• Welcome to RCTalk! 🚀

    Join the #1 RC community where hobbyists connect, share, and get expert advice on RC cars, trucks, boats, drones, and more!

    • ✓ Friendly & passionate RC enthusiasts
    • ✓ RC tips & troubleshooting
    • ✓ Buy, sell & trade RC gear
    • ✓ Share builds & upgrades

possible alternator?

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
N

NooP

RCTalk Addict
Messages
526
Reaction score
0
Points
0
RC Driving Style
I know, I just wanted to know if someone has tried at all with any type of success. It would be nice to not have to worry about batteries.

--NooP
 
Are you talking about running an alternator on an r/c? If so i'd think it'd rob too much power from the engine. Not to mention adding a lot of weight to the car.
 
I was thinking some small magnets on the flywheel, and a small coil mounted to the chassis. It wouldn't rob too much power at all that way. The tough part would be geting the voltage right, I think.
 
I think getting the voltage right is the easy part. Findind something to make voltage effeciently is the tough part. No matter what, power will be rob from the engine, but if there was a very effecient way of doing it, it would be worth doing. any one have any good ideas on how this can be done?

--NooP
 
I am reall thinking small magnets mounted to the flywheel, make that the alternator. You already have a spinning wheel, why not make use of it. Instead of adding an aditional rotating mass, just add magnets.
 
Wouldn't magnets on the flywheel cause balance issues? It would takea lot of messing with to get it right
 
not if you place them accross from eachother that would counteract each others weight or put a continuous magnet all the way accross but i think the hard part is to keep the magnets on the flywheel will spinning at 45,000 rpms and then getting the voltage right
 
Epoxy to keep them on the flywheel. You're rigth about balance issuses Diver
 
Why wouldn't you just use a tiny motor?

Throw a gear on output shaft, before the flywheel.

Actually if you used one small lightweight rechargable battery (that output the volts you needed), you could gear the motor off the clutch bell. When the car is moving the battery would get recharged, when the car is stopped the battery alone would supply the juice.
 
I was thinking tiny motor too. The flywheel idea is good, but like said, keeping the magnets on the fly wheel can turn into an issue. Also keeping the magnets clean can turn into a greater issue. Also, I use a start box and magnets on the flywheel will not work too great. But if your not using a starterbox, magnets on the flywheel can work.

I was thinking of putting a pulley where the shaft is for the pull starter and a small motor. but like a said, finding a motor that is small enough and one that is effecient enough to charge the batteries, i believe, is the hardest task.

1. weight, we certainly do not want to add a lot of weight.
2. a motor strong enough to charge the batteries can take too much power from the engine. The car maybe be able to run for hours, but if its slow, there would be no point.

To find out what kind of motor we need, we need to know how much voltage a reciever needs to power the servos. As far as i know the recievers need 6v. Can we find a motor that will put out 6v? next how many amps do we need? I have no idea.

does anyone know how amps a reciver needs?

Now lets say we can produce enough voltage and amps for the servo and at the same time keep power loss to a minimum. That would be awesome. Then, theoretically we do not need batteries.

More than likely I do not think we can find a motor that will put that much power out. That is when batteries come into affect. If we use some 2300mah batteries(the highest mah I could find) we can then require a motor that puts out less power. I think we will still need 6v, but importantly, we do not need as many amps and we could just charge the battery at a slower rate.

so does anyone know how many amps we need? Then we can figure out if we can find a motor strong enough.

--NooP
 
Now your talking my language!!

You guys are on the right track! I have been thinking about an alternator type set up for a long time. I was leaning more toward magnets myself. With the new neodymium (rare earth) magnets I think it could be quite easy to make a very powerfull (perhaps too powerfull) alternator. Those magnets are extremely powerful; two small magnets (1/8"-3/16"diax1/16" thick) and a small coil combined with the RPM's produced by an RC car engine could produce an amazing amount of energy. I think with the proper conditioning (capacitors and voltage regulator) that a decent charge current could be achieved. The biggest hurdle I see would be a way to monitor the packs condition to prevent overcharging.

I would like to see the car electrics powered by the "alternator" and only have the battery for back up when voltage drops (engine idle or component failure) with a little juice fed to it as a trickle charge. If a reliable setup could be found a much smaller battery could be used to build the pack, thus less weight.


I never even considered using a motor to supply the voltage (I was using motorcycle engines as a model). I do know that a motor from a stomper (small battery powered truck that was extremely popular about 15 years ago and used a single AA battery to climb all over my parents nerves) when attached to an LED (2.5 volts to power an LED I believe) would light pretty well while spinning the motor with my fingers. A small high quality motor turning at rated RPM's could produce a pretty decent charge, but I think the magnets would be more flexable to work with. NooP is all over it and has the right idea, with a little research I think this could be done.


BTW...I've been lurking here for a while, learned a ton from all the genious that you guys share and couln't resist popping in on this thread! Thanks so much!

Sorry I'm so long winded

Brian J
 
Last edited:
The reciever and servos don't draw much, about 200-400 mah average. So a 1000 mah battery lasts 2.5 to 5 hours. IMO rc cars are enough trouble to keep up and running without an extra generator and regulator circuit. But I am also a tinkerer, and I can see the fun in trying. Good luck.
 
cool, we need 200-400 mah. How could we do that? motor or magnets? Which is more effecient? anyone know how big of a motor or how strong of magnets we need to make 200-400 mah at 6v? Even if magnets is better, I can still fab up a wheel to go on to the pull starter shaft to hold magnets. If we can find out how we can make 200-400 mah lets give it a try.

--NooP
 
There used to be an onboard alternator/charger that ran on flywheel mounted magnets like you guys have been talking about. I remember it, but can't find it on Towers. It was for giant scale airplanes. Anyway, if yall want to explore this avenue, that'd be a good place to start looking.
 
Thats cool! It is for plane engines though which only turn 12-15000 rpm. Car engines hit 30-40,000.
 
Originally posted by scottm
Thats cool! It is for plane engines though which only turn 12-15000 rpm. Car engines hit 30-40,000.
Click to expand...

Not really, a lot of car engines are capable of 30-40k rpm, but they'll never get there. At most they'll MAYBE hit 30k...but more realistically in the mid 20k rpm
 

RC Builds

Back
Top