Sun-Thing28 Ebike Kit Build

[ipub]

lo,

I am going to build a simple commuter bike and decided that I may as well try an all in one kit as a first entry into the world of ebiking. I've ordered and just taken receipt of an ebay seller in china called sun-thing28 who I've seen various reviews about. Afaik he is just an individual with an interest in the field. I've no idea who makes the motor I've received.


Donor Bike (vbrakes)
https://lh4.googleusercontent.com/-dz3l99LrqhU/Ud2ZQeJxrDI/AAAAAAAAEVQ/pgFJqJNLIIo/w958-h540-no/IMAG0620.jpg

Ebike Kit (bog standard ebay 2012 kit 1000w, 48v 20ah huge lifepo battery on its way)
https://lh3.googleusercontent.com/-C1lywzQILF0/UjsmhKcFBWI/AAAAAAAAExw/Sx4ysRLbe7Y/w464-h823-no/IMAG0709.jpg

Hopefully I can use this without the disc brake...
https://lh6.googleusercontent.com/-Kv364ecSpes/UjsuDLYYCnI/AAAAAAAAEyI/rtf6kHfGx_0/w464-h823-no/IMAG0710.jpg

Is anybody interested in me blogging my progress on here?

 

[mark5]

Sure, why not--there's not that much info on Sun-Thing28's products here right now.

 

[dogman dan]

Use this thread for asking questions about getting it done.

Then when you are up and riding, start a new thread in the review section, and detail all the good and bad about your experience in one easier to follow summary.

How do you plan to carry the battery? 48v 20 ah is a big chunk to stick on a rear rack.

The donor bike looks good enough, even though it's a cheap bike. Good dropouts for a rear wheel. The rim will work with V brakes, so you don't have to keep the disk.

 

[dnmun]

if you could find a bike with disk brakes on the front and use that wheel if would be best. or is this a rear wheel?

 

[Needmorespeed]

lo,

I am going to build a simple commuter bike and decided that I may as well try an all in one kit as a first entry into the world of ebiking. I've ordered and just taken receipt of an ebay seller in china called sun-thing28 who I've seen various reviews about. Afaik he is just an individual with an interest in the field. I've no idea who makes the motor I've received.


Donor Bike (vbrakes)
https://lh4.googleusercontent.com/-dz3l99LrqhU/Ud2ZQeJxrDI/AAAAAAAAEVQ/pgFJqJNLIIo/w958-h540-no/IMAG0620.jpg

Ebike Kit (bog standard ebay 2012 kit 1000w, 48v 20ah huge lifepo battery on its way)
https://lh3.googleusercontent.com/-C1lywzQILF0/UjsmhKcFBWI/AAAAAAAAExw/Sx4ysRLbe7Y/w464-h823-no/IMAG0709.jpg

Hopefully I can use this without the disc brake...
https://lh6.googleusercontent.com/-Kv364ecSpes/UjsuDLYYCnI/AAAAAAAAEyI/rtf6kHfGx_0/w464-h823-no/IMAG0710.jpg

Is anybody interested in me blogging my progress on here?

I've got an old sun thing motor on my dual drive. I'm running 72v through it and is ok on that. It's been through the wars and I've abused it a lot but it still going strong! Apart from having to replace the rear crank fitting as the motor one broke!The only thing I'm using from the kit is the motor. I've sold the life batts and gone for some lipos instead. And now running a Lyen controller on it. I've got no idea where the motor originated from either I'm afraid. Good luck!

 

[ipub]

Thanks guys. As much as I've read in the last year on this forum I still feel like a complete noob.


I'll get started once I receive the battery in the next few days. It's taken 57 to receive the hub
Suspect the boat was powered by steam.

Motor is a rear hub from this kit :

http://www.ebay.co.uk/itm/2013-48V-...porting_Goods_Scooters_LE&hash=item1e7ca5417f

I bought directly saving some cash on ebay fees. Not something I would typically do but the process was painless. Also got two chargers so I can leave one in my garage and one for work / spares. Commute to work is 8.4 miles by road or 7.4 by canal tow path - round trip. I've done this before and it is an enjoyable ride but I hate arriving at work stuck to my clothes. Speed isn't important but I expect to cruise at 15 - 20


To do / Concerns:

