SD20 14 pin
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Beat me to it
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This is genius for a rolling build thread
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Captive nuts are your friend, my friend.
- Design a simple 2d plate with hexagonal nut pockets lined up with the mounting pattern. Have that laser-cut from SendCutSend out of whatever metal.
- 3d-print a cap that will hold the nuts in place in the metal piece (so they cant just fall out).
- Glue the 3d print to the metal captive nut plate, populate the captive nut plate with high quality nylock nuts (so you dont have to worry about servicing them anytime soon), and glue the whole assembly to the underside of your board lined up with the mounting pattern.
Now, when you have two or more bolts threaded, the bolts themselves will act as a wrench keeping the nuts tensioned, so you can tighten the bolts as hard as you want. And the captive nut plate will keep the nuts from falling out when you remove the bolts.
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The “Road interface” Update!
I’m having fun with these names I’ll stop if it’s too much
Huge thanks to @MoeStooge for a new bellypan! 
Might be the IKEA effect, but it looks siiiiiick. Excited to get a coat of paint/wrap/something onto it.
Measuring the flat bottom, It’s about an inch narrower then my old one and the sides are at a shallower angle. Haven’t ridden it yet, but can already tell it’s fixed the scraping issue. I can’t get anything to touch the ground even if I try.
Not only that, but we sized it so another two batteries could squeeze in there. Because why not.
16s, here I come.
YES, I know it's kinda stupid...
b/c it probably won’t fix my overheating issues(see post 49) which is likely being caused by iron losses.
I’ll also be pushing vesc ERPM limits (I calculate 178k, G300 max is 200k).
It’ll add even more weight to an already heavy raceboard.
so like, yeah
That acknowledged, I feel the need to explain myself;
A) I could use the additional energy capacity
B) It’s my understanding that going 16s won’t hurt anything, assuming an identical mechanical configuration?
C) two more batteries isn’t expensive (relatively speaking)
D) I see new motors in my future anyway
E) When has more lipo been a bad thing
F) [insert irrational rationalization #6]
It wouuuuld let me brag about my board being geared for 80mph, not that I’d ever want to go that fast…
Or I could throw 10T pinions on and have a 2+kN board. The possibilities are endless.
TIIIIREEESSSSS
BRPs arrived last week
Fess posted a picture better then any I’ve got at the moment.
I’m now running 4x BRP 45A wides. Makes the “normal” BRP tires look like BKBs in comparison.
Still unsure if I’m going to keep this config. I’m going to race with it for a few weeks, see if it feels stickier (or if I struggle to heat them up).
Also,
I’ve been thinking about this comment weekly for the past several months. But every time I do, either my board is dead or it’s the middle of the night (apartment complex + 4x open gear drives don’t mix well). Better late then never, I guess.
Board was upside down and pinned at full throttle for several seconds.
58 battery amps at 48.5V.
2.8kW in losses in freespin 
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Looks like you’ve got the cursor on the high point of that graph before it drops and levels off. Is that high point your start-up current to get the wheels spinning, and the low leveled of part the actual no-load portion? Or is that high point the entirety of the test, and the low leveled off portion is after you let of the throttle?
HV no powah babeh. Lol. Look forward to hearing results
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Yup yup. I was seeing comparable numbers on the display when it was running
Looks like you did the test at 12s so here’s a thought before you buy more lipos.
Moving up to 16s will make the iron losses worse than they currently are. Your free spin load could easily jump to 3.7kw.
Assuming you gear down the system with a smaller pinion, to keep the 50mph top speed, your motors rpm will be 33% faster than it currently is, all the time. This means more heat and worse efficiency.
Of course, I could be wrong about the source of your efficiency issues, but given the 2.8kw free spin, I think iron losses at speed are a safe bet. It seems unlikely you’d see high copper losses (resistive losses) with 4wd and those big chonker motors.
If you do move to 16s, it will be an interesting experiment to see if my theory is right or wrong. Very easy to test too. Just repeat your freespin test. 
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Yup, fully concur.
Probably won’t run a smaller pinion for this reason (except briefly for the meme)
Good point! I could plug 4 of my batteries in series right now and see how bad it is 
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he can then move to 8s4p if iron losses get worse. lol. 
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Working on stuff tonight
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Been a few weeks, feels like time for another update!
Today I present “Opportune 68V Bushings”
Mini IE race
esk8hustle hosted two i2s track days with informal race brackets.
@Ruxx Pushed held me back to 2nd on the first day, but I managed to stay in front on the 2nd day.
Was fun racing with everyone! Looking forward to the next one.
Thanks Michael(esk8hustle) for hosting and giving away an i2s engraved shortboard, trophies and a bunch of other prizes.
Deck Camber
Thanks @andoug for the mbs camber pads! They arrived without a scratch. I cut one apart, then peel and stick. Some Vicious in the middle. Easy as pie.
