MV brainstorm -- run golf cart motor on 110 AC?

[rodiponer]

Have you looked at electric bicycle/scooter/razor motors and their controllers? You can get a 1000 watt motor, controller, and thumb throttle for under $150. Chinese people who can't afford a car or motorcycle use these motors to commute, so there are probably hundreds of millions made and the prices are ridiculously low. Some of them have reduction gears built in, so the output shaft is only running at about 300 RPM, and they often come with a sprocket that works with bike chains, for easy further reduction gears.

I agree with The Captain that the duty cycle on your motor will be low enough that you could run it off batteries that are charged with a 10 amp DC charger from your generator. A friend of mine had two small car batteries running his DC motor on a ~200 pound machine, and it lasted days before the batteries were flat.

[Elliot]

You will still need a controller for the electric motor, if you use it.

You may be right, Gyre. But I'm not certain.
I wonder if the Captain keeps a tally of "competing" boats on the Playa? Near me lives a guy named Robert who used to take a much smaller boat to BRC. (And other electric vehicles also, I think.) He has built a lot of electric vehicles, and he uses just relays. His vehicles do jump a bit from a standing start, but apparently this is not fatal.

Any of youse guys ever operate electric pallet jacks? I sure have, and they operate with distinct "clicks" of power. They have two or three power levels. You can turn the twist grip just to the first step, or all the way. If you turn it all the way at once, there is a delay while the machine accelerates in low power before the high power kicks in. I've used some downright ancient such machines (Moto-Truck?) -- from before fancy electronics had even been invented I imagine, and they worked great. You just had to learn to lean forward and flex your knees when you threw the switch.

[Elliot]

Rodiponer, that reminds me I have an electric wheelchair / mobility scooter that a neighbor gave me a couple of years ago. I ought to dig it out and see what it is made up of.

I'm really looking forward to moving into my new shop, so I can go thru all the Stuff I have crammed into in the old garage!

[Captain Goddammit]

You absolutely do not need a controller to turn an electric motor on and off. It's done all the time in all sorts of machinery with just a solenoid or manual switch. What I'm suggesting is just turning the motor on or off, with all control of vehicle speed done with gearing.
I like the spring-loaded tensioner on the drive side of the chain idea for taking out the initial shock.

If you wanted to get really silly, maybe you could even convert a few of the piano keys to operate switches for the vehicle functions...

[unjonharley]

I ran a 12v scooter with rechargable drill guts.. burned up.. was controling from the hot side.. oops..

Ran a overhead crane that had trolly car control switches..440v the cab was a hot house near the roof in the summer.. damn thing must have been 100 years old in the sixtys..prob still running..

[pk]

The drive train on my’09 mutant vehicle was similar to what you are thinking...

[youtube]http://www.youtube.com/watch?v=Y6Hc2CMYmjQ

I had:

Honda 2000i -> Surplus 20A Variac -> $5/25A bridge rectifiers -> Two 24 VDC 1/4 HP motors geared 20:1 (wired in series)

It kinda worked after putting a bigger heat sink on the rectifiers (a big thanks to heroes at Black Rock City Hardware Shoppe!)

As a point of reference the vehicle was underpowered it could not push 10 inch 'wheels' through minor soft spots. I don’t know if I was pushing the limits of the Variac or motors, the Honda only tripped once during an aggressive start.

If I were to do it again, I think I’d go for 90 VDC motors and find a surplus motor speed controller.

~:~

sorry about the kludgey youtube link, I'm supposed to be working instead of learning how to post

[pk]

The drive train on my’09 mutant vehicle was similar to what you are thinking...

http://www.youtube.com/watch?v=Y6Hc2CMYmjQ

I had:

Honda 2000i -> Surplus 20A Variac -> $5/25A bridge rectifiers -> Two 24 VDC 1/4 HP motors geared 20:1 (wired in series)

It kinda worked after putting a bigger heat sink on the rectifiers (a big thanks to heroes at Black Rock City Hardware Shoppe!)

