Maximising the stealth bomber frame

[Trenavix]

Hi all,

I've seen lots of posts from this forum but never got around to posting anything myself.

My last build was on a bomber frame and had a QS 273 and a KLS7230s, 72v30ah battery going almost 65mph (just over 100kmph) on a flat.

Unfortunately the bike got stolen and I haven't been able to get a trace on it, so I have begun building a new bike with a monstrous 72v70ah battery that had been sitting in my garage for over a year.

On craigslist, I managed to find a KTM 525 SX 2006 front fork with the triple tree along with the front brake (lever & calliper), all given to me for 200 bucks. STEAL.

I did some grinding on the side of the stealth bomber frame to even be able to slide the battery in, because that shit is going to fill up like 90% of the space in the frame, wall to wall.

My old roommate has a mill down the street so I did some yardwork for him and he's gonna mill me a new sidewall to bolt up the side, 14 gauge steel.
I repainted the triple tree and clamps on the fork, cleaned it up, and would you believe it.. the steerer tube on the KTM is 1-1/8. It's a perfect fit in the bomber's headtube. No need for any steerer tube replacement, and you can use the stock headset. Talk about luck.

At this point I'm waiting for a tonne of parts coming left and right, but I'm going with 19in wheels again. Front wheel is currently being built, rear with the 273 50H is being built, and in the meantime I will begin making wire ports on the frame and some of the 12v wiring in the front. Looking forward to finally being able to go freeway speeds. Hoping to register this bike.

Edit: Forogt to mention. This time I'm going with the Kelly 8080h. 600 phase amps is probably gonna give me a heart attack.

 

[BlueSeas]

I'd say maximizing is a good description. I'm just one test ride into a build on the same frame. But my build is 5T QS205. No way it's gonna do 60. I will follow your thread, if the frame survives that kind of power, I don't have to worry about the welds....

I might eventually borrow your idea to make battery access easier. I've considered replacing the steel side panels with plastic to save weight. But not sure if they aren't integral to frame strength.

 

[Yermommy]

I read through your website about the evolutions of your first build, sorry it got stolen. The new build looks great, I'm very interested in seeing the continued progress. What are the specs of the 72v 70ah battery?

 

[Trenavix]

Yeah new build will have a GPS tracker inside the frame, not dealing with a stolen bike again.
72v70ah battery has a 2 wire BMS and samsung 35E cells. 100A continuous rating, 400A peak, though the cells should never exceed 260A. Charge rate should be good at 30A, maximum 40A.

Christmas came early...

The kelly 8080h is massive.. base plate is like 2cm solid aluminium lol.

14g steel sheets came in, dropped em off at my miller today. Those things do not bend!

Got the headlight housing and headlight all on, and got the seat mounted.

Gonna be out of town for a few days, when I'm back I'll make a little mounting bracket for the controller.

 

[Trenavix]

Got some work done today. The seat is mounted, the shape of the bike will end up something like this:

(Gonna go with the michelin touring tire in front too, just waiting on an order)

I used a drill press on the base plate of the 8080h to make some new mounting holes to barely fit it on the bomber frame without having to make a bracket.

I also carved in a hole for an anderson powerpole charging port with a little waterproof lid:

I also took the liberty to repaint the brake calliper. Will probably repaint the lever/reservoir later.

Up next will be a hole for battery discharge wires and a whole load of wiring.
The CT-22 dashboard arrived but has two bolts coming out the back of it, no clear way to mount. Might need to carve some aluminium strips for it.

 

[litespeed]

Will you be able to bolt the side covers on without the bolts rubbing the battery?

Like to see this when it’s complete.

Tom

 

[amberwolf]

Will you be able to bolt the side covers on without the bolts rubbing the battery?

Use shorter bolts.

If you can't, then add "caps" inside the frame to cover the holes so when you hit them you know to stop, and then use stacked washers to take up the rest of the space between bolt head and outer face of cover/

 

[litespeed]

Reason I mentioned is because the picture with the battery in frame looks really, really tight! I worry for him!

Tom

 

[Trenavix]

Will you be able to bolt the side covers on without the bolts rubbing the battery?

Glad you asked. Yeah the way it's set up, the battery slides in like a child's puzzle, then the sidewall bolts in around the outside of the battery.

