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E-bike E-xperiences?
Jakedata writes "I am in the process of building my first e-bike. I intend to use it to commute to work a couple times a week, weather permitting. I can only assume that many members of the /. crowd are already riding e-bikes and would be only too happy to share their experiences. I am looking at a very affordable e-bike conversion kit from Golden Island Machinery. They offer a 36 volt lead-acid battery pack for it, but I am concerned that it will be too heavy. Rabbit tool has a selection of components and power options but they are pretty pricy. So, is Golden Motor's kit any good? Is lead acid OK to start off with? Does someone want to donate a direct-conversion methanol fuel cell to the project?"
I'm not sure why on the fuel cell, but from racing I can tell you a few things.
You can't (not as a fuel) buy ethanol, you can buy e-95 (95% ethanol, 5% methanol) Drinking ethanol (100% ethanol) is strictly taxed. They use e-80 and the like a lot in brazil instead of fossel-fuels. e-95 got a bad name as of late becouse it can be used in explosives with ease. Methanol works better as a fuel becouse it absorbs less water from the air (but is still really bad about it) and its cheaper. Also, it smells really good when its burning, but if you drink it, it will pickle your liver. In world war II the us used methonal in torpeados, some people still call it torpeado juice. Also methanol has a higher octain rating (really high, like 130 or something like that) and it can cool your manifold better then gas.
!
After getting into BattleBots years ago, I decided to reduce my commute to college (before I graduated) by building an electric scooter out of "spare" parts. It's not an e-bike from the standpoint that I didn't want to have to input any energy into the system myself (i.e. the motors had to do all the work). For cost and simplicity reasons, I chose to go with SLA (sealed lead acid) batteries and a couple of overvolted motors. With the proper timing, I achieved a flat speed of 16.5 MPH on two 1HP motors. With 64Ah (@12V) of Pb-acid chemistry onboard (this weighed a whopping 50 pounds), I had a maximum range (tested on all terrain including large hills) of just over 12 miles.
:-)
That's what I did and perhaps you can learn from what I would have done differently. First off, I would have used NiMh batteries. This would have cut the weight in more than half and also would have allowed me to customize the pack more both in shape and capacity (I only needed to go 9 miles in a day). The only downside to this was the charge time. SLA batteries are pretty indestructible and I could charge the full 64Ah in around an hour. With NiMh, you're talking about several hours or less if you don't mind compromising lifespan (with the right charger you could charge the same capacity in NiMh in the same time if you didn't mind getting only ~100 charges out of your packs). If I had the cash, I would probably use the high capacity, high discharge Li-Ion batteries from PowerStream (http://www.powerstream.com/LL.htm) as they would be incredibly light (~10 pounds for the same capacity).
As far as the motors went, I was fairly satisfied with the power output, but would have liked more. If you compare it to a car (~100HP for ~2000 pounds), you should have ~10-15HP available for the same performance. Now with electric motors, due to their differing torque curves (in comparison to internal combustion engines), you can achieve similar results from significantly less overall horsepower, but I still would have preferred having 3-6HP on my project.
Of course, if you go with high output motors, you need a speed controller capable of handling the current. And if you go with the Li-Ion batts, you need a fairly expensive charger.
You can take a look at some basic pics of my scooter at:
http://sloviper.com/hobbies/scooter/index.html
A good place for parts is:
http://www.robotmarketplace.com/
Cheap Ni-Mh batteries can be found at:
http://www.batteryspace.com/
I have used them in BattleBots before and they hold up decently, almost as well as the "expensive" ones from http://www.battlepack.com/
If you have any specific questions, feel free to contact me. I love discussing this sort of thing and have had tons of experience.
In theory, theory always works in practice. In practice, theory rarely works. <><
Hi, I would avoid trying to deal with Golden Island Motor directly for ordering a single conversion kit, they don't do the english/communicating thing very well and the cost to wire transfer and ship just one hub motor will exceed the listed kit price considerably. You can get very similar value hub motors that are distributed locally through http://www.wildernessenergy.com/ and http://www.evsolutions.net/, a supplier of the http://www.crystalyte.com/. These are all direct drive motors, no gears to wear out and perfectly silent, but also fairly heavy for their power output.
I've also ordered reasonably cheap hub motors from http://www.elebike.com.tw/. They have an interesting selection including some internally geared models, and are quick to respond to queries.
Good Batteries continue to be the biggest hurdle for DIY e-bike experimenters because even though there are tons of asian companies that reportedly make them for cheap, there are simply no local suppliers. If you don't mind trying to import from China, some companies to check out:
1 http://www.peacebay.com/,
2 http://http//www.hyperbattery.com,
3 http://splendidbattery.com/,
4 http://www.gmbattery.com/,
5 http://www.thunder-sky.com/en/index.htm
Personally haven't ordered from 1 or 2 yet, 3 has very reasonably priced lithium polymer ($.82/watt-hour) and NiMH ($.40/w-hr) packs and will sell in individual qunatities. My favorite so far are the prismatic NiMH packs from 4, GMBattery, because you can access each individual cell and restack them easily. Finally there is the infamous thundersky who have lithium-ion batteries for less than most companies' NiMH. Their old 10Ah 36V setup had no protection circuitry and a few problems, but their new 20Ah 36V ebike pack looks a bit more reputable. Note that the 24V 4Ah NiMH packs from batteryspace.com that someone recomended are GARBAGE. Ours turned out to have only 2.6 Ah capacity and couldn't deliver more than about 5 amps. If you buy from batteryspace, be sure to get the 30Amp high rate pack.
Lead acid isn't really that bad if you're generally doing ~20km ish trips so you can get away with lower capacity pack. NiMH has about twice the energy density, and Lithium packs are 2-3 times better than NiMH.
I see a lot of people here have misconceptions about ebikes and exercise. I find I pedal as hard or harder riding an assisted bicycle than a regular bike. The difference is that I move at 42km/hr instead of 26, I don't slow down on the hills, and no matter how hard I work I don't get sweaty because the breeze at those speeds is so strong. This is a much overlooked fact of ebiking, the wind keeps you cool and dry.
Justin Lemire-Elmore