Project notes for an e-bike or some other LEV.
Page started in August 2008.
Now 2011 and my e-bike project is on this page.
This is an Australian site. We have different ebike laws compared to most countries. The laws may also vary between different states. The bikes shown in some of the external links would not be legal here.
The motor I'm playing with is also above the legal limit but could be electronically limited.
I've bought a 600XL Brushless Motor and an (eWatts) 85-3-12 85 A governor speed controller as candidates for an ebike conversion.
These are model aircraft components similar to what I use in my flying toys but much more powerful.
The motor is rated at 1.6/2 kW peak for 60 seconds - it weighs 300 grams. What the continuous rating is remains to be seen. It draws 85 amps at 22 V.
I don't have a gear box or batteries yet. A model helicopter main reduction gear may be feasible as the first stage in gearing.
I found this motor at gobrushless.
430 grams 4200 watts CONTINUOUS!!!
That is twice the power of a 50 cc scooter engine.
More here - http://www.ampaviators.com/index.php?option=com_content&task=view&id=55&Itemid=27
|Testing a Chinese hub motor with the EW-G85A ESC|
Nerds playing video - divx 10.5 meg
Same video - mpg 23.5 meg
BatteriesLithium-iron (LiFe) seems to be where the action is in new battery technology. It isn't as energy dense as LiPo but cheaper, easier to charge and longer lasting.
The recumbent ebike (links below) claims 16 watt-hours per mile. In modern units this is about 10 Wh/km or 36 kJ/km. A 22.2 V 5200 mAh (800 gram, AU$270 ) LiPo like this one has about 400 kJ. This would give a range of only 12 km or so. This seems a bit low.
Reality check.If the above figures are true then we can take some guesses at riding costs.
With the above battery pack and range it goes something like this.
If we get a low number of charge cycles - say 270 to choose an easy figure - we're spending $1 a full charge on battery replacement alone. We should get 500 charge cycles so in rough figures - 50 cents a charge or about 4.5 cents per km. This doesn't count the cost of the power or any other expenses.
My car (a small FWD) costs 12 cents a km for fuel at current prices.
If I take two passengers we get a faster, safer more comfortable ride for the same costs per person.
This doesn't count other costs such as rego, insurance, maintenance, parking or depreciation.
Fuel prices are going up and some battery prices are going down (for now). Lead acid batteries are going up but I'm not interested in those anyway.
LiFe batteries could slash the riding cost substantially.
Riding slow (ie sticking to the 200 W legal limit) and improving the aero-dynamics will also increase the range and reduce costs.
Factoring in the cost of your own time could totally wipe any ebike cost advantages.
These crude sums are for electric only riding not human assisted. The economics of unassisted ebikes will give us some clues about the feasibility of slightly larger EVs.
Right now I'm not sure EV is clear winner. A 50 cc postman's scooter might prove more cost effective. Reducing the weight of our vehicles may be more important than electrifying them.
Increasing oil prices should tip the balance towards EV.
Carbon footprint issues are another thing but I think the average Joe is still more interested in saving money than saving the planet.
(2011 things are looking better - there are some nice products on the market and LiFe is good.)
In Oz the real problem with ebikes and light electric vehicles isn't the technology - we can make these things. Our problem is legislation. A 200 W power limit for unregistered bikes makes them pretty lame for carrying adults on anything but level ground. Add a load of groceries and things get even worse.
Affordable EVs are not a direct replacement for a regular car. People shouldn't have to pay registration and insurance twice if they use a small EV run-about and keep their fuel burning car at home.
Registration should be cheap and fuel expensive - Aussie politicians and voters just don't seem to get that.
2008.An excellent recumbent ebike conversion page.
http://www.hackaday.com/2008/07/24/drill-powered-mini-bike/ Note this is probably a LiFe pack.
Some LiFe pages.
(lots of sensors based apsnotes on the atmel site as well)
Doesn't like model motors - http://www.peltzer.net/ebike/PA_FAQ.htm