Spacers (aluminium/wood blocks) will keep the battery out of the pockets.
I had a battery fire on a soft cell lifepo4 using a bomber frame a few years ago, so I definitely keep em outta the way of the sidewall bolts now.
My miller also carved the sidewall, it's almost perfect.

I'll finish tapping the bolt holes tomorrow and paint the sidewall, and start on more wiring. Main battery wires are cut and soldered to XT150s.

Also I bent a little steel strip to make an adapter to fit the dashboard.

The brake paint is also done

Still on course to finish the build before March, hopefully around the 23rd or so.

 

[Trenavix]

Got a lot of wiring done.

[youtube]TLv-5TOgSGI[/youtube]

Made a little crappy diagram for my splicing mess:

Also, the new sidewall is drilled and painted. Looks pretty good!

Wheel shop is still waiting on spokes to come and I'm still waiting on QS Motor to ship my 273 so will have a delay on the wheels... still aiming to be done before March hopefully.

 

[Trenavix]

Front wheel came out great. Three coats of paint ended up perfect.

I converted the brake levers to have a brakelight signal using some magnet kits on Amazon.

Turns out I need a new bracket for my calliper to mount on for the large brake rotor I got, so waiting for that to arrive... of course from China... At the moment the rotor hits the back of the calliper just barely. Shouldn't take long, might use a placeholder rotor for testriding until bracket arrives.

I got an 850lb coil fitted to the RCP 2S, for now just 220mm but considering a 240mm replacement. We'll see proportions when the rear wheel comes.
The QS 273 is due to arrive early this following week. So I'll be dremelling/filing the drop-outs the next few days for it, and once the shop slaps the other tire on it, we'll be good for a test ride.

 

[Trenavix]

Well boys, it's on the road!
The battery fitment is hilarious. You cannot say I did not maximise space here. Wiring completely stuffed into the front of the bike.

The torque is absolutely nuts and I even limited phase amps to 300. I skipped the "self learning" motor calibration on my last build (on the kelly controller), might have been a reason I was not experiencing torque like this. At 150 phase amps, the front end lifts off the ground. Absolutely nuts.
I rode around quite a bit today. At 110km, my voltage read 76.6v, implying I used 35% battery to go 110km, averaging around 70kmph (43mph). This included riding up and down a mountain. So city range looking to be around 300km? I wasn't even being careful on the throttle. Very surprised.

I still have more testing to do on top speed. I have battery amps set to 90A atm and was fighting strong wind but managed just over 100kmph.

On a side note, suspension and braking are god tier compared to my last build. The regen braking is more than enough stopping power already, but you combine that with the 270mm front moto brake and you can stop practically instantly. The 850lb coil version of the dnm RCP shock is handling the 273 very well.

 

[litespeed]

Turned out cool.

Enjoy.

Tom

BTW.....keep it locked up this time and put a tracker on it.

 

[Trenavix]

Just an update on this rig: I heavily do not recommend using Unit Pack Power for larger battery packs.
They used 8awg on the main terminals for a 100A battery. 8awg can technically handle 100A........ but at 200°c.
So first issue was my XT150 connectors completely melted with a 90A limit set going up a mountain highway at 100kmph for about 10 min. This was on the CA-60 highway where there is no shoulder and you're locked in by concrete walls. Near death experience, semi trucks going 110kmph less than a meter in front of me while I was sidled against the wall with my bike. Police were the heroes that night, blocking the lane to let me push my 120kg bike up a mountain. I was sore for a few days after that.

To make it back home with limited tools where I was, I did a direct solder to replace the connectors, and here comes the next issue.... that heat now going to the battery's terminal cell group.
Fighting 60-65kmph headwinds trying to leave the coachella valley through the i10, I was again pushing 90A. Should have learned my lesson the first time, because this time, a cell could have (and should have) exploded the way they wired this.

So a truck ride home later, I found out the battery was sizzled, and pry the cell off the positive terminal with a flathead and mallet. Reads 0v. If that doesn't spell out thermal runaway..... man am I lucky the other cells are all okay.
Unfortunately no one wants to work on >60v batteries in my area. So... I got a spot welder and some new 35e's, and some 2awg wire.
First off I pried off damaged cells, and put in some new 35e's using the spot welder and nickel strips.
Then I started off trying to use a 180w solder gun on the 2awg to solder onto nickel strip and it was not melting into the wire whatsoever. So I stopped by home depot and got a propane blowtorch and MAN that did the trick.