- x2 front 2100 lumen and one rear USB lights, powered by a seperate battery source. (It's getting dark and wet in the UK)
- Need to buy or make rear torque arms.
- Check to see I can mount without the disc brake block on the hub ( which seems removable )
- Fit the ebrakes to my existing brakes as they are intergral to my gears
- Donor bike is 21 speed, ebike comes with a 6 gear cassette so not sure if I should just put my existing cassette on or not.
- Planning on middle mounting the battery and controller into the triangle. Probably into a wooden frame bolted to the triangle?
- I then plan on covering this with a custom made water resistant ebike bag similar to :
https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-prn1/72287_359619794167569_757756948_n.jpg (It's getting dark and wet in the UK)

My main issue with the kit are the awful headlights / power monitor in the above ebay link. I don't have any other way of checking battery power so for now it will have to do. I'm not sure this set up warrants anything expensive such as the cycle analyst. I've seen another chinese bluetooth to mobile option which I may consider but I'll see how I get on if there are no

Open to suggestions otherwise

 

[ipub]

Can anybody tell me how I take the freewheel off? None of my tools seem to get any purchase on the hub.
Wasn't quite expecting to fail at step one.

 

[TheBeastie]

Any standard bike proceedure is available on youtube.
http://www.youtube.com/results?search_query=remove+freewheel&oq=remove+free&gs_l=youtube.1.0.0l10.1953.4817.0.7236.11.11.0.0.0.0.229.1790.3j1j7.11.0...0.0...1ac.1.11.youtube.27tknoE4QSg

Get the tool from ebay, you want a non-cassette type.. a threaded freewheel removal tool
http://www.ebay.com.au/sch/i.html?_odkw=bicycle+freewheel+remover&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.Xbicycle+freewheel+tool&_nkw=bicycle+freewheel+tool&_sacat=0

 

[ipub]

That's what I'm using, doesn't seem to grip into the hub. I'm just doing it wrong?

This is my tool set, bottom right I think
https://lh5.googleusercontent.com/-zTYJ_ee_4b8/UgPUO4tM8EI/AAAAAAAAEhs/Rro8wfF62GI/w944-h532-no/IMAG0655.jpg

 

[TheBeastie]

Might be a weirder type of freewheel, maybe some one else on the forum can identify it so you can buy the correct freewheel unlocking nut-ring thingy.
If your taking it off the old wheel to put on your new motored-wheel odds are it wont be compatible, just buy a compatible freewheel and toss the old wheel+freewheel and you will save money/time trying to find the correct tool.

 

[ipub]

I've got an old sun thing motor on my dual drive. I'm running 72v through it and is ok on that. It's been through the wars and I've abused it a lot but it still going strong! Apart from having to replace the rear crank fitting as the motor one broke!The only thing I'm using from the kit is the motor. I've sold the life batts and gone for some lipos instead. And now running a Lyen controller on it. I've got no idea where the motor originated from either I'm afraid. Good luck!

I think this freewheel might come off with a shimano tool but that doesn't fit over the axle. Is there a way of taking that off as it doesn't seem obvious to me. I am a noob but I'm trying to learn!

 

[pdf]

You need a freewheel removal tool with a large enough opening.
http://www.ebikes.ca/store/photos/FWTool.jpg

or you can drill a big hole in one without it.
Most people just buy a freewheel if there isn't one on the motor. They can be a bear to get off.

 

[TheBeastie]

That's what I'm using, doesn't seem to grip into the hub. I'm just doing it wrong?

This is my tool set, bottom right I think
https://lh5.googleusercontent.com/-zTYJ_ee_4b8/UgPUO4tM8EI/AAAAAAAAEhs/Rro8wfF62GI/w944-h532-no/IMAG0655.jpg

It looks like that tool at the right container bottom middle looks like it.
If your new motor wheel doesn't have a freewheel on it you can just buy a new freewheel and put it on with out a tool, it just screws on, you only need the special tool to take it off.

 

[ipub]

It looks like that tool at the right container bottom middle looks like it.
If your new motor wheel doesn't have a freewheel on it you can just buy a new freewheel and put it on with out a tool, it just screws on, you only need the special tool to take it off.

Definitely doesn't fit unfortunately so for now I am stuck with the cassette. Literally a couple of millimeters too big. I've given up with that for now and spent the last couple of nights truing the wheel as it arrived buckled and bent. I'm not sure what I expected but I didn't expect any of this in the build so far. I've never done this before so it's an interesting learning process.

The good news is that the hub fits the rear dropouts quite well (with some encouragement).

