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Glen
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Joined: 16 Jun 2004
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Electric vehicle

slightly OT in regards to combat robots but still tech chat none the less.

im looking at building a small electric scooter/trike that use a 240v AC washing machine motor with a belt drive.

i have a few questions in regard to this:

1) i dont want 10 SLAs in the thing so is it possible to have a conventer (inverter or transformer?) that can step the voltage up to 240v AC from the 12vDC 60ah SLA.

2) how would i control the 240v motor? ive heard that you need vastly different techniques to DC motors to control the motors.

any help muchly appreciated.

Post Sun Jun 20, 2004 6:11 pm 
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Knightrous
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Simpler Solution Glen, Ev Warrior on 24v with two 15amp SLA's Smile cheaper and less dangerous Cool
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Post Sun Jun 20, 2004 6:18 pm 
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Glen
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good point...

typical of me using DC motors never passed my mind, too much power tool drag racing!

how would i go about calculating the capacity i need to ride the thing 3km if its geared to go about 40-50km/h with an EV warrior?

not that ill still do this, but does anyone have any answers to the q's above?

Post Sun Jun 20, 2004 6:23 pm 
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kkeerroo
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We have 2 EV's in Hellbringer 3 running at 12V with a 4:1 reduction and when the robot weighed 15kg it went about 18km/hr. Even at 24V with the same set up it would have maybe hit 50km/hr, but if went and added a 60kg person on the top you would deffently reduce the speed to about 20km/hr. Plus the 2.3 Ah battery we had that was fully charged died in 1.5mins.
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Post Sun Jun 20, 2004 6:35 pm 
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Nexus
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@Kkeeroo, What is the size of your wheels to get that speed and how do you think an ev would go with a 2.7 reduction? would it get too close to stall currents under load, sounds like thay suck juice a bit.
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Post Sun Jun 20, 2004 6:48 pm 
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prong
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I also one day want to try something along these lines, i figured on using the largest car starter motors i could find, building some very large speed controllers, running two motors and feeding each one at least peak 200 amps at 12v. This gives a total power otuput at 5kw, only slightly above the maximum of 200 watts you can have!! on anything that goes on the road without having the register it. Razz Of course running 5kw for more than a short time will overheat the motors and drain the batteries very quickly. But then of course with some high capacity car batteries you could get decent range with impressive acceleration, as long as you didnt use full power very often! Smile

Hopefully one day i will get the time, money and effort involed to make such a project, but it would be fun.

Post Sun Jun 20, 2004 11:06 pm 
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colin



Joined: 16 Jun 2004
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I want one of these:
http://www.newscientist.com/opinion/opinterview.jsp;jsessionid=FOGLEHHLHFBE?id=ns24521

even uses AC:
It's quite different from what you might expect. For a start there isn't one huge engine powering the wheels, as you would get in a regular truck. Instead, a 3650-horsepower (2723-kilowatt) diesel engine generates power for two electric motors in the rear axles. So it's more like a huge electric railroad locomotive than a conventional truck. Older giant trucks used a DC electrical drive system but this one uses AC, which is more efficient.

Post Mon Jun 21, 2004 12:22 am 
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kkeerroo
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Hellbringer 3 has 20cm wheels. The wheels were pneumatic, but have since been changed to the solid rubber type as they are easier to remove weight from. 250g removed from each wheel and 500g from the large sprokets hs put Hellbringer 3 at 12.9kg with a 2.3 Ah SLA. But we'll also try old drill NiCd's and changinging the center panel and a smaller axial.
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Post Mon Jun 21, 2004 7:33 am 
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andrew



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I am thinking of a electric bike/trike similar in style to sparky (www.atomiczombie.com) using the golf buggy motor tim is bringing to event or something.
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Post Mon Jun 21, 2004 8:54 am 
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prong
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speaking of hybrid electric vehicles, i want one of these!!

http://www.italdesign.it/dinamic/webspecials/home.html

The Toyota Volta, 300kw hydrid. 3 seater, weighs 1250kg, all wheel drive, 0 to 100 kms in 4.03 seconds!
Now that would be fun to drive!
It is especially interesting because like that massive truck it only uses the electric motor to drive the car, the petrol engine is just set up as a generator.

