View Full Version : Car alternator's on my Green Thang!

Jack Riggi
30 November 2011, 2054
I need alittle help here not quite sure what to do. Has anybody on the list ever used a car alternator for charging your bike before? What would be the best thing to charge up my 3-24 V packs of 40ah GBS batteries. While investigating and seeing where I could mount a car alternator on the back wheel underneath the swingarm I was looking at the brackets that I welded on my frame to hold my solar shade awning on my bike I got the idea of mounting 2 alternators one on each side. The only alternator I have now I got at the junkyard for $10. It is a standard 12 V alternator. People that I've been asking have told me they have high-powered alternators on certain trucks, & I believe Cadillacs for all the power windows in everything, also on ambulances, firetrucks, anyway there on a assortment of different vehicles. One guy told me he had 128 V alternator on his Chevy truck and then another person told me they are 120 V I have no idea at this time at all how many amps or watts they are putting out any of you guys know? Anyway I've been so busy working on my bike and trying not to fight with my wife that I really haven't checked it out at this time but I thought I would ask you guys. Also I heard they are 24 V alternators. I was thinking that possibly one of them if I can pick one up would work great for at least 1-24 V battery pack Now all's I need are three more alternators if they work! But I just don't want to waste any money until I find out what would be the best ones to use for this new particular application One could be used on the 12 V battery for the lights, I can use the one that I have now and then I can use 3-24 V alternator's to charge my 72 V pack. Also I was thinking I might be better off using PMA alternators which I think would work much better when the bike was parked to continue to charge the batteries if the wind was strong and fast enough! Here's a few pictures of the alternator that I have mounted now. I really would appreciate a little bit of input on my new idea. Do you guys think it will work? Or not? I know all you will be asking the same question but I will tell you more about that later after I pick your brains about which device you and I should or would use!

30 November 2011, 2117

EDIT: You know what, I will bite....... for grins. Jack, what do you mean by recharge your bike? Plugging into the wall and spinning the alternators with an additional motor or recharging (regen) the bike when the bike is running on the street? Either way, I truly suggest you sit down on a computer and research electric vehicles online to understand the different basic components involved with a vehicle.

Per Charging
- Battery Chargers
- Multiple Wall worts to charge system *Simple, elegant and safe solution (Ed)
- DC-DC Converters
- Regenerative Braking

Reasons not to use Alternators
- Mechanical Losses
- Efficiency
- Please research alternator Power vs. RPM curves
- Perpetual Motion

Per Solar Panels
- Boost Converter
- Aerodynamics

30 November 2011, 2307
Those alt. numbers the guys were telling you are amp ratings not volts. Heavy duty alt is 128 amp 12v and standard is 120amp 12v. They might use 24v alt in diesel trucks and tractors though.

Jack Riggi
30 November 2011, 2324
No sorry, none of the above you didn't guess it. And I have set down at a computer and I do understand the basic components involved in electric vehicle in more ways that you could comprehend. I'm not reinventing the wheel i am just kind of making a new design!but it is not a wheel!

Jack Riggi
30 November 2011, 2339
They use those 24 V alternator's somewhere but I'm just not sure where that's what I am trying to find out if anybody knows anything about them or where I can get not even sure that's what I want to use yet possibly there might be something more efficient higher wattage amps more volts less RPMs a lot of different applications I might be able to use but not quite sure what I will use yet! And by the way how many watts in 128 Amps 12 V?

01 December 2011, 0007
...to continue to charge the batteries if the wind was strong and fast enough!

oh god :O ..... you are going to make wind turbines....... out of alternators.......

Jack, just do one thing for me on this project, just one thing. I will say this as respectfully as I can, please be safe and don't kill yourself because I see a million different ways this project can turn out very, very badly.

I'm done, I have no one to blame but myself for engaging this project.
Sean out.

01 December 2011, 0024
If you want to use a common car alternator in this type of scenario, you can find the information you will need for making a custom voltage regulator and the gearing necessary to achieve your required voltage levels. http://islandcastaway.com/alternator-secrets/ It is certainly possible to do so.

