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

unjonharley · Post by **unjonharley** » Sat Mar 13, 2010 9:46 am

[quote="theCryptofishist"]And wheelchair chargers from ebay are a sucky thing too.

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

I had to cough up 50 bucks for a 36v for the Zappy..And that just a toy compared to the big chairs..

Elliot · Post by **Elliot** » Sat Mar 13, 2010 10:30 am

Thanks PK! So much great info! I'll be on that McMaster-Carr web site for a while! But if I want to use a real DC motor speed controller, I might just get a golf cart one that belongs with the motor.

Jafe is lending me his 10 Amp variac so I can get started experimenting.

About the 110-220 transformers.... Too bad yours malfunctioned. These are no doubt made to sit still in a house, so vibration may have been a factor. But I'm thinking that a vibration break ... no, wait, I suppose it would arc when it broke, so it would look melted either way.

Oh... PK, any thoughts on omitting the rectifier? From what I have read, a series-wound DC motor will run just fine on AC. I suppose I will know in a few days!

New topic: I also own a giant AC motor, but know only what it says on the label -- which tells me very little. It has more wires coming out of it than the Borg Queen. I suppose I'll try Jafe's variac on that one also -- nothing to lose, since the thing is just a 100 lbs paperweight now.

EspressoDude · Post by **EspressoDude** » Sat Mar 13, 2010 12:43 pm

OK..

Transformers have a voltage rating and a wattage rating. From the voltage rating the turns ratio is calculated like described earlier. 220/110v is a 2:1 winding ratio. As another consideration is the wattage/kva rating of the transformer. As in the above example with a 3000watt transfromer at 220v, the primary current is about 14 amps and the secondary current capacity is 28 amps. That is based on wire size and does not increase as voltage is lowered.

As mentioned previously, AC induction motors draw HUGE currents on startup, 8 -15 times nameplate rating, until they reach speed. Some big AC motors actually use torque converters like in an automatic transmission to allow them to come up to speed when starting loads that are slow to accelerate.
Universal motors or AC motors with brushes have less starting torque, but less startup current. Dc motors can provide almost full torque at start-up and low speeds.

unjonharley · Post by **unjonharley** » Sat Mar 13, 2010 2:00 pm

How about a sentrifugal cluch on the AC motor.. Be less start up load.. No jump/lurch when it takes hold.. Speed controled by gear selection..

But there would have be a cluch in the drive train..

Or concider a power belt drive off a sentrifugal .. Just use a belt idler

EspressoDude · Post by **EspressoDude** » Sat Mar 13, 2010 2:30 pm

interesting idea...centrifugal clutch at about 75% motor speed.
press ON button in first gear, up to full motor speed,
release ON button, motor disengages from clutch, MV coasts,
shift to next gear, press ON button...

unjonharley · Post by **unjonharley** » Sat Mar 13, 2010 3:15 pm

EspressoDude wrote:interesting idea...centrifugal clutch at about 75% motor speed.
press ON button in first gear, up to full motor speed,
release ON button, motor disengages from clutch, MV coasts,
shift to next gear, press ON button...

Your idea is better yet.. Ya think riding lawn mower rearend would work off that set up?

Captain Goddammit · Post by **Captain Goddammit** » Sat Mar 13, 2010 4:20 pm

Hey did you notice, as pointed out in that link to the oscilloscope photos, the Honda's output voltage is wired similar to the way 240VAC home circuits are?
A home-type 120VAC circuit has a hot, a neutral, and a ground, with the neutral connected to the ground. There is a 120 volt difference between hot and neutral, and between hot and ground.
The Honda seems to have two hots and a ground, like a 240VAC home circuit.
It has a 120 volt difference between the two hots, and a 60 volt difference between either hot and ground.

You might have to be careful about how that plays into the variac or whatever controller system you try.

If direct gas power is "out", I'd stay with 12VDC, a big charger and a battery or two for lots of practical reasons.

Elliot · Post by **Elliot** » Sat Mar 13, 2010 4:34 pm

Yes, I did notice that. Come to think of it, I have never been happy with the American domestic 110 system -- it seems illogical to me. For example, if you run two space heaters in a house, each close to the capacity of its own circuit, the odds are 50/50 that both will run on the same side of the main. That makes no sense to me. Two big 110 loads ought to be balanced on the 220 main. On a grid-wide basis, I suppose it evens out OK, but....

Yes, I'll be watching (with my trusty Radio Shack multi-meter) for voltage where there should be none!

Captain Goddammit · Post by **Captain Goddammit** » Sat Mar 13, 2010 5:54 pm

I think I'll go as far as never plugging an old metal-bodied power tool into one of my Hondas without attaching a real ground to the Honda's ground terminal!