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TexasElectric 02-23-2017 02:39 PM

TexasElectric - eBike build
 
Hi, my name is Adam.

I am in the early stages of building my first electric bike. I have been playing with electronic motors and batteries for many years, only in the past year or two I've gotten into circuitry and making my own batteries and super capacitors.

For my ebike I have chosen to use 32650 LiFePO4 cells. The reason for this is because of LiFePO's inherent safety over the more popular 18650 Lithium Ion cells. I purchased 80 32650 LiFePO4 cells. I plan to use 75 of the cells. Each cell weighs approx 145 grams. (75 cells x 145 grams = approx 24lbs)

Each cell is 3.2v 5500mah. 75 cells in a 5p x 15s or 15s x 5p configuration to give me 48v with 27.5mah.

Question 1:
If I connect the cells in a 5 parallel x 15 series configuration, is that the same as a 15 series x 5 parallel configuration? Is there a benefit of one configuration over the other?

Question 2:
What type of BMS (Battery management system) or PCB (Protection circuit board) do you recommend I use?

For the motor I plan to purchase a 48v 1500w direct drive rear hub motor. I plan to buy the motor and all associated accessories as a kit on eBay.

For the bicycle, I will be purchasing a used 26" mountain bike from my local bike shop. My budget for purchasing the bike is $400-$500. -just a side note, i've owned big box store bikes and currently own a high end name brand bike. There is a HUGE difference between the two, at the end of the day you get what you pay for.

I will store the battery and motor controller in a rear rack mounted bag that will sit on top of the rack.

Technical:
I am an avid cyclist, I ride weekly by myself and with a club. On my bicycle I have what's called a power meter. Bicycle power meters are very accurate and very expensive ($xxx to $xxxx). For those that don't know, a bicycle power meter is a strain gauge that measures the torsion (or flex) of the surface it's mounted on. In the case of my power meter, it's mounted on the crank arm. The power meter calculates the RPM of my pedaling cadence and the strain (or flex) of the amount of force I apply to the pedals to give me a number represented in "watts".

My bike weighs approx 14lbs, I weigh approx 150lbs. When fully loaded with water, spare tubes, pump, etc... I estimate the total weight to be approx 170lbs.

When I am riding at a steady pace of 18mph with a 5-8mph head wind, I can hold 18mph by putting out 175-225 watts.

If I estimate this eBike i'm building 'with me included' to weigh: (approx 225lbs)
- Bike 17lbs
- motor 15lbs
- motor controller 1lb
- batteries 25lbs
- me 150lbs :)

Using the data I have from my power meter and the estimated weight/power of my proposed eBike. I estimate I would need 250-300 watts to maintain 18mph on a relativity flat surface with a small head wind. With an estimated range of 80 miles to 95 miles? (48v x 27.5ah = 1320 watt hours / estimated watts needed to maintain 18mph 'ie. 250-300 watts')


I'll post pictures and videos as things progress.


I'm sure i'm missing a few things, but that's what i've got figured out for now... i've got to go to work.:)

vskid3 02-23-2017 11:29 PM

Have you been on Endless Sphere? That's the place to go if you looking for the gritty details of ebikes.

You'll want to do groups of 5 parallel cells in series with each other. Makes balancing/protection easier and I believe there are several other benefits that I can't think of right now. On a related note, "48v" LiFePO4 batteries are 16s, not 15s. Helps keep you from hitting the low voltage cutoff of the controller if you're drawing a lot of power (probably not an issue with such a big pack), gives you more watt hours, and keeps the voltage higher throughout the discharge, allowing more power.

From my experience with my ebike and a ~16lb 48v 15Ah LiFePO4 battery, I highly recommend not mounting the battery to a rear rack. All that weight plus the weight of the motor back there makes for a bike that handles like garbage. If you decide to use a rear rack anyway, I would put half of the battery on each side as low as possible and do whatever you can to make the rack stiff.

Here's my ebike's build thread: http://ecomodder.com/forum/showthrea...ike-28487.html

jjackstone 02-25-2017 12:54 AM

What type of motor? Hub or frame mount? Frame is likely more efficient but hub needs less maintenance. Do you ride in a tuck? Your power levels seem a bit high for a 14 pound bike. You might consider a recumbent bike since they can be more efficient due to less aerodynamic drag. I ride a trike and have about the same speed as you with the same average power output you mentioned. I agree with vskid about keeping the batteries as low as possible. If you're going to run a two horse motor you'll want beefier wheels(at least the drive wheel) to be able to handle the additional torque on them. If you use a hub motor then you'll need a torque arm to attach the motor to the frame so it can't spin out of the dropouts.