As a point of reference the vehicle was underpowered it could not push 10 inch 'wheels' through minor soft spots. I don’t know if I was pushing the limits of the Variac or motors, the Honda only tripped once during an aggressive start.

If I were to do it again, I think I’d go for 90 VDC motors and find a surplus motor speed controller.

[Elliot]

Love those wheels, PK! But I would obviously need more power for a Grand Piano to move reliably.

Now... did you have any batteries in this system? You say the Honda tripped once. That makes me think you were running without batteries to "buffer" the electric flow.

One thing I really need to get these things clear in my mind, is the relationship between Watts and Horsepower. If I knew the CCs of the Honda engines, I would have a good idea. Your "evolution fish" suggests that 1/2 HP was about equal to 2000 watts.... I imagine I could look this up and be done with it.

[Elliot]

...but the post did post after all.

1 HP = 746 watts.

[Captain Goddammit]

I think you'll be OK because of the earlier-mentioned duty cycle. Your batteries can be building charge continuously, but you probably won't be cruising continously... I think it'll work out.

[Elliot]

EPlaya works again! A powerful addiction, this mode of communication.

With some normal inefficiency, call it One Honda EU-1000 = 1 Horsepower. Now I feel more comfortable.

[pk]

Now... did you have any batteries in this system? You say the Honda tripped once. That makes me think you were running without batteries to "buffer" the electric flow.

I did not have a battery... the Variac was my only speed control and it is an AC thingy.

As for the Honda tripping, I think that rider just ask for too much to fast... the generator was at idle and couldn’t spin up before the voltage dropped. I probably had the Eco-throttle on which makes it idle slower/quieter. Btw, the EU2000i has a rated output of 1.6KVA (=1600 W) and a maximum output of 2.0 KVA. Not that it is useful, but you asked: the engine is 98.5cc and runs at 4300-5000 rpm with the Eco-throttle off.

Further evidence that the generator was poopy enough: I did drive it once at night with piles of ~400W rope lights

http://www.flickr.com/photos/praxis69/3907889290/

The lights only dimmed briefly during acceleration.

A couple other specs that I should clear up:

The 1/4 HP rating on the motors is for continuous duty... the peak power is 0.6 HP with a 50A draw at ~1/2 speed.

The 20A rating on the Variac is for continuous duty... the data sheet has a time dependant curve that allows for a 4 sec surge of 200A.

The 25A rating on the bridge rectifier is for continuous duty... it’ll tolerate 400A for 8.3 ms (= 1/2 cycle at 60 Hz). I’ve no data for longer short surges. For my MV, I used two rectifiers in parallel because they were cheap and I was chicken. Where I blundered is on the heat sink: the rectifier drops 1.1V so at the rated 25A current it is a 27.5W heater... my original heat sink has just a short bit of 1x1x1/16 thk aluminum angle so the 1st pair cook themselves on the way to DMV.

~:~
fyi datasheets:

TA-A001-30CI-20-00 Transaxle.pdf
General Radio V-20 Variac.pdf (warning: a slow 3.6MB download)
Silicon Bridge Rectifier

[Elliot]

Great information, PK!

I read the whole information sheet on the Variac. My kind of technology -- I can actually understand it!

[Zhust]

... EU2000i has a rated output of 1.6KVA (=1600 W) and a maximum output of 2.0 KVA.

The 20A rating on the Variac is for continuous duty... the data sheet has a time dependant curve that allows for a 4 sec surge of 200A.

The "i" in the "EU2000i" model number is for the inverter. As far as I know, it's modified-sine (which, is a goofy designation: it's a square wave that spends some time at 0V so the RMS voltage is the same as a sine wave with the same peak; it's efficient but not a sine wave at all). I think this might have been some of your trouble: the Variac probably got quite hot as it was designed for a 60Hz sine wave and you were giving it a 60Hz "modified square" wave instead.

