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Thread: 50cc Scooter conversion

  1. #21
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    50cc Scooter conversion - Motor/Controller final connections

    On the home straight now !

    Just a bunch of wires (all with plugs / sockets on) to connect to the scoot and we're pretty much ready for a dry test !

    [1] Throttle / Twistgrip
    It was day 2 or 3, I think, when I got round to disconnecting the twist grip cable from both the carburettor and throttle ends. After that the original handlebar grips were pretty simple to remove; friction fit, so... a little brute force... and off they both popped. The throttle / 5K twist grip and clutch side had already arrived...(again, a friction fit) and were pushed on taking care to align the right hand / throttle cable exit so as not to interfere with the front brake or cylinder...

    Unfortunately the connector wasn't the same type as that on the controller harness. Fortunately, I had some spares, so removed the un-required, black, cable end connector, trimmed the three cores, matched up the colours (red/+ve, black/-ve and green/throttle), crimped on new terminals to match the new connector and connected the cables / plug'n'socket !

    Throttle... done... until the dry run / test !!

    [2] High Level Brake
    According to the manual, this is to remove power from the motor when the brake is applied - makes sense. But, upon reflection... that would mean that pulling away on a hill would require a little more... finesse / timing... As this was simply a question of adding a suitable connector to the brake tell-tale I'd already 'T'ed off the brake light cable (during week 2 electrics tidy-up) and putting cable plug into controller loom (beige wire) socket I thought I'd add an in-line switch to enable / disable this feature. I mounted the switch adjacent to the fuse panel.

    In theory, 'making' the switch would disable motor power whilst one or other (or both) of the brakes were on and 'breaking' the switch would disable this feature, thereby enabling power to the motor even though the brakes were on ! It took me no more that 15 minutes to complete so I thought it was worth it ! We'll see...

    [3] Hi-Speed / Lo-Speed
    The controller loom has a 3-wire (blue/black/white) connector. Apparently blue/black = Hi-Speed and white/black = Lo-Speed. Making a change here (switching between Hi and Lo speeds using the cable loom), when all the bodywork was back in place, would be difficult, I thought. So, again, I added a wee switch, adjacent to the High level brake switch at the fuse panel to select Hi...or... Lo.

    A little more time to complete than the brake switch but... bound to be useful... although I'm sure the only 'real' / 'likely' position will be High !! Again, we'll see...

    [4] Cruise control
    The controller comes with a black-white cable pair for cruise control... I thought there would probably be more disadvantages to this that advantages... and I'd already allocated the kill switch as Controller 'Enable' so... there were no more handlebar switches and... adding one wouldn't be too easy / pretty and... like I say, why would 'Cruise' functionality be required on a wee scoot ? !
    I left this connector in the loom - disconnected.

    [5] Reverse
    The controller also has a black/blue cable pair for reverse... I'd already modified the Starter button for just this purpose so... I crimped the terminals onto the two wires I'd led aft to the controller area from the Starter switch and connected the two up. In theory... we've now gotten a Reverse !!

    [6] Display
    This is a single purple cable exiting the controller. I have absolutely no idea as to what capabilities it has or what specific display to connect it to. Currently I have left the original Chinese instrument panel display as-was EXCEPT where I'd taken the fuel gauge cable back to the controller / shunt area along with the Low Oil Warning lamp cable. These two are going to be re-tasked as battery level / SoC gauge and a Lo Voltage (<68V ?) lamp...

    [7] Hall sensor
    The 6 pin hall sensor cable existing the controller simply plugged into the matching cable exiting the motor. Simple.

    [8] Power
    The thick red and black cables exiting the controller were connected :
    red --> HV SSR out (HV 'relay' output terminal)
    black -> output side of the shunt (opposite side of the shunt to the battery -ve terminal)

    [9] Motor phase
    The thick blue, green and yellow cables existing the controller were connected to the same cables exiting the motor via a 50A terminal block.

    [10] Power Lock
    The controller has a power lock cable. The controller will not become active / energise the motor if this cable is not connected to 12V. This cable was, therefore connected with the 2x SSR energising cables to the ignition switch via the kill switch and side-stand switch.