Check out Justin at ebikes.ca for controllers and power monitors. I haven't been there in a while but when I had a problem with one of his controllers many years ago he took care of the problem immediately. He also may be able to help you with charging and cell balancing which you need to do with Lifepo4. Good luck with your build. Hope you document it here for us.
JJ

Grant-53 02-25-2017 07:56 AM

Weight balance and aerodynamics are key to a comfortable and efficient ride. A battery box in the frame helps with both. There are a couple options for aero bars. One is to move the bar end grips inboard, about 10 in. apart. The other is to make or buy TT style aero bars. If they are 7/8 in. diameter the throttle should mount easily. A true streamlined body is not on the market yet. You can use the HPV shell design program at recumbents.com to design a shell for an upright bike too.

TexasElectric 02-25-2017 11:15 AM

Awesome feedback from everyone!

vskid3
I have heard of "endless sphere." I've been a long time reader of this forums automotive aerodynamic threads (very interesting stuff), and when I discovered that there was a place to discuss e-bikes I figured why not...

I kinda figured that 15/16 cells in series would be the ideal configuration, I just wanted a second opinion. My thinking is that each cell has a nominal voltage of 3.2 volts, but in reality when fully charged the voltage should be a tiny bit higher (ie. 0.1-0.3 volts higher). With a total of 15 cells in series, (taking into account the tiny bit higher voltage when fully charged) I should get 49.5 volts to 52.5 volts. I could be wrong about the cells being a "tiny" bit higher when fully charged, i'm just going by what I see on YouTube videos. That could be a higher voltage that lasts temporarily once the battery is disconnected from the charger.

I've also given more consideration to where I am going to mount the battery. I am thinking that the more weight I have on the rear wheel the faster the rear tire is going to wear. Plus, as you mentioned the instability/overall poor weight distribution of all the weight being in the rear.

BTW, i've been reading about your e-bike build. It looks very cool. I am glad to see that other people are also using LiFePO batteries over Li-ion. (not that there's anything wrong with anyone using Li-ion aside from explosions and fires :p <--- Just kidding... But seriously be safe/careful with Li-ion)

jjackstone
I will be using a rear wheel direct drive hub motor. I plan to ride the bike is a full upright position (the more comfortable I am the better).

Recumbent bike's look pretty cool, but I would prefer to stay in an upright seated position.

I will look into ebikes.ca (i'll tell them jjackstone sent me :))

Grant-53
I am now working on a new plan/design to mount the batteries just below the top tube and down the seat tube (ie. the inside of the frame. not literally the inside, you know... the outside inside:p)

I spent about 8-10 years of my childhood and now into adulthood (now at the age of 30) riding mountain bikes. 3 years ago I got into road bikes and haven't looked back. With that being said I do prefer a narrower handlebar.

I just googled "HPV shell", that's wild. I've watched many YouTube videos on that stuff. I've got two reasons (or excuses) for using a "traditional" bicycle.
1. It's less obvious to law enforcement that I have an e-bike (should I find myself doing 30mph uphill). Also less obvious to the public/other cars on the road.
2. I have special access to the back of the building I work at. I am able to badge into the building from a service entrance that is relatively out of sight and walk into my office with the bike. (Security doesn't care what I do, but I cant go walking around cubicles with a bicycle or an HPV :p)

I am sure that HPV's are legal on the road (as I have heard many YouTube videos talk about), but I would prefer to be as under the law enforcement radar as possible (ie. less conspicuous) when riding on the road.

Update
I stopped by my local bike shop yesterday to test ride a few different mountain bikes. To my surprise I was able to find new name brand mountain bikes priced around $500 (within my budget). At this time I am leaning towards the Specialized RockHopper. This bike is a 29r. While I would prefer a 26" wheel, I think the benefit of a larger wheel is less power required to maintain speed? (not to mention a smoother ride).

My plan is to use the pedals to get the bike to about 10mph then ease in the electric motor to speed up to and maintain 18-20mph. And of course, assist the motor when climbing up steep hills (of which I'd only have 2 short steep hills on my regular route).

Since I plan to use this bike as a replacement for my car to go to and from work, I will be wearing my work clothes (button down shirt and khaki pants). I can always wear something else (ie. lycra) and change when I get into work, but my idea behind using an e-bike over my regular bike is that I wont be sweaty when I arrive at work.

TexasElectric 02-25-2017 11:56 AM

Step 1 - building the battery:

I watch plenty of YouTube videos of people building battery packs with 18650 Li-ion cells. I see that they use thin strips of nickel to connect them together. Then they either solder or spot weld the nickel strips to the ends of the cells.

TexasElectric 02-25-2017 11:57 AM

I have a problem with this method... As mentioned in many of the videos "if one cell fails, it can cause a problem for the whole pack." Some of these people shrug their shoulders when this happens and either chuck the whole pack or try to salvage it. It's a lot of work to salvage the pack for one cell (depending on the size of the pack). Not to mention a worst case scenario of one of those cells (specifically an 18650 Li-ion cell) going rouge and exploding/catching fire and starting a chain reaction with the other cells.

TexasElectric 02-25-2017 11:58 AM

Here's my plan...
I purchased 4 of these "D" cell battery holders on eBay. They are not tall enough to accommodate the 32650 LiFePO cells, so I will cut the holder in half (see pictures in next post).

