Another Stealth bomber (clone) build

[shortcircuit911]

Hey what’s up guys. It’s been about a year since I’ve posted here during my last build which was a 72v scooter. It’s been running like a champ and is fun and all, but I need something else. Anyway, I need to get to the train station everyday ( 5miles) and I also need to get around SF throughout the day. I also want something I can put a motocross seat on and go off road on trails.

I saw the stealth bomber and like everyone else said no way when I saw the price. I then saw that quite a few people have built clones that perform just as well as the bomber for a fraction of the price, so I decided to give it a go and build one myself. I’m trying to keep the build in the $2,500 area so we’ll see how it goes. My plan is to put the best stuff I can afford so that I can take it off road on some trails and have enough power to get around. There’s a guy called Andy Kirby on youtube who put out some good videos on how to build one of these and what parts to use. Another guy Marokajer on youtube had some good videos on his build, he’s pretty funny too.

I ordered the frame a few weeks ago and it just came in yesterday, still waiting on the suspension. I have also ordered a 5kw motor laced into a 19” motorcycle rim, front wheel (19”), 150A sabvoton sine wave controller with TFT screen. I’m currently trying to find a good battery pack for this build. I want lifepo4 if possible with 60-80a continuous discharge and 150a or more burst, it’s a bit tough finding one with the size requirements I have (350*140*180mm) - the search continues.

I was only able to find one other build on ES which was a bit helpful. I’ll post pics and progress for anyone that is interested.

 

[lionman]

Awesome, I look forward to following this.

For batteries, maybe see if you can get one custom made? I know EM3EV do custom battery builds, not sure what sort of money they charge though.

I see Andy Kirby has been using 4x 36V power tool batteries in a 2S2P config. That might be an option too if you can source some quality ones for a reasonable price.

 

[John in CR]

Shortcircuit,

I can't find dimensions for that frame. How wide it the interior of the battery bay?

 

[shortcircuit911]

John, dimensions of the battery box (tray in the bottom portion of the enclosure not the entire enclosure) are 340*120*150mm according to the manufacturer (Candy Song). Inner walls of frame are 140mm, so 130-135mm is max I can do without modifying the side panels.

Lionman, I checked out em3ev and didn't see any 72v packs, they do have some cool stuff though.

So I've been going back and forth with battery manufacturers on alibaba trying to find the best option for a week or so. I really wanted a pack with headway cells, but they won't fit in the configuration I need (I want to run the controller internally).

They've basically told me to go with panasonic cells, he mention the 29pf cell. He said Panasonic 20S9P 72V 29ah price is EXW USD 895. 84V 3A charger: USD 58, plus shipping.

Another mfg is saying "Our battery at 72v 30ah with 60amp continues is $850, including a 5.5A charger, shipping cost for battery to USA is $165."

I'm still not sure what I want to do yet. I definitely want 30ah, and enough C rating to get silly off- road. I'll keep you guys posted , also open to suggestion.

Edit* Got the front forks installed this morning, it's starting to come together. Hopefully the wheels show up next week.

 

[StudRock]

Please dont mind if I tag along for the ride. I'm looking to build the same.

 

[lionman]

https://em3ev.com/shop/em3ev-72v-20s10p-rectangle-battery-pack-24-5ah-29-5ah/

Likely to be much better quality than any ali seller. If you contact them they will do a custom shape for your too.

 

[markz]

Another mfg is saying "Our battery at 72v 30ah with 60amp continues is $850, including a 5.5A charger, shipping cost for battery to USA is $165."

Alibaba / Aliexpress - What a gamble you are taking! I mean sure there are reputable companies on there, I'd trust UNIT PACK POWER and I am sure there are others around on those websites. As mentioned go with either www.ebikes.ca in Western Canada or www.em3ev.com from China, reputable, reliable suppliers. Headway cells are bulky and heavy compared to 18650. The 2.9Ah PF's are good, you could buy them in bulk from the website url called ru.nkon.nl from the Netherlands for a reasonable price, 100% geniune cells. But you'd have to make the pack! Can even get them to tab weld them for you so you dont have to do that part. Thats their non VAT tax site for us North Americans. Shipping is reasonable, 40-50 euros for the amount your getting, all easily checked on the site. Its a viable option if you are into it.