    If the ignition switch is 'Off' or the kill switch is in the 'Off' position or the side stand is down then this cable is disconnected from 12V and the controller remains inoperative.

    [11] Anti-theft
    As of yet, I don't have an alarm for the scoot. I did spend a little time looking into bluetooth , and other keyless-type alarms but although pretty cheap I felt that, for where we live (extremely quiet) didn't really require anything... yet...

    [12] Control panel electrics
    During the electrics tidy-up phase I 'found' the cable (original ignition output) that supplies the instrument panel and, therefore, the onboard scoot electrics (head light, side lights, indicators and horn etc...) This cable was connected, via a 10A fuse, at the fusepanel to the DCDC convertor output. Remember the DCDC convertor is fed with 72V from the LV SSR only when the ignition switch is on and regardless of the kill switch / side stand positions.

    All electrics finished (NOT tested). Just refit the battery tray and connect up the Batteries !
    Now, I'm almost finished, I can smell it... I'm off to dry-test... YIPEE !!

    Couldn't stop myself, ignition On and the lights all work... the horn doesn't.... hmmmmm

  2. #22
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    50cc Scooter conversion - Test V/A Meter

    At the outset I decided it would be really handy to be able to see battery voltage and motor / controller current primarily for test purposes but also whilst riding. However, because I hadn't found a relatively in-expensive meter and because it was simpler at the time and because I really had no idea where I would fit such a meter on the bike and because I didn't want to 'invest' in 'just' a V/A meter without knowing if I would later wish for more (power, temperature and maybe speed...) and because... because... because...
    all I did was fit a 100A shunt and a 5 pin test port (both of which I had) ;
    pin 1 = Gnd
    pin 2 = 12V (DCDC converter
    pin 3 = 72V (Battery pack)
    pin 4 = Shunt 'A'
    pin 5 = Shunt 'B'
    All in all a really simple 'test port'...

    Later down the line, I found a volt / amp meter on eBay (about 10 euro) using the same 200mA shunt. Needless to say, I ordered one and here it is cabled up and plugged in to the test port :

    Now though, some 6 weeks into the build, I've arrived at this point and I really think I'm going to need to see this stuff whilst riding. So, whilst I had the covers / fairings off (to add an earth cable to the charge IEC socket - good point Bill), I'm revisited my 'test port' idea and ran a multi-core, screened, cable from the port up to the instrument panel and terminated it with a standard cable socket. In fact, at the same time, I ran a second multi-core, screened, cable from the port up to the instrument panel although not having any immediate real use for it - I'm bound to want it later and, if not, nothing lost !!

    Keeping to my original, circa 800Euro costs, I still couldn't find a waterproof V/A meter, that could be retro-fitted on the scoot and be seen whilst riding, for any reasonable price. There was, however, a clock built into the instrument panel... maybe I could remove it and re-task the vacated space for the new V/A meter...

    Anyways, like I said, I already had all the covers off again, so I removed the instrument panel and stripped it; 3 screws and it was off, 4 more screws and it was opened up, 2 more screws and disconnect 3 cables and the clock was out. No damage done...
    Unfortunately, no matter how I tried I couldn't fit the V/A meter in it's place - it was simply too tall. What I came up with though was to split the two 3-digit displays into two, and site them separately.

    I left the voltmeter on the PCB - it fitted just fine in the available space - then added 100mm of cable between the, now removed, 3-digit display panel (Amps) and the original solder pads on the PCB. I then re-sited (with a little help from Sketchup and the 3D printer) the Amps 3-digit display within the housing...

    I then fitted a matching cable plug to the previous one I'd fitted on the end on the new cable from the controller / battery area to the instrument panel, connected it up and tested it all out...

    Result !

    All's good... ready for testing !

    So... back onto the motor 'stutter' and clutch...

  3. #23
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    50cc Scooter conversion - Clutch and Motor 'Stutter'

    After 'playing about' with the Volt / Amp meter it was time to re-visit the motor 'stutter' and the un-modified clutch.