TexasElectric 02-25-2017 12:18 PM

Sorry, I had to have 5 posts before I could upload pictures.

Picture of the 32650 cells (80 cells total)

http://i1262.photobucket.com/albums/...pslsafrhxg.jpg

http://i1262.photobucket.com/albums/...pskllw9ln0.jpg

My plan...

http://i1262.photobucket.com/albums/...psby6rxhep.jpg

http://i1262.photobucket.com/albums/...psrrjptjti.jpg

http://i1262.photobucket.com/albums/...psa3tnwlca.jpg

By using these "D" cell battery holders I am able to easily test and replace one cell should it go bad.

vskid3 02-25-2017 01:50 PM

How far are your commute and other rides you would be doing? I would go with the smallest battery that'll get you where you need to go and be able to handle powering your motor, anything bigger will just be extra weight. And why go 20MPH when you have the power to be going 25 or 30? ;)

When I built my bike, not many options for good pre-built batteries existed. I went with my Ping LiFePO4 because they had good reviews and if something went wrong I wouldn't have a chemical fire on my hands. I also wanted enough range to be able to do all my commuting for a typical day on one charge. It's a brick and the worst part of my ebike experience has been trying to find a good way to bring its fatness with me. Fast forward to today and there are several options for 18650-based batteries that are pretty safe and better options for chargers. Right now I would go with a Mighty Mini Cube battery and a Cycle Satiator charger (which I do have) for my current needs. Less than 8lbs and I could go around 10 miles at top speed and recharge in an hour and a half.

TexasElectric 02-25-2017 02:53 PM

vskid3

My daily commute is 14.5 miles (we'll call it 15 miles) one way. 30 miles round trip.

I agree completely about having enough batteries to complete my trip, and not lugging around a bunch of extra weight. Part of my thought behind having the setup i'm proposing (75-80 cells, 15-16 in series x 5 parallel), I can get longer life out of the batteries if I only drain them down to 80% or 70% between charges. Where as if I drained the batteries completely (or nearly completely) they might not last as long?

An average speed of 18mph-20mph is just a figure I am going to throw around until I get the bike built. Who knows, I may actually ride it closer to 30mph once built, (that will depend on real world testing).

3D:

I am very proficient in the 3D modeling/rendering software Autodesk 3DS Max. I will start posting renderings of the proposed battery setup and various other components until the bike is built.

Here's two ideas for the battery:

16 series x 5 parallel (oops, I accidentally only made 4 parallel in the renders, but you get the idea)

http://i1262.photobucket.com/albums/...psg9xawjaj.png

http://i1262.photobucket.com/albums/...psnklodggz.png

Once cut into two pieces, the blue "D" cell battery holders will require something on the back side that I can glue them to (not pictured above). I was thinking maybe thin (3mm) plexi-glass or balsa wood?

skyking 02-25-2017 03:58 PM

Nice project!
I'd face the cell opening all the same direction, and make a template. Then I'd use fiberglass cloth and epoxy to make up the modules. They would be strong and light.
Put a piece of tape across the battery side of the holder to back up the glassing operation.
2 layers of 4 Oz cloth and epoxy would be plenty.
Then I'd make some sort of system that clamps each module into the pack. You could do a quick health check of each module with a meter, and pull out that module to see what was up.

jjackstone 02-25-2017 05:02 PM

You're correct about the batteries. Their nominal state is at 3.2 volts per cell. Full charge level is 3.6 volts per cell which means you would need about a 56 volt charger for full charge on 15 cells. Probably 60 volts to charge 16 cells. I like the battery holders. In most states the maximum legal speed for an ebike is 20 mph on a level surface with no help from the rider. You can go faster with rider input but I would check Texas laws. Apparently California changed the max speed of ebikes to 28 mph a few years ago before they call it a moped which needs to be licensed. Anyway it's good to know your local laws. Your two horse motor should easily go 30 mph if you want it to. My one horse would do 30 with room to spare and that was with 75 pounds of bike, motor and battery plus my 200 pounds. My bike might be in the archives on this site. Can't remember if I posted it here or not. I'll look.
JJ
JJ

jjackstone 02-25-2017 05:23 PM

Not on this site, but found it on Endless sphere.
https://endless-sphere.com/forums/viewtopic.php?t=2339

Mine is near the bottom of the first page.
JJ

vskid3 02-25-2017 09:08 PM

I don't think LiFePO4 really benefits from shallow discharges. I think it's better to only go down to 20% instead of completely discharging it, but most batteries are that way. The new thing with Lithium batteries is only charging to 80%, which gives a pretty good increase in cycles, but I don't think LiFePO4 benefits from that as much. There's some that are of the mindset that extreme babying of batteries to increase the cycles you get out of them isn't really worth it, because the cycles most batteries will give are enough for years of use for most people. By then, the batteries will have also degraded due to time and new batteries will be better/cheaper.

