Full-throttle's 2nd - in progress

Hobby City sell two different cameras very very similar if you don't like dealing
through flebay

KiM
 
Ride to work - take 2.

Made it this time, just..
Distance 23km
Vmin 40.67V
Amax 30A
Pmax 1500W
P 420Wh
Ah 9Ah

Comparing with my current setup
Average speed 30km/hr vs 30 km/hr - no change
Total time 45min vs 45 min - no change
Total Ah used 9Ah vs 5.5Ah - new setup used 63% more energy
Top speed 53km/hr vs 42km/hr - thumbs up for MAC
new_2.jpg
 
I can eke out 28km from my 9Ah, but at 64v I have more watt hours.


I have to slow down and pedal to get 25-30kmm range.


You'll have to program some speed switches.
 
full-throttle said:
Ride to work - take 2.

Comparing with my current setup
Average speed 30km/hr vs 30 km/hr - no change
Total time 45min vs 45 min - no change
Total Ah used 9Ah vs 5.5Ah - new setup used 63% more energy
Top speed 53km/hr vs 42km/hr - thumbs up for MAC
Click to expand...

Damn that is a lot more Ah's. I would have expected a much higher average speed, not just top.

What is up with that? Just burning it up on acceleration, or more power required to cruise?

- Adrian
 
adrian_sm said:
Damn that is a lot more Ah's. I would have expected a much higher average speed, not just top.
What is up with that? Just burning it up on acceleration, or more power required to cruise?
- Adrian
Click to expand...

I would suspect higher cruising speeds. The slower you go, the greater the percentage that pedaling contributes to the total power and energy output. Plus, higher cruising speeds entail more energy consumption due to "exponential" wind resistance - going 1.5 times as fast would imply 2.25 times the energy consumption as the energy is square to the speed, so 1.63 ^ (1/2) would suggest a cruising speed about 1.27 times higher than "usual", which the top speeds seem to confirm. The total trip time wouldn't surprise me much if you have a lot of stops (Since the majority of time would consist of slowing, speeding up or being stopped instead of going), which appears you do from your graph.

Acceleration shouldn't matter much, unless you pedal to accelerate, and for the same reason.
 
Power goes with cube of velocity, but in this case is more to do with delta/star. Don't hold me on it, but I think BPM is wired in star and MAC is wired in delta. Would be nice to confirm it though.
 
Just had a look at the bike in the shed, and it looks very slick mate.

No real visual battery bulk. Tyres look massive. Suspension is so soft.

How are you going to close up the electrics from the elements? I am still note sure what my long term strategy is.
 
Thanks, I really like the handling. Hit the dirt yesterday - so much fun! Wish I had the camera..

Carbon fibre enclosure would be nice, would like to avoid duct tape.
 
Would love to see the vid's. Grab the camera off me whenever you want. It is on my desk.
 
full-throttle said:
Power goes with cube of velocity, but in this case is more to do with delta/star.
Click to expand...

Speed: Power is cubed but energy is squared over some distance, indeed.

Some physics ahead...
This is because F ~ k1*v^2, and P = F*v = k1*v^3. But, work/energy is.. W = F*d = k1*v^2*d. k1 and k2 are just some constant that represent the other constants in the equation that I didn't feel like writing, F is force and P is power.
Click to expand...


So are you saying that delta/star has some distinctly different efficiency profile in your application(One is less efficient than the other), or that the motor wind type affects the average top speed which itself influences the energy consumption?
 
swbluto said:
So are you saying that delta/star has some distinctly different efficiency profile in your application(One is less efficient than the other), or that the motor wind type affects the average top speed which itself influences the energy consumption?
Click to expand...
Correct me if I'm wrong, but a motor wired in delta would draw more current than the same motor wired in star. I'd say twice as much. At the same time delta-wired-motor will spin faster then star-wired-motor at a given voltage. I'm not sure what the ratio is, but 1.73:1 springs to mind.

All I know for sure is - MAC draws 4A at no load, BPM draws 1.5A. Both @ 52V. MAC spins faster though.

The main reason for the average speed being unaffected is my commute is full of corners and crossings - BPM @ 26A peak accelerates faster than MAC @ 30A thanks to slower wind and slightly lighter setup. It can be seen in the graphs.