 

[2old]

+1 with above. If the Chinese vendor (except em3ev) hasn't been recommended by someone you trust, you're taking a big gamble. The horror stories run the gamut from minor problems to major ones.

 

[shortcircuit911]

1st off I'm so glad you all chimed in, I really need people to bounce ideas off of- Thank you so much for the replies.

Lionman, nice find! I must have been on the wrong site because I only saw 2 different 50v batteries. That looks like a contender for sure.

I agree it is a big gamble, which is why I wanted to post here before buying a $1k pack that won't last.

So I was looking around and saw the pack in the link below. The pack is made of panasonic pf cells and the dimensions work in one of the configurations they offer, but the price is pretty high. I asked the guy I've been in contact with if he could make a pack with PF cells and he said he could for $1,050 plus shipping-which is very tempting. I don't want to have to be dealing with a busted pack and no support even though they offer a 1 year warranty, I'm not quite sure what's involved.

Battery:
http://www.theebikemotor.com/productshow.asp?ArticleID=1521&title=72V35AH%20Panasonic%20Li-on%20E-Bike%20Battery%20Pack%20for%20Stealth%20Bomber%20E%20bike-5A%20charger&bigclassname=Products&smallclassname=EV%20Battery


The more I think about it the more I like the pack lionman posted. The only issue is that it is 140mm wide, so is my frame, perhaps they can accommodate. Peak current is also only 120A, which I think I'm cool with. Going to sleep on it and revisit tomorrow, can't focus on anything else

 

[lionman]

Check out Bruno's tour of the EM3EV factory. They mention that they build custom packs to customer specs.

[youtube]oNfTEHBz_bg[/youtube]

Bruno is a bit of an excitable character but his videos do have some good content.

 

[shortcircuit911]

Thanks for sharing! I've seen that guy's videos before, he can be pretty animated, but excellent content. I think I'm sold, I'm going to send them an email this week and see if they can make the pack slightly narrower, if not, I'll add standoffs to the side panels to accommodate.

So I loosely assembled the front end and bars and noticed a problem. The bearings for the headset are 44mm which I think is standard, but the tube in the frame is slightly undersized (even after wire wheeling paint out of the bores). I talked to my friend at work and he says he has a boring tool and press for the bearings that I can borrow (sweet!), but I have to wait until Monday to get the tools for him.Bummer Also getting a crank puller from him to pull the crank off of a sacrificial motobecane mountain bike I have. I plan on pulling as many parts from motobecane as possible to get the bike going, and upgrade later.

Also, I noticed immediately that this thing is going to need some high rise bars.

I just ordered a couple of fans for the battery box as well. I figured I can get those mounted this weekend.

 

[harmonist]

Just finished my build a few days ago, went with the em3ev 30ah 72v 30Q battery, its a very nice battery, have yet to put it through its paces though.

 

[shortcircuit911]

Harmonist, Dude that thing looks sweet. Let me know how you like that battery.

I sent em3ev and email about getting a slightly narrower pack (130-135mm) we'll see what they say. I think I'll get the pack regardless and modify the side panels if I have to.

Hubmotor, front wheel, controllers, and screen haven't shipped yet. I should have the front end squared away by next week. Trying to think of little mods and tweaks to do now. Also getting organized in the garage which will help in the build.

 

[shortcircuit911]

So I was able to borrow the tools from my friend before the weekend so that I could get the front end done this weekend. I ended up reaming the headset for the bearings and got them pressed in as well. The front end feels so good now that it's back together. I ended up stripping the head on one of the top triple clamp bolts so now I need to get an M7X20 machine screw to replace it.

I also received my fans today. They're 5v which I'll run off the pack through dc-dc converters. I plan on mounting one internally above the battery and have it act as an input. I over sized the controller, so I don't expect it to get too hot, so the fan should be a little added security against overheating.

