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Old 06-16-13, 02:42 PM   #1
joweaver88
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need help deciding on specs

Ok so I live in San Francisco where the hills are stupidly steep. I have a little Schwinn "Hinge" folding 20in bike that I want to convert to an e-bike. I just dont know that much about the power requirements and what they actually mean in real world riding. I have gotten my selection down to two different kits (which do not include batteries) and I need help selecting one.

My priorities are:
- Torque (I need to be able to get up these hills without drenching my work clothes in sweat).
- Low weight
- Price

Not a priority:
- Speed (anywhere from 12-20mph is perfectly fine)
- Range (10 -15 miles is sufficient for my commute, especially considering I can charge it while I am at work).

That being said which kit should I purchase, a 500w 48v kit or a 500w 36v kit? The kits are the same price but the batteries are less for 36v and they weigh less... Also how large of a battery should I get for the range I am looking for? I am thinking 10ah?

Thanks in advance!
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Old 06-16-13, 03:49 PM   #2
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Member Sammy5001 on page 22 of the Papamotor thread built a 20" folding e-bike: http://www.bikeforums.net/showthread...onversion-kits

Send him a PM if he's still around. There are pictures of his 20" folding e-bike on page 22 and he also lives in San Francisco.
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Old 06-16-13, 04:18 PM   #3
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Wow yea thats cool, his build is a little more extreme than what I want to do though... I dont need a 1000w motor, I dont plan to go 35mph on this thing. I think I will go with the 500w 48v though, better to have a bit too much power than not enough, the hills around here are murder. I am a FL transplant so I am used to things being FLAT haha.

The kit is $280 with everything but the battery, (hub mounted to rim with tire, battery controller with regenerative braking function, throttle, etc). So my question is, what type of battery should I look into? would 10ah be enough? or should I go higher? also what would be the cheapest way to get a battery, they seem to be the most expensive part of this whole thing so I would like to get only what I need and nothing more. I have seen the prices all over the board anywhere from $350-700
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Old 06-16-13, 04:40 PM   #4
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You won't be doing 35 mph up those San Francisco hills even with the 48v 1000w hub motor. I've only once been able to hit 34 mph and that was with all the right conditions, i.e., weather, tires, and lack of cargo. There are a number of threads on this forum of members complaining of not having enough power. You don't want to fall into the same scenario.

You can always control your power via the thumb or twist throttle if you feel you're going too fast up a hill. If you plan on hauling more than just yourself up those San Francisco hills then you'll definitely need the extra power.

You want to have a good foundation on your e-bike setup. Having a strong motor and the right battery is the best way to do it. San Francisco hills will reduce your distance using a 10 Ah battery; you're better off going with a 15 Ah or 20 Ah battery. Check out Ping Batteries at http://www.pingbattery.com/servlet/StoreFront.

If you make a good investment in the e-bike components up-front it'll pay off in the long run with less breakdowns and better customer service.
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Old 06-16-13, 05:46 PM   #5
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You won't be doing 35 mph up those San Francisco hills even with the 48v 1000w hub motor. I've only once been able to hit 34 mph and that was with all the right conditions, i.e., weather, tires, and lack of cargo. There are a number of threads on this forum of members complaining of not having enough power. You don't want to fall into the same scenario.

You can always control your power via the thumb or twist throttle if you feel you're going too fast up a hill. If you plan on hauling more than just yourself up those San Francisco hills then you'll definitely need the extra power.

You want to have a good foundation on your e-bike setup. Having a strong motor and the right battery is the best way to do it. San Francisco hills will reduce your distance using a 10 Ah battery; you're better off going with a 15 Ah or 20 Ah battery. Check out Ping Batteries at http://www.pingbattery.com/servlet/StoreFront.

If you make a good investment in the e-bike components up-front it'll pay off in the long run with less breakdowns and better customer service.
Well my commute is 4 segments 2 miles down hill, then 4 miles flat that gets me to work... then on the way home 4 miles flat and then 2 miles up hill, 1 mile of that is steep.

