My new build

[coln72]

G'day all,
This is my first post so be gentle I guess this is the right area to post.

Thought I would give a brief run down of the trike that I am currently working on. It is a electric/petrol hybrid designed to compete in a 24hr race against other schools. The event is the RACV Energy Breakthrough racvenergybreakthrough.net and we are competing under the following restrictions:
3 litres of fuel for the event either to use in a petrol motor or generator or both
restrictions on the amount of batteries we can use eg. 100kg of lead acids down to 30kg of lithiums
no mains power to recharge batteries
only "riders" (max of 8) can recharge batteries.

We are using a 300W motor driving the freewheel that I found at school with two 12V 18Ah batteries to give 24V and a 31cc petrol motor to use a friction drive on the tyre.

Currently we have half a frame built with both motors attatched, a mock up of the seat and a controller roughly fitted.




Thes photos show a belt drive which has been abandoned for the moment due to the difficulty of dropping the speed to a sane level (120km/h unloaded was a little high). Have changed to a chain drive so I can easily change gearing. May revert to the belt drive if I can find/make suitable pulleys.

Will post up more pics and reports in the future. If anyone has ideas, questions or criticisms feel free to post them.

 

[Drunkskunk]

Looks like an fun project. The frame looks good too.


Just a couple points. The voltage seems low. Since waste heat is a factor of P = I^2 * R , and since the resistance in the motor is fixed, then lower voltage means higher amperage for the same wattage, and higher wattage waste heat. double the voltage, and the waste heat is reuced by a factor of 4



If that is a 2 stroke then it needs a tuned pipe. a propper tuned pipe can double the power and more importantly, the efficancy of the motor.
A 2 stroke will naturaly spill part of it's air/fuel mixture out the tailpipe on the compression stroke. its the only way to push the exhaust out. what a tuned pipe does is cause a pressure wave, tuned to hit at exactly the same time as the good air and fule wuld spill out, and forces it back in, meaning more fuel gets burned, less is wasted.
http://en.wikipedia.org/wiki/Expansion_chamber

 

[spinningmagnets]

Since the contest limit is 24-hrs, i assume its a test of range? Which motor are you using?, providing a part number would help track down its most efficient RPM. That info plus the diameter of the wheel (20"?) will identify the optimum gear ratio to get max range from your battery pack.

What speeds do you plan on travelling? Aerodynamics can have a very beneficial effect in this type of contest. They dont need to be heavy or expensive. Anything is better than nothing, but of course the sleeker the better.

http://www.craigvetter.com/pages/470MPG/Last Vetter Fairing.html

 

[chet]

Looks like a OVH valve 4 stroke. Greener than a 2 cycle. Generators use less energy than direct drive. more batteries for higher voltage. looks good.

 

[Drunkskunk]

Looks like a OVH valve 4 stroke. Greener than a 2 cycle. Generators use less energy than direct drive. more batteries for higher voltage. looks good.

You're right. I missed the OHV stamp on the top of that thing.

The Lipo I run are 18.5V, 5 amp (acutal usable) and 640 grams. that means you could run 37volts, 50AH worth (1850Watts hours) for under 30 pounds. (28.2 pounds, plus the wiring harness for 20 packs). thats about 4 times more power than 100lbs of Lead acid can deliver

 

[tostino]

Is it a race of speed or endurance? How is it measured?

 

[dnmun]

why not run with a hubmotor in the wheel and then use gear reduction from your smoker onto the freewheel. or add a big ring as the single gear on the freewheel and then you can avoid the friction drive and it will allow the smoker to have a direct drive for efficiency.

 

[coln72]

The reason I am not using a hub motor is cost. At the moment I have a budget of approx. $1000 for the build so I am recycling a large number of components from previous trikes.
This is why I am using the electric motor I am. It is a "unitemotor" unitemotor.com model number MY1016. Its voltage is 24V at a rated current of 16.4A for an output of 300W.

I have gone the friction drive as in the past, another one of our teams (petrol/pedal) has had issues with direct drive using too much fuel. The difference was about 2 or 3 hours of fuel use so I am copying his idea :lol:

I am hoping to complete 800km or more this year as we have done over 700km just on pedal power. Last years winning bike averaged 35km/h so I am hoping for a top speed of around 50km/h but I am not really concerned. For me range is more important but this may change :?

The shape will be close to our last trike

 

[Grinhill]

That fairing looks great. Good luck!

Have you seen Brett's faired trike on this thread?

http://endless-sphere.com/forums/viewtopic.php?f=6&t=6025

 

[coln72]

motor specs from web site

http://74.125.153.132/translate_c?h...le.com&usg=ALkJrhhLluWjhf_ENPKIMC-rMAM2GyQa3A

 

[tostino]

I would suggest against that brushed motor if you want better efficiency.

Maybe go for a kollmorgen motor like this: http://www.monsterscooterparts.com/24-volt-350-watt-brushless-motor-11-tooth-8mm-05t-chain-sprocket-1318.html

You can use it exactly how you were using the My1016.

 

[coln72]

double post sorry

 

[coln72]

That fairing looks great. Good luck!
/quote]

Thanks for that. This is what happened to it on the first flying lap of qualifying

http://www.youtube.com/watch?v=dZ29MFr7pZs

Up until 3am repairing it :x Still started 19th out of 90plus trikes

 

[coln72]

Thought I'd throw in an update. IT MOVES!!!!!!! Had the trike moving under electric power this morning Imagine a 6', 86kg guy riding in circles with his feet in the air (nothing forward of the front axle). Lots of strange looks from the students :lol: The team members took it out for a spin on a basket ball court and they were rapped. Ran it for 20-25 min with no issues other than the chain dropping off .