I talked to the guy I bough the wheel and electronics from and he also sells some of the parts I needed. So I picked up a set of hydraulic tektro brakes, rotors, crank, chain ring, and chain. There shouldn't be too many more parts to buy other than the batter. I'm so eager to finish this thing, I smile every time I see it in the garage.

 

[Ham]

Nice build,

can I ask which Tektra brakes you got as it looks like your frame is very similar to mine? I am now at the stage of mounting rear brakes and none of my existing Hope or Shimano fit the brackets.

Thank you

 

[cheeko]

Looks Interesting, I myself took Plunge and bought a Stealth Beta Building it now, only reason I bought it was it was Locally Built and the quality of it welds etc, everyone is hand welded.

Good luck with it

 

[shortcircuit911]

@cheecko I don’t know, the vendor I was dealing with on alibaba said that they sold tektro brakes, I should know more when they arrive.

@Ham thanks man. I share your concerns with having quality welds especially with the abuse I plan to put this thing through.

So it’s been a while since I posted last, but things have been happening, just slowly. I received my dc-dc converters, one to step the pack voltage down to 12v, then another to step the 12v down to 5v for the fan and usb ports, etc. I haven’t mounted those yet as I want the battery and controller to arrive so I can dry fit things before mounting components.

I heard back from the seller of the wheels, brakes, and controller I purchased, and they just shipped (after basically threatening him). Hopefully that stuff arrives within a week, it shipped express, so we’ll see. Getting the wheels installed will help me decide what I want to do for a stand. Since I want to take this thing off road I wanted to have a peg option available just like a dirt bike. So I ordered some pitbike pegs and am just starting on the design for the peg mount, really need the wheels mounted to take measurements. So as soon as they come in I can get going on a few things.

I just ordered a 72v 24.5ah pack from EM3EV made out of 25R cells. I also got a 4A charger and a moto seat. Their site says that they can take up to 2 weeks to make the pack, hopefully it’s here by early september. I have also been toying with the option of possibly having 2 battery packs, the one I just ordered and another made of lipos with my 160A BMS from my scooter build, just a thought at this point.

I’m dying to get this thing together, waiting for parts just sucks. I’ve been scoping out all the trails by my house I want to go rip up. Also been toying with the idea of making some videos, possibly how to videos, definitely some riding videos to complement the pictures and write up- feedback welcome.

More info and pics to come.

 

[mrsnow]

where do i buy this lol

 

[shortcircuit911]

@mrsnow Don't buy it, build it! I've been seeing these locally on CL for $6k :lol:

Well finally got a bunch of parts in last night, now things can start moving.

I tried to mount one of the tires and struggled a bit and gave up. I pulled something in my back the other day and don’t feel like monkeying with it. I called the bike shop and they said they can mount them no problem. The plan is to take them in the morning and get them mounted up, going to see if they have tire liner that will fit as well. If all goes well I can get the wife to pick them up this week so I can mount the rotors, wheels, and test the motor.

I got the electronics setup on the bench to see if they work, and they did. The controller was throwing an error on the screen, probably because I didn’t connect the motor. I need to figure out what the app in called that I need to download to program the sabvoton. There was no manual included with the controller so I’m going to do a bit of research to find out what I need to do to get this thing connected to my phone. As soon as the wheels are back I can do the hall test and get the electronics signed off and ready for install.

So I ran into my first issue, actually I F’d up a long time ago when I ordered the parts. I put too much trust in the guy I bought the stuff from and assumed he would send me the correct parts (didn’t see pics of what I was buying). The crank I purchased (really shitty) doesn’t have the bolt pattern for a chain ring, and the sprocket mounted hits the swingarm bolt. So, I need to buy another one now, would love to get suggestions for an inexpensive crank to get me going, I don’t plan on pedaling much.

I hope to make a lot of progress within the next week as I can really get moving when the wheels come back. If there is any interest in a specific step in the build, let me know and I’ll try and get some good pics and details, otherwise I’ll try and cover it all the best I can. I still haven’t heard from EM3Ev yet so I’m assuming they’re still building my pack. At the moment all I have is a small hoverboard battery(36v), so I might bring my dual hub scooter home from work (I use it to get around SF) and pull the 12s 10ah 20c lipo pack out of it. It has a 160A BMS customized by ElectricGod so it should make the bike move if it isn’t too far gone.

