Need help in choosing a motor and setup

[Desertprep]

I have a Dahon folding bike that I really enjoy riding. I live in Portland, Oregon, however, and I don't think I have found a stretch of flat land that is more than half a mile long. I just returned to school - actually I just returned to the U.S. from a 10 year stay in China so I am close to broke. I need to get a part time job but all of the good jobs are 6-10 miles away, a little too far for a bike in these hilly conditions in the winter.

I want to convert my Dahon to an electric bicycle but I only have $500 to spend to do it. The bike now weighs 24 pounds - I am hoping that when all is said and done, the bike will weigh no more than 35 pounds - not including the battery - and will still be "foldable". I need to be able to go at least 25 miles on a charge, hopefully at at least 15 mph, preferably 20 but I am willing to pedal. I have been told that I need about a 500 watt motor here but not sure. Also, there are hills all over this place!!

Help!

 

[pwbset]

$500... tough one. I'd say for the time being get a http://ampedbikes.com kit $360+shipping and spend the rest on cheap-ass lead acid batts until you can get better batts.

 

[Link]

I'm inclined to agree. But you're not going to be able to keep it under 35lbs without a geared motor and either LiFe or LiPo. :wink:

 

[dogman dan]

Yeah brace yourself for weight. My ebike weighs 75 pounds and I have lithium batteries! that includes a lock, tools etc.

The folder has small wheels right? If they are 20'' you should be able to get up hills and such pretty good. There are some ebay sellers of the Wilderness Energy kit that includes batteries for around 500 bucks or less. Dales best for bikes is getting a good service reputation. That is important, since it seems like a lot of kits have at least one nonfunctional part in them. They work good once you get a complete functioning set though. For more range than 10 miles you have to go very slow, or get lifepo4 batteries. I find using the bus and the bike a good way to go to go farther. The bike gets you where buses don't go. If you want a rear wheel motor, the WE doesn't have that, but ampedbikes does.

 

[Desertprep]

Thanks! Yes, I don't mind if the batteries push the weight of the vehicle over 35 pounds. If I ever have to fly somewhere I can always take the batteries off and put them in another suitcase. I just wanted the bike, motor and controller to be pretty close to 35 pounds. Southwest airlines is pretty lenient with a 3-4 pounds.

The problem with the Dahon's and frontwheel hubs is that the front hub is not a standard size.

I am looking very intensely at the following motor: http://www.hobby-lobby.com/brushless-axi4130.htm

It is a high rpm motor, however and needs some stepping down. That part would not be to difficult to manage - I have a friend who has a machine shop in his garage. The trouble is I would like the power to the rear wheel to be applied on the left hand side of the bike so that I can leave the 7 speed derailleur alone and not add more mess to the right side. Have you seen a "part" that is available off the shelf to do this?

There is a bent that already has one of these installed (see: http://www.wisil.recumbents.com/wisil/shumaker/default.htm) The motor is light but expensive but this guy claims that it is durable. I have seen other posts online that have made the same claims. I don't mind paying $200 for a motor like this but the killer is that the controller is almost as expensive - they are all radio controlled airplane/toy parts so they are super light, super expensive and have very little demand for the parts. There are other less powerful motors, which this guy said would probably work for me, but these motors are not rated as clearly as the motors I have been looking at for ebikes. While I understand some about electric motors I understand virtually nothing about controllers. I am sure it would be possible to find a suitable controller for this motor for $60-100 but I wouldn't know how to go about doing it. It also seems that this motor is capable of taking a variety of voltages which could be helpful - 24 volt battery packs are much cheaper than 48 - but I am not sure what this would mean for performance. This guy has solved the problem of the transmission but his solution was very labor intensive.

Yes, the "hybrid" bus/ebike solution is a good solution. That might get me through for a few months. I want to apply for a job in a shipping company and the hours of the shift I want are 10 pm to 2 am. There is a 9 pm bus to get me there but no 2 a.m. to get me home Still, the bus might buy me enough distance so that my ebike can make it until I can afford bigger batteries. At that point I can save almost half an hour riding my ebike directly to work - the bus takes more than 50 minutes to make what I could do in about 30 - by riding the bike i can take a much more direct route.

Another option, with such a light motor, would be to use it to power the front wheels. Again I would have the power transmission issue, unless it is possible to put a freewheel on the dahon front hub? I suppose, for the time being I could pick up a second hand mountain bike to experiment with, and then, when things were working right could start transferring to the Dahon. Another issue with the Dahon is that total weight on the bike is not supposed to exceed 215 pounds - I am already 180. There are also not many places to string SLA batteries either.

Then again, there is this electric scooter: http://cgi.ebay.com/Black-SUPER-TURBO-800WATT-ELECTRIC-MOTOR-SCOOTER-nt-gas_W0QQitemZ330272315579QQcmdZViewItem?hash=item330272315579&_trkparms=72%3A1207|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3286.c0.m14

that claims to have an 800 watt motor. It seems small also...I will look into where the parts of this come from, or just break down and buy one and skelatonize it for parts The bottom line on all of the chain driven options is that, if I want to stay out of the way of the present derailer/gear system I have to get creative on the transmission side of things.

Thanks for the suggestions! But by all means, do not let the think-tanking stop I am intrigued by the idea of using motors like this because, if they prove to be durable and suitable, they can be used in a lot of ebike situations.

Yours truly in the battle for a clean environment,

T

 

[Drunkskunk]

What you are trying to do is almost impossable on a $500 budget.

Almost.