    I grabbed my hand-held tacho (nothing special here, 15-oddEuro on Amazon), removed the chain between front / rear sprockets and applied a little reflective tape the motor shaft / gear.

    Ahhhh.... All became apparent... The 'stutter' kicked in at between 5700rpm and 5850rpm. The light dawned... with ears alone, I had absolutely no idea the motor was spinning that fast !! Oops ! The stated maximum motor revs is stated as being 5000rpm and 5900rpm absolute tops ! OK the controller was either deliberately limiting the revs of I'd reached the motor / controller capability limit... either way... " I have a problem Houston ! "

    So, using the tacho it became apparent that the onboard clutch only kicked in at around 3000 motor rpm.

    The motor arrived with a 13tooth sprocket and the lowest rear (driven) sprocket I could find with a large enough centre through-hole (to pass over the rear vari-drive / clutch drive shaft) was 69tooth. I should have done some more math... Idiot !

    Anyways, couple the 13 / 69 sprocket ratio, the clutch and the, internal-to-rear-wheel, gearbox ratio of 14:1 and... nothing surprising here... high motor revs = low wheel revs ! I should have thought of this way before now. Idiot (again!).

    OK. I immediately reverted to a plan I'd been concocting that was to simply lock off the clutch by welding 4 short studs between the outer (driven) clutch bell-housing and the inner (drive) clutch pad plate. That took 10 minutes; I popped then off the end of the gearbox input shaft, slipped the bell housing off, welded on 4 short 10mm studs and reassembled (the studs simply located in 4 similar holes in the driven (inner) section of the clutch.

    Stand up, wheels back on the floor and... OK... 11kmh max speed but.. although I'm disappointed at the, not-so-dazzling, top speed, I'm also grinning - I have converted a petrol scoot to an, albeit rather slow, electric scoot !!

    After a poodle (I wanted to say 'whiz' but that really wasn't the case) around the garden and patio with my wife saying... 'Nice dear... but won't won't the milk have gone off by the time you get it home ??? " I reverted to the garage. I stripped down the clutch assembly and started to re-work the plan... but this time with some math first !

    Accepting that there is very little I can do with the internal-to-rear-wheel gearbox (14:1) ratio and that the maximum motor revs are 5000 (forget about the over-rev portion (that can simply be a later date 'Brucie' bonus ! ) and the rear wheel circumference of 1.45m I calculated for a 45Kmh top speed (matches the original top speed - although still not dazzling) :
    Gearing-2 Gearbox(250x141px).jpg

    5000rpm x chain/sprocket ratio (CSR) x internal gearbox ratio (GBR) x 1.45 = speed (mtrs / min)
    => 5000 x CSR x GBR x 1.45 x 60 = Speed (mtrs / hr)

    convert revs per minute into revs per hour (because I need Km per hour - kmh - at the end)
    => (5000 / 1000) = 5

    => 5 x CSR x GBR x 1.45 x 60 = Speed (Kmh)

    I know GBR = 14:1, so 1 / 14 = 0.0714 (GBR = a multiplication factor of 0.0714)
    => 5 x CSR x 0.0714 x 1.45 x 60 = Kmh

    to isolate the CSR (chain sprocket ratio)
    5 x 0.0714 x 1.45 x 60 x CSR = Kmh
    => 31.1 x CSR = Kmh

    ... or...
    => CSR = Kmh / 31.1

    so, for a top speed of 45Kmh :
    => CSR = 45 / 31.1
    CSR = 1.45

    and, for a top speed of 60kmh - illegal :
    => CSR = 60 / 31.1
    => CSR = 1.93

    and for 75kmh - also illegal but fun to work out :
    => CSR = 75 / 31.1
    => CSR = 2.41

    That's to say;
    for 45kmh, the front sprocket has to have 1.45 more teeth than the rear sprocket
    for 60kmh, the front sprocket has to have 1.93 more teeth than the rear sprocket
    for 75kmh, the front sprocket has to have 2.41 more teeth than the rear sprocket

    So, math over, the motor arrived with a T8F sprocket / shaft fitting, that's to say a double 'D' fitting on a 10mm shaft or a 10mm shaft with two flats cut into it, 180' opposed.