Still need to sort out gearing, as under load, the motor is getting no where near its full revs with gearing of 63:16. This afternoon we modded the drive system to change the gearing to 63:12. Hopefully this will make a big enough difference as the acceleration with my weight was sluggish to say the least.

If this gearing change doesn't work, I will look into running a clutch to up the engine revs before driving the back wheel. Any ideas if this will work??????

 

[amberwolf]

I don't know how it works with ICEs, but I know that with my electric motor if I keep it running faster (by shifting down for starts, then up progressively as the bike speeds up) then I get much zippier performance. Even better than just doing that is to have it at higher voltages (36V instead of 24V), since current draw is a lot less for the same power.

I suspect the clutch will help the inital start/engagement of the ICE, but you could also try getting started via your electric motor, then as soon as you're at a speed the ICE is efficient at with your high-speed gearing, then engage the ICE.

 

[coln72]

I was looking to use the clutch on the electric motor to give it a bit of revs so we are not starting from a stall condition. The ICE set up really needs the trike to be mobile before it can be used. The motor is started by dropping it onto the rear tyre. I feel that this will only be used to assist the electric motor to accelerate at the start of the straights.

I am considering going 36v but need to weigh up the extra weight/reduced current/less time to recharge as we are limited to the number of batteries we are allowed. Will the benefit of reduced current usage over come the charging issues I have. I am not allowed to use mains power to charge the batteries Would it be better to have 7 24v packs or 4 36v packs and 1 24v pack????? Have a battery weight limit as well.

 

[amberwolf]

I don't know if the clutch will make that kind of a difference on the electric motor; I've never tried that. It might, but remember when you suddenly apply a load on it, it's torque is going to be higher than that of an ICE doing the same thing, probably, and might break things (potentially the motor itself, based on it's quality--see farther down). A more powerful motor could break stuff in your drivetrain, if it's not made to take that kind of sudden torque, rather than a gradual but fast buildup of power.

If you can do it, using higher voltage with more batteries that have less capacity will still net you the same power, and with less losses, plus the Peukert effect will be reduced and you'll actually end up being able to pull more total power out of the same batteries.

I would go with 36V packs at a minimum (if you can use 48V with your controller, you might try that--the motor can probably handle it).

Based on the motor specs, of 16.0/10.7A at 24V/36V, then with those 18Ah batteries, if you pull 16 amps at 24V, a pair of those batteries aren't even going to last (at a guess) 20 minutes. If you pull only 11 amps at 36V, you have a chance of lasting at least twice as long. If you can put that up to 48V, it's much better.

It depends on the batteries' specifications, since some are made for higher current draw than others, but if you pull out power of an SLA at a rate close to the actual Ah rating, you won't get anywhere near it's actual capacity, which is usually rated for *20 hours* of discharging, meaning that typically, those 18Ah batteries are not meant to supply even a whole amp at a time, if the goal is to have them supply their total rated amount of power.





I may have missed this, but are you using the ICE to recharge the batteries, via an alternator? If so, then since the ICE runs fast, you could run a motor or alternator that outputs a higher voltage to recharge a larger pack with again less current needed, etc.

That little bitty (relatively) electric motor is not the greatest thing in the world. I had one of the 250W ones in that series, by that same company, on the remains of the ScootNGo I salvaged for my first serious attempt at an ebike, and the first one that actually moved it down the road. Shortly before frying the motor by melting it's windings.

They were already damaged by whoever had the SNG before me, along with it's controller, but even without that I don't think it would have lasted very long. I was trying to drive the bike via the two SLAs 12V 12Ah that came with the scooter, using the 11 tooth sprocket on the motor, and the 110? tooth on the rear wheel. It did sort of work, but the motor was under far too much load at that gearing, and couldn't take it.

So watch out for your motor's condition, and if you can possibly do so, heatsink it and ventilate it well.

Also, before really using it under any loads, you might want to first open it up and separate the two red/black input power wires, and put some sort of high temperature tubing over each one separately. On mine, they'd obviously gotten so hot under load that the insulation melted them together, pressed together by the zip tie used to keep them from being pulled out of the motor. I think that is what actually fried the controller before I got it.

Mine was a four pole motor, so capable of a lot of torque (relative to a two pole of the same design), but it ate up the power trying to do it, and got very hot as a result.

 

[coln72]

Well, I am getting sick of letting the kids (most of them are academic students) work on the trike - seems that I am fixing more of their stuff ups than actually going forward. Yesterday was spent making a new adapter to go over the freewheel to hold the 63t rear sprocket after the original one, which had done 2 24hr races, was somehow broken...... It was only made from cast iron so I have started to make a new one from steel. Like to see the students break this one!!!! Will post pics up next week.

 

[coln72]

Thought I'd throw in an update.

Finished the rear gear adaptor. This was a #$%# to machine as I started with a sheet of 10mm steel that I cut a circle out of using an oxy. This hardened the steel so much that it was wearing out the cutting tools and not cutting the steel Had to resort to tungsten carbide tips to even look at it. Its finished now.

Next step was to re align the motor which was mounted to two pieces of angle iron which I milled slots into. Unfortunately, each piece of angle iron were not aligned with each other, causing the motor to twist as the motor moved to adjust the chain. Cut cut grind grind some more to remove this motor mount. Made a motor mount out of flat plate with the same milled slots to take this mis alignment out. All good after taking ages to ensure that everything was aligned perfectly before it was welded. Now it better not start throwing chains now or I will take to it with a grinder I'm hoping to start the petrol motor mounting and engaging system soon.

The other major project on the way at the moment is the pedal powered battery charger that was made from an old trike. Looks complicated, with a double drive to give the 18 to 1 gearing required to spin an alternator fast enough. I am not fit anymore but I can put in over 9 amps. The regulator was removed tonight. Can put out up to 16 amps now.