Following a number of good solder joints on a 2-way split on each terminal, I spot welded the nickel strip attached to the 2awg onto the terminal cell group and reduced an awful ~18mOhm resistance down to about 2-3mOhms. For the record, UPP seems to use nickel-coated steel strips, so their resistance isn't very good.

This seemingly should fix the heat issue and I have the battery and bike back up and running. I reduced the awful voltage sag that used to be about 11v drop at 90A down to about 6v, but I still feel like that is pretty high, so I'll have to check around other parts of the battery later.

Crazy how I trust myself with 0 battery building experience over this company that does nothing but build batteries. I guess cost reduction really goes a way in risk management... I'll just build my own batteries from now on.

 

[BlueSeas]

Be wary of solder in high current connections. It can melt. I've seen battery cable connected to terminal lugs with solder pellets pull out when resistance somewhere caused them to heat up beyond the solder melting point. It's better to have a mechanical connections like hydraulic crimps, screw terminals (like your main electric panel), or I suppose welded since the failure temp is much higher....

That said, I'm not sure how you do that with a traditional spot welded pack.

I assume you also looked at the pack B- connections, likely to the BMS?

 

[Trenavix]

The ending you were all waiting for... I retrieved my stolen bike, six months after it was stolen!

Old bike goes 100kmph max, new bike goes 130kmph max. Love both!

 

[Roguenite]

Wow congratulations on getting the old bike back. Did the police find it for you?

I am building my first stealth bomber ebike at the moment. I am also going to use a motorbike fork. It's coming tomorrow and I am nervous about the head tube. Dont know the dimensions till I receive it. I have no workshop or garage, just building this in my bedroom and kitchen
I ordered it from alibaba. They fitted brake mounts on both legs on my request. Charged $20 extra.

Learned a few tips on building my battery pack from what you went through. Thanks for posting all that.
I'm building a 26S 5P pack using Liitokala 5000mah 21700 cells.
I am planning to spot weld the last 10 cells inside the frame because the side opening of the frame isn't large enough to slide the battery in.
Still have my doubts about the nickel, copper, 8awg wires that I am going to use for the pack. I extracted a lot of copper from an old socket extension cord I had. I am going to do 1 layer of 0.2mm x 8.5mm pure nickel ladder strip. Then lay a twisted copper strip that I made and do a 2nd layer of the same pure nickel on top of it, instead of soldering the copper. Battery end groups will have 1.5mm thick copper bars. Haven't decided how I will attach the copper bars to the cells and 8awg wires yet. Doing this with very limited tools and knowledge of these things. Just going with my instincts

Peak battery amps will be 120 because controller is SVMC96120. 300A ANT BMS. Cells are 3C continuous, 5C instantaneous.

I've never built a large pack before. Biggest I've done before is a couple of 48v 12.5ah packs into hailong cases.
Just waiting for the Nickel Strips to come now.

I've already put Statorade in the motor.
Will take the hubsinks from my old bike.

QS 205 5T V3. 19inch front and back. Mitas E07 Front tyres on both wheels. Spokes, nickel strips, fork and a gopro hero 5 coming tomorrow. Next weekend will be my busiest ever
I will start with lacing both wheels.

If I managed to get some decent footage of whatever I do I will post on the forum. Hope you guys will guide me before the day I connect the ignition wires

 

[Trenavix]

Did the police find it for you?

Yeah it's a long story. I'll just copy paste what I wrote on reddit:

It was posted on Facebook marketplace a few days ago by some dude for $750 in Jurupa Valley near Riverside (I live in the Los Angeles area. This is about an hour away).

Someone from Manhattan Beach saw it (MB is right by my house) and looked up parts and found it on stokenbikeindex (my post) and called me.

Tried to arrange "buying" it from seller and he said I could only come in morning and when I asked what time he ignored me. I called JV Police Department and gave them all info from MBPD and they kinda didn't do much and end of day it was marked as sold. I thought hope was lost there but wanted to get this guy in deep shit so I did some stalking and found his address, called the Sheriff and shared it with him and he confirmed with DMV records and went to the guy's house.

Dude was a huge hoarder/peddler according to the Sheriff and Sheriff got the buyer's number, called them, let them know it was stolen, and the Facebook seller had to refund the guy. The buyer was in Irvine (35 min away) so I just picked it up from him today.