I would probably only do 3 in parallel to save weight, provided the batteries can supply enough power with that many.

A reason I've read that people don't do plastic holders for the batteries is durability. They're fine for a stationary setup, but an ebike is a lot harder on materials.

TexasElectric 02-27-2017 12:40 AM

skyking
That's a neat idea. A few years ago (in 2009) I bought a few sheets of carbon fiber and resin to play around with. Irregardless of what material is used with resin (ie. carbon fiber or fiberglass), the resin will get crazy hard, which is good. It's an idea.

jjackstone
I agree, always a good idea to know the local state laws. I just checked out your bike on Endless Sphere. 72v, wow! I love the idea of high voltage low amperage. I also like your DIY setup of the wooden holder for the batteries.

vskid3
I plan on being careful with the batteries (and the bike as a whole) from the stand point that I'm not going to ride it like a bat out of hell everywhere I go, constantly slamming on the gas and brakes, etc... However, once built I do want to test the upper limits of the bike (see what it's capable of).


Plastic holders
Bad news... The plastic holder idea is dead. The problem with the plastic holders (as I found out this afternoon), is that when connected it creates a short. To illustrate what I'm talking about, Imagine you had 4 batteries connected in parallel. You then take two of those batteries and flip them around (ie. swapping positive for negative). It would create a short. Which is how those plastic holders are designed. Oh well... The plastic holders was an expensive option anyway.


Today's update
Going against my previous post where I cursed the idea of using Nickel strips to connect the cells. I purchased the following items on eBay.

http://i1262.photobucket.com/albums/...pssnknqbp3.png

I am going to use solder to attach the Nickel strips. Later this week I'll purchase a good soldering iron (any suggestions?).

Lastly, I found this video on YouTube for excellent (step-by-step) instructions for making the battery.

https://www.youtube.com/watch?v=BzTOD8GA_nM

Grant-53 02-28-2017 09:15 AM

The more cells in parallel the more amperage is available for torque. Motors draw maximum current at start up and some are designed with capacitors to give that initial boost. My garden shredder is that way as it has a heavy flywheel.

For gearing look at triple chain rings such as 28/38/48T and a rear cluster 28-11T. Check to see that the thumb shifter clears the throttle.

Since you are adept with Autodesk you may be able to use the fluid flow software to determine wind drag. The HPV shell software is designed to do upright bikes as well and the file will transfer. Wayne is very helpful if you have questions. There are a range of options to reduce drag once you get the bike set to where you are most comfortable.

TexasElectric 02-28-2017 12:29 PM

Grant-53
Thanks for the heads up. According to the YouTube video i posed in my previous post (as well as the information on the BMS i ordered), I will be connecting 5 cells in parallel and then connect each parallel stack in series (16 total).

I'll look deeper into HPV shell software. As you say, i'm sure there is some compatibility between Autodesk products.

Update:
My next purchase is going to be a bicycle. In the next 2-3 weeks I plan to make a purchase. I am going to check out used bikes before making a new bike purchase. I've been lucky to find a lot of used 26" full suspension bikes on craigslist (some are local, some are not).

I am going to wait to construct the battery pack until I purchase a bike, because I don't know how the frame will be configured (full suspension geometry is different than hard tail geometry). In the mean time I will make sure I have all the appropriate gear/equipment to assemble the battery.

teoman 03-08-2017 03:28 PM

You could find a pvc tube or carbon fibre tube and stuff the batteries in there to get one series chain.

samwichse 03-09-2017 02:46 PM

From what I understand, soldering LiFePO4 batteries will make you sad. Spot welding your nickel tabs is what you really want to do. My batteries (which are totally wrong for ebike use, but I got them cheap... $7/cell and I'm just doing 1P) are screw terminaled with solid bus bars and heavy duty interlocking plastic holders.

They look just like this:
http://www.copybook.com/media/milita...er_Cell800.jpg
https://www.copybook.com/companies/goodwolfe-energy

What motor are you looking at? I recently got a Bafang BBS02 mid drive. The kit is very complete and the only thing you really need to supply yourself is the battery+bms.

As for BMS, the best one for LiFePO4 is the SignalLab (now Ping Battery). That's what I've bought. I did my initial chargeup and everything is going well. I just need to wrap/mount my battery now: What's new on V5 LiFePO4 BMS (Battery Management System)? - PingBattery

Grant-53 03-10-2017 08:15 PM

Look for mountain bikes with the spring/shock parallel to the seat tube. Or my Jamis Aragon has a shock seat post and spring handle bar stem along with a spring seat. Very comfy and light with the aluminum frame.

TexasElectric 03-14-2017 12:51 PM

teoman
I've investigated the idea of using a plexi-glass tube to put the cells in series, but the problem I ran into was the cells have a 32.75mm diameter and the closest sized tube I could find was 1 1/2 inch (38.1mm) inner diameter tube. I'd have to play around with securely filling the 5.35mm gap between the cells and the inside of the tube. For the time being I've tabled the idea.

samwichse
I've since backed away from my plans to solder the cells. I'm going to spot weld them.

