Power-trip, noun. : an activity or way of behaving that makes a person feel powerful : something that a person does for the pleasure of using power to control…
It is my first real diy esk8, so I jumped into the deep end a bit.
Not bad for a double stack enclosure, I couldn’t get much lower without it. Pictured is with 20mm risers, 7” tires and a couple mm clearance for flex so I can go lower and still turn.
I wanted power and range, to go fast and far even if I have to pick it up to get around corners. Pneumatics for sure, with wide trucks on low angles to take stability out of the question. I also want the cruising speed, battery power and the 21 amp charging for long trips with the family, especially towing one of the younger ones like in the past.
I live in Ireland and there is a few cm of water on the roads a few weeks a year so waterproofing is important.
It’s on a tight budget but I think I did a decent job and got lucky apart from some dumb choices. This is another teen’s esk8 journey. (Big fan of your work @Dnollie)
I will edit this later on, as I have been waiting until it’s done to show y’all as a bit of an introduction to me and what I’m doing here but it’s been taking forever and I need some help deciding some stuff at the end of this thread. It’s going to look a bit different by the time it’s properly done if such a thing exists. I am a bit afraid of criticism doing this, not that it wouldn’t be absolutely correct criticism.
I bought a lot from all you lovely people, and was even lucky enough to be given some stuff. Second hand prices were great.
Parts from the forum
If you notice a long time between buying parts and finishing it, it was rideable in multiple stages before being finished, and I had some big exams but still it’s a bit ridiculous.
I got 6374s from ruisins, VESCs and wheels from @monsterbuilder, Matrix 2 and bindings from Xsynatic, I was gifted a load of materials and parts from @Halbj613 as well as a working and a fixable 210kv 6396, huge thanks. The deck and enclosure bought from @infiniteoffset, and after I asked for a free one with a bent kingpin, @vinnysaj gifted me a brand new 3DS truck, I’ll buy a matching front one asap (but might need to drill bushings if I can’t find softer ones). Thank you @ac53n for help on the Discord.
Due to the budget and what I wanted, I had to design and machine some parts myself instead of buying them even used. Split angle brackets, offset motor mount thing, 80T pulleys, anti-sink plates and a tow point for carrying and hooking a bike onto.
Custom (CNC) parts
I made angled drop brackets, 20 degrees in the back and 30 in the front with more drop at the back to make up for the angle. I will update with more pics when I am back able to sand and polish them in the metalwork classroom.
I think I overdid the drop bc I’m on 20mm of risers atm. Also made some 80T pulleys and anti sink plates. The brackets curve back and I use a shorter mounting pattern that’s 6 holes instead of 4 to help with keeping the wheelbase in check and withstand big risers. It’s cheaper than buying even used pulleys and brackets. I 3d printed wheel spacers during work experience at a materials research centre which was cool.
12S10P budget battery build, 500amps?
Deets and pics
I couldn’t afford to pay someone to build a battery or buy a built one, so I bought 126x Samsung 30T from Nkon at €1.16 a piece + €9 ship. I think I did a pretty neat job bending the tabs, wrapping the groups, wire management etc except the series soldering isn’t pretty.
Trigger warning, not extreme but bad practices inside
I know it’s not flexible but I’m not building a bendy esk8 and it can carry more current than I could need so not a word please and thank you. Also don’t try figure out what’s going one with the extra 12S2P, it’s only going to make you more upset and by the time I realised what I would have to do it was too late. I really regret a lot.
The community welder was super helpful and credit to @mr.shiteside for fixing it. The pack is welded with 0.3mm slotted tabs and 3P of 8awg so it should at least make use of the amps if only 30 amp hours. 30T were tested to 50 amps here, so theoretically it could do 500 amps (aka never worried about overheating or too many battery amps through flipskies).
I was actually thinking of selling it but after it wasn’t built by a skilled local builder with a kweld I’m friends with but a 15 year old (me at the time) I wouldn’t be comfortable with that. The reason for the “smelly” sale thread a while ago was in case anyone wanted it in a mtb format or with the normal balance lead attached as well before I clear heat shrink the whole thing.
I am charging really weirdly using 2 LiPo chargers, a 1.5kw server psu I diyed and separating it into 2x 6S10P with the loopkeys so I can charge from our solar batteries when the power goes out and plug my TS100 straight into it the extremely shocking number of times I have to solder excavator wiring or some bs away from home. I believe each group is at around 1 miliohm of resistance. I can charge less or more for health or range and at 0.1-21amps. I could theoretically take a 1kwh 12v starter battery to the nearby-ish track and top up on location at 750w. It’s going to be neater than those pics I’m making some panel mount connectors and charger holder thing.
The deck and enclosure, I would have loooved to get a Lacroix and there was a $100 Nazare deck and free (in need of repair) enclosure. A flux or Tomiboi mtb would be the dream but it gets expensive. After the effort on the brackets and aluminium standing platform extension it’s still worse than a Lacroix. Man if only glyphics hadn’t thrown away the damaged Nazare enclosure (no hard feelings obviously).
Deck and enclosure work
I sanded the paint off and cut the ends off for the brackets and put in M5 rivnuts. I want to make an extension to the standing platform by bending alu flat bar, I would get more leverage on a wider deck and if I’m accelerating flat out I can plant my foot further back against the bracket/on the mounting holes.
The enclosure was a little thin so I wanted to skin it in cf considering the battery inside it and distance to the ground. I will do the deck later on.