The whole "inverter" models of Honda generators are what give it the ability to have an "Eco-Mode". A magnet-based AC generator has to run at a fixed speed (some fraction of 60 rotations-per-second = 3600 rpm) to generate 60Hz.

[pk]

The "i" in the "EU2000i" model number is for the inverter. As far as I know, it's modified-sine (which, is a goofy designation: it's a square wave that spends some time at 0V so the RMS voltage is the same as a sine wave with the same peak; it's efficient but not a sine wave at all). I think this might have been some of your trouble: the Variac probably got quite hot as it was designed for a 60Hz sine wave and you were giving it a 60Hz "modified square" wave instead.

I did not notice a problem Variac's temperature, but your point reminded me about concerns I had with a phase converter (a non BM project) and got me curious on the the quality of inverter's output. Honda claims the power good enough to run electronics so I never hooked up an oscilloscope to see. Luckily, with a quick Google I found this:

http://www.jkovach.net/projects/powerquality/

Looks like Honda's inverter is pretty clean.

[LeChatNoir]

Flywheel and gears?

1.75 Hp moved The Contraption at 2.3 mph on smooth playa with an estimated gross weight of +/- 3500lbs.

I think the EU genny driving a motor would work fine if you can get the electronic stuff worked out. Resistors and such are not my field of expertise, though. And it'd pretty quiet, too. As much as I like noisy mechanical stuff, I really like the idea of seeing you off in the distance, tux with tails sitting at a piano, cruising silently along.

[Captain Goddammit]

I really like the idea of seeing you off in the distance, tux with tails sitting at a piano, cruising silently along.

I know you're ALWAYS a polite and nice guy... but is that your way of saying Elliot is a horrible piano player?

[Elliot]

The information pouring in here is absolutely magnificent. I printed that power quality article for future reference.

The Baby Grand weighs only a few hundred pounds. (A Concert Grand can weigh as much as a thousand pounds.) Even with the chassis and dancing pole and three people it should weigh less than The Contraption. I could use my EU3000 and maybe go 3 or 4 MPH. Quietly. That would be perfect. And the 3000 is rated even quieter than the 1000.

Yes, the best visual of this MV would be from a bit of a distance. The incongruity of it. Of course, this is true for many MVs.

PK, did you try to run your motors without the rectifiers? From what I read, a series-wound motor, such as generally used for traction motors, will run on AC also.

[Zhust]

Luckily, with a quick Google I found this:

http://www.jkovach.net/projects/powerquality/

Looks like Honda's inverter is pretty clean.

Cool: thanks!

[Elliot]

...is that your way of saying Elliot is a horrible piano player?

Good one! But I cannot play at all! I'm building this for others to play.

[LeChatNoir]

I really like the idea of seeing you off in the distance, tux with tails sitting at a piano, cruising silently along.

I know you're ALWAYS a polite and nice guy... but is that your way of saying Elliot is a horrible piano player?

AHaa Haa ha!! The further away he is the better he looks, too!

[unjonharley]

I really like the idea of seeing you off in the distance, tux with tails sitting at a piano, cruising silently along.

I know you're ALWAYS a polite and nice guy... but is that your way of saying Elliot is a horrible piano player?

AHaa Haa ha!! The further away he is the better he looks, too!

you have him confused with that butt ugly captian gawddammit..

[Elliot]

AHaa Haa ha!! The further away he is the better he looks, too!

Hey, I resemble that remark!

[Elorrum]

If you start to get a lot of requests to play, "Far, Far, Away" you'll know.

[Elliot]

Having learned about Variacs, I'm thinking I may try that route.

Now.... On page 3 of this document that PK gave us about Variac transformers...

General Radio V-20 Variac.pdf (the link is a few posts above)

...there is a discussion of Limited Range Operation using a Supplementary Transformer. That would seem to be suitable for me, as my golf cart motor is for 36 Volts.

I've figured out how to buy a Variac on eBay. Now I need to learn about a suitable Supplementary Transformer. Looking for a "transformer" on eBay gets me 49.000-some-odd children's plastic toys. Anybody?