PS. I'd love to have "screw terminaled" cells, sounds like they'd be easier to work with.

I'm considering kits from eBay. There is a seller in Michigan "eBikeling". He sells Chinese no name hub motors, and brands them with his companies name. I know this because his hub motors and rims use the exact same make/model parts as most other no name Chinese hub motors on eBay.

48V 1500W Direct Drive REAR 700C eBike Kit Electric Bicycle Ebikeling | eBay

What's nice about this guy "eBikeling" is that he is based in the US and offers free shipping, whereas the Chinese sellers are asking over $100 for shipping to the US.

I know about the stigma of buying no name Chinese products. Although, 3 years ago I purchased a set of no name Chinese carbon fiber wheels for my road bike on eBay. I put around 2,000 miles on those wheels, I had multiple situations where I was riding at speeds in excess on 40+mph with no concerns of them failing on me. I sold the wheels right around 2,000 miles of use because I needed the money more than the wheels, but they were still in good condition when I sold them.

My thoughts with this motor is that (irregardless of who/where I buy it from), I plan to only use this 1500w motor at 1/3 or less of it's full potential and by doing so it should last a long time: as apposed to buying a 250w or 500w motor and pegging it at 100% every time I use it. Plus it doesn't hurt to have a little extra power.;)

Grant-53
I will look into mountain bikes with suspensions in that configuration.



Update on where I stand today
Last week my BMS arrived from China. (fast shipping, only took 10 days)

http://i1262.photobucket.com/albums/...psnqailmqe.jpg

http://i1262.photobucket.com/albums/...ps2wk3tmxu.jpg

In addition to the BMS, the Kapton take I ordered arrived. I need to re-place an order for Nickel strips. I accidentally bought Nickel platted tape instead of strips. :rolleyes:

I am moving at the end of this month, but before I can move I have to take care of some maintenance to my home. In my free time I will continue working on assembling the battery.

I flip-flopping back to the idea of using a 29r mountain bike. My research online (as well as talking to the local bike shop mechanics), tells me that 29r mountain bikes use 700c rims (same as road bikes). My biggest concern is being able to find a good quality bike. I know Specialized makes good quality bicycles, (as I am currently thinking about buying a brand new RockHopper 29r for this build). But finding a used 26" name brand mountain bike (full suspension or hardtail) that's my size, in good condition and priced around $500-$700 is hit or miss.

Lastly, this is a new configuration I am looking at for my battery. The battery pack (once assembled) would be mounted on the down tube.

5p, 16s

http://i1262.photobucket.com/albums/...psat0fxf3r.png

I don't wan't to come off sounding like a snob when I talk about buying a brand new name brand bike. In the past I've bought el-cheapo stuff (electronics, bikes, cars, etc...). Sometimes you get lucky and you discover a diamond in the rough, but generally speaking "you get what you pay for." My current bike is a Colnago cyclocross bicycle. It's not cheap ($,$$$) by any means, but I've had it for over 3,500 miles and it's required very little tweaking/tuning and takes a beating from time to time.

For my e-bike build, my feelings are that the bike is the foundation (and should not be skimped on). The Batteries I bought are good quality (not el-cheapo). The motor I am considering (from eBikeling) is rated for 1500w, if I only use 300w-400w of the motors potential it should last a long time. Likewise the BMS I bought (albeit a no name Chinese brand) is rated at 48v 60a, if I'm running 6-8 amps through it, it should also last a long time.

I would have purchased the BMS through a name brand US seller, but I was unable to find a LiFePO4 48v 60a BMS for under $100 in the US.

samwichse 03-14-2017 03:41 PM

This is going to come as a weird recommendation, but Costco's mountain bikes are a steal for the quality:
http://https//m.costco.com/Diamondba...100303215.html

The tube welds are nice and even, the hardware is all decent mid-grade stuff... if you can get over the Diamondback name, you won't find a nicer ebike project base for $400 IMO.

Quote:

Specifications
Color: Green
Frame: Overdrive 27" Butted 6061-T6 Aluminum with Formed Top / Down Tube, Machined Headtube, Forged Drop Outs with Replaceable Hanger, disc only
Fork: SR Suntour XCT, 80mm Travel, Coil Spring, 28.6mm Stanchions
Headset: FSA IS-3 Integrated
Cranks: Suntour XCT, 42/32/22T
Bottom Bracket: Square Taper - 5pc
F. Derailleur: Shimano TX50, Top Swing, Dual Pull, 34.9mm Band Clamp
R. Derailleur: Shimano Acera M360 8spd
Shifter: Shimano Altus EF-51 8spd
Cogset: Shimano HG-31 8spd Cassette (11-32t)
Chain: KMC Z82
Brakes: Tektro Aries Mechanical Disc w/ 160mm Rotors
Brake Levers: Shimano Altus EF-51
Front Hub: 32h SL-7 Alloy w/ CNC Disc Mount
Rear Hub: 32h SL-7 Alloy Cassette w/ CNC Disc mount
Spokes: Black 14g Stainless Steel
Rims: DB SL-27 27.5" 32h Doublewall
Tires: Chaoyang Hornet 27.5x2.1
Handlebar: DB Laser Series, Low Rise, 600mm Wide, 31.8mm Bar Bore
Grips: DB4L 135mm Kraton
Stem: DB AL6061 Ahead, 31.8mm, 7°
Seatpost: DB Micro Adjust 30.9mm
Seat: DB Race s M-series saddle
You can usually find them in store if you want to go take it for a spin, although beware the store demo models are apparently assembled by chimpanzees (out at least employees with no clue about bicycles). Is be using one myself if I wasn't so in love with my old Trek 820.

Grant-53 03-14-2017 05:34 PM

The Diamondback bikes are well known. Mongoose built a suspension with a lever and a shock just in front off the seat tube. Lots of options.

TexasElectric 03-15-2017 11:18 AM

samwichse & Grant-53

When I got back into bicycling (4 years ago), the bike I purchased was a DiamondBack mountain bike. I grew up riding DiamondBack mountain bikes. I like the brand a lot. I have given consideration to their bikes, kind of a maybe...

I rode with a guy for 2 years, he had a GT mountain bike. He liked it a lot, no problems. There are definitely other options.:)

samwichse 03-15-2017 11:24 AM

I only meant that some people get snooty about them because Wal-Mart sells some of their cheaper bikes.

A lot of people won't get caught dead riding a "Wal-Mart bike" for... ego(?) reasons. No matter what the quality.

vskid3 03-16-2017 02:21 AM

Quote:

Originally Posted by samwichse (Post 536172)
I only meant that some people get snooty about them because Wal-Mart sells some of their cheaper bikes.

A lot of people won't get caught dead riding a "Wal-Mart bike" for... ego(?) reasons. No matter what the quality.

Do they sell Diamondback bikes? I've never seen one in their stores and the only 2 I can find on their website look like they come from third party sellers. Walmart has some decent bikes if you know what you're looking for and/or upgrading most of the parts, but the average person looking for a reliable bike would probably be better off visiting a bike shop.

TexasElectric- With the lower speeds you're planning on riding, a decent hardtail with wide tires should do great. You'll have a lot more room inside the triangle for your battery, too.

Grant-53 03-16-2017 05:28 PM

There was an issue with some of the low end bikes such as Next having poor wheel bearings and clunky components. I'm building a mountain bike out of spare parts and a Next frame left for junk. If the screwdriver fits your hand use it. If someone wants to name their dog 'Phydeaux' let them. My Huffy 3 speed will be 50 years old this spring!

Shortie771 03-24-2017 09:45 PM

Definitely following this. Keep up the good work! Will pedal power assist in recharging the batteries on this?

I've been floating around the idea of building an enclosed electric reverse trike for running into town (about 4 miles) for things. Maybe even to and from work, but that's about 15 miles of mostly interstate each way.

vskid3 03-25-2017 02:17 AM

Quote:

Originally Posted by Shortie771 (Post 537022)
Will pedal power assist in recharging the batteries on this?

Some kits/controllers support regen that's enabled through either the brake switch or another switch. They're good for recovering some power when braking, but you're better off to power the wheel directly with the pedals than trying to charge the battery. It's more efficient to power a bike with electricity than a human/food, so trying to use a human to charge the battery will just make the human power that much worse (PDF of a paper comparing ebike to human powered bike). You can pedal in addition to the motor for increased range or acceleration, but it doesn't actually charge the battery.

Shortie771 03-25-2017 09:23 AM

Quote:

Originally Posted by vskid3 (Post 537031)
Some kits/controllers support regen that's enabled through either the brake switch or another switch. They're good for recovering some power when braking, but you're better off to power the wheel directly with the pedals than trying to charge the battery. It's more efficient to power a bike with electricity than a human/food, so trying to use a human to charge the battery will just make the human power that much worse (PDF of a paper comparing ebike to human powered bike). You can pedal in addition to the motor for increased range or acceleration, but it doesn't actually charge the battery.

Just the kind of of info I was looking for... And more. Thanks.
I wasn't aware that you could pedal along with the motor to increase range by taking some of the load. That does seem much more efficient. I just never thought of that I tend to over complicate things in my head.

Grant-53 03-27-2017 12:16 PM

Shortie771: First check all state and local ordinances on bikes and e-bikes. Interstate highways are usually off limits to limited use vehicles, e-bikes, horses, and pedestrians. A reverse trike or tadpole design with a body shell is also known as a velomobile. There is an enormous amount of information at recumbents.com on building trikes. The least expensive way to go is to build a trike from square tubing and get the body from Blue Sky Designs. The only drawback is the low seat heights may make it difficult to see and be seen in traffic. I suggest having your eye level at 36+ inches when your seat back angle is 45 degrees. A good aero package with a ventilation system copied from sailplane designs helps too.

