TRUE Hybrid RC

[dog8spam]

With Lithium batts being so powerful, Id like to see a hybrid RC car, and by hybrid I mean a true hybrid, the 1:1 hybrids most people think of arent in my opinion arent TRUE hybrids since all thier energy is derived from gas, they are just really efficient gas cars that utilize electric motors and generators to conserve energy.

I mean having Lithium batts as a secondary source of energy that would get its energy from your charger, NOT the gas in the tank. You could have a small electric motor (mini size) that would kick in when the nitro reaches a certain RPM, increasing top speed.

[slat26]

interesting :)

[ducati777]

That idea has been floating around in my head for years. I totally agree.

HOWEVER!!! I think you'd want a 540 size motor, full size ESC and batteries, and just hook it up to the spur and use a Y harness on the throttle servo.

My thinking here is that electric motors make excellent low speed torque, but have crap top end. Nitro is the exact opposite. A true hybrid would RIP at any rpm.


-Ducati.

[InspGadgt]

Well that all depends on how you define a true hybrid. If your saying the battery gets charged only by the charger then what do you do when the battery runs out? Currently there are 2 types of hybrids in the 1:1 world: gas-electric and electric-gas. What you describe is essentially a gas-electric which uses primarily a gas engine with an electric assist at higher loads. This is how the early hybrids were made. Newer hybrids are electric-gas which uses electric motors only for the first 20-25mph then kicks in the gas motor for higher speeds. Because it uses the electric motors for stop and go traffic and city traffic it's more fuel effecient then the gas-electric.

This would be an interesting idea for a project sometime, if only to see if the power gain would be worth the gain in weight.

[ducati777]

True true. I'm not going to argue about whether its a "true" hybrid... Because then you have the diesel-electric train setup where the gas motor runs a generator that runs an electric motor on the wheels... gah.

But in my setup described above, I can almost promise it would be worth it. Consider this, an electric rc motor can put out decent power. Usually it has to drag a car along with it... But in this case, the car already exists, and the electric setup is only adding the weight of 1. Batteries, 2. Motor 3. ESC 4. Y harness 5. Mounting stuff.

The low speed boost should be well worth it. Top end will remain pretty much the same. As RPM increases electric motors create backward voltage, and their torque drops off... so it won't help much at speed. I think it would be a great setup in a Titan, a big ass truck that has room for it, and would really benefit from the low rpm boost.

[dog8spam]

I dont think some of you are getting my point about 1:1 hybrids...

The law of conservation of energy states that energy cannot be created or destroyed.
The only source of energy that comes into a car is chemical energy in the fuel. The electrical energy that powers electric motors in 1:1 hybrids comes from the fuel. 1:1 hybrids only use electricity as a way of increasing efficiency.

True hybrids, in my opinion should have two sources of energy. The fuel in the tank supplies energy and the battery supplies even more.

Using a 540 would produce some wicked power, but for racing machines a MiniT mod motor with a lithium pack the size of a NICD reciever pack would make a huge difference in accelaration.

Im also learning how to program chips so that the electric motor would only be during certain RPMs.

The more I talk about this, the more I think I want to try it...

[thefordmccord]

But where is the energy to charge the batteries coming from??

If you said the wall outlet, then you still have some kind of fuel being burnt to generate power for the batteries.

[InspGadgt]

1:1 hybrids use fuel and batteries. Fuel powers the motor which drives the car at certain and it recharges the batteries when not in use. When running on electric power it runs off batteries which are recharged by the gas engine. If you were to seperate the systems into 2 systems as you suggest your battery wouldn't last long. To get longer run times would mean bigger batteries which in turn would add weight to the car. And you'd have to plug your car into a wall outlet every night to charge back up.

Nitro cars allready will spin tires off the line if you punch the throttle hard and accelerate very fast. Even so I still think it would be an interesting project to pursue.

