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A motors max KWs are based off its weight, cooling and duration.

Major has a good thread on this subject

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It does not work like that!

Your controller gives the motor the voltage that it needs for the demanded current

So when stationary it may need 10 v to get the desired 600 amps

As soon as the motor is spinning it develops a back EMF - so it needs MORE voltage for the same current

Example

Stationary 600 amps - 10 v -

1000 rpm - 600 amps - 40 v

2000 rpm - 600 amps - 70 v

3000 rpm - 600 amps - 100 v

4000 rpm - 600 amps - 130 v

The Three terms - current/voltage and rpm are linked

Advancing the motor enables you to use more RPM - but it also drops the torque from a given current at low speeds

My motor is advanced by 8 degrees - that means that I lose nearly 20% of my torque

Or that I need to run about 20% more current to get the same torque - the opposite of the effect you wanted

Increased battery voltage does reduce battery current

Example - 150 volt battery

Stationary 600 amps - 10 v - - 150v - 40 amps

1000 rpm - 600 amps - 40 v-- 150v - 160 amps

2000 rpm - 600 amps - 70 v- - 150v - - 280 amps

3000 rpm - 600 amps - 100 v- 150v - 400 amps

4000 rpm - 600 amps - 130 v- 150v - 520 amps

Example - 300 volt battery

Stationary 600 amps - 10 v - - 300v - 20 amps

1000 rpm - 600 amps - 40 v-- 300v - 80 amps

2000 rpm - 600 amps - 70 v- - 300v - - 140 amps

3000 rpm - 600 amps - 100 v- 300v - 200 amps

4000 rpm - 600 amps - 130 v- 300v - 260 amps

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They advance brush timing to increase the power available at higher motor speed, at the expense of lower power and efficiency at low motor speed. Like everything else in life, and especially in technology, it's a tradeoff.So why do people advanced them if there losing power by doing so?

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Nope

If you use a higher BATTERY voltage it reduces BATTERY current

But motor current remains the same!

Advancing reduces the available torque - but it enables me to run more rpm

Which is what I need

https://www.youtube.com/watch?v=LUpyAY2sFWw

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That's nonsense. I think you really need to concentrate on physical reality, rather than rumour and myths, if you want a successful design....diesel only has power at low rpm whereas gasoline at higher rpm...

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Of course diesel fuel is ignited; "ignition" just means the initiation of combustion. The more generic name for diesel engines is compression-ignition engines, while gasoline engines are normally spark-ignition.So you're saying diesel don't loose power the higher the rpm?

...

Diesel is not ignited it combust from compression so how does that make power from higher rpm really work.

While high-speed ability of diesels is limited by the duration of combustion (since the fuel is burned as the fuel is injected, rather than rapidly as in a spark-ignition engine), this isn't an issue at normal automotive engine speeds. Many diesel engines are designed for low speeds; that doesn't mean that you cannot have a high-speed diesel engine, and the Audi R10 racing engine produced peak power at 5,000 rpm... more than twice the maximum speed of a big truck engine.

This illustrates the importance of understanding why things work as they do, not just observing a trend and thinking it is a fundamental limitation.

A heavy truck (such as a highway tractor with semi-trailer) weighs 20 to 60 tons loaded, and is driven by an engine only capable of a few hundred horsepower, and even that only at one specific peak engine speed. To make the most of the engine, many gear ratios are provided to keep the engine close to the optimal point.So why tf the they put so many more gears in the semis ?

That's not true. The speed of the peak torque of an engine depends on the specific engine design, including intake and exhaust tuning and camshaft profile. The big difference between common diesel and gasoline engines in low-speed torque production is that all of the diesels are turbocharged, and few gasoline engines are. If you compare a modern turbodiesel and modern turbocharged direct-injection gasoline engine of the same displacement at the same speed and boost, the gasoline engine will produce comparable or higher torque... but most people compare turbodiesels to non-turbo gas engines, or huge (6.7 L) diesels in pickup trucks to much smaller turbocharged gasoline engines.And gasoline don't get much power behind it until you get to a higher rpm

Power is just the product of torque and speed, so if two engines produce similar torque at low speeds but one of them can continue to work well at higher speeds, the higher-speed engine will produce more power... and yes, the extra power will be at the highest speed, even though the higher-speed engine may produce superior power at all speeds, even the low end.

This illustrates the importance of considering the application context of any technology, instead of jumping to conclusions about the fundamental technology.

While this may look like it is all about gasoline and diesel engines, it is really about understanding the characteristics of technical designs, such as DC and AC electric motors, rather than jumping to invalid conclusions based on incomplete knowledge of some specific applications.

Regardless of type, electric motors are typically limited in torque by current, and limited to a fixed maximum current from zero speed to a significant part of the way up their speed range - that's the constant-torque region. At the other end of the scale, the current through the motor is limited by the available voltage at high speeds, as an increasing amount of voltage is required to overcome back-EMF at higher speeds. In-between, while the motor itself could be limited by current or voltage, in practice in EVs they are limited by the power that the battery or controller or cooling system can handle, so they are effectively constant-power (so decreasing torque with speed) over much of their speed range.

So

- constant-torque (limited by current) from zero to some transition point,
- constant-power (limited by battery, electronics, and cooling) from the transition point to nearly the maximum speed, and
- decreasing power approaching top speed.

In a DIY system with a brushed DC motor, it may go straight from constant-torque to decreasing power, since it is so voltage-limited and control is so basic.

If the design of the system is messed up badly enough, it might be current-limited over the entire usable speed range - that would give you constant torque from a standstill to top speed, and indicates poor use of the capabilities of the battery and/or the motor.

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