====== Overview ====== {{:img_0143.jpg?150 }}{{ :img_4744.jpg}} eWalker: **E**lectric Side**walker** Scooter I took a [[http://www.sidewalkerusa.com/old/model_micro.htm|Sidewalker Micro]], added airless tires, and a brushless outrunner motor...and in doing so, turned this adult-sized kick-scooter into a viable primary vehicle for quickly zipping around short distances. ===== Power Assist Highlights ===== * 20lbs - all equipment, including battery * Assembled with roughly $800 in parts and materials (including scooter) ===== Original Design ===== ^ GOAL ^STATUS^ | Sustain 20MPH on flats|testing | | Sustain 10MPH on 4% inclines|testing | | Under 20lbs total weight|Final weight: 22lbs | | Travel 2+ miles per charge|testing | ====== Ride Highlights ====== I've used the scooter as purely a kick-scooter...works alright so-far. ====== Parts List ====== ^ Item^Model^Price^Notes^ | Motor|[[http://www.scorpionsystem.com/catalog/motors/s40/S-4025-16/|Scorpion 4025-16]]|$99.95|While its fairly over-rated for my intended uses, Scorpion motors are apparently the ONLY brand which uses N50 NdFeB magnets (200C/392F temperature rating)...meaning they have a far higher heat tolerance than most other outrunner motors on the market.| | Motor Pulley|6A25M013DF0906|$9.61|This is an aluminum pulley, I'd recommend procuring a hardened steel one. If you can find them, please let me know too :-)| | FreeWheel/Clutch Bearing|||It's a standard screw-on freewheel, I'll add info once I dig it up| | Wheel Sprocket|||Currie branded 65-tooth #25 chain sprocket| | Belt|5mm HTD, 9mm wide||| | Speed Controller (ESC)|[[http://www.castlecreations.com/downloads/frh-phoenix.html|Castle Phoenix HV85]]|$169.95|This ESC is larger than I //need//, but my use/load-patterns dont exactly match a model aircraft...so I'm shooting high. Model [[http://www.progressiverc.com/Brushless_ESC.html|comparison]].| | Voltage Regulator|[[http://koolflightsystems.com/ultimatebec.htm|KoolSystems Ultimate BEC]]|$49|A [[http://www.gobrushless.com/shop/index.php?app=ccp0&ns=prodshow&ref=MOTROLFLY10-UBEC|different model]] pushed me about 20 feel before going up in a little ball of smoke...despite working fine through at least a dozen zero-load tests. On the other hand, the KoolSystems model has worked for at least 20 miles, without issue. Model [[http://www.progressiverc.com/BEC.html|comparisons]].| | Servo Tester| [[http://www.gobrushless.com/shop/index.php?app=ccp0&ns=prodshow&ref=SERVOTESTER|E-Sky]] EK2-0907 1-2ms|$13.95|This device sends the necessary PWM signals to the ESC...it effectively acts as your throttle. Since the Castle Phoenix ESC only responds to 1.5ms-2ms signals, this particular test unit has more than sufficiency capacity as a throttle.| | Battery Connectors|Deans UltraPlugs|$5/pair|These can handle upwards of 200A at 50V, with ZERO resistive losses. They're also relatively cheap, and idiot-proof to connect - what could go wrong 8-)| | Motor Connectors|4mm female bullet connector|$1/each|El-cheapo 4mm bullet connectors. The motor came with male connectors already soldered on, and I was simply too lazy (and cheap) to change anything out. They're working...we'll see for how long.| | Motor Housing|Matt's [[http://www.wisil.recumbents.com/wisil/shumaker/edrive.htm|eDrive]] |$230|beautiful piece of work...and fits VERY well!| | Motor Mount |||angle-bar...cut & drilled to fit| | ESC Housing|||Still testing a few ideas.| | 10 gauge wire|Deans Wet Noodle|$5|A single foot of this wire cost $5...though it's 10-gauge wire that's as flexible as a wet noodle. I'm using it between various connections.