bottom version:
[link=http://my.voyager.net/~jrrandall/PronyBrake/PronyBrake.html]prony brake[/link]
or this version:
[link=http://www.geocities.com/koneheadx/measuringshaftpower.html]prony brake II[/link]
If you build either of said brakes, this discussion becomes mute and proven/disproved through reality.
This is Matthew007 and I approve this message.
HAPPY NEW YEAR!
I don't think you understood what I was saying. All Pony brakes and horse play aside, what I was trying to get across in simplified terms was that going up in voltage with the gearing being the
same would cause the motor to pull more amps which = more total power available i.e. volts x amps = watts...
for example...
7v x 10 amps = 70 watts,
Running higher volts through the same exact truck and motor and gearing might roughly yield...
14v x 20 amps = 240 watts, or about 4 times the watts.... remember Ohms' rule, amps can go up or down proportionally to voltage ASSUMING the resistance is the same..
(Amps = Volts / Resistance....
10A = 7v / 0.7 Ohms
20A = 14v / .7 Ohms.. just to help you understand what I am trying to say....using a hypothetical situation where the motor is NOT reaching its max amp saturation and has "wiggle room" to draw more amps)
SOOOOoo, if I gear down my motor with a smaller pinion, lets say I go down from 20t to 10t pinion, and run DOUBLE the voltage, say go from 7 up to 14 volts , I have effectively halved the
load on the motor with the smaller pinion, and because I have cut down the load by 1/2 on the motor, the amp draw would be prevented from being doubled, to say staying roughly similar as the amp draw was on 7 volts with the bigger 20t pinion.... get what I mean?
So.. let's take a rough example of what I mean by using more volts, smaller pinion or low gearing and we might get something like...
14v x 5 amps = 70 watts... same as when using 7 volts and 20t pinion, but now we lower the amp draw somewhat and get more runtime and cooler running motor... This is all a little bit hypothetical but should get my point across..
What I am trying to say is, and I don't know why I started to go into this tangent in the first place before, in order to keep the same performance with higher voltage, you need to use a smaller pinion to ease the load on the motor which will therefore reduce the amp draw which will allow the potential total power to remain the same as before, except now with reduced amp draw you get the benefit of extra runtime....
There, that should be more clearer to understand. I hope....I don't know how I even started this whole "debate..."