Looking at building a bike, got questions

[Chris456345234]

Hi,

My requirements:
- The most I would travel travel is 20km (~12.5 miles), but 95% of the time it will be half this distance.
- Speed is not important, but 20 KPH up to 30 KPH/18.6MPH should be optimal.
- I am about 230 pounds, and there are some 20 degree hills, but also a lot of semi-flat surface on top and above those hills.
- I want to spend about $600-800.
- I also have an existing bike ("26 wheel), but I would be willing to buy a new one.
- Reliability would be a bonus

I am hoping for something that can give me power to go around town quickly and easily. I like the idea of using almost pure electric power on hot +30c days, but most of the time I want pedal assist. I already get around on a bike, so just want something that lets me go further without burning out my energy. Or arriving sweaty at my destination on hot days.


So far, I am thinking maybe:
(picking the 36v RPM motor and the $26 controller, apparently this wheel will work with disc breaks)
http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2013-9T-F37E.74VMQ
or this kit:
http://www.yescomusa.com/Brushless_Electric_Bicycle_Engine-_48v_800w_Front_Wheel_Hub_Motor_Kit.html
or even this kit looks very interesting:
http://www.leafbike.com/products/diy-bike-conversion-kit/26-inch-electric-hub-motor-kit/newest-26-inch-36v-750w-electric-bike-kit-front-wheel-911.html

And this battery (but at 36v and 15a, this battery would only work on 500w max motor, so only the first I listed):
https://bmsbattery.com/ebike-battery/501-36v18ah-lifepo4-electric-bicycle-battery-pack-battery.html

That would be $350 battery + $237 for the kit = $587 total. Then Id just need a case and a way to hold the battery, and nothing else right?

Have other suggestions, or does this look good?

And would there be an easy way I can lock the battery in place? And maybe even a key to turn the bike on/off?

edit: I am also considering this pre-built bikes from amazon. But I figure if I build it, I can make something more powerful...

Chris.

 

[Nobuo]

1000W motor at 48V will get ~40KPH easily so if you get a 20A continuous controller, and a cheap 9C 1000W Hub motor, then You could spend the rest of the money on a good 48V 12Ah (with a case) - 20Ah (without a case) battery, and won't be more than $600 - $800.

 

[Chris456345234]

I am In Canada, so the max I can go is 32 KPH. Speed is not a primary concern (torque and good battery life is more important). I am sure if I was 2-3 KPH over it, it would not be an issue, but some of these 1000w list them as going well over 50 KPH.

Also wouldn't a 500w at 36 volt give me more torque then a 1000w at 44v?

And at the very least I also want to buy a wheel pre-built, but preferably an entire kit that is missing only a better/charger.

 

[nutnspecial]

Your picks look good for criteria. It would work. Did you mean 20deg or 20%? With 20deg (and maybe in general) you'd like a mac- they automatically have more torque by their internal gearing design. They're on em3ev.com
You could try ebay or I think em3ev has triangle bags/batts.

Electricscooterparts.com has some keyed switches- they might work.

Increased voltage and current will always give more speed and torque- These things are pretty closely related.

The only way to gain torque on a direct drive (non mac) hub beyond maxed out controller current is a smaller wheel around the hub- that's the only type of gearing for these things.

 

[docnjoj]

Just remember that no matter how good your geared motor is, it will have a higher chance of failure than a direct drive motor.
otherDoc

 

[Chris456345234]

I am not sure what the angle is, but my guess is about 20. The city I live in is basically on the hill and bellow the hill. Getting on the hill is relativly steep angle, but the rest of the city is relatively flat.

What do you think of this kit:
http://em3ev.com/store/index.php?route=product/product&path=45&product_id=179
with 36v 16.5 ah battery, 32kmh speed (must be 10T?), with 26" disc wheel (what is a disc wheel? Allows for disc breaking?).

But that comes out to $877, is it worth it for the battery and motor?

 

[wesnewell]

It's usually cheaper to buy from within your own country. This kit in either 36V or 48V should work well for you.
http://www.goldenmotor.ca/products/26-Inch-Rear-Black-Magic-Conversion-Kit.html

 

[nutnspecial]

I didn't realize it would be that much more money, and that's b4 shipping.
Seeing alot of the price is the batt and the shipping of, you could check ebay (hallomotor comes to mind) for batts that are already close to you, and maybe for less$. I was in the same spot not long ago, and had an 11.6ah picked out. Then I figured out how much less lipo I would need to do the same thing, and how much less it would cost. It's a touchy subject with some on here, and more volatile/dangerous, but you could read up on lipo. There's sticky's, the wiki, youtube.

I have no firsthand experience with geared vs directdrive. Just alot of reading and youtube.

So, to help your decision this is what I'd do. Use mapmyride.com to trace a route for incline measurement. Include that in a new post asking if mac or dd would be better for the situation.
This should ensure you get the most informed opinions directly.

Of course this would be moot if you don't want to spend the extra $. In which case go with your first choice, it will be about 3x more power than what you can pedal, just be cautious of heat on long hills. (good advice with any motor)

And yep, disc would refer to the hubs ability to accept a disc brake. I forget what they mean by cnc, but it's explained somewhere on that site. 10t is what I would choose in a mac.

ps- on em3 you can do the pick-and-mix to be sure what you're getting

 

[Chris456345234]

I tried mapmyride.com on several roads I may have to go up. According to that tool it looks like they are between 7-9% (I really think its more then that, but I wont argue with the tool).