I can always have two chargers and charge it while I am at work too... that being said do you think a 10ah battery would be sufficient for a 750-1000w motor?

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Old 06-16-13, 06:03 PM   #6
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Check out http://ebikes.ca/simulator/, that may help you decide what you want/need for you project.
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Old 06-16-13, 06:10 PM   #7
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A 10 Ah would probably be sufficient but a 10 Ah would discharge close to an 80% level which would decrease the life expectancy of the battery. You'll end up purchasing another 10 Ah before too long.

If you get the 15 Ah you'll only need to charge it once a day and hit the 65%-75% discharge level. A 15 Ah will be cheaper for you in the long run and in case you need to make a trip other than just to work and back then you'll have the extra power.

What are the wind speeds like on your commute to work and back? Riding against the wind will slow you down and eat up the battery power as well.
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Old 06-16-13, 06:13 PM   #8
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Check out http://ebikes.ca/simulator/, that may help you decide what you want/need for you project.
oOoO! thats cool... it took me a few mins to figure it out, it looks like a 48v 750w motor and a 12ah battery should be sufficient so as long as I have a charger on each end of my trip (one at home and one at work). Sound about right to you guys?
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Old 06-16-13, 06:17 PM   #9
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also keep in mind that on the flat sections which are the main portion of my ride I will be able to pedal more to assist. I doubt I will purely use the electric function. The wind speeds should be low especially down where I work... I work in Los Altos, so I commute to caltrain then from caltrain to my office then back. The San Francisco segments are going to be the most brutal but they are also the shorter segments. As far as using it outside of work, I probably wont... I only leave SF in order to go to work, all my leisure activities I do here in town and I will just take the bus and walk for those.
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Old 06-16-13, 08:35 PM   #10
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oOoO! thats cool... it took me a few mins to figure it out, it looks like a 48v 750w motor and a 12ah battery should be sufficient so as long as I have a charger on each end of my trip (one at home and one at work). Sound about right to you guys?
I think a 48v12ah should be enough with a bit to spare. A lot of depends on speed; as you go faster and faster, you really start to use up the battery. How much you pedal can have a large impact on range too, but I think 48v12ah will do the trick.
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Old 06-19-13, 10:17 AM   #11
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There are a lot of variables involved, but in general a 48v motor is going to spin faster and use more current (amps) and require a larger more expensive battery than a 36v. 48v is 33% more power than a 36v (includes more weight, expense, size etc.)

I like small and light, after all I can ride a bike without a motor and don't mind the exercise.

Battery is really your most important item (size, weight, cost, happiness). Many of the motors (within a brand) are basically the same, just geared different for different speeds based on the battery. The big difference between these motors is the controller. the 1000 watt motors are going to have a controller that uses more current, and that is going to require a bigger battery.
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Old 06-20-13, 07:54 PM   #12
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For serious hill climbing ability in most cases you really need to consider using a motor that drives through the bikes gears to allow gearing down down the motor for hill climbing (I'm assuming your folder has derailer gears on the rear hub). This is the cheapest decent quality kit I know of being offered:

http://www.sickbikeparts.com/catalog...roducts_id=170

I don't know if it would work on your folder or not (room available in the chain line where it needs to be mounted without interfering with the folding mechanism) but I thought I would at least provide the link for you. The kit is either a 650w "Cyclone" brand name external controller kit or a close clone of same.
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Old 07-08-13, 11:00 AM   #13
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A little late in posting but here is a chart we developed for our customers. http://california-ebike.com/how-to-select/ it's an empirical chart and is based on you answering 3 questions. That being said, your 20" wheels will even give you more torque than reflected in this chart. I personally would buy a geared hub 500+ watts and at least a 48 volt-10Ah battery with at least a 5c rating. If you are able to charge at work 10Ah should be plenty of power. Now the icing on the cake. Get the Lyen 6FET controller (made in San Francisco) and the Cycle Analyst to monitor your performance and power levels. This kind of package may sound expensive but just remember, you don't live in Kansas and those beautiful hill of SF are a real challenge for the best of eBikes.
Good luck
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