Pow-Pow-Power Wheels
09-19-2016, 12:34 PM
#11
09-20-2016, 06:18 AM
#13
Originally Posted by jeffbrig' timestamp='1474306186' post='24065077
[quote name='Mr.E.G.' timestamp='1474305461' post='24065070']
The more voltage you run through the motors, the faster they spin.
The more voltage you run through the motors, the faster they spin.
Of course, you really need a motor rated for that higher voltage/current, so the real advantage is that you can switch to a bigger (faster or more torque) motor. At some point, I'm sure temperature will rear its ugly head...Are you going to front mount the gun? I'd put it smack dab in the middle of the hood so the driver or passenger can control it while seated.
It's been a while since my DC electrical theory class, but I don't think that's totally right either. Higher voltage doesn't necessarily mean more current. You can have 120 volts and 10 amps to get 1200 watts of power or you can have 1200 volts and 1 amp to produce the same 1200 watts of power. Voltage and current are inversely related. Plus, the current draw is fixed in a DC circuit (under normal load). So if you have an electric motor that draws 3 amps to run, you can have a battery that is capable of delivering a gajillion amps, and that only means that there is a big pool from which the circuit can slowly draw 3 amps before the pool is sucked dry.
The motor's output becomes greater as you add voltage because of the increase in power (watts), but you're increasing the power by adding voltage, not by adding voltage and current.
Some exceptions. If a wheel were to get stuck (increased load), then the current draw would be greater. But assuming a constant load (which isn't always possible), the current draw will be the same, whether you have one battery or ten batteries.
Long story short, true, the voltage doesn't "go anywhere," but more voltage also does not mean an increased amount of current. Rather, it means more power (watts) for a given current draw.
Nomsayin?
[/quote]
Ohm's law says V = I*R. V is voltage, I is current, R is resistance. A motor winding has a fixed resistance, absent any additional rheostat used for speed control (by increasing the resistance). Wide open, the resistance is simply whatever the motor windings have. If you double the voltage, you will double the current. They are proportionally related. Voltage and resistance of the load (motor in this case) determine current.
You're jumping ahead to power: P = I*V. While your example is true that you need less current at a higher voltage to get the same power (watts), the only thing you can use to control current is changing the resistance of the load. Loads/motors don't automatically use a maximum wattage. They are rated to be able to handle a certain wattage. If you look at a motor running in a 12V system that's designed for up to 10 amps, it can handle 120 watts of power. If you apply 24V to that same motor, it will draw 20amps, which is 480 watts and probably cook itself or the supply wiring in short order. Doubling the voltage results in doubling the current, and four times the power!
09-20-2016, 08:53 AM
#14
You're right (mostly). I didn't think it through. I'll nitpick the smaller details when I have more time. 
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