The Duty Cycle AWD

j3tch1u

10 kW
Joined
Dec 26, 2008
Messages
695
Location
Taipei, Taiwan
The goal of this project was to build a full-size folding mountain bike that I could bring onto the high-speed rail here in Taiwan and explore the mountainous terrain of this country. In addition to being light-weight and portable, it had to be reliable, fast enough to keep up with traffic (60kph) and able to climb very steep hills. I decided against building a custom frame (and kept a lot of components stock) in order to get rolling asap and be able to build a few more for friends quickly/economically.

Specs of the bike are as follows:

Frame/fork: Montague Paratrooper
Battery: 14s7p Panasonic NCR18650PD
Capacity: 20.3Ah
Front/rear motor: MAC 8T (courtesy of paul aka cell-man)
Controllers: 12FET 4110 Infineon (EM3EV)
BMS: 14s Li-on (EM3EV)
Throttle: Magura 5k
Torque Sensor: Thun X-CELL RT
Brakes: Magura MT-4
Battery Bag: Salsa El Mariachi
Controller Bag: Revelate Pika
No Load Speed: 69kph
Real Speed: 60kph on flat road

I have the throttle input going into the CA V3. The CA DP connects to only the rear controller but both throttle lines are tied together (this required i remove the throttle diodes inside each controller and replace with a 1k resistor). The controller arming wires are also tied together to one switch. I am not using the 3-speed switch or e-brake (I don't use them and they add more wires) however I am planning to use an auxilliary pot to adjust the pedal assist level.

First let me say that I am totally sold on dual motors. There is a hill near my house that bogs down the bike on a single motor at 2.5kw. With both motors I am able to zip up that hill. It feels like more than double. The motors stay luke-warm (sorry no quantitative data). With the original knobby tyres the front wheel would get a little squirrelly on WOT from a dead start. After I replaced the tyres with some Schwalbe City Jets, the squirreliness has subsided.

What I'd really like to know is how much the bike weighs. It feels light (29kg-ish). Unfortunately, a couple weeks ago my bi-polar, psycho ex disappeared with my scale, some of my personal belongings and my 5 beloved dogs. I was at my workshop all day working on my battery pack and came home to discover everything/everyone was gone. Didn't even get a chance to say goodbye to my kids (still don't know where she is). At the time I went into panic/shock/depression but i'm ok now (learned to see things from a different perspective). Life rolls on..

IMG_0828 small.jpg
 
started out with a bunch of 18650 cell holders. these are great for prototyping non-rectangular packs.
View attachment 2

modelled the bike and battery up in solidworks. tip: using "fill pattern", you can sketch the bag outline and solidworks will try to fit as many cells in the area as possible. tick "geometry pattern" to speed up the rendering.
DUTY CYCLE.JPG

assembled the cells into the cell holders and checked fitment in the bag. brings back memories of playing with lego when i was a kid.
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before any tabs were welded, I laid strips of kapton across the areas where the copper bus bars would cross (ie. it goes underneath the nickel and copper tabs). this will insulate the heat from the plastic cell holders and cell coverings when it comes time to solder the copper (couldn't spot weld the copper and nickel with my $100 cheap-o china welder). managed to blow the fuse and triac on the spot welder several times.
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5x0.15mm nickel tabs were spot welded across the parallel connections. i used 8x0.3mm copper for the series connections (at least 3 per connection). i tinned/pre-heated the copper and held it on the nickel for max 3 seconds. you will notice i didn't solder the copper over the area where the nickel was spot welded to the cell. this makes it easier to replace cells in the future. finally a layer of kapton over everything.
View attachment 10

1mm polypropylene covers to protect the pack. pp is tough to glue so i riveted the pieces together. they are doubled up at the bottom of the pack where the cells are most vulnerable.
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pack in the bag. 3mm aluminum plate forms a rigid frame mount. added clips for the wire harness.
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the salsa bag has an isolated compartment on the other side that fits the bms. anderson mini spec-pak plug for charging.
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i found these locking seat-post clamps online (http://www.grovetools.com/) and modified them to work as a quick release anti-theft battery mount. i added 8mm rivnuts to the frame and made 22mm posts that bolt onto the top tube. made 35mm OD, 22mm ID slitted bushings to fit in the clamps. the bushing and clamp is bolted to the aluminum plate in the bag.
IMG_0829.JPG

i needed to sew additional velcro straps to support the bag. my ex made off with my sewing machine so i went out and bought a better one for revenge (take that!). Juki is known for their industrial sewing and pick-n-place machines.
View attachment 4

Duty Cycle alongside Dogati in my workshop
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I was just starting to scoff and think "dream on buddy" when I realized you were talking about two 8t macs.