For the heatsink, I wanted to not lose any height and may as well get all the cooling possible so it makes up some of the back and sides and sticks up inside the enclosure a lot.
I added 2 layers, it was a disaster I didn’t use enough epoxy so in places around the top/edge it’s up off by a few mm and I then sanded through and re-applied like €40 of easy composites epoxy just to wreck the result on the last layer trying to help with curing and getting the bubbles out by leaving it somewhere warm which was fine for the cf and epoxy but the fibreglass bubbled up. 
cough350Cfireplacecough
(before)
I’m using loads of small metal cable glands for waterproofing, but I think they look kinda cool too. (6/8 pictured). FYI M8 cable glands fit 12awg and sensor wires, M10 fits 8awg but that is both incredibly tight and one size up is probably better.
Assembling it was something else, the battery must make it the densest enclosure you have ever seen. 60x17x5cm with 120x 21700s, VESCs, and heatsink inside the enclosure.
Rolling chassis
Fitment and assembly stuff
I got super lucky with everything fitting, the enclosure just about holds 8 cells lengths X 8 cell widths and double stack. The first 7 cell lengths are double stack and the last is a single stack that fits over the VESC over the heatsink. For height I took off the flipsky heatsink and dremelled a shallow length in my heatsink for the tall resistors. You would be hard pressed to fit a marble in this thing anywhere.
Routine flipsky death
I blew up the flipsky after a few days, good chance it was my own dumb ass fault. I was also keeping it pinned at 180A but never needed to for long enough to overheat it (possibly bc of the huge direct mounted heatsink). I wanted to solder across the flipsky pcb in some way to be able to run one motor from both sides of the dual VESC for 100 battery amps but that would have been tricky and unreliable.
The only option I see from here is a Spintend Ubox, they are powerful enough to get all the battery amps I could want, and they are cheap as there are plenty used ones around. I have bought one from @SalamToU (thank you). A DV6S would be expensive, and the mosfets look surprisingly uninspiring when
More high performance ideas below compared to the plan at the start.
I realised some of what I was doing is also kinda the perfect thing for T-race. The config in that pic clears the ground but not quite in a turn, (although I could put the 4x 4S coil gun LiPos on top instead of the Li-Ion under if I was doing t-race)
Now here’s the question, do I take out the 12s2p on the end of the 12s8p and add 4S8P making it 16S8P since a Ubox would only fit with the case off anyway? I would have to cut out the heatsink after making sure there were no leaks which sucks. It’s way more rpm than I need but it would help with top end torque through the VESC. There aren’t too many miles on these cells at all, I was using a bunch of FPV LiPos for short trips while getting it finished lol. Bc of the brackets I can fit uboxes in front of and behind the enclosure. (Already designed a case and sent the stl to my teacher with a bambu lab). €40 for 32 more cells is fine but €47 (mostly shipping from Bioboards) for the fourth order of nickel for one pack is so so stupid of me to need.
16S pros- More charging through my current limited chargers. More power through the VESC, more efficient, I don’t need so much heavy wiring, 128 cells instead of a measly 120
12S pros- less risk of crying after cutting apart hours of work the 6th time, less work and €60 cheaper, compatible with more stuff in the future.
Power ceiling in the future and 4wd
Disclaimer I’m probably not going to tap into the kind of power in 4wd any time soon, these numbers don’t count for shit
A Spintend Ubox can be used up to 180 amps according to Spintend, which I calculate means approx 100-102.5 battery amps, I can cool them exceptionally well but I’m more looking at 2 second peak current here anyway. The 16S8P would conveniently be able to supply 400 amps, perfect for 4wd but I don’t think my 190kv 6374s and 210kv 6396s would do 180 phase in Antarctica on a cool morning.
6396 cooling mods
I already removed the big sealing bearing on the end, I’m using an alu adapter that will take more heat out of the motor base, I want to drill holes in the top of the can and 3dp little vents and lathe some shallow fins on the can to keep the magnets cooler. Budget reachers basically. This will help with cooling but not peak current.
If I remain interested in drag racing times I can laser cut a mod 1.5 gear barely lower in diameter to the tire and gear 16S 210kv to <30mph and lean into battery amps rather than phase amps for drag race times. I weigh fairly little too.
If 16S reaches 6 more votes than 12S I will hit order on my Nkon cart.
- Keep 12S10P, external Uboxes
- Keep 12S10P, internal naked Ubox
- Send 16S8P, external Uboxes
As well as help deciding that, I would be super grateful if I could get some help keeping Uboxes alive in terms of the VESC setup. It looks like lots of VESCs have died from high erpm stuff or back emf rather than high current. I’m not going to be reaching the top speed of 210kv 16S but it could jump to nearly 100k erpm if breaks traction and idk if an rpm limit for example is the best or worst thing to do.
Is ramp time something to look at? I’ve heard of loads of (obscure) settings being changed for it.
I did the thing.
16S update
I could have fit 14S8P and the Ubox and 20x10x1.6cm heatsink within the area of the enclosure and had it waterproof by now but I want the extra power and range so put it outside.
I got in a little bit of actual riding, 6396/ubox, 210kv 16S is fairly capable but I want more torque than 90A motor 80A batt currently. The chargers only do 1.2kW, not sure if it’s thermal throttling or something slowing it down. Idk if iR numbers are useful but I think this is pretty low especially for it being not fully charged. (One of the 2 chargers each charging 8S at a time)
Lazy version of kicking the front around
