[JKReece]

And tell me if I am reading all of this wrong, but a battery bank in sufficient size that would power a D/C motor that would produce 60hp would be in the neighborhood of 96V?

 

[cricketo]

You can get either AC or DC motor rated for 60HP, but you won't be able to squeeze out 60HP out of either unless you have twice the power than what you got now. Regarding AC there are a lot more different kinds of motors, and I was specifically saying you won't find a SINGLE phase motor rated for that much power, all high powered AC motors are 3 phase.

 

[JKReece]

Ok, so you’ve narrowed this down even more for me. Once again, this is why I’m here.

It has to be blatantly obvious that I know nothing about electric motors. I’m a diesel mechanic and retired firefighter. I have a lot to learn.

 

[floydr]

So I need to go after a D/C motor, as I see those readily available at 60+hp. Yes/No?

to use as a generator on your 58HP engine ? or to be powered by your 20kW generator head though a VFD?
Later floyd

 

[cricketo]

A battery bank can be constructed for virtually any voltage given that power requirement. Assuming 5C maximum rate of discharge, to pull 40kW you'd need at least 83Ah at 96V or say 166Ah at 48V.

 

[JKReece]

What is a VFD? To me that stands for Volunteer Fire Department, and I know that sounds dumb, but I really don’t know what it means in this world.

 

[floydr]

Variable Frequency Drive
later floyd

 

[JKReece]

Ok, I just looked it up and now I understand what it is and what it does.

I’m of the impression that I should be looking at a D/C motor set up, and also powering it with rectified A/C power, but only if my 20kW of A/C power is enough to power this.

Do any of you know of a website that would educate me on more about how all of this works?

 

[cricketo]

You should just read other impossible threads on this board, there is lots of knowledge here

 

[JKReece]

Thanks

 

[Simon WS]

Shouldn't this thread be put into the "perpetual motion" section?

 

[Zieg]

One thought - a great way to improve efficiency of an electric vehicle is regenerative braking. That is, when the vehicle is slowing down, the motor driving the wheels can be used as a generator and store a good portion of that energy in a battery. Of course if you don't have a battery then you can't do this, and that kinetic energy is instead converted to heat by the brake pads.

Imagine if you will, being able to come to a complete stop without ever needing to engage the hydraulic brakes, and then when the traffic light turns green you dump that energy back out of the battery and into the motor to get you going again. It's not a 100% efficient conversion because nothing ever is, but it can translate to pretty significant increases in mpg over time. You aren't even limited to using this regenerative braking when slowing down - if you're going downhill you can apply just enough regen to put just enough drag on the vehicle to keep your speed constant. And all the while, you're pumping extra juice into the battery that you can use to help get you back up the other side of the valley.

 

[piotrsko]

Do any of you know of a website that would educate me on more about how all of this works?

Nope this is pretty much the only site that I know of for an all in one size fits all vehicle conversion or build for non engineering people. Could be a couple of books out by now and there are several extensive build threads and videos. Googling just returns a computer full of chineseium sales ads any more. Ev west does some videos, but mainly showcase their expen$$ive shiney parts. Most everybody else here in this thread offering advise has some sort of engineering background, automotive, or electrical experience save for the couple that are massively stubborn like woodsmith was back about 7 years ago.

 

[smokeycanadian]

to @brian_ and others I somehow managed to run into one very good example on the web finally..

The Alton Transportation Company Mega Bus | The Old Motor

An entertaining & informative vintage automobile internet magazine.

theoldmotor.com

(and if you click on the url for coackbuilt it definitively backs that up with "The front-mounted power plant could be removed as a unit and replaced with a new one in less than an hour, as were the 2 sets of trucks that held the electric motors.")

still I imagine it was just modest in the acceleration department and did not have quite a big top speed (compared to 55-90mph for modern highways from what i've seen in trucker comments elsewhere) for a so-so total efficiency out of a 100hp genset drive

 

[brian_]

I'm talking about utilizing my already 44mpg 4cyl diesel engine to direct-power a 20kW 240V generator head, and then wiring through a controller, directly to a 240V motor that will produce at least the same 58hp as my diesel engine does.

No, the motor can't produce 58 hp (43 kW) from only 20 kW of input power. Without a battery, you need a generator which can produce all of the power needed by the motor.

And what do you mean by "direct to a 240V motor"? If that's a DC motor, you have what trains use. If that's an AC motor, it won't work without a controller... so it's direct to a controller, which feeds the motor.

 

[brian_]

My intentional gain is MPG. I don't know how true this is yet, but with an electric drive, I should see upwards of 75-80MPG because the diesel engine will for the most part, just be idling, (1000 - 1200RPM?), to achieve the 60Hz needed to produce the 240V A/C power.

It is absolutely not true. You seem to think that running slowly means "idling", and not consuming fuel. An engine turns fuel energy into mechanical energy, and you still need the same amount of energy to move the vehicle, so running the engine slowly to run a generator gains nothing compared to running the engine slowly (in a high enough gear to get the engine as slow as desired) through a mechanical transmission.

 

[brian_]

I just checked the tag on the generator head. It says that it produces single phase, 20kW, 240V, 60Hz, 83.4Amps at 1800RPM.

240 V multiplied by 83.4 A is 20 kW with a power factor of 1, so that makes sense.

So that would be my operating RPM if I am reading this right.

That's the design speed, intended to produce 60 Hz. As I said before, there is no reason to run at specifically 60 Hz; it could produce more power at higher speed if it doesn't overheat, and less at a lower speed... and less at 1800 if the load is lower.

 

[brian_]

No reason at all for the RPM's to be all over the place, because I can go outside right now and start it up, hold it at whatever is higher than idle, and it doesn't raise or lower in RPM's all by itself. That makes no sense anyway.

As I said before, if you are running an AC motor without a controller, the AC frequency must change to match the motor speed... and while no one would do that, it would mean that the whole system would act like a single-speed transmission (but heavier, more expensive, and less efficient). If you use a motor controller, then there is no reason to fix the motor speed at 1800 RPM.

 

[brian_]

I don't have a tach on this truck, so I don't know what 1800RPM sounds like...

My suggestion is that you get a tach, learn to drive, and achieve your fuel economy improvement at nearly zero cost.

 

[brian_]

Remember this when you're thinking about offering information; I am building a 20kW generator that will produce 240V A/C power, to supply that electricity to an electric drive motor. That's it. The generator just happens to be bolted in my pickup and it has wheels. This would be nothing different than you buying a 20kW generator to provide emergency backup power for your home. I'm just using it in a different application, and regulating the speed of the electric drive motor with a controller. That's all.

The huge difference is that your home is not a vehicle. Everything that uses electricity in your home to turn a shaft controls its own speed, yet you wanted to plug 240 V AC power directly into a motor without any controller like the "engineering" crew on the Enterprise plugging in a "power conduit" and everything just works... but the real world is not Star Trek.

Now you are accepting that you need a controller. Okay, that works, but that home backup generator is very inefficient because it is forced to run at 1800 RPM all the time; a dedicated generator set driving a vehicle can be controlled much more appropriately. Even common Honda "inverter type" gasoline-engine generator sets vary their speed so that the engine doesn't run faster than required to produce the required power.

And at this point you were still planning on a generator with less than half of the required capacity... like putting 5 kW generator on your house and wanting to run 12 kilowatts of appliances at the same time.