Help with first build

[flyinbrick]

Hi, I'm looking to build an e-bike to commute to work and get my workout in at the same time. I'm new to ebikes, but have some electronic and limited bike-building skills. I can solder, know circuits, can wrench but can't weld. I've never welded a battery, but understand I may have to given my budget.

Here is what I'm looking to do:

Donor bike: 90's Trek 920 steel frame with steel forks, 26" wheels, currently setup with 9-speed Shimano MTB gearset
Weight: 165 lbs bike + rider
Distance: 18.5 miles one-way, mostly flat, mostly on a bike trail with little stopping. I can re-charge in my office.
Speed: 30 mph minimum with pedaling
Budget: $600
Front/Rear: not sure. Front hub will give me better weight distribution but will probably need a torque arm. Rear hub: I questions the quality of the cassette that comes with the hub. Either way, I'm guessing I'll need a larger front chainring, right?

So, yeah, my budget is pretty low but that's what I have to work with. I'm pretty sure I'm going to have to buy from eBay and perhaps repair/replace stuff as needed.

I figure that I will need a 48v/1000w system with a 15ah to 20ah battery.

What I have in mind:
http://www.ebay.com/itm/48V-1000W-E...896?pt=LH_DefaultDomain_0&hash=item339dcf9fe8
Anyone know what kind of motor this is? This seems to be the most common type on eBay at this voltage/wattage.
There is another type such as in this kit:
http://www.ebay.com/itm/48V1000W26-Front-Wheel-Electric-Bicycle-Motor-Kit-E-Bike-Cycling-Hub-Conversion-/291308554392?pt=LH_DefaultDomain_0&hash=item43d357c898

I'm also open to a geared 48V hub like the Q100/Q128 low-turn, high RPM models. Keeping in mind that I want to pedal, will this get me to 30 mph?

As for battery, what AH will I need? I'm eyeing something like this:
http://www.ebay.com/itm/48v-15ah-LiFePO4-Battery-5A-Charger-BMS-E-bike-Kits-Powerful-Rechargeable-8Weeks-/141504683565?pt=LH_DefaultDomain_0&hash=item20f2561e2d
I'm steering clear of the 2-wire packs with shared charge/discharge negative leads.

There is probably lots more reading I can do, but would appreciate if members here can start steering me the right way before I pull the trigger and start buying stuff.

Thanks!

 

[brooklynboy]

Hey!

I purchased the exact kit you listed. I've installed, and done a quick test run and it is a blast ( ordered tues and got it thurs NJ to brooklyn,NY. I think most ppl on this forum will recommend that you install on the rear if you are new to this. I also have a steel frame and will install torque arms ( i've laid down a motorcycle once, the ground is not forgiving). The general consensus is 20-21 watts per mile ( 48v x 20ah = 960wh and then 960wh/21wpm=45.71, so your estimate 20ah( including pedaling ) sounds about right since you don't want to bring you pack to it's knees. You said you are charging at the office, so it should offset the relatively high speed you are traveling at. Speed kills range according to the unwritten electric bible. My own battery experience is limited to ryobi18v macgyvered into a 54v 8ah cardboard box. If i were to do it again, i would try the kit from xcceries on ebay. It includes an lcd for 236.90 and the seller has a reputation on these forums. I can't confirm the speed yet, but 25mph on this kit seems trivial. You mentioned your bike is a 90's trek, but I'm not sure if it has disc brakes. The cantilever brakes on my bike do not inspire confidence even on flat ground. One last piece of advice is to check for rim tape so the holes for the spokes don't puncture the inner tube.

BTW i'm the FNG, wait for the real gurus to speak. Maybe I'll get a pat on the head & and cookie.

 

[Nobuo]

Both kits are OK for the price. That motors are two slightly variations 9C clones, but I prefer personally the first one. Although the second kit you linked is also good (I personally prefer thumb throttle than twist Throttle, and the rear mount rack is interesting), I would choose the first one for the motor.

In both kits the "bottle neck" are those controllers. Although neither are specified, I could determine by sight that both are 17A continuos controllers, that is right for assisting but won't be able to achieve 45Km/h as they claim by themselves (will need a little pedal power ).

About the battery, is great for the power and cycles life. LiFePo4 will give you powerful feel in almost the whole battery cycle, and you can charge and discharge daily even several times with no issues. But is heavy and large for the Energy, 48V 15Ah in 7.5Kg and 3.9 liters. For a quick comparison I built a 48V 42Ah lithium-ion battery that weight 10Kg in 4 liters.