Yeah baby, I bet it climbs like a goat eh? And retains some top speed. Best of both worlds.

Good thing you have it running on a fairly big battery. What do you see on the CA climbing? 4000w? Or do the motors climb so good you only see 2500?

I was wanting to try dual motor with a fairly fast rear dd motor, and a slow wind gearmotor up front. Never got around to it, especially after getting a nice 5304. It needs no help on the hills. The idea was if the rear motor started to stall up a hill, you'd flip a switch and power up the gearmotor to help.

Bummer about the dogs. Sounds like a relief that the human left though. At least getting new good dogs is easy.
 
hey dogman. she left one dog (i had him with another gf and she hates him). used to blame him for all her problems (no joke). now he can suck up all the attention and love i had previously spread thinly across my six dogs.

yep, it climbs like a mountain goat on red bull and can still outrun most of the scooters here. the most i pulled was around 4kw on that steep last stretch to my house when i was using my temporary A123 16s 20Ah pack. however my 18650 20.3Ah pack pushes around 3000w before the bms shuts me out. i still need to adjust my ca shunt setting so i don't have to run the calcs in the my head (which doesn't calc as fast as a microprocessor).

personally, i like the symmetry/simplicity/redundancy of identical motors/controllers. for more speed i'd just run two 6T's at 72v /w sinewave controllers. with two motors, the bike thinks it's still on the stand with the wheels off the ground 8)

dogman said:
I was just starting to scoff and think "dream on buddy" when I realized you were talking about two 8t macs.

Yeah baby, I bet it climbs like a goat eh? And retains some top speed. Best of both worlds.

Good thing you have it running on a fairly big battery. What do you see on the CA climbing? 4000w? Or do the motors climb so good you only see 2500?

I was wanting to try dual motor with a fairly fast rear dd motor, and a slow wind gearmotor up front. Never got around to it, especially after getting a nice 5304. It needs no help on the hills. The idea was if the rear motor started to stall up a hill, you'd flip a switch and power up the gearmotor to help.

Bummer about the dogs. Sounds like a relief that the human left though. At least getting new good dogs is easy.
 
Well taught out and beautiful execution. Mind snapping some pictures of the "seat clamp lock attachment" installation?

Btw how does the controllers fare with being enclosed?
 
sure, i will take some more pictures of the battery clamp and how it all works together. my battery cannot hit the 2 x 40a max of the 12FET controllers so i don't see a problem. there is a large hole where the wires come out that lets in some air. haven't pushed the bike that hard yet but i'll be sure to check the temps.

Observator said:
Well taught out and beautiful execution. Mind snapping some pictures of the "seat clamp lock attachment" installation?

Btw how does the controllers fare with being enclosed?
 
forgot to mention, thanks go out to paul (cell-man) who dropped into town a few months ago during taipei cycle and helped square away the components i used in this build. with his help, we slapped everything together (temporarily) in one day to demonstrate how a real, untethered ebike should perform at the cycle show. this is the only pic i have. the battery at that time was a A123 16s 20Ah split into two packs and stored in saddle bags. the handling really sucked having so much weight in the rear so high up. fortunately the the demo area was a straight road and we didn't need to turn :lol:

that's paul on the left and my buddy azizi (tesla motor employee #60). they are probably bantering away, absorbed in some ebike nerd talk. note the inconspicuous miniature man behind the seatpost (he is probably a spy from ningbo, china pretending not to eavesdrop on the exchange of es trade secrets).

