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La Croix Long Range Cruiser Carving Machine

My latest DIY build is an extra long-range cruiser based on La Croix deck and enclosure and MBS trucks and wheels. This is part of five of these boards in a group DIY in Perth Australia.

Basic details and major components of build are:

  • La Croix deck and carbon fibre enclosure link
  • MBS Matrix II Pro Trucks link with MBS Rock Star hubs link and 200mm Roadie tyres link
  • Flipsky DUAL FSESC 6.6 link
  • Samsung 21700 51E cells link 5Ah each in 10S 6P configuration to give 30Ah pack) 5Ah each in 10S 6P configuration to give 30Ah pack
  • 2 x Maytech 6374 170KV 65A FLC 3.5kW sensored and with motor temp link
  • Custom made Aluminium Motor mounts with cross-struts (from @Idea)
  • 72T Aluminium wheel hubs (from @Idea) and 18T motor gear link with 20mm belts link
  • Metr Pro module https://metr.at/shopfor telemetry and vesc interfacing (with antenna due to carbon fibre enclosure)
  • Charging circuit designed for 20A but intend to normally charge board at 10A maximum (divided by 6 cells = 1.7A each = 0.34C – so conservative)
  • External DieBieMS BMS DIY 6S to 12S BMS with CAN - DieBieMS for charging only (build includes a new external BMS charging box housing the DieBieMS BMS )
  • Relay based board main switch (no failing anti-spark switches for me)
  • On board headlights powered from main battery pack
  • Rear Brake lights triggered from remote PPM signal passing below 50%

Basic design parameters considered were:

Board Speed – based on 90% vesc and overall mech/electrical efficiency, 4:1 gear ratio, 200mm wheels, total board mass of 93kg, no head wind and level path, 0.9 sq m frontal area, smooth asphalt path , steady state conditions – the max speed at 95% duty cycle is as below. The gearing and motor KV was selected to give minimum 40km/hr board speed over all battery voltages.

Range/Battery Pack – desire on this build was to maximise range by installing maximum battery Ah in the La Croix enclosure compartments. After a bit of searching – settled on a brand new 21700 cell from Samsung 1NR21700 50E with basic specs -5Ah 10A continuous discharge capacity and 15A intermittent discharge capacity. Decided to go for 60 of these cells in 10S 6P which gives approx. 1,080Wh with 60A continuous discharge capacity.

Based on my current DIY board average consumption on Evolve pneumatics ATs of 13 Wh/km (average over approx. 1,500 km of rides over past 6 months) this gives a calculated range of 83km.

After looking at the La Croix enclosure battery compartments – determined that the compartment width was approx. 240mm - which would fit very nicely 11 x 21700 cells but not 12 (short by about 20mm). But decided to order the 60 Samsung 1NR21700 50E cells and have a play with a few options to see how they could be fitted with a fall-back position to go with 10S 5P or maybe 12S 5P with two parallel packs in rear compartment.

Motor and motor mounts - Decided to go with sealed Maytech 6374 motors with @Idea mount V7.3 with cross struts but without idlers. My current board (with 175mm AT tyres) has a pair of Racestar 5065 200 KV motors rated at 1,650 W with a pair of FocBoxes and this has plenty of power and acceleration torque – so the Maytechs 3.5kW motors are a bit of an overkill – but they should run very cool and efficiently.

All the major material and equipment was ordered during Nov 2018 including the lots of misc. stuff for building boards such as nickel strip (10mm x 0.15mm), 12 awg silicon wire, 14 awg silicon wire, 22 awg silicon wire, pack heat shrink, fish paper insulation, neoprene foam sheet, bullet connectors, switches, charge sockets, headlights, etc.

Boards rocked up from Canada last week - thanks Alex

and cells rocked up from nkon and motors from Maytech ( about 4 week delivery for both)

so now the build starts :grinning:

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@moone i think it’s time for you to make some new friends

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These are the boys I skate with @mynamesmatt. They got scared of the evo build so they thought they better pick up their game.

Isn’t that right Roger :joy::joy:

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Loving every bit of this build. Keep up the good work.

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Haha @moone catch us if you can :wink:

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So first thing is to sort out battery cell configuration

After cells and enclosures arrived - first mock up was

on closer inspection the raised cell was sitting just proud on the enclosure lip - so then the idea was hatched to raise two outer cells to reduce the height . something like 2018-10-24_7-52-32

@Brucey0 ( one of the gang of 5 and a master craftsman) then build a wooden jig to enable pack hot gluing with cells in correct position battery%20jig%20bare (a patent has been applied for this jig)

What a pack looks like in the jig battery%20jig%20no%201%20

and what the packs look like in the enclosure pack%20%202%20raised%20

Then hot glued two trial packs complete with heat shrink and trial fitted in all four compartments using this configuration - and looked at the deck underside clearance to top of packs. No 2 (from front) and No 5 are the closest due the decks 3D concaveness . A bit more group discussion was had and @MattyG was tasked with some mod to gain a 1-2 more mm clearance- details to follow

The very front compartment will need a different configuration due to lack of enclosure depth - so plan is to run 11 cells ( 1x 6P pack and 1x 5P pack) across the enclosure with one loose cell to make up the 6P on front face

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Have you tried a silicone gasket? Waterproofed, black, and adds a bit of enclosure height.