Also 1 KWh doesn't worth today more than $350 (that battery is 0.72 KWh)

good luck and welcome

 

[flyinbrick]

Thanks for your replies!

Brookyln boy, I don't quite "get" your calculation. (960watt-hours)/(21watts/mi) = (960watt-hours)*(1/21)miles/watt = 45.7 mile-hours?
What makes more sense to me is at full throttle, I'm drawing 20A. Assuming 30 mph, I need 37 minutes to go the distance, so this is 12.3AH. If I want to draw no more than 80% of battery capacity to preserve it, I need a 15.4AH pack. So if I go with a 15 ah pack, then I'll slow down a bit to get a bit more efficiency. Am I close? But what if the cheap pack I get from eBay doesn't give me the rated AH, then do I really need, say, 18AH?

Nobuo: I see your point on LiPo, but I simply can't take the risk of burning down my house or workplace. That would not be good - I can be a real idiot sometimes! At least I would need some experience before going down that route. That's cool you can tell the type of controller just from dimensions. For that price, I guess 17A is close enough for now.

I've also been looking at smaller geared hub motors like this:
http://www.ebay.com/itm/48V-500W-Ge...t=LH_DefaultDomain_0&var=&hash=item3f41dbc608
This listing is for a 700c wheel, but I called them and they said they can lace it to a 26" wheel. I like that I would be able to freewheel without drag and be close to my speed goal. Ebikeling seems to be a known vendor around here and it's nice I can call them here in the US. I'm exploring the option of lower speed in exchange for smaller battery.

Questions:
1. What kind of motor is this? Is it a Cute Q100 motor?
2. will I be able to go 25 mph with this running at 10A?
3. Battery: At 10A @ 25mph, I need 45 min, or 7.5AH. Factoring in max 80% discharge to preserve the battery, I'll need a 10AH pack. Am I close? Should I also factor in a larger pack (12AH) to account for the fact that a cheap pack may be over-rated (have an under-performing cell)?

 

[Nobuo]

I did not indicate LiPo chemistry, Lithium-Ion is not Lithium Polymer. Lithium-ion are with LiFePo4, the safest lithium batteries. But Lithium-ion is the most density and specific energy capables chemistry batteries at the moment.

That motor is more like a 350W rated one at 48V.

It depends on many factors, but you would need something btween 10A to 15A at 48V to mantain 25mph in average terrain, and a bigger motor probably (If we are not including pedaling)

That numbers are right. The brand of the cells changes the whole thing. try to look samsung cells, they are the cheapest quality cells that chinese vendors use to put on the packs and use to be authentic.

 

[2old]

Hope that Dogman Dan sees your post since he'll really help. Probably you'll need a 1000w, 48V motor for 30 mph (DD will let you know how little your pedaling contributes at this speed), and a 48V, 20 ah battery (960 wh) will take you about 960/40 or 20 - 24 miles on flat ground with no hills or headwind if you weigh 160 pounds or so. The yes.com (acceries on ebay) or similar motor comes with a 26 or 30 amp controller, respectively, for a non-disc, disc wheel (pretty sure that your frame won't accept discs) and is an excellent consideration from my experience and many others on ES.. Sunthing batteries are a gamble according to some posts on this forum, but at least one person will disagree with this statement. Good luck.

 

[brooklynboy]

Sorry about that. I'll try to clear it up.

20-21 watts per mile , so 21w/m
48v x 20ah = 960wh ( I think people measure their batteries by watt hours as well as amp hours )
960wh / 21w/m = 45.71 mile range, factor in your max 80% and you have a theoretical 36.56 mile range.
your commute is 18.5 miles one way and 37 total, so thats what I meant by 20ah being spot on. If you fully charge at work, then 10ah would work according to these numbers. Other members, please chime in if I'm wrong.

I just tested my setup up yesterday and posted it in the batteries forum. It went up to 31 mph on flat ground according to the phone gps in my pocket. I thought I was doing 20 mph because I wasn't full throttle for more than a few seconds. The steel fork was slightly bent after test. My bike is a huffy from late 90's. Someone mentioned kool stop pads to fix my inadequate v-brakes.

I'm posting a picture of the controller that came with the kit( same as you listed). I took it apart to check the quality of the capacitors and see if Nobuo can confirm it's 17A continuous . My multimeter maxes out at 10A, so I can't check.

 

[USAEBIKECO]

I always tell new ebikers to make sure to invest in some good solid tires and tubes. Having a flat on an ebike is a real pain.