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Beautiful build. Excellent choice in cells. Those PD's are the first of all the 18650 cells that really make a lot of sense in an ebike IMHO. Reasonable C-rates, good energy density, very high cycle life, good safety.
 
here a montague paratrooper photo-mocked up in an EVOC bike bag ready to drop out of an airplane behind enemy lines. any base jumpers here? i'd pay to film a promo video of someone jump with a wingsuit, bike strapped to their chest, unfold the bike in the air, pull the chute and make a rolling downhill landing at 100kph.

travel bag.jpg
 
That is really nice Ben, top job as usual :wink: I expected it to be nice, but it looks better than I expected 8)

Trust me, Ben's description does not do the hill in question justice. I had the pleasure of spending some time with Ben when the Taiwan Bike Show was on, and let me tell you, that is no ordinary hill leading up to Ben's rather nice pad on the hill. It is frankly kind of scary to go up it, as you are scared the bike will flip or go down for fear of the brakes not stopping you, or going over the bars. Get a movie up dude.

I've been threatening to make some plastic enclosures for my triangle packs forever, seeing your handy work has pushed that idea back on the front burner. I'll have to get over to Taiwan again sometime soon when things are quieter. Taiwan is cool, kind of like China but with better manners, except the scooter riders, those guys are crazy....

Chat Soon
Paul
 
thanks luke, i'm quite happy with the cells though they haven't stood the test of time. the bike..rides like a bike. i can do endo's, bunny-hop curbs, trackstands and feel safe. hell, the other night i rode to a muddy bmx track and did a few jumps. next day, hosed the bike down top to bottom (my weather testing center is not quite as fancy as yours). best of all, it's emotionally robust--i didn't slave away at the intricate custom parts and details so i have less reservation about manhandling it and using it as a tool for transportation rather than functional art.

i also did a mockup sketch for Dogati using samsung INR18650-20R 20A cells..i can fit a whopping 17s12p (24Ah) in the same space as my lower nominal 16s 20Ah a123 pack. anybody selling ev's should definitely keep a flexible design and low inventory...i believe the 18650 format is getting a lot of attention.

liveforphysics said:
Beautiful build. Excellent choice in cells. Those PD's are the first of all the 18650 cells that really make a lot of sense in an ebike IMHO. Reasonable C-rates, good energy density, very high cycle life, good safety.
 
i will get a go-pro sequence riding up my "hill". pudding cannot even make it up the hill without stopping halfway and he's got 4 legs. i think it's more correct to refer to it as an inclined wall of death. story: i flipped Dogati on my driveway and tore my knee ligament--while incapacitated but not decapitated, Duty Cycle popped into my head.

i already have orders for this thing. chicks like riding it too (and i don't worry as much about letting them).

paul, your vacation turned into a working non-vacation lol--next time i will not let you hop on the wifi to reply to your equally steep wall of emails :D

cell_man said:
That is really nice Ben, top job as usual :wink: I expected it to be nice, but it looks better than I expected 8)

Trust me, Ben's description does not do the hill in question justice. I had the pleasure of spending some time with Ben when the Taiwan Bike Show was on, and let me tell you, that is no ordinary hill leading up to Ben's rather nice pad on the hill. It is frankly kind of scary to go up it, as you are scared the bike will flip or go down for fear of the brakes not stopping you, or going over the bars. Get a movie up dude.

I've been threatening to make some plastic enclosures for my triangle packs forever, seeing your handy work has pushed that idea back on the front burner. I'll have to get over to Taiwan again sometime soon when things are quieter. Taiwan is cool, kind of like China but with better manners, except the scooter riders, those guys are crazy....

Chat Soon
Paul
 
Hey Ben,

We must have a chat about about how you did a couple of things, it looks really nice, hope you don't mind if I adapt an idea or 2 :)

The Taiwan trip wasn't really meant to be a holiday and it also coincided with the highest sales we've ever done through PayPal to date. Unfortunately sales also come with lots of sales enquiries, service/support questions and the odd problem to deal with. Oh well, it comes with the territory, but doesn't leave much time for anything else. Don't happen to know any keen engineers with excellent English and low salary expectations do you? I need more time to play and get my ebike grin back :wink:

You should add your build to the Ebike Photos and Video Section when you get a chance:
http://endless-sphere.com/forums/viewforum.php?f=6

This build deserves to be seen in the coming months, posting in this section means it might be buried quite soon.