(Oh, and... Jafe, I may take you up on that loan of your Variac for R&D. Wonder what postage would be?)

[unjonharley]

Search "voltage transformer"..

The U S Mail... If it fit in the box... same price up to 40 pounds

[Elliot]

Search "voltage transformer"..

Silly me! It never dawned on me that a transformer could transform anything other than voltage. Maybe I need to get out more!

Reminds me of a time, in the 1970s, when I was handed a work order to fix a rattling "converter cover" on a car. I lifted the car, found a bolt missing on the automatic transmission torque converter cover, installed a bolt and made sure that silly thing could not possibly rattle.
The car came right back. It was the exhaust pipe catalytic converter heat shield that rattled. Might have been the first such I ever saw up close!

OK, so eBay is awash in transformers that are designed to convert between 220V and 110V -- up and down. 3000 Watt capacity for under 100 bucks delivered to my door. (I owned such a transformer around 35 years ago, using an American (110 V) water bed heater in Norway (220 V)!)

I suppose I could use one of those and put 110 from the Honda EU into the 220 inlet, and wind up with 55 volts... Am I correct?

I'd be using 2/3 of the range of the variac instead of only 1/3. Heck, I might enjoy an occational burst of 55 V acceleration -- all the way up to 5 MPH.

Am I thinking right?


Oh.... We have an idea what this thing is going to look like now:

[dragonfly Jafe]

I suppose I could use one of those and put 110 from the Honda EU into the 220 inlet, and wind up with 55 volts... Am I correct?

Pretty sure that is right. if the transformer goes from 220ac-110ac it is a 2:1 (twice as many turns on one side than the other). should work just as well doing 110ac-55ac.

PM me your address. BTW - it is a "Powerstat" type 116b single phase ac 0-140v 10 amps - so that 2:1 transformer would go 0-70 v, not 0-55v

[pk]

OK, so eBay is awash in transformers that are designed to convert between 220V and 110V -- up and down. 3000 Watt capacity for under 100 bucks delivered to my door.

Warning: Those eBay transformers are not top-shelf quality

My original plan was to use a step down transformer between the Variac and Rectifiers to:

- Halve the current thru the Variac
- Double the useful range of the Variac's dial

Here's what I learned about the 3000W transformer I bought from eBay seller unlockedcellphoneexpert:

- I think it is an autotransformer, the guts only have 3 leads (the 2nd output lead is wired around the transformer to one of the input leads). The pigtail leads seem skinny, the stranded wire measures ~Ø1.8mm which is a touch heavier than 14 ga. I don't know what the core is wound with.

- The 3000W rating is peak, the box recommends running it at 1/2 rating. (btw the power rating is deceiving for your application, it really hints at a current rating while in 110/220 V use... for you, a 3000W transformer is 13.6A in/27.2A out max)

- The fuse holder is crap... it ejects the fuse with the slightest jostle. (btw, it comes with a 30A fast blow fuse & 2 spares, I replaced it with a bit of Ø6mm copper tube and added an external breaker).

- Its heavy... ~28 lb.

The one I started to use on the playa died early. After returning home I opened it up and found one of the solder joints had come apart. The soldering quality was poor, I do not know if it failed due to vibration or overheating.

Warnings on eBay Variacs:

- The 22 lb puppies are expensive to ship! I bought a pair of V-20's for just $100 but the UPS/Mailbox Etc. shipping added another $76.

- If you buy used, be careful when you power up for the first time, I probed one of mine and found the case at 40 V.


fyi if you reconsider running off batteries.

Here's a pricey speed controller that will give you ideas:

McMaster-Carr 7729K12
Low-Voltage DC Motor Speed Controller 60 Maximum Amps, 36/48 VDC Input/Output

Keep your eyes peeled on eBay/Craiglist for a cheap one

[theCryptofishist]

And wheelchair chargers from ebay are a sucky thing too.

Maybe Meg Whitman will pay me 39 MIllion dollars for one.