 

[brooklynboy]

http://electricbikerange.info/Electric_bike_range.html

I found this searching though the forums. range+ calculator+
Avitt posted the link
Re: "Storm" ebike - new fat tire entry

input where you are, where to be, what you got and then BAMM!! it tells you battery consumption, avg speed and other things to give you an e-gasm.

 

[flyinbrick]

Brooklynboy: thanks! your build validates that 30 mph is achievable. Actually, I only need to go 18.5 mi one-way since I can charge at work, so I'm leaning towards 12ah and slowing down if needed to stay at a lower price point. Are you able to get real life wh/m numbers? And that site is awesome!

Nobuo: That went completely over my head the first time - I had to do a re-take. OK, Lithium-ion is not LiPo, got it! What cells did you use on your build and where did you get them? I'm now contemplating building a pack to stay within budget. I'm having trouble finding pre-made packs made with Samsung cells. I did find Samsung cells at Aliexpress. Is that a good place to get them?

Can I get some opinions on these options:
Panasonic NCR18650PF at bmsbattery. 64 cells shipped comes to $340 (48V 11.6AH). A last-generation Signalab BMS (with leds) on eBay I saw for $60. Total would be $400.
BMSbattery Panasonic Li-Ion bottle battery (11.6ah) $308, but no mention of BMS (?)
BMSbattery High C-rate (15AH) Li-Ion $377 - I guess generic cells
Any other recommended options? Looks like I'll be cruising aliexpress in my spare time.

 

[brooklynboy]

You're welcome. I have very little experience with ebikes and my skill set is similar to yours. The 10 minute testing I did seems to validate the estimates. However without a cycle analyst ( CA ) or ammeter ( mine has 10A limit), I'm reluctant to confirm real life wh/m. The speed I can confirm because a gps speedometer is accurate - or +0.5mph and my goofy grin doesn't affect the results. The other thing is my battery is not 48V, it's 54V ( 62.4V fresh off the charger) and that may affect the efficiency for a 48V controller. This is just a long winded way of saying YMMV.

If you are interested, my test run is here:
http://endless-sphere.com/forums/viewtopic.php?f=14&t=68281

 

[Nobuo]

Nobuo: That went completely over my head the first time - I had to do a re-take. OK, Lithium-ion is not LiPo, got it! What cells did you use on your build and where did you get them? I'm now contemplating building a pack to stay within budget. I'm having trouble finding pre-made packs made with Samsung cells. I did find Samsung cells at Aliexpress. Is that a good place to get them?

The cells I used in the build I mention as an example are 18650 2.85Ah 7A LG cells. I get them from Tumich ES user in Poland. here you have his post about the cells he get from rejected packs. Are completely new cells you need to unsolder.

http://endless-sphere.com/forums/viewtopic.php?f=31&t=61608

go here for wide information including sources to get things --> http://endless-sphere.com/forums/viewtopic.php?f=14&t=68005

The place you get the cells depends of where are you purchasing. Aliexpress/ebay/Alibaba/taodao are the most risky places to get authentic cells, You must be cautious.

Can I get some opinions on these options:
Panasonic NCR18650PF at bmsbattery. 64 cells shipped comes to $340 (48V 11.6AH). A last-generation Signalab BMS (with leds) on eBay I saw for $60. Total would be $400.
BMSbattery Panasonic Li-Ion bottle battery (11.6ah) $308, but no mention of BMS (?)
BMSbattery High C-rate (15AH) Li-Ion $377 - I guess generic cells
Any other recommended options? Looks like I'll be cruising aliexpress in my spare time.

BMS is always included in packs, if not, I wouldn't trust the vendor. To sell a battery without BMS for the public consumer is a recklessness. I bet the BMS is included there but not mentioned.

I would buy the panasonic cells packs/bottles

 

[flyinbrick]

Thanks for all the info everyone - so much to take in and digest.

Brooklynboy, that was one hellova sale on those batteries. I did an analysis on the calculator you linked and it said I would need 9.2ah at an average speed of 25 mph. Factoring in 80% discharge and 10% loss over time, that brings me to 12.8ah. So I'll go for either 12 or 15ah.

Nobuo, that video is as awesome as the pack you made!

Still undecided on what to do. I don't think I want to make a Li-ion pack with 64 cells to deal with. I simply don't have the time for research and construction. So that leaves me with a pre-made Samsung or Panasonic pack and over-budget or maybe Headways DIY kit - I've got access to lugs and wires at work, but that will be bigger and heavier than Li-ion.