I also tried mapping the biggest trip I would probably ever take in town (the 20km one I estimated above), that trip basically goes down the big hill once, stays in the downtown flat'ish area, then goes up it again when I head home.

Also here is another question: How do I need to look at amps?
For example if I got a motor that is 500w at 36v, then in theory wont it only handle 13.8A max?
Or a motor 750 watts at 36v will only be able handle 20 amps max?

I assume using less amps then the motor can handle would be ok?

And I guess the biggest most important question: What about the controller and battery? What if the battery can do 15A (continuous like the 36V18Ah LiFePO4 Electric Bicycle Battery Pack), but the controller and motor are both do 20A? Wouldnt the controller be pushing the battery too hard? Is the safest bet to always make sure the battery can do a steady amount of amps that the controller/motor can do?

Honestly, if there is a battery with a good warranty, is safe, lots of recharge cycles, then I could increase my battery budget on it. Even if its slightly over kill, I figure I could always just use it in another build in the future.

edit: I also have no problems pedaling with the motor up these hills. When I am healthy I can go up them on my normal bike.

 

[coolbreezz17]

This bag was only 15 bucks on ebay.This is a large they also come in medium and small.

 

[nutnspecial]

I tried mapmyride.com on several roads I may have to go up. According to that tool it looks like they are between 7-9% (I really think its more then that, but I wont argue with the tool).

I was surprised the first time using it also. I would have to say the simpler cheaper dd hub will have no problems. If you want to get other opinions try a new topic asking specifically about that. Otherwise it easily gets overlooked.

How do I need to look at amps?

Is the safest bet to always make sure the battery can do a steady amount of amps that the controller/motor can do?

They are the overall power the motor draws from the batt thru the controller.
If you go with 500w 36v (w times v = a) so 15+ amps.
Do you understand c-rates of batteries? 'c' stands for capacity which is referred to by 'ah'. It is used to define maximum charge and discharge ratings for battery considered safe. 1c is 1x the ah of battery, 2c is 2x. So a battery 15ah 2c discharge is good for up to 30 amp. Just make sure the battery can safely feed the controller for a balanced setup for when you have the pedal-to-the-metal for long periods. Yes, if anything you want the batt to be overqualified for the power you plan to draw, although just because a controller is capable of drawing 20a doesn't mean you have to use it. The kits come with a 3 pos switch, and you don't have to use the highest set. If it looks like the battery might be stressed from too much draw, monitor the heat. Preferably you want no noticible increase. You can ease up on the throttle or choose a lower setting for the controller if the batt is a little weak.

Since I don't think you need geared, check this out.
http://www.amazon.com/48V1000W26-Electric-Bicycle-Cycling-Conversion/dp/B00OLSJGGG/ref=sr_1_5?ie=UTF8&qid=1426813024&sr=8-5&keywords=48v+hub
Best price and complete. It was my first choice before going with a 4000w midmount motor.

http://www.ebay.com/itm/2015-Latest-48v-12AH-Samsung-INR18650-29E-Seatpost-Frog-Li-ion-Battery-Akku-/171595731304?pt=LH_DefaultDomain_0&hash=item27f3e71168
I would honestly get this battery! It would pair very nicely and is very versitile. It's the one I planned on, and pairs perfectly with the kit.

This combo will be perfect for you imo and has room to grow, power to spare.
To help get other opinions, do a new topic specific post to get peoples attention- ie geared vs dd for that incline and trip length, or this batt vs that batt.

 

[Chris456345234]

I did not know about the "C" thing, thanks.

But looking at that build, the kit is 1000w at 48v, that would mean 20.8A at max setting, but that battery is only 6a 2c, so it would appear that battery would not be powerful enough for that kit?

 

[nutnspecial]

Are you sure? I reclicked the link and it says 12ah 2c and actually rated up to 30 amps in the specs. Free shipping too. (at least for US)

 

[Chris456345234]

When I click on it it tells me in the red "Powerful battery with excellent Samsung 6A 2C high discharge rate cell". But the specs (in the pic) do list it as a 17.4A discharge rated current with a 'maximum continuous discharge current' of 23.2A.

Seems for another $60 from the same seller you can get this (10A at 3c) 20AH. this one Literally has more then double the batteries in parallel (9 instead of 4) and has a rated discharge of 39.6A.
http://www.ebay.com/itm/2015-48V-20AH-OEM-Cell-Rear-Carrier-Li-ion-Battery-with-BMS-Charger-Akku-Li-Po-/191464725626?pt=LH_DefaultDomain_0&hash=item2c942fdc7a

edit: Seems with that battery and this kit id have a lot of power:
http://www.leafbike.com/products/diy-bike-conversion-kit/26-inch-electric-hub-motor-kit/newest-26-inch-48v-1500w-rear-hub-motor-bike-conversion-kit-987.html

BTW: Free shipping from china is nice, but expect to wait a long time. I got several orders coming from china right now (on much smaller cheaper things), none have gotten to me yet.

 

[nutnspecial]

You're right, they rated it at ~17a. I was looking at the bms current. the 24a max cont. discharge would suit the motor though, and you would *edit* -wouldn't- be lugging around more than you need for range or power.

----Although absolutely for another 60 that one is worth it for the extra ah. -more range, more power to spare. Decision may depend on your desired form factor.

I agree, china will take a bit of time. I don't know of any better source though.
** this is more exception than rule, especially when considering batteries but I got my motor from hongkong in 4 days- I couldn't freakn believe it.

I'm curious to hear other's opinions on that deal. Also maybe there's something in the classifieds?