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Snorg 01-24-2009 05:42 AM

Help me build hybrid trike.
 
Greetings from Snorg. :)
I would like to build hybrid trike.
Propelled by 1/2 HP 120VAC electric motor, or two if one is not enough power.
Said 120VAC motor will be fed by a 120VDC battery pack of nine 12V batteries in series.
A "1500 Watt" 120VAC portable generator will be on board to extend the trike's range. The generator's nominal capacity is actually 1200W (120VACx10AMPS), diodes will be used to change the 120VAC to 120VDC.

The first question I have is what to do for speed control. I think I will have nine power taps, one after each successive battery this will give me nine speeds that I select manually. Do you think that would work fine??

Next I need to know what to do for brakes. If I'm going downhill at top speed and simply select a lower speed will that provide effective braking and if so will it be enough?

I don't know allot about electric motors, I know that a 120VAC motor that has brushes will run fine on DC, but do motors that are commonly used for bench grinders and compressors run on DC?

Ryland 01-24-2009 05:23 PM

120 volt DC motors are not very common and changing an AC motor to DC is not an easy, practical, or efficient way to go.
Using only part of your battery pack for low speeds is a bad idea unless you really like buying new batteries as some of your batteries will always be used and some will only be used at high speeds and putting partially charged batteries of different states of charge in the same string will damage your batteries, it might even reverse cell polarity on the first few batteries in the set.
Before spending any money on this project I highly recommend that you made a trip to your local used book store and look for a book with a title like Understanding Electricity and Electronics (I own two copies of this book, one is to loan to people with questions like this).
Last of all, at low speeds you want peek amp output of the battery pack, not the amp output of a single battery in the pack, this is where solid state speed controllers have made electric vehicles a practical thing to build, switches have arcing ever time they open and close, they also become very complex when trying to vary voltage like you want to do.

Bicycle Bob 01-24-2009 09:03 PM

Actually, power tools do have "universal" motors, so they do count as 120 V DC motors. Unfortunately, they are built for light weight and small size, not efficiency or quietness.

Your basic plan is OK, but you'll probably change and improve the details after a bit of reading. A nominal 120 V battery is usually made from 10 nominal 12 V batteries; they are only over 13 V when fresh charged. For brakes, you will need regular friction brakes to stop much harder than you can accelerate. Regenerative braking will extend your range a bit if you can use it downhill or for gentle stops. With such low power, you'll want excellent streamlining, and that, with a bit of battery weight, seems to coast forever so it is handy to rig it so that it goes into regenerative braking if you take your foot off the go pedal. That way, you can get used to gentle stops without touching the energy-wasting brake at speed.

Ryland 01-24-2009 10:19 PM

Quote:

Originally Posted by Bicycle Bob (Post 84896)
Actually, power tools do have "universal" motors, so they do count as 120 V DC motors. Unfortunately, they are built for light weight and small size, not efficiency or quietness.

That is part of why I ignored them all together, that they are not efficient or practical, in my mind you would be better off getting an inverter if you wanted to run an ac motor but I can't think of any variable speed ac motors off the top of my head, other then blenders, but those are just weird.

I think this project needs to be re-thought, also someone who doesn't understand electricity working with 120 volts dc makes me a bit uncomfortable, people being killed by home built electric vehicles is not something I want to hear about.

order99 01-24-2009 11:21 PM

May I recommend:

DIY Electric Car Forums - Electric Vehicle Build and Conversion Community


I've been haunting the site for a few months, and i've gone from total ignorance to...er...knowing to ask the right questions, at least. :o Make sure to check out the Wiki, located in the upper-right corner of the page-it's a treasure trove of free brain-candy!

The really basic questions need to be addressed first-how heavy do you estimate this Trike, and how many passengers/cargo do you envision for the load? How fast do you wish to go and how far? Delta(trike) or Tadpole(reverse-trike) configuration? And above all else, how much money do you have to play with?

Bear in mind that I haven't built my own EV yet (no funds, but i'm saving up!) so right now my Search-fu is all I have to offer...