Post Mon Jun 21, 2004 11:41 am 
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timmeh
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Im thinken of makin a electric car with 3 12v 12amp hawkers on the back with a wheel chair motor will go faster then a go cart and i can ride it round the street at knight Cool
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Post Mon Aug 02, 2004 10:09 pm 
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andrew



Joined: 16 Jun 2004
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Well when i get a job or something i want to make a electric bike similar to http://www.atomiczombie.com/electric.htm.

It will have large go art like wheelbarrow wheels (teh really big wheels), will be driven by a golf buggy motor which requires no extra gearing and does 800 rpm at 24 volts. SO this should give me a really fast machine.

Only thing is i have to figure out if the 350 watt scooter speed controller or drill speed controller can run it, if teh motor gets hot after a while and the correct gearing and voltage run so its fast yet still safe.

Should be fun though.
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Post Tue Aug 03, 2004 7:01 am 
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DavidM



Joined: 07 Jul 2004
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Location: Victoria, Australia, Earth, Milky Way Galaxy


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I was involved in building a solar car for Sunrace 97, it was a hybrid (solar and human power), after the event I was fired for electric transport, I wanted to build a scooter like you suggested and did!

But it was terribly underpowered, but thats because I spent about $30 on it. I used a fan motor (Ford Laser), on the motor shaft I had an aluminium rod (30mm) and squeezed on the rod was some rubber - the idea being to use friction drive from this to the rear wheel. The motor was mounted on a spring loaded pedal (half a poly chopping board), when you pushed down with your foot it engaged the motor/rod/rubber to the rear wheel. This is important for electric vehicles as free wheeling/coasting is a part of efficient traveling. The scooter I built out of aluminium tube sections and the steering believe it or not was a gate hinge, the whole scooter was built from scratch - with no welding but about 300 pop rivets, it had an aviation look to it. The electrical part was simple - an on/off switch, ammeter (essential to regulate power usage and pressure to the motor pedal), voltmeter, fuse and 7.5 Ah battery slung underneath the foot plate (the other half of the poly chopping board).

Still lots of fun, still have it.

At the time electric scooters were not the common, so it took me more half an hour to go to the 7-11, as it was 3 minutes to go the 7-11 and 30 minutes to explain the scooter to people going in and out of the store, everybody wanted to ride it, and 3 minutes to go back home after I finally got inside to by the milk.

I built mine in two weeks by keeping it simple, make it complex and you probably wont finish it (like 3 others I know of).
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Post Tue Aug 03, 2004 6:49 pm 
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Spockie-Tech
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Thats a very similair design to the infamous "EV Warrior" electric bike. yes, where the well-loved robot motor came from. They ran 2 motors for drive (one clockwise, one counter clockwise) facing opposite directions, but coupled to a single rubber roller that pressed on the back wheel for friction drive.

I wonder if regenerative braking would be worthwhile doing, you would have to figure in a fair few stops and starts and why not put at least some of the energy back into the battery ?

7Ah doesnt sound like much for an EV though. a 7ah battery only drives your average combat robot for 5-10 minutes, although multiple drill motors are a lot less efficient than a good scooter motor would be. It might be interesting to make up some monster-sized nicad packs out of drill batteries since they're cheap and seem to cope with 5 minute discharges better.

One of my techno-dreams has been to make a *serious* wheelchair for some disabled rev-head. Electric Wheel chairs always seem like such wussy things to me.. why doesnt someone make one with a few horsepower for drive, a nice comfy car-style reclining seat with a steering-wheel, and a little petrol engine that you can fire up once out of the shopping center so you can give the guys on petrol scooters a run for their money ? If you are going to spend a major part of your life in the thing, I would have expected people would at least make them as funky as the shopping karts the grannies get around in.
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Last edited by Spockie-Tech on Tue Aug 03, 2004 8:46 pm; edited 1 time in total

Post Tue Aug 03, 2004 8:10 pm 
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Knightrous
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What about a wheel chair with two B&S Etek's on 60v with 5 12v Hawker SLA' under it! About 40HP of continous power!
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Post Tue Aug 03, 2004 8:19 pm 
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