Shortie771 03-27-2017 12:39 PM

Yeah I don't think I would ever take a bike (of any sort) on that interstate. The speed limit there is 75mph and most people go 80mph, not me ofc. I used Google maps to see if there is another way without highways and there is. It's about the same distance on county roads. Didn't mean to sidetrack the thread...

How is the project going? Any updates?

Grant-53 03-28-2017 03:02 PM

Balky shifters and too much run out on new chain rings. I need to double check the frame alignment too. Still fine tuning the rear tailbox design as it is critical to low drag.

TexasElectric 05-09-2017 12:07 PM

May 9th Update
 
Here's where I stand on this project...

The items highlighted in red are on order (should arrive in the next week).

eBay
$289.99 - 1x, 48V 1500W Direct Drive REAR 700C eBike Kit Electric Bicycle Ebikeling
$119.99 - 1x, NEW Box of 80 Tenergy LiFePO4 32650 3.2V 5500mAh Rechargeable Batteries 5.5Ah
$48.49 - 1x, 48V 60A LiFePo4 Battery BMS LFP PCM SMT System 16S 16x 3.2V eBike Battery 16x 3V
$42.90 - 1x, Topeak TT9646B MTX EX Rigid Trunk Rack Bike Bag QuickTrack System 480ci
$39.84 - 1x, Topeak Bike Rack Rr Explorer Mtx 29, Black
$24.04 - 1x, 8 Gauge Silicone Wire 20 feet 8 AWG Silicone Wire Flexible Silicone Wire
$22.49 - 1x, Joe Rocket Velocity 2.0 Street Motorcycle Gloves
$20.99 - 1x, 20 feet of Pure Nickel Battery tabs for spot welding 0.2mm Heavy Duty DIY Pack
$15.88 - 2x, 6 Modes COB 1 LED Bicycle Bike Cycling Front Rear Light USB Rechargeable Battery
$8.30 - 1x, 25 mm x 33 m Gold Kapton Tape Polyimide High Temp 1" x 36yds 25mm; US stock

Amazon
$78.66 - 1x, HJC FG-X Legendary Lucha Off-Road Motocross Helmet (MC-3H, Medium)
$43.23 - 1x, Cygolite Metro 700 USB Rechargeable Bike Light, Black
$19.90 - 1x, SCOTT Recoil XI Adult Motocross MX UTV ATV Goggle Black Anti-Fog Clear Lens

Richardson Bike Mart - Frisco (Local Bike Shop)
$676.56 - 1x, 2017 Specialized RockHopper Sport 29r (XL Frame)

Home Depot
$21.42 - 2x, (4'x0.5"x3.5") Oak wood
$3.00 - 8x, Washers
$1.35 - 4x Screws

Still needed:
- battery charger
- Matte black spray paint
- EVA foam
- wire connectors
- 1/4 inch wood paneling (for the sides of battery box)

Total up to this point:
$1477.03

This past weekend I purchased the bike from a local bike shop. I decided to buy the Specialized RockHopper Sport 29er (one model up from the base RockHopper) because this bike has hydraulic brakes. I figure hydraulic brakes should preform better over mechanical brakes when braking from high speeds.:)

I estimate that I should have the bike completely built and functional in about 2 weeks. Once complete I'll be riding it 70 miles a day (35 miles each way to work). I plan to use a combination of pedal assist and motor only. I would like to be able to maintain an average speed of 25-30mph on the flats. I will do some testing on watt usage as soon as I finish building the bike.

samwichse 05-09-2017 12:12 PM

So you're going to do 16S5P?

Where did you find the cells so cheap? That's a heck of a price.

EDIT: NM, it's DougDeals on Amazon. ~$30 shipping, still a good deal. If only they were easier to connect.

TexasElectric 05-09-2017 12:20 PM

samwichse
Yes, I will be doing 16s,5p for a total of 27.5 amp hours.

I bought the cells on eBay (brand new):
NEW Box of 80 Tenergy LiFePO4 32650 3.2V 5500mAh Rechargeable Batteries 5.5Ah | eBay

Picture of the bike:
http://i1262.photobucket.com/albums/...psfjfz9qcl.jpg

Picture of the wooden frame for holding (most, but not all of the cells). The remaining cells will be stored in the rear mounted bike rack.
http://i1262.photobucket.com/albums/...psw11bjero.jpg

I also decided to buy a motocross helmet and goggles. I figure if i'm going to be traveling at speeds of 25-30mph, should I have a crash I want my head/face to be well protected. I regularly hit speeds of 30-40+mph on my cyclocross bike, but only for a few seconds (5-15 seconds at a time) and I feel comfortable wearing a regular bicycle helmet.