    The challenge here is that for the (theoretical) power involved (3000W / 3Kw) this type of fitting doesn't allow for larger than 17tooth sprockets (not unless custom built - or someone has a source I haven't found ) To be fair, above 17tooth is probably placing a HUGE amount of stress (even with the 14:1 rear gearbox ratio) on the motor shaft and as the number of teeth are increased so too does the sprocket diameter and, therefore, so too does the side or cross stress and the torsional stress.
    The long and the short of all this ?
    17 teeth front sprocket is (probably) the limit (but, if I could find a 19tooth sprocket I wouldn't mind a try !).

    So, taking the 17tooth front sprocket and the CSR for the three 'required' top speeds above :
    to calculate the drive ratio of these two sprockets :

    Front Sprocket Teeth (FST) / Rear Sprocket Teeth (RST) = CSR

    FST / RST = CSR
    => RST = FST / CSR

    Front sprocket teeth (FST) = 17teeth

    feeding the numbers into the final equation :
    for 45Kmh and a CSR = 1.45 :
    => RST = FST / CSR
    => RST = 17 / 1.45
    => RST = 11.7
    obviously, a sprocket can only have a WHOLE NUMBER of teeth. A 12tooth sprocket will provide a top speed of slightly under 45kmh, whereas an 11tooth sprocket would provide a slightly greater than 45kmh top speed.

    for 60kmh, CSR = 1.93
    => RST = FST / CSR
    => RST = 17 / 1.93
    => RST = 8.8
    A 9tooth sprocket will provide a top speed of slightly under 60kmh, whereas an 8tooth sprocket would provide a slightly greater than 60kmh top speed.

    for 75kmh, CSR = 2.41
    => RST = FST / CSR
    => RST = 17 / 2.41
    => RST = 7.1
    An 8tooth sprocket will provide a top speed of slightly under 75kmh, whereas an 7tooth sprocket would provide a slightly greater than 75kmh top speed.

    It should be noted here that a 9tooth sprocket is the smallest I was able to find BUT I'd be very surprised if the chain ran smoothly over it on a standard shaft. Obviously, sprocket tooth stress increases with a lower number of teeth on that sprocket - there are simply fewer teeth for the chain to engage with and transfer power to.
    It should also be noted that whilst some even number sprockets exist within the available 9-17 tooth range, there are more odd numbered ones that there are even numbered ones. I believe this is because sprockets with an odd number of teeth wear, both themselves and the chain, more uniformly that sprockets with even numbers of teeth. If a sprocket has an even number of teeth, then the same tooth will be engaged by the same pair of chain rollers upon each rotation. This, in turn, leads to uneven wear on the chain and sprocket and a shortened service life for both... as I understand things.

    I thought about the above for a good few hours whilst I was away on business someplace else and couldn't see any other, relatively simple (DIY) and low cost approach to my speed dilemma...
    As I was originally 'aiming' to replicate the original / standard scoot I decided to settle for slightly improved 45kmh performance and opted for an 11tooth sprocket.

    Working out the math on this one from the original formula :
    5 x CSR x 0.0714 x 1.45 x 60 = Kmh
    CSR = 17/11 = 1.55

    => 5 x 1.55 x 0.0714 x 1.45 x 60 = Kmh
    = 48Kmh
    ...and... the max motor rpm was stated (and seen on the tacho as the 'limiter' cut in) as being 5900
    => 5.9 x 1.55 x 0.0714 x 1.45 x 60 = Kmh
    = 57Kmh

    So, with a 17tooth sprocket up front (on the motor) and an 11tooth sprocket on the rear (gearbox input shaft) I should expect a top speed somewhere in the region of 48 to 57Kmh.

    That was OK. I was 'happy' again... the question though was how to get an 11tooth T8F sprocket onto an overly long, 38mm diameter shaft !!