I'm not sure if I needed one or not but I also got hold of a torque arm which fits the precut holes in the frame. These things are like goldust in the UK and I don't have the confidence to manufacture one from scratch on my first build.

My sun-thing28 battery also arrived, it is pretty huge and also heavier than expected. It's going to be tricky getting everything to fit into the frame.

the size of controller about 30*11*6 cm
the size of batttery about 27*15*14 cm

[*]https://lh3.googleusercontent.com/-...AAAAE1M/0qlFkIHj87w/w464-h823-no/IMAG0719.jpg

No idea what the writing means. Sold as Life-po4. I'd say it was about 8 - 9 Kg.
[*]https://lh6.googleusercontent.com/-...AAAAE1A/Ak4Tc7bUFyk/w958-h540-no/IMAG0718.jpg

 

[dogman dan]

I think it's pretty much standard for you to need to spread the frame just a few mm with that design of motor.

Steel, bend it all you want, Alloy you can still flex it 2-3 mm on each side with no damage or risk. Add washers as needed to get the thing to line up and not rub any frame parts with the gears.

Since you will not be using disk, it can be a possibility to cut the notch on the other side. But that means dishing the wheel to re align the rim.

The rim arriving in bad shape is standard with these cheapest kits. The first 50 miles will stretch the spokes a lot, and it will require at least one more truing very soon after you start riding.

Carrying a 48v 20 ah pouch lifepo4 pack is a bitch. It's too big. Ideally, you get that size split in half to carry each half in a pannier.

 

[ipub]

I spent three hours (my first time) truing the single wall rim it came with to find that whilst it turned ok, it's buckled all over the place and is of such poor quality I'd be amazed if it lasts over any bump. This is the risk buying from a man in china. I've not mentioned it to sunthing28 as I doubt there is anything he'd be able to do, assuming he didnt know what he was sending was factory spoilt (or drop kicked by himself whilst boxing up.)

I've given in and taken it to a local bike shop to replace the rim and probably the spokes. Why is nothing a standard size?! Even the spokes are too long for another rim. This may take a while..

 

[skeetab5780]

I have the ParkTool Fr-5 freewheel removal tool, i got it thinking it would take my freewheel off my Gm 48v 1000w. First problem i ran into was the axle wouldn't fit thru the tool...so i filed the hole larger only to realize it didn't fit just like in your scenario. There's many different styles so if you buy another don't get the one i got. I ended up taking the motor side cover off and bringing it to the LBS for them to use the correct removal tool.

Your spokes are probably a different length due to you putting on a better rim(double walled) so you ERD effective rim diameter has changed from that of your stock. I hate dealing with wheel but theres alot of great wheel builders here that can chime in.

 

[ipub]

well, I gave up and had a new double wall rim fitted which goes with the two tone of the motor :

https://lh5.googleusercontent.com/8rrh8c9r501RySgRKlHK_k0tfonJIR5qhBynr-I50mc=w338-h597-no

I've ordered two schwalbe marathon tyres. I'm no expert but they seem to be recommended and I'd rather not repair a puncture on a 35 - 40kg bike on the way to work.

With hindsight, I would have ordered two 10ah batteries rather than one 20ah battery. As you can here here, there is no way this is going to comfortably fit :

I'm going to have to split the pack. Starting to wish I bought a ready made bike

Some photos of me cutting up the battery for anybody interested :

https://lh6.googleusercontent.com/-pGFbNWyxgP0/UnAcqJ-LqqI/AAAAAAAAFK0/lZwbOcC0xjc/w958-h542-no/IMAG0762.jpg
https://lh4.googleusercontent.com/-B9XrCbACqFs/UnAeAxJqgkI/AAAAAAAAFLI/_6KvD0gcuVo/w338-h597-no/IMAG0763.jpg
https://lh5.googleusercontent.com/-kvTyYcHSvSE/UnAeRNnWX_I/AAAAAAAAFLU/VkcXO2MS-xU/w338-h597-no/IMAG0764.jpg
https://lh4.googleusercontent.com/RQj3CIxWDfFJ9I1-OG9_74fz4OpwrvXo0GZnfsFvR7o=w958-h542-no

So if I split the pack into two, I should get the best mix between width and shape. This design cuts the width (14.5cm) in half.

https://lh6.googleusercontent.com/-wZH9Awjz3eo/UnAlmEL_yXI/AAAAAAAAFLs/CstUbWdNlEQ/w958-h542-no/IMAG0765.jpg


Wife is not happy about the mess..