My thinking is that since this eBike will weigh around 75lbs (compared to my cyclocross bike at 13lbs), if I had an accident I'd have more mass accelerating me toward the ground or a tree. Think of two vehicles traveling down the road at 30mph, one is a semi truck with a full load, the other is a 4 door sedan. Both slam into a wall and come to a full stop. The likelihood of the semi truck driver walking away is slim because of the large mass, vs the driver of the sedan. (I don't know... that's just my 2 cents. Maybe i've watched too many YouTube videos of car crashes, lol.)

http://i1262.photobucket.com/albums/...psgarzhwgb.jpg

TexasElectric 05-09-2017 01:40 PM

Some other things i'm thinking about...

After reading a lot of different articles online about eBike speeds and watts, and watching a bunch of YouTube videos of people scientifically testing their eBikes I've decided I want to do the same. For example...

1. I've seen similar build eBikes use 400-450w to maintain 20mph. This would mean I could hypothetically get 61-68 miles on a full charge at an average speed of 20mph (assuming minimal wind and relatively flat roads). I am curious to know how many watts will be used at 25mph and 30mph (or even 35mph)? Plus I need to test watts used for pure electric vs pedal assist.

2. I plan to use the tires that came on the bike (29x2.1) knobby tires until they are bald. Once they are ready to be replaced, I am looking to replace them with a 700x35, 700x40, or 29x1.5 non-knobby tire. The idea being that I'd have less rotational mass and rolling resistance but still have good contact with the ground. Plus (in theory) a smaller/smoother tire should use less watts to maintain speed.

3. Lastly, I'm giving consideration to buying a few more LiFePo4 cells for 16s,7p for a total of 38.5 amp hours. The total weight of the battery with the addition of 2 additional cells in parallel would be 36lbs (compared to my current setup at 27lbs). If the addition of 2 more cells in parallel would allow me to ride at an average speed of 30mph (for my ride of 35 miles, one way), i'd consider it. But, i'll make this decision after doing a bunch of testing.

samwichse 05-09-2017 02:06 PM

My bike has a 500w motor. All out on level ground is about 27-28mph without pedaling (I run out of pedals around 24-25mph with my gearing).

Actual battery watts drawn is more like 700-750 at that speed, if that helps your calculations any. Let's say you need ~800w for 30mph cruise with pedaling and slight elevation changes. Your upgraded battery would be 1.85 kwh. That means you'd go 69 mi at 30mph. Your current setup is good for 50 mi at that speed.

The upgrade doesn't sound worth it unless you can't charge at that 35 mile destination.

vskid3 05-09-2017 02:23 PM

Quote:

Originally Posted by TexasElectric (Post 540259)
Some other things i'm thinking about...

After reading a lot of different articles online about eBike speeds and watts, and watching a bunch of YouTube videos of people scientifically testing their eBikes I've decided I want to do the same. For example...

1. I've seen similar build eBikes use 400-450w to maintain 20mph. This would mean I could hypothetically get 61-68 miles on a full charge at an average speed of 20mph (assuming minimal wind and relatively flat roads). I am curious to know how many watts will be used at 25mph and 30mph (or even 35mph)? Plus I need to test watts used for pure electric vs pedal assist.

My ebike used 25-34 wh/mile over a trip with me doing 25-28MPH and mainly only pedal assisting when accelerating (you'll likely have to change the gearing to be able to pedal at top speed). Your battery is about 1400-1500wh, 35wh/mi would give you a range of about 40 miles.

Quote:

Originally Posted by TexasElectric (Post 540259)
2. I plan to use the tires that came on the bike (29x2.1) knobby tires until they are bald. Once they are ready to be replaced, I am looking to replace them with a 700x35, 700x40, or 29x1.5 non-knobby tire. The idea being that I'd have less rotational mass and rolling resistance but still have good contact with the ground. Plus (in theory) a smaller/smoother tire should use less watts to maintain speed.

How smooth are the roads you'll be riding? 30MPH on a hardtail can be hard on the backside. Do some research about the skinny tires, I believe I've read that the "logically" best route of skinny and high pressure isn't necessarily the lowest rolling resistance.

Quote:

Originally Posted by TexasElectric (Post 540259)
3. Lastly, I'm giving consideration to buying a few more LiFePo4 cells for 16s,7p for a total of 38.5 amp hours. The total weight of the battery with the addition of 2 additional cells in parallel would be 36lbs (compared to my current setup at 27lbs). If the addition of 2 more cells in parallel would allow me to ride at an average speed of 30mph (for my ride of 35 miles, one way), i'd consider it. But, i'll make this decision after doing a bunch of testing.

Going to 6p or even sticking with 5p might be good enough, as I figured above. It comes down to just how much power your setup actually ends up using, how much you're willing to push the batteries, and how much cushion you want to have to account for headwinds or days that you don't pedal much.

For a charger, check out the Cycle Satiator. It's expensive, but you're certainly getting what you pay for. You could take it with you to charge at work and not have to worry about it falling apart like most chargers.


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