The only way to make it work is going to be to use Used parts. RC motors are great, but unless you're familure with them, and a very skilled machinest, it will very likely fail several times before you get it working right. thats just part of developing something new. And when you have a $500 budget, thats going to kill it fast.

WHat you can do is hit up Craigslist. there are any number of electric scooters on there you can rob parts from. I've seen them as cheap as "free to good home. needs battery" Use the scooter for parts, then spend your budget on batteries.


800watts is a lot. I blow the doors off small motorcycles with a 500W motor.

 

[GGoodrum]

I'd also stay away from the RC motors, especially the cheaper ones. They are not designed for this sort of loads, and they will tend to run really hot. You also have to use RC controllers for them, and these are not compatible with the resistive/hall effect-type of throttles needed for a bike.

Here's an option that would meet your budget: http://www.cyclone-tw.com/order.htm. The 650W motor kit is $358, and has everything you need, including a bag to hold the SLA batteries. The quality of this kit is very good. I have the 1000W/1500W version on my Dahon folding bike (http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=5297), and I'm very happy with it. There is someone else doing a conversion with the 650W kit, which you can read about here: http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=6348.

I'm quite amazed at how much lighter my 1000W setup is than the Crystalyte 5303 it replaced. I can easily hold the bike up with one hand, where that was impossible with the hubmotor setup. Grnated, there are lighter hubmotors, but in my case, I needed to use the larger 5303 with a 72V setup in order to get enough performance to get up and down the hills in my area. The Cyclone setups make use of the bike's gearing, so you can get away with smaller, lighter motors.

-- Gary

 

[dogman dan]

If you go front hub motor, surely a front fork can be found that fits both bike and motor for cheap. Our bus service is similar, I can get home ok, but I can't ride it in the morning and get there early enough. But you are still stuck on the weight thing, typical hubmotor weight is around 15 pounds.

 

[Desertprep]

Thanks! Especially to you GGoodrum. I have seen that motor before but did not like the idea of putting it under the bike - it is already so low to begin with. Now that I see yours mounted above the bb I think I will go for it. Hmmmm it is also tempting to go for a bigger motor for an additional 1.6 pounds (extra weight of 650 vs. 1000 watt)...what is the total weight of your bike (including motor, controller, etc but not including batteries)? Which batteries did you go for? I guess the batteries are going to cost more than the conversion. If I choose one of the smaller motors (at 24 or 36v) I don't think 3 SLA's are going to get me more than 12-15 miles, especially on the hills here. Is 36 volts an option for the 1000 watt motor? It is probably the best option for a 500 watt but 48 volts is probably best for the 1000 or 1500 watt.

As I recall, if I buy a motor that is more powerful than what I need, and if I don't do the speed demon thing, it will not use more electricity, is that correct? To be honest, I have only ridden 50 or 60 miles on my Dahon so far and do not really feel very comfortable going faster than about 20 mph. Maybe after I get used to it...

If I did their 1,000 watt motor and cruised around on flat land at 15 mph, how far do you think I could go on a 20 A/48 volt? Ping says 50-60 miles. Ohhhhhhh I just noticed that Ping on ebay is selling a 40A/48 volt pack! Kowabunga! But it is $ 1,500 Wonder if I could get 120 miles from that battery? I could almost ride my bike all the way from Portland to my sisters house near Aberdeen Washington!

Where did you get your batteries?

Thanks for your input. I still like the idea of the RC motors but I can see that it is still out of my league...now, after I win the lottery....

 

[Desertprep]

but wait! Now that I have your url and started googling on related words...I found this little critter:

http://www.econvergence.net/pedelec.htm

The cyclone looks good - I just don't like the idea of messing around with the chain. Also, if I am going to be actively pedaling and using the motor at the same time, it doesn't seem logical to me that the ideal speed to shift gears for my legs sake and for the motor's sake will be the same rpm. It would take a little doing but with this second option I could slip in a 3 speed gear hub in between the motor and the gigantic gear in the rear. To be honest, that gear looks wayyyyyyyy to big and unstable.

 

[marvingalaxy]

"I just noticed that Ping on ebay is selling a 40A/48 volt pack!"

NO. THAT IS NOT LI PING. THAT IS ANOTHER SELLER USING HIS "BRAND". pingping227 is the only name that Li Ping is using to sell battery packs. His email is pingping227@hotmail.com and he will sell direct. His typical ebay prices are similar to his direct prices but you can get the pack a custom size/shape.

For a relatively low-cost system you might consider Knuckles' Bafang kit for $415. That is stretching your budget but a geared motor is your best bet to save money if weight and cost are an issue. The down side is a lower top speed but that is not your primary consideration. The reason a kit like this would save money is that you could build your own 36V NiMH pack from 10AH D-cells from ebay. The charger would only cost about $30 if you can put up with a slow/overnight charge. Still, this puts you above the $500 price tag but there is only so much you can sacrifice to get reasonable performance. I don't think you will like pedaling with 30 pounds of dead SLA which is what you will have if you don't get an efficient motor and decent batteries. Good SLA (12AH AGM) will still cost ~$150 which is approaching the cost of a DIY NiMH pack and weigh much more.

A small geared motor kit won't require the big battery of a fast gearless hub motor which will suck a lot of amps to create thrust at lower speeds. Gearless might be better at high speeds but there is an efficiency reduction at lower speeds. At higher speeds, you need more battery to fight wind resistance. If going 15-20mph with hills is your typical usage, get a geared motor.

Edit

I forgot to add that a geared kit with freewheel feature is going to be a bit easier to pedal than a gearless. Check with Knuckles about his kit to find out if it is easy to pedal.