All the best
Paul
 
i'm quite curious as to how 2 mac motors perform as well.
 
j3tch1u said:
mounting post on the bike frame
Thank you.

I really like this idea, might try to incorporate it myself. For the cylinder fastened to the bike frame, did you simply thread the frame material? or is there more than meets the eye?
 
nice job j3tch1u, that's a really nice bike

I see you bought one of those ebay battery tab welders... is it any good ?

I've got most of the stuff to build my own from designs on the net, but I'm tempted to get one of those ebay ones to save myself some time



how did you like the cell holders ? I was going to buy some of those too, but I've got a 3D printer on the way so I'm thinking I could just print myself some instead :)
 
Great bike. Sorry about the dogs, but otherwise psycho did you a favor, because you're better off without the crazy bitch...plenty of fish in the ocean. Wife #2 was one of those, and thank goodness that cheating bitch bailed, because my life would have been ruined. Hurt like hell, but it was one of the best things that ever happened to me.
 
you can't thread the frame tube directly. i used an 8mm rivnut (kind of like a blind rivet with threads).

Observator said:
j3tch1u said:
mounting post on the bike frame
Thank you.

I really like this idea, might try to incorporate it myself. For the cylinder fastened to the bike frame, did you simply thread the frame material? or is there more than meets the eye?
 
the first one i ordered was doa and i had to exchange it for another one. 2nd one worked for a few welds then one of the 220v mains wires blew its housing. took it apart to find they used really thin gauge wire for the mains. replaced the wire then kept on blowing fuses and then the triac. replaced the triac and blew it again at the 80% power setting. kept it around 65 and was able to finish the pack. i didn't use their welding head because i need to work on pack with cells assembled. instead, took a couple center punches, replaced the punch with copper tungsten electrode and put a switch inside one of them so it would activate when you press down. i connected the electrodes to 4ga pure copper audio cable. welds were inconsistent so had to do a lot of tiny ones spaced really close together.

if you're not in a hurry, i'd suggest build your own using good caps like the 1f rockford fosgate. if you don't want to build one, then maybe try one of the china spot welders in the 300-500 range. the cheap $100 ones in the black box are pretty sketchy.

this diy kit would have been nice but i don't know if fritz is offering them anymore:
http://frikkieg.blogspot.com/


knighty said:
nice job j3tch1u, that's a really nice bike

I see you bought one of those ebay battery tab welders... is it any good ?

I've got most of the stuff to build my own from designs on the net, but I'm tempted to get one of those ebay ones to save myself some time



how did you like the cell holders ? I was going to buy some of those too, but I've got a 3D printer on the way so I'm thinking I could just print myself some instead :)
 
the cell holders are dandy :)
i got mine here: http://www.aliexpress.com/item/18650-LiFePO4-battery-cell-plastic-holder-with-3-holes/910984536.html

3d printing might have tolerance issues (the blocks have to have smooth surfaces and fit really tight)

knighty said:
how did you like the cell holders ? I was going to buy some of those too, but I've got a 3D printer on the way so I'm thinking I could just print myself some instead :)
 
wow, glad I didn't buy one then! I was about to order one just to try it out :eek:

if I use this guid http://www.ledhacks.com/power/tab_welder%20ii.htm

then I've already got most of the stuff to build one

I still need a psu... but I'm half tempted to try with a car battery (on charge) as a power supply first... (will trigger welding with a 2 position relay to disconnect battery and fire scr)

fixed voltage won;t be as good, but it should mean I can weld super fast... (going with dual pulse welding too)... I'm planning on using over 1000 laptop cells (because... why not?) so fast welding would be a big bonus once I get into the swing of it :)

thanks for the info, you just saved me buying one, then the headache of all the problems they have!

that's a good price on cell holders, I couldn't find any on there before just ebay :(
I'll probably play with the printer and see how it goes first then decide later on.... I was thinking if I print them right, they could double up to protect from shorting any of the cells out ?
(come of the cells plastic coating is damaged, where the case of the battery is -ve right up and around the +ve connection

Alan :)

EDIT: p.s. thanks again for the help/info and the link :)
 
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