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looking at a foam/neoprene/soft rubber strip around enclosure lip (to replace one that comes with deck) - want it look mint from outside the enclosure

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@SkaterBoy58 nice project you have, but I’m not really sure the enclosure will allow a double stack of battery, as @pat_arch already explain the deck s a concave and is not completely straight, maybe you should check with @Arch before starting to build your battery, if you don’t want to end up having to rebuild it again at some point.

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Yeah, agreed. The double stack might work for the cell on the extremity, but the double stack near the center of the board will likely not work.

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You may want to change out the baseplate on the matrix trucks as some people have had them snap because they are made out of nylong i think etorxx made some metal baseplates for them that would be a much better upgrade.

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Really cool build!

@JohnnyMeduse @Arch Thanks for your comments

yeah It is not a double stack of cells per se the whole width - just two cells slightly raised closest to lip of enclosure to fit 2 packs of 6P in the 240mm compartment width

The jig sets all 6P packs to be identical with 119mm width for the 6P pack .

This only works in compartments 2 - 5 , the front compartment will be different and will contain a 5P flat pack , a flat 6P flat pack and one loose cell connected to the flat 5P pack.

This is not a build that inexperienced people can copy as the cell configuration is being pushed to the limit a bit and inter-pack insulation is a big consideration - but with the reward being the additional Ah offered by the 60 x 21700 cells.

Will post a close up photo of two completed 6P packs in the enclosure over next few days

Cheers

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Nice build, really looking forward to how these cell handle, at last some high capacity and acceptable discharge cells are available to buy

Following… and part of the RAMMMs squad👌

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A bit of battery pack stuff Nickel Strip Using 2 x 10mm wide x 0.2mm thick pure nickel strips for the 6P packs . Had to order from an Aussie supplier after the Chinese eBay seller send 8mm x 0.15mm in lieu of ordered 10mm x 0.15mm strip.

Using my just developed nickel strip resistivity calculator ( SkaterBoy58 nickel strip purity calculator link ) I checked both the Chinese eBay seller nickel strip and the aussie 10mm x 0.2mm - both checked out as pure nickel so all good - results of 5A test below

Pack Series Connections - using 2 x 12awg silicon flexible soldered onto top nickel strip

First task was to cut up nickel strip with 2 x +ve strips and 2 x -ve strips per pack. +ve strips have a radius end to avoid contact with cell shell with -ve strips just a square cut end.

RAMMMs Group member @maxbicyclemax portrayed a hidden skill in neatly cutting up nickel strips

plan is to spot weld first nickel strip to cells - then put solder blobs on second strip - then spot weld second strip to first strip leaving solder blobs for series 12 awg soldered connections .

nickel%20strip%20plan

this is a 6P pack hot glued in precise position in the jig , then wrapped end on end with 20m wide Kapton tape , then with outer heat shrink applied . these packs are exactly 119mm wide for 2 to fit in the 240mm wide enclosure compartment with 2 pieces of fish paper cardboard between the two packs.

@maxbicyclemax is going for a 10S 5P configuration - so all of his packs can be flat (and much simpler)

Next task is to finish heat shrinking all 24 x 6P packs and 10 x 5P flat packs , complete spot welding of both nickel strips layers and prepare packs for installation in enclosures

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I get seriously jelly everytime I see someone building with the lacroix deck and enclosure. Absolute work of art. Going to follow this build with avid interest. Awesome stuff. Hopefully one of you guys will do a thane version a la @Sender
@moone then the evo might be under threat mate.

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It might be @dareno, but only because @SkaterBoy58 is the master.

But then again it’s an evo :heart_eyes::heart:

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I love the lacroix but never would I take a set of mbs trucks where I would the rkp’s.

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Bit of an update - motor mounts have arrived from @Idea - very impressive machining

%20Mounts%20-%20opened %20gear%20thickness %20motor%20mount%20thickness
%20mounts%20close%20up

motor mounts are 10mm thick for the whole length - so super strong

Next was a trial fit of the mounts on the mbs trucks - needed to slightly file out the motor mount plate aperture that fits over the mbs truck - the mbs truck axle is a weird pattern - part circle part straight edge - but eventually it fitted fine.

The Maytech 6374 motors are very beefy compared to the 5065s I run on current DIY board.

Went with 20mm belts to match the 3.6kW available from each motor!

It all fitted OK with a loose mock up .including cross-strut

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