| ===== Battery Options ===== Battery packs utilizes a LiFePO4 battery chemistry; one of the newest mass-produced battery chemistry, and also an ideal type for EV use. ==== DeWalt Battery Pack ==== These battery packs retail for around $150, but eBay often has these for as low as $50...I picked mine up for $70 (including shipping). The packs utilize A123 brand LiFePO4 batteries; arguably the best brand available. ====== Construction Details ====== ===== Rear Wheel ===== ===== Motor Selection ===== I selected a Brushless Outrunner simply because: - The RC modeling market has been flooded with this highly efficient motor design over the past couple of years. - These motors efficiently pack a tremendous amount of power inside a very small package. - It's brushless, which means less wear & tear and a minimal amount of maintenance. - I wanted to use an AC tri-phase motor simply because I sought to incorpoate Nikola Tesla's technologies. ===== Motor Mount ===== {{ :img_0142.jpg}} ===== Pulley Discussion ===== ^ Stage ^ Ratio ^ Details ^ | Motor/belt reduction | 5.45:1 | 11-tooth HTD --> 60-tooth HTD | | Chain/wheel reduction | 2.6:1 | 25-tooth #25 chain sprocket --> 65-tooth | | Chain/wheel reduction | 3.25:1 | 20-tooth #25 chain sprocket --> 65-tooth | | Chain/wheel reduction | 4.33:1 | 15-tooth #25 chain sprocket --> 65-tooth | At 8,000 RPM, the following top-speeds are possible (12.5" tire = 34.5" rollout): ^ Belt Ratio ^ Chain Ratio ^ Final Ratio ^ Output RPM ^ Top Ground Speed ^ | 5.45:1 | 2.6:1 | 14.7:1 | 564.57 RPM | 18.45 MPH | | 5.45:1 | 3.25:1 | 17.7125:1 | 451.66 RPM | 14.756 MPH | | 5.45:1 | 4.33:1 | 23.599:1 | 338.997 RPM | 11.08 MPH | ===== Engineering Discussions ===== As for me, I just need to move around town (friends, clients, office, social) within "reasonable" timeframes. =====Design Improvements ===== Not "flaws"...areas for improvement :-) These folks supplied my metal: [[http://www.onlinemetals.com|{{http://www.onlinemetals.com/button/onlinemetal88.gif}}]] ==== Throttle ==== The basic idea is to [[http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=556&st=0&sk=t&sd=a&start=15|mount]] a fully sealed cermet [[http://www.vishay.com/resistors-variable/list/product-51037/|potentiometer]] to the handlebars...then run the wires into the PWM signaling device (aka: servo tester). This allows for on-handlebar throttle control. [[http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=9700380&MPN=PE30L0FL472MAB&R=9700380&SEARCH=9700380&DESC=PE30L0FL472MAB|Allied Electronics]] carries what I was looking for; 4.7K ohm, 3W, sealed cermet "PE30". Mfg part # {{:vishay_9700377.pdf|PE30L0FL472MAB}} (click for detailed specs). ==== Belt Tensioner? ==== http://www.york-ind.com/cgi-bin/png_dp.cgi?ttype=DP&size=4&hhtype=P&btype=UB&pmaterial=A&pprofile=F&diam=100&pwidth=&pwidthI=.42&bearingt=B&mclear=.23&mclearM=&threadst=E&amov=AC&springs=S&part=DP4UB-F100A42-B23PE-ACS http://www.york-ind.com/tensioners/instock_DP.htm === Links === [[http://www.vxb.com/page/bearings/CTGY/One-Way-Bearings|VXB's one way bearings list]] [[http://www.vxb.com/page/bearings/PROD/kit949]] [[https://sdp-si.com/eStore/Direct.asp?Exp1=41799&GroupID=227]] [[http://store.todayshightech.com/e7070197.html]] [[http://gbgearworks.com/]] [[http://www.torquetrans.com/pulleys/timing/index.htm]] [[http://www.gears-reducers.com/timing-belt-pulleys.html]] [[http://www.onviollc.com/dotnetnuke/Pulleys/tabid/73/Default.aspx]] ==== Kill Switches ==== * For the main battery, I'm thinking a deans-plug style kill switch. * A coworker suggested a [[http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/59639/377%20710/0/cutoff%20switch/Primary%20Search/mode%20matchallpartial/0/0?N=377%20710&Ne=0&Ntt=cutoff%20switch&Ntk=Primary%20Search&Ntx=mode%20matchallpartial&Nao=0&Ns=0&keyword=cutoff%20switch&isLTokenURL=true&storeNum=5002&subdeptNum=9&classNum=294|watersports equipment killswitch lanyard]]. =====Other Photos ===== ====== Lessons Learned ====== ===== Speed Controller ===== ====== Links & Inspirations ====== http://www.ebikes.ca/drainbrain.shtml http://www.electricvehiclesusa.com/product_p/th-bnl-103.htm http://www.eagletreesystems.com/MicroPower/micro.htm