Excited to build...Pics soon

 

[Ham]

Good to see it coming together. I finally got a test run on mine yesterday to make sure the new motor mounts at least stayed on

Pretty sure our frames are the same and the bottom bracket I use is the Truvativ gigapipe that came with my Tangent kit fwiw...no clearance issues at all....I did have a little too small a gap between inner crank and motor for comfort but just tapped the spindle through 2mm on the bearings....

I need to sort a rear shock now and a rear brake caliper mount for my hope set up

 

[lionman]

Can I ask where you got the tektro ebrake levers from?

 

[steven7601]

I built the same bike with 100volt 30ah pack it has the 120 volt version power velocity controller. With all the bells and whistles.Here is a picture of it.

 

[shortcircuit911]

@Ham, that's awesome man. How does it run?
Thanks for the info on the bottom bracket. I talked to the guy I bought it from in China and he ended up giving me a $30 refund which was what I paid for the crank so that was a small win.

@lionmam I purchased the braked from Alibaba, the seller I got them from was Green Tree ebike co . They came were $120 came with 203mm rotors and of course have the built in switches.

@steven Damn I bet 100v is a blast on these things!

So yesterday I dropped the wheels off at the bike shop to get the tires mounted. Today the wife is going to swing by and pick them up so I can build tonight . I was also able to get my scooter home and pulled the battery out so I can get it on the bench to set the motor/controller/screen up tonight. I also had a typo in my last post, this pack is an 18s (not 12s) 10ah, 20c pack. If all goes well I'll have the electronics validated and the the frame will be a rolling chassis.

Pics of the scooter battery pack and BMS below. Be back with progress pics.

 

[Ham]

It runs...I am happy with that for now!

I have a lot of niggly bits to pull together for it to be right for abuse. Rear brake caliper mount, crank freewheel new bearing, new front forks but the current ones "work" just a little spindly for my taste on this lump and more on the list too

Headset bearings...what size did you end up fitting for yours? I know you had to bore the hole a little...

You have an isolator switch too...on my list also...just need to find one that can handle the current demands of the Astro 3220!

 

[shortcircuit911]

Well I got the wheels back from the bike shop the other day and it's been non-stop since then. I have been able to make so much progress and the process hasn't been too bad. Not a lot of head scratching- just the way I like it. Progress below.

-Wired up scooter battery and placed in bay:

This took a bit of time as I had to swap some connectors and reconfigure (physically) the battery so that it fits in the battery bay. The 6 lipos looked tiny in there, can't wait to get my battery from EM3EV. The lipos from my scooter worked ok, I've been able to get everything setup because of it. I was able to pull 10Kw for a bit on a flat stretch, then the lipos started to sag so I had to let off. Performance is ok, nothing spectacular, but I think when the new battery is installed that will be a different story.

-Got brakes mounted:
I was able to do this in no time at all. I did have to remove the plastic washer for the rotor on the rear wheel to create more room for the wiring coming out of the axle. The brakes work ok, but could have more grab. I need to get the hardware installed on the swingarm so that the dropouts clamp the axle, then I'll start playing with regen.


-Crank mounted
So I was getting ready to go for a test ride and remembered I had no place to put my feet. I started out by bolting on the L side crank then decided to remove the chain guard from the R side of the crank and what to you know, it fits. It looks pretty ugly, but who cares, not really interested in pedaling-just want to be able to get home and 'look' legal. Chain isn't hooked up yet, need to work on that soon, probably won't mess with a derailleur.

-Downloaded app (MQCON) and got Sabvoton bluetooth to work:

This part was not straight forward, so I had to look on google a bit to figure it out (no directions included).
1. Download MQCON from the app store
2. Disconnect 3 wire connector on the controller (This caused me some headache, saw in a video some guy had it disconnected)
3.Turn on Bluetooth on Phone
4.Turn on bike
5.Open MQCON and hit connect

Going to keep getting small tasks and adjustments done while I wait for the battery-hopefully it ships this week. Back with pics and updates.