[dog8spam]

But where is the energy to charge the batteries coming from??
If you said the wall outlet, then you still have some kind of fuel being burnt to generate power for the batteries.

Excellent point. Yes in some cases fuel is burnt to power your homes, but the key is its not the fuel thats in your cars tank, it doesnt matter where the energy from the wall outlet comes from, the total energy the car has to expend will be increased by taking chemical energy from fuel and electrical energy from electricity.

Now back to 1:1 cars and InspGadgt post...

I am not saying these two systems should be separated on 1:1 cars, as you point out it would be very impractical. Though something most people miss is that even though the gas motor turns a generator, it takes extra energy to turn the generator. It doesnt just freewheel and generate electricity, to generate enough electricity to push a car up a hill will take the same amount of gas neccisary to just drive it up the hill.

How 1:1 hybrids achieve such high efficiencies is something you missed, the brakes. Instead of using friction brakes that generate heat, they use brakes that generate electricity, conserving some of the momentum the engine put into the car.

I am saying that only for RC, make two seperate sysems. And nitro cars do have lots of power, but why settle for less? Now I can spin tires even longer! :D

[ducati777]

I agree dogspam... ummm spamming dogs?

Anyway you're right on the fuel savings in the brakes. The other idea is that they can generate electricity and send it to the wheels more efficiently than using a transmission... Least thats the idea. The funny thing is in real life, outside EPA testing, Hybrids have hardly any savings in fuel. They usually have substantially less power, which I take to mean if I drive my car really really slow I'll probably save gas too.

But again, think about the different power curves on a nitro engine vs electric. If you had the low end punch out of the electric motor, and then the high end rip from the nitro, you could come up with some really neat gearing options.

And while most nitro's have tire spinning power off the line, the big trucks often don't... well at least my old Monster Pirate didn't. Thats why I mentioned the Titan being a good platform for a Hybrid design.

Dog now you got me thinking about electric brakes for RC cars... although hardly any of us worry about fuel economy (I don't), its a fun idea.

[evaderstman]

why not take a dual engine nitro truck such as the twin titan and pull one of the engines, tanks and throttle servos and replace it with an electric motor and a lithium pack then you would have a nice powerband

[InspGadgt]

Regenerative braking has been around for years in RC...however the amount of energy recouped is quite minimal. Another area missed is that of the energy savings using electric motors at speeds under 25mph as electric-gas hybrids do. The majority of driving below 25 is stop and go traffic type driving. In these instances when you are stopped a hybrid car shuts off where a conventional car continues to burn fuel as the engine idles. Then there's also the torque characteristics of an electric motor that makes it use the energy more effeciently then a gas motor. Because the torque curve is nearly instantaneous there's less need for a clutch to slip until the motor reaches the right RPMs to engage. This is another area where gas engines alone waste energy. Now for the ratio of fuel used to move a car with a gas engine vs fuel used to power a generator to power an electric car to move it the same distance...This ratio is not 1:1. I'm not sure exactly what it is or if it's better or worse then that. But what it is depends on the effeciency of the motors. Take 2 electric motors for example...a brushed motor and a brushless motor using the same batter. The brushless motor is going to not only have more power then the brushed but will also have more run time then the brushed motor for the same amount of battery energy used.

The fuel economy you get from a hybrid is largely dependant on the type of driving you do. If you live out in the boonies and do a lot of driving over 45mph your not going to have any better effeciency with a hybrid then a normal car...but if your like the majority of middle class workers you'll be doing a lot of city driving and rush hour traffic stop and go driving. In this case you will probably get much better economy with a hybrid then a conventional gas car.

True most hybrid cars have very poor power in comparison but it's only a matter of time before that is no longer the case. Toyota has some very interesting things in the works. The first of which is the hybrid version of the Highlander. This SUV is rated to have greater then a 1000lb towing capacity and gets a combined mileage around 35mpg. And then there's this cool gem: http://www.toyota.com/vehicles/future/volta.html