This is probably the best upgrade I’ve made to my board yet. It’s crazy how massive a change 5 degrees of deck camber makes. Makes me even more confident that I don’t want a binding on this board.
16s!
My board is now two batteries heavier. Not too much else to say 
I also took this as an opportunity to put 1mm adhesive foam on the batteries, to keep them from getting scrapped up against the belly pan.
Plugging the batteries in was more of a hassle then I expected. I fried two AS150s(with very loud pops). I guess 4x G300s at 16s is too much for AS150s. (don’t worry, I replaced em)
I have an old power resistor laying around that I salvaged from some electronics years ago. I touched either end to the male/female AS150 connectors to charge the capacitors, and after a couple seconds, I quickly dropped it and mated the AS150s. Janky solution, but it worked.
Smart Active Balancer
Upgrading to 16s meant that my 12s charging harness is obsolete. (And good riddens, with the design flaw it had. Read about it here:)
Also took this opportunity to incorporate a Smart Active Balancer into the board, letting me charge like a “normal” esk8 (no balance charger required).
It also lets me quickly check all of my cell voltages via iphone app(super nice for quick troubleshooting). I did measure 10~20mV drop over a few days in my testing, so it definitely has a non-negligible power draw. That’s fine though, as I’m riding this board every couple days.
Even with my new bellypan (which has been GREAT), There was no room to put it underneath the deck. The best place to put it was awkwardly wire-tied on top of the rear G300s. Not elegant, but it’s worked great for several track sessions without a single issue. Maybe I find a smaller smart BMS in the future.
I’ve been using a panel-mounted XT60 plug to charge, pictured above in roughly center frame. It connects to a 600W 72V charger, that I’ve adjusted down to 68V.
Here’s the new balance lead harness before I installed it into the board (no more DSUB!). Happy with how this came out. imo solder wire splices are underrated, especially for harness work like this
The big bundle ended up fitting perfectly between the G300s and the central spine of the frame Good luck getting a good view of it tho, this board has so much going on. This is the best I could get
New bushings
Riding on track, I kept wanting to loosen the board. However, I reached a point where any looser would cause me to loose the center. Obvious solution, step down the duro.
My only gripe with 3-link trucks- you need to fully disassemble them to be able to change the bushings.
Massive gigga shoutout to @HAIRYMANJACK for sacrificing his hands to the process (and the help)
Between us, we were able to swap out the front and back in around 4 hours.
Narrower Wheelbase
Considering we had the trucks fully apart, we took the opportunity to narrow the wheelbase by ~
25mm in the front and back. This just required moving the motor mounts closer together to remove the gap between the motors- the wheel’s themselves could be brought in by removing axle spacers.
Small wrinkle, the motor mounts are connected via a threaded female-to-female crossbar.
But nothing an angle grinder and tap can’t fix.
Narrower wheelbase beauty shot
Esk8con Track
We’ve been setting up the @Esk8Con track at the San Diego zoo the past couple weeks. It’s a tight track!! Serious competition coming from @HAIRYMANJACK this year. (His times aren’t mine to share, but they’re quick)
Running with 16s hasn’t made any change to the efficiency to the board (as expected). However, the additional energy capacity has noticeably increased my range, I’m able to ride about 30% more every night.
Also, new personal best for power with 13.57kW. I’m still nowhere near peak performance 
No load test
lol imagine 3.7kW of losses
Yeah, so, uh…I did a no-load test. Here’s the play by play:
- I spool up the motors over ~10 seconds with the board upside down
- The motors went go 30C to 40C.
- I backed off because I got a freaked by the loud gear drives
- I gave myself ringing in my ears and a splitting headache for the next hour.
TIL; don’t spin this up indoors.
All in the name of data…
73.2A * 61.8V = 4.52kW of freespin losses at 81kph(50mph)
F*ckin silly.
What’s ever crazier is right now it’s geared for a max speed of ~80mph(22:78 ratio), so if I understand things right the losses will go even higher if I dared to push it faster.
(I’ve got Vesc eRPM limited to ~60mph, but still)
TIL; don’t spin this up indoors. (Or at all, really).
When Moe posted a video of me riding at i2s OC this past Saturday,
I realized I’ve never posted riding footage. Shame on me!
Thanks @HAIRYMANJACK for capturing this candid, especially my save at the end.
Bonus vid: @MarioChacon taking a lap at i2s intro to garage
The real race board is the friends we made along the way
??? sure why not
Thanks @Lyfe_Of_Jimmy for these great photos! He’s got some great stuff on his insta and youtube, go check him out.
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jeti afc anti sparks is what you need
Oh wow, those would be awesome. noted.
You can also formalize your manual pre-charge power resistor by making a parallel connector (small bullet connector or whatever) that you connect first, then connect the AS150, then disconnect the pre-charge bullet connector.
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I stopped reading at the ethoslab reference 
Damn replied to the wrong post
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Damn bro getting at it, nice!