Said all that I did ride home in a very quick time by taking the corners harder last night.
 
full-throttle said:
swbluto said:
So are you saying that delta/star has some distinctly different efficiency profile in your application(One is less efficient than the other), or that the motor wind type affects the average top speed which itself influences the energy consumption?
Click to expand...
Correct me if I'm wrong, but a motor wired in delta would draw more current than the same motor wired in star. I'd say twice as much. At the same time delta-wired-motor will spin faster then star-wired-motor at a given voltage. I'm not sure what the ratio is, but 1.73:1 springs to mind.
Click to expand...

The kV changes by 1.73, but the resistance changes by the square of that so that's approximately 3 times less resistance.

At a given speed, you're passing through the same motor torque in delta or wye. That'd suggest that the amps would increase by 1.73 times to compensate since the torque constant decreases by that much. If the resistance is 3 times less, that'd suggest the motor heat hasn't changed at a given speed.

Add in more speed, then you're burning more energy in air resistance and also the increased current from the higher motor torque needed to go faster increases your motor heating. So, it seems likely that it's both due to increased air resistance and increased motor heating from higher currents. I'd think the air resistance would be the dominating factor, though. You're talking about a difference of 100's of watts as opposed to 10's of watts with motor heating.
 
swbluto said:
..the resistance changes by the square of that so that's approximately 3 times less resistance..
Click to expand...
That explains why the current is higher at no load.

swbluto said:
I'd think the air resistance would be the dominating factor
Click to expand...
So you're saying: by speed-limiting it to 42km/hr (same as the other bike) will get me similar economy?
 
full-throttle said:
So you're saying: by speed-limiting it to 42km/hr (same as the other bike) will get me similar economy?
Click to expand...

That's the hypothesis derived from theory. You may get a few percentage difference in either direction due to whatever individual differences (Such as different connection resistances, possibly different controller efficiencies, etc.), but it shouldn't be a difference as high as ~63%.
 
full-throttle said:
So you're saying: by speed-limiting it to 42km/hr (same as the other bike) will get me similar economy?
Click to expand...
It's definately a big factor - on my star delta hub I can pull 60-80 amps going flat chat in delta and about 30-35 amps rolling along the flat at top speed (about 70-75 km/hr @72v) but if I back off to 30 km/hr it'll draw as little as 5 amps rolling along the flat.
 
I also noticed burty say that his Astro motor didn't "like" either wye or delta due to its geometry or whatever, as was evidenced by overheating, so I guess it might be possible your motor might generate more heat just by not "liking" wye or delta. That would kind of suck if that was the case.
 
Not sure about at 50ks, I basically use it as a "turbo boost" when I'm already doing 60 km/hr or more. Where it's also good is for powering down a hill, if you're top speed is maxed out and the motor is basically holding your freewheel speed back flicking into delta accelerates down it. Mind you I don't do that anymore after pulling about 70 amps for a minute and melting my 45a andersons together and spending 25 mins on the side of the road as it got dark trying to pry the melted plastic back apart! (one contact sitting slightly lower than the others and it heated up and melted)

If you back the throttle right off it does use alot less current but not much point in being in delta at lower speeds as it lacks to torque of star and sucks more current.
 
Well, the camera arrived and worked.. for a day or so. I'm sending it back tomorrow. Got a couple of brief snippets, nothing worth posting though. The good news is: when it worked, it worked well - the picture is crisp and the light response is quick. Also, the maker is about to release a waterproof version in a month time.

The other updates: fitted a heavier spring and a couple of other bits. Will be tidying up the wiring once I decide if the 6-fet controller is up to the job or not.
 
The motor is here

Will test it next week. I've been using 350W Code-13 for almost a year now - some 7,000km or so. Rain, hail or shine. Its happy with 1400W peak, torque and efficiency are quite impressive. Top speed is around 40kph. This 500W Code-9 is a faster wind, so given same copper fill it will have same torque (using more current) and higher top speed at the same time.
 
Very keen to see how it performs.

Keep the updates coming.

- Adrian
 
Oh and put Andersons on the phase wires, and jst-sm on the halls so I can try it on my bike.

:D
 
Oh, forgot to mention one important detail: the motor is not a stock BPM Climber - its made to BenMoore's specifications which include:
* smaller 2.8mm spoke hole
* Hall sensors fitted
* black in colour (well, the next batch will be completely black)

BenMoore has a stock of them, as well as slower winds (code10, 11 and 12) and will be happy to sell them within Australia.

cell_man will be able to sell them too.
 
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