 

[ipub]

Incremental update.

I've cut the pack in half (more or less) with a bit of a gap on one half for the bms. The kettle lead plug socket was part of an extension. I found this extension made by wrapping two wires together with electrical tape rather than solder. I figured this probably wasnt safe and removed it.

I used what made the extension to solder the two packs together as pictured by tinning solder onto the cell tab.

Initially i wanted this to be a removable pack. I'm still convinced it's too heavy to move around but just in case, I'm going to box this up into a hardboard frame.

I think this was probably the trickiest part of the project. I believe Sun-thing28 is able to repack these as required but without knowing the cell sizes it was tricky to know what to do. The quality of the built battery was acceptable but it's obvious some shortcuts were made. There is no writing on any of the cells so I'm not sure if there is a way to identify what I have purchased.

 

[dnmun]

you will need to increase the size of the cable that connects the two sections of the battery together. it should be at least 12 or 10 is better, and the sense wire should be soldered into the middle of the wire between the two packs, even if you have to add an extension onto the sense wire to reach it.

you want it in the middle, between the two sections.

just tack it to a spot you cut through the insulation on the side of the stranded, flux it and solder the sense wire to the conductor.

that divides the voltage drop on that section of wire so the cell has equal amounts of the delta V from the sag. so the larger the wire the less of a problem it is for causing LVC too early.

 

[ipub]

I see what you're saying. I wasn't sure about cable thickness, I just used what came with it so thought that would be enough. I think it's about 6mm?
Does this mean I need to replace the cables to the kettle lead plug ?

As for the sensor wires, I haven't moved them, they all connect to the other side of each cell and are soldered in place. Are you saying I should move the one for this cell to the middle of the green cable between the two split packs?

 

[dnmun]

yes, only this piece in the middle is what i am talking about. what you try to do is keep the voltage drop across this piece of wire small and the voltage sense wire has to be attached in the middle of that piece of wire. so use a large diameter wire, and stranded since the two sections move with resspect to each other.

this extra voltage drop on cell #8 on top of the voltage drop inside the cell from internal resistance will cause the #8 cell to hit the LVC earlier than the others so you split that voltage drop between the #8 and #9 cell to reduce the impact of sag on just that one channel, #8.

 

[ipub]

I will check the voltage drop when I'm ready to hook it all up. If I have to change the cable between the packs, should I be doing the same to the cable to the kettle plug? This is the cable that came with the battery so I assumed this would be good enough. The controller has no values on it so I have no idea how many Amps are going through.

In other news, I took my first ride with the motor on with my kevlar tyres. It's definitely no longer a bicycle..


Ordered some new brakes as my ten year old pads have started to crumble..

Appreciate Vbrakes arent ideal but I dont intend on going fast for long. My friend came off his road bike yesterday after slipping on some wet bricks, landed on his face and lost all his front teeth. Helmet took the brunt of the impact and the front of it around his forehead, smashed off. Lucky man. Imagine that at 30mph would have meant death.

 

[ipub]

Received a wholesale pack of 10 sets of clarkes vbrake pads today, only £10 so even if they only last a year, I'm happy with that.

What may interest some of you, particulary any Brits, is the triangle frame bag I'm going for. I saw the Falcon EV bag but for me it wasn't wide enough and also a bit far away. I've found a UK based custom bag maker, bike-bag.co.uk. They will make you any bag for any vehicle purpose from what I understand and have recently started making ebike battery bags, for example :

Looking at £60 posted to UK mainland and can include velcro and extra webbing for support.

 

[ipub]

Finally feel like I'm making progress! I have very little idea on how to engineer things and pretty much all of my friends think this is hilarious but I am giving it a go.The battery was way too wide on arrival, about 160mm. I've split the pack and now it's narrower than the controller which is about 100mm

I've covered the cells in insulated plastic and mounted that into a hardboard case which in turn sits on a wooden shelf. With very little room to spare I also mounted the controller into the triangle although I suspect I may have to move this externally once the cables are wired in. There is very little space and so no rattling if you shake the box. I guess this is a good thing. I'll then cover this in a black cordura cover.

You'll notice I've cut a vent for the controller. The pictures are quite grainy and dark but I live in England and here is where it can go from sunny to arctic in the same hour. Starting to feel a little excited about my first test ride. Flash shows off the reflector tyres quite well.