Free Development Plans, Software and Information Trike plans (gas, EV and Hybrid) with free advice on Body Moldings and handling stats on Trike configurations.

3-wheelers.com MainPage A total love affair with all things Trike and an A-Z list of all 3-wheelers ever made commercially (with links to the active distributors)

http://solarvehicles.org/home.html Probably less power and range than you're shooting for-but the plans are free and can be scaled up...

EV Photo Album: Our Electric Cars on the Web Just to drool over-keeps me going while I save penny upon penny! :D

Best of luck.

Snorg 01-25-2009 05:08 PM

Ok Bob
 
Quote:

Originally Posted by Bicycle Bob (Post 84896)
A nominal 120 V battery is usually made from 10 nominal 12 V batteries; they are only over 13 V when fresh charged.

Ok Bob, but with 10 batteries will the onboard 120V generator be able to fully charge them ?? If they only get charged to 12V each is that good enough??


Quote:

Originally Posted by Bicycle Bob (Post 84896)
For brakes, you will need regular friction brakes to stop much harder than you can accelerate. Regenerative braking will extend your range a bit if you can use it downhill or for gentle stops.

OK Bob, regenerative braking would be very good here in this hilly country.
If I buy a 120V motor made for EVs and a proper controller will the controller provide regenerative braking??
Im in BC can you give me web links to where I could by the motor and controller??

thanks Eh?

Bicycle Bob 01-25-2009 05:27 PM

Ahh, so there was method to that. :-) Actually, 120 VAC peaks at something over 150 V AFAIR - the 120 is the average under a sine curve. However, chargers often have more differential than that. A transformer to boost the voltage ahead of your rectifier might help. However, if you want to regulate power by switching batteries in and out, you probably want individual chargers for each battery. These can be modern, high-tech units that produce pulses and all sorts of help tailored to the battery. Or, you could go to modern battery controllers. Once we moved from relays and big sparking contacts to silicon, it became easy to switch the power on and off again rapidly enough it works like a voltage change in a motor. From there, the art has progressed to controlling the spin of strong, permanent magnets, which has done a lot to get more range from the batteries. The new motors are simple and versatile, but totally dependent on silicon.

This may be a good time to read up on the specs of available controllers. Offhand, I can't remember the details of how to maximize regenerative braking. It pays to "overload" the motor more when gathering free energy. Unfortunately, you may wind up reading about a lot of ideal hardware that is 'way too big for your trike. Why not start from what's available for electric bicycles?

Snorg 01-25-2009 06:10 PM

Quote:

Originally Posted by Bicycle Bob (Post 85012)
Why not start from what's available for electric bicycles?

Ok Bob, bicycle stuff wont give me the range and speed I need.
I found a web site of an out fit here in BC, Im getting info on a 13HP 120VDC motor and controller, they dont show any prices so I had to email them.
I will post here again when I get some info from them, probably by the end of the week.

Bicycle Bob 01-25-2009 06:21 PM

I thought you were aiming for 1/2 to 1 HP? That's 375 to 750 watts in electric-bike terms, a very common size for one or two wheels. For range, leaving the generator at home, you either add more batteries or else add streamlining, which also increases speed. What did you have in mind for the rest of it?

Snorg 01-25-2009 07:07 PM

Quote:

Originally Posted by Bicycle Bob (Post 85017)
What did you have in mind for the rest of it?

If you mean the rest of the electric stuff I dont know about what else I need.

As for mechanical stuff I want to build most of it myself, a pipe frame and fiberglass body. I'll have to figure out what to do for drive axle and wheels, probably chain drive, I dont want to use an old rear end because thats too heavy. Probably use motorcycle parts for front wheel and steering.

I do have a Ford Courier wreck I could use the rear end from but I would like to build something lighter, but the Courier rear end would be easier to rig up and has the brakes and springs and shocks on it.

Probably use plexiglass for the windshield if it will bend enough to make it curved.


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