Facebook seller claims to not have known it was stolen (He had to have had a clue but can't fight in court without solid proof of know clause) and had bought it in some storage auction. So Sheriff is trying to backtrack that.

The bike had been hot wired at some point with exposed 72v wire wrapped together and the battery was dead, key ignition gone. I had a backup key ignition and wired it up, charged the battery, and everything is working!

The fun part is that the old bike could only go 100km/h due to power constraint, but the motor was wound for 135km/h.

The new bike I had ordered another 135km/h 273 motor, but received a 100km/h motor, so the torque was way high and speed kinda sucked.

So when I got the old bike back I swapped them and so much joy ensued. Old bike got a torque boost, and new bike got a speed boost

I need to swap whatever garbage BMS UPP put in my battery. I have an ANT 300A BMS with bluetooth but I have to grind off some tabs of the heatsink to make it fit, and resolder some of the wires that hardened widening it. Super tight fit but I think I will make it fit soon. I have a good feeling the majority of my voltage sag is coming from that garbage BMS, we'll find out.

After that's done, I have 200 more 35E cells, and I plan to make pannier batteries that plug into the charger port for +50% range. Ah, the building never stops!

Looking forward to more of your build as well. Seems like 96v25ah battery? Decent for getting around a county (2.4kWH). Mine is 5kWH atm, trying to get to 7.5kWH so I can hit the freeway and go like 80 miles before a charge.

 

[Roguenite]

Thanks for sharing the story.

My build is mainly for going to work and back. Currently I go to work on a road that cars travel at whatever speed they like. I have go on the side running over all the drains and pot holes at 35mph on a dual drive 3000w bike. I am only building the stealth for more speed. But when I realised that the 3T winding requires a lot of AMPS I figured I will just over volt a 5T winbding. It will give me the speed that I need so I don't need to let the cars pass.

Will share some of the work as I progress. I don't own any tools, so all the drilling and grinding for extra fabrications are being done at places where friends allow me to quickly borrow their workshops.

 

[Trenavix]

Been a while since an update. I've done quite a bit.
A couple weeks ago I got a cargo rack bolted in, and bolted in my 3kW charger underneath it. So now I have a lot of cargo space (two side pannier bags, one top bag) and the charger is always on-board with both a 120vac mode and 240vac mode.

I did a ride through Malibu Canyon for fun which you can see here:
[youtube]_VOpmgUovDw[/youtube]
So about a week ago I did the biggest ugprade, and most needed one since the beginning: I swapped whatever garbage BMS was being used from when UPP built the battery, and re-wired a smart ANT bluetooth BMS.
The old BMS was very barebones. It only had balance wires and I guess monitored its own mosfet temp and current.

It was quite a lot of work to get that to barely fit, but now I have 4 different temp probes along the battery and can monitor current, cell group voltages, all different temps (mosfets as well), and purposely shut off battery when needed (ie taking off lug connectors - no more spark!)
It is also at this point I found out I am pulling a SHIT LOAD of power. I didn't think I was but saw last night 177A max being pulled. Holy hell.
I went into the Kelly KLS software again and there's the battery limit setting here with a very very vague description.

When I first built the bike and had that melted battery wire I had it at 90, thinking 90A. Then found somewhere on this forum it's actually a percentage of the motor nominal current setting, so I tried 72% of 130A for ~94A, but because I had no way to monitor battery amps, I just tried that, and it worked "fine" for the past couple months with very high speeds and such. But I guess I was pulling over 13kW! Jesus Christ.

Today I figured it out, though. It's a percentage of MAX PHASE AMPS. Kelly really really needs to explain this setting, it is important. For me, it's a percentage of 600A. I brought it down to 25%, which is 150 battery amps, and the BMS readings reflect it.

On a more personal note, I'm in the midst of moving out of the beach area, and am staying with my family in Palm Desert for a bit. Issue is, they have been having temps just around 50°C, and both me and my bike and battery all hate it. It is miserable. I think I will head back to the beach for a bit despite no internet because this heat is unbearable!
(My website will be down for a while as well which had the bike build logs so be patient until I move over my home server to hell, aka the desert!)

 

[ryanxdaa]

hello can you provide any more info on the fitting of the forks to the frame thanks