    In the end, the solution was pretty simple, if a little drastic. But, hey, what the heck, I'd already gone way past the point of no return...

    Adapt the shaft !
    So, I'm off to do just that !!

  4. #24
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    50cc Scooter conversion - Gearing : Attempt 2

    Having experienced the results of my NOT having done some math (I guess, at the outset, I had just 'hoped' all would be well because it was the simplest solution - not to mention that the conversion itself seemed pretty daunting and I was impatient to start. D'Oh !! ) and having just recently worked out the chain / sprocket ratio I was looking for, I ordered up and received three T8F / double 'D' sprockets; 9tooth, 11tooth and 17tooth.
    The 17tooth is for the motor sprocket
    The 9tooth is for the rear sprocket along with the 11tooth sprocket should the 9tooth be, as expected, simply too small for the chain / shaft diameter... it IS sold for this chain but maybe not this shaft diameter and I'm loathe to reduce the original diameter of the shaft on the gearbox side of the sprocket. Each sprocket was around was 7Euro, so why not give the 9tooth one a go anyways ?!

    So, in steps (always easier for my tiny brain ! ) :
    I'm going to need to :
    shorten the existing input shaft,
    reduce its diameter, creating a 10mm shoulder for the T8F sprocket,
    reduce the shaft diameter still further (to 8mm) so that the T8F sprocket fits over it and up to the 10mm shoulder,
    cut two flats on the 10mm portion of the shaft to suit the T8F sprocket, ensuring they are 6mm deep - the depth of the sprocket,
    cut an 8mm / M8 thread onto the newly created 8mm portion of the shaft,
    slide the sprocket into place, followed by a lock washer and then the M8 nut (the lock washer not only helps prevent the nut from backing off but also takes up the 'slack' between the 10mm-to-8mm shoulder and the thread on the 8mm shaft due to the shoulders on the thread cutting die).

    When put like that, it all sounded pretty simple but how to achieve concentric faces on the shaft whilst the shaft is still fixed to the gearbox ? I really needed to remove the shaft and lathe it up... but... that's definitely NOT within the realms of your average DIY'er I thought and most certainly outwith my budget to have it professionally done (not to mention that it's outwith the original scope of the project)...

    What I came up with was slightly simpler: reassemble and back-drive the gearbox with a drill. So, attaching a suitable socket to the drill and driving the gearbox from the wheel end gave me a rotational advantage of 14:1 (the gearbox ratio in reverse) and the ability to rotate the input side of the shaft just like it was on a lathe ! Well, that was the idea... So, sticking to my step-by-step approach, I :

    1: reassembled the gearbox and removed the existing clutch / variable-drive unit for the gearbox input shaft :

    2: measured the required offset; the distance between the shaft bearing face and the end of the 'to-be modified-and-threaded' shaft, taking into account the depth / thickness of the sprocket, lock washer and nut (+ a wee bit).
    3: attached the drill to the output side of the gearbox and had my 'helpful assistant' on the drill trigger ! And now, cut the shaft to suit. No going back now !!

    4: carefully re-measured the offset of the 10mm shaft shoulder and, with the help of a spinning gearbox input shaft (drill and helpful assistant), a grinder (for the initial 'get-me-close' work) and a file and some digital callipers (for the finishing / precision work), reduced the shaft diameter to 10mm (for the sprocket).
    5: carefully measured a 6.5mm offset on the newly created 10mm shaft and reduced the shaft end to 8mm, thereby creating a second shoulder for the washer and nut...
    6: locked the shaft and filed two opposing flats on the 10mm portion to accept the T8F sprocket.

    7: threaded the 8mm portion of the shaft getting as close to the 100mm/8mm shoulder as was possible.I was very careful here to get as close as possible but not to have the die come up hard against the shoulder and thereby damage the newly cut thread. The split / spring washer is here to 'take up' that 'slack'.

    8: offer up the sprocket and make any adjustments. This was slow work, you can't add a bit back onto the shaft after taking too much off... slow but sure, testing and measuring all the time.
    9: fit the split / spring washer and the nut !!

    10: Use a rule for the check the final lateral alignment between the motor pinion and the gearbox sprocket. There is around 15mm of lateral movement in the 4 x motor mountings so final alignment was simple enough.

    11: Cut and split-link the chain to suit and then tension in the usual 'alternator-style' way at the motor. In the case of a scoot and particularly in the method I'd selected to mount the motor, there is no 'play' needed in the chain to take up suspension travel. The motor, chain and rear wheel all move on the same swingarm / frame... No idler, sprung tension sprocket needed - one of the clever design features of a scoot's transmission.

    All in, from start to finish (once I had the math pegged), this took the best part of an afternoon ! Nice 'n' steady was the name of the game here, like I said, I was very aware I couldn't easily remedy removal of too much of the shaft...
    As it happened, all worked out just fine and, remember, I'm an electrician (of sorts) to trade, not a machinist or mechanic ! If I can do it, then anyone can !
    I should have done this from the start but feared messing about with the mechanical stuff - just go nice and slow, take your time, better to get a good result and take your time than to rush a mistake... especially as a 'mistake' on the shaft work is not easily recovered from.

    That's me for the initial conversion. All-in-all around 37 hours work. The next one would be MUCH quicker (barring any mistakes) IF I was ever to do another scoot - what I'd REALLY like to do is a Kawasaki VN 650 or similar - now that would be fun !

    Anyways, I'm off to have some fun and (gently) road-test the Scoot-ee !!

    There will undoubtedly be some alterations and additions but they're for another day as is whether this could ever be documented with a view to creating a 'kit' of parts. I'm also keen to make a small video of Scoot-ee on the road after some basic road-tests. Maybe it could indicate the performance, how it sounds and behaves and. . . and whether I feel it was all worth or not...

  5. #25
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    50cc Scooter conversion - Road Tests

    Wow !
    So this is an EV grin ! I'm still picking the flies out of my teeth (yeuch) !

    I'm not quite sure where to start. I realise this project was only for a 50cc scooter and by many standards it was pretty simply / basic but I am blown away - not by my work but rather by the result; quiet, cheap to run, non CO2 polluting, low maintenance...
    It's true, you HAVE to try electric before knocking it and then... well, after a a try, you most definitely won't be knocking it !
    Grassy shot (Front LHS)-2(250x188px).jpg
    Grassy Shot (Rear RHS)(250x334px).jpg

    Anyways, I'm a pretty 'picky' kinda guy and, normally, the first to criticise my own work and the results of it so, let's start with the criticisms :

    To be fair, at this stage, after 34km on Scoot-ee, I don't have many criticisms :

    1: take-off is a little... 'vicious' / quick. There seems to be no gentle / soft-start I guess I'd call it. Just have to be careful when starting off that you're pointing in the right direction. To be fair, it's nothing horrible, just not quite the soft / gentle start I'd have preferred for normal kick-offs...

    2: the batteries are hard to remove - I'll re-design them from long'n'thin (20 18650 cells long and 4 cells wide) to short and fat (10 cells long and 8 cells wide). The new size is just within the capabilities of Prusa mk3 printer and should allow me to fit 3 (3Kw) (in lieu of 2 - 2Kw) if I want / need to. To be fair, 34km and not dead is better than I imagined... so... 3 packs most likely will not be necessary but...

    3: the V / A 'test' meter could be better. I'd like to improve upon this with a coulomb counter type meter or maybe a full screen / instrument panel to replace the one that's there... it's not a 'requirement (especially as I scraped in, just under the 800Euro budget) to be fair but if such a display could be fitted and look good then it would definitely be better.

    4: in an ideal world I'd have been able to keep to a belt drive. Much quieter, but really... it's a little like a turbine powering up... not loud or annoying... I'd have simply preferred EVEN quieter !

    Having said that...
    SwingArm cover-1(250x188px).jpg

    Top Speed
    the top speed is in excess of 60kmh down hill (rev limiter cuts in again at around 65-68Kph) and easily 57kmh on the flat (wind or no wind) VERY happy !

    seems more than adequate.
    0-30Kmh in 5.1 seconds
    0-45Kmh in 9.8 seconds
    0-50Kmh in 19.9 seconds
    250metres from standing start 21.6 seconds
    Definitely NOT blistering but better than stock. It probably didn't help that my mouth was wide open in an electric / ecstatic kind of grin - must have increased drag / resistance
    I'm also pretty sure that a Kelly KBL72101X controller would make a huge difference but then it would add an additional 300Euro to the budget ! But... once I receive thoughts from you, more experienced guys, I'd be more than happy now to swap out the controllers for a test... Currently max amps through the controller is 'limited' to 40A - it's just the controller. Loading up the two battery packs through their BMS's and breakers delivers in excess of 75A so... Kelly controller upgrade would seem to be appropriate if I need / want more dazzling performance.

    Impressive, almost none, just a chain 'rattle'... and a turbo-style whine... not bad at all and a HUGE improvement over the original !! I'd still like a belt though. This motor just won't accept a belt very easily...
    Again, if I were doing another conversion I would spend more time researching the motor and get something that could handle a belt pulley, maybe with an additional end-of-shaft bearing for less shaft stress... thoughts anyone ?

    Having said all the above, I still can't quite believe it all works so well.
    I'm monitoring controller temperature (fishtanks style digital thermometer clamped to two controller fins and heat paste. Currently, (just 34Kms) the max recorded temperature is 36'C / 97'F. I think that's OK but, again... thoughts... I'm also going to do some decent hill work this week to test and check controller amps / temperature / volts...
    Batteries (V2) Installed-2(250x188px).jpg

    What more can I say ?

    Conversion work (give or take a wee bit) : 40 Hrs

    Original RPS Scoot purchase price : 200 Euro
    Batteries (2 x 20S4P LiFePo4 / 1Kw ea) : 498 Euro
    Throttle, DCDC converter, SSRs : 75 Euro
    Cable, Plugs+Sockets, Meter+Shunt : 50 Euro
    Fibreglass, paint, clips... : 25 Euro
    Total (give or take a wee bit) : 850 Euro

    Bear in mind,
    I have never undertaken a conversion before...
    I am only your standard electrician / electronics engineer...
    Granted, I have a pretty extensive set of tools but...
    I solder and braze regularly but, although I have a MIG welder, I have less than a full day's welding experience (slightly more now !) ...
    I can fibre glass (used to build beach-rescue canoes etc) but there wasn't much to do on this project anyways and anyone can make a cardboard template or two and apply some fibreglass, so...

    90% of this project could be undertaken without any specialist tools; a 'standard' toolbox (spanners, screwdrivers & files etc), a drill, a grinder, a multi-meter and a soldering iron.
    The last 10% would involve a welder (stick would be fine, I used a MIG), a method to make up your battery pack(s) or you could buy it (them) ready made, a hot air gun and a glue gun...
    Granted, I DO have use of a 3D printer and I have extensive experience with both it and Sketchup BUT neither are absolutely necessary...

    Re-registration in France is all but impossible BUT in the UK, it took less than 30 minutes to arrange, the road tax is zero and the insurance cheaper than the original ICE scooter. Having said that, I live in France and haven't physically done a re-registration BUT I have spoken at length to DVLA (thanks Bob) and various insurance brokers...
    I have no idea as to how difficult it is in Germany, Netherlands or the US but, remember there were ZERO frame, swingarm, brake or original equipment mods - all I did was remove the ICE kit...

    Cost Justification
    As if we need one nowadays to switch from fossil fuels, not to mention the fun to be had during the project and the amount I learnt... but...
    All of the work was completed for a total expenditure of (give or take) 1,000 Euro. That includes the original ICE scooter purchase !!! There are quite literally thousands of 50cc / 125cc scooters, mopeds and motorcycles in Europe alone that don't work but could be brought back to life for less than a thousand Euro / Pounds with almost zero running charges ! It might be illegal (strictly speaking) to ride a conversion on the road today in France and, maybe, other countries, but in 12 months, 2 years or 5 years time and