For your wattage question, you can use P = I * V, or Watts = Amps * Volts. 128A * 12V = 1536W

Any common car alternator can be configured for voltages ranging from a few volts up to near or over 120VAC/DC, given high enough RPM to support the voltage requirement. You do not need multiple alternators to achieve your 72V goal.

You probably gathered that most people will advise against using alternators in this type of scenario (on EVs in general), but that is not to say that they cannot be used as regenerative braking devices - they certainly can. It is important to note of course that you never want to have any generating device (alternator) under load at the same time you are applying power to you traction motor - doing so would be extremely wasteful and decrease your range quite substatially, exactly the opposite of what you want to achieve by adding a regenerative device...

I also do not recommend attaching a windmill to a lightweight mobile object, FWIW. If you want to research DIY wind power generation, plenty of resources online for making a nice axial flux wind generator - you will find the best advice is to 1. install large, efficient blades on the turbine and 2. mount the turbine high in the air above all obstructions, with wind, more height = more power. Charging your DIY bike with a DIY wind turbine at home would be quite cool.

One last thing to consider regarding simple DIY wind, higher voltage requires higher wind speeds. If you hook up a 72V configured alternator to a wind mill, you would probably need wind speeds in excess of 80-100mph sustained to begin generating any electricity. Usually you would configure the alternator for lower voltage to make use of lower wind speeds, and step up the voltage to your bank/pack voltage using an electronic power supply - this way you can generate smaller amounts of usable energy without needing to wait for a hurricane to use your windmill.

Have fun!

Jack Riggi
01 December 2011, 0207
Thank you for your encouragement and I know it is certainly possible to do so I just have to figure out all the right things to do and it will work and especially with help with good friends like you guys that help me out with the things I don't know about. I have invented quite a few different things one is a fully automatic awning for an RV that doesn't just go over the side like the standard ones, the one I invented goes completely over the top and both sides if you wish, to keep it totally cooler! Later on I'll put some pictures of it so you see what I'm talking about I'm sure you've never seen anything like this! You would've but I told the government to screw off when they wanted to use my patented invention when they started the war in Iraq quite some time back I believe it was in 97-98, the state when I went for funding ended up having me talking to two separate different individual generals a couple weeks apart that wanted to use it but they told me right before I signed the papers that if I did I couldn't sell it to the public and I told them I made this for 80-year-old lady's when their husbands died that they can open it with a touch of a button without getting out of RV without getting hurt, and being young and dumb and stupid I walked out and shined the whole thing on. At the time I was working with Carefree awning that were talking about possibly buying my patent also so at that time the government was not my only option either. Now that I think about it that was really stupid because I would've been a millionaire!! Or just really rich. They wanted to make my design awning out of carbon fiber for hundred thousand dollars apiece to go over ground missile launchers and ground troop haulers and I'm not making this stuff up either. When I do post some pictures of my awning (it is electric) I will also include a three page government study by the ECAP which stands for in energy conservation assistance program, Anyway I been working quite a few hours, days fiberglassing and sanding on a new type of blade like nobody's ever has ever seen or used before, something totally new! Another one of my inventions! Something that cuts through the air like a knife on one side with almost 0 drag and scoops the air like you won't believe. The only problem is I really can't even test it correctly until I get my motorcycle running all I need are two more 24 V battery packs and the contactor and hook it up and get some help with hooking up the kill switch right, I've already found someone else on the list that is already talking and telling me about how to do it when I get the time and the parts the only problem is the more I work on these new wind blades the further behind I get on getting my motorcycle going but thanks again for the information on the alternators and I have been checking out all the stuff you been talking about plus more. I could make my own custom regulator and maybe will but I been checking out solar regulators that only cost $66 that will work good on the PMA's or the solar if I decide to put solar on it, I might just leave it on for the shade or if I do decide to go with a alternator type they have built-in regulators already! so many choices! That's what makes it so interesting and fun coming up with something that nobody else has! and as far as using different gearing to get the voltage that I require I do not believe I will need that because of the different shapes of blades I been working on they should or will give me different RPMs that I need, like I said I just need to get my bike running so I can do more experimentation, like I did with my minibike but this is not a minibike! . I'm considering some type of a way to activate the alternator only when the throttle is completely closed for regenerative braking or some kind switch that will make it work just like a car charges a battery up as you drive along. Where there is a will there is a way and I will get it, I am contemplating a lot of different applications and ways to do it many many multiple choices, different voltages and all the things that go with it. I been thinking about this for quite some time around 15 years. I have always been too busy doing ironwork and working out of town to ever accomplish anything I wanted to do on my own. But now that I'm retired I have the time to play but because I didn't take the money from the government, I have to work on a shoestring budget at this particular time, but things can change and are changing just like the pot laws! Over and out that's it for now time for me to go to sleep. Will continue the conversation about these alternators and things tomorrow after I read a few more post and get a few more ideas on different applications for my new project!

01 December 2011, 0444
Anyway I been working quite a few hours, days fiberglassing and sanding on a new type of blade like nobody's ever has ever seen or used before, something totally new! Another one of my inventions! Something that cuts through the air like a knife on one side with almost 0 drag and scoops the air like you won't believe. The only problem is I really can't even test it correctly until I get my motorcycle running ....

some kind switch that will make it work just like a car charges a battery up as you drive along.

The only way you can make it work just like a car, is to add a gasoline engine, to provide the energy to spin it.

If you use the energy of "wind" that is created by the electric motor pushing your bike, the electric motor will require more energy to compensate for the extra drag created by the windmills. In the end, you will decrease your range, rather than increase it.

Even if you just use wind energy (from blowing wind) to provide charging when the bike is parked (excellent idea), you'll need blades that collapse for travel so they don't create offsetting drag when you are riding under electric power, or that will also require more power from the batteries than if they weren't there, reducing your range. Now, if you put those windmills on poles, in your yard it may not sit well with your wife, but you'll have clean energy charging your bike. That's exactly what GasFreeEarth (used to be an ElMoto regular, hasn't been around in a while) is doing with his electric dirtbike in Orlando.

Just moving the extra mass of those alternators is going to require more energy than not having them, reducing your range.

01 December 2011, 0457
EDIT - OK, I just looked at the rest of the pictures - and can see the alternator is mounted to the frame, not the fork, as it appears in the first picture, so my rant below doesn't really apply.


Holy Cats!



I had read this thread on my phone before, so pictures were small and I didn't see them clearly. If the solar panels would make this a death trap, putting windmills on the front forks would make this a death trap with extra killing sauce.

Putting windmills off the forks is like making a second set of handlebars - except instead of you applying force to them, the wind is applying force to them. You'll be going along, and a gust of wind hits one side stronger than or before the other, and wham, the bars are thrown in a direction you didn't plan and the momentum of the bike causes them to tank-slap, then you high-side, and if you're lucky wherever you are thrown in the process isn't the place where that solar panel comes slamming into the ground like a giant knife.

But think for a moment, not about yourself, but the kids in the minivan that plows into a power pole as the soccer-mom driving swerves to avoid this rolling mass of metal...

Just putting the weight of the alternators out on those arms, without the windmills is a recipe for handling disaster, let alone with the drag of windmill blades.

The game of mousetrap is amusing - as a board game made of plastic sitting still on a table - not made of steel and aluminum weighing several hundred pounds and going 50mph down the street balanced on only two contact points with the ground.

If you were putting GoldWing training wheels on this bike, and planning to run it at a top speed of 10Mph as a neighborhood electric vehicle, I'd say you were right on target for something that is fun, whimsical and entertaining (I'd also expect pinwheels, seashells and buttons glued all over it, and wild Jamaican colors) - perfect for a parade in Key West. But not at 30-50mph in traffic.

01 December 2011, 0830
death trap with extra killing sauce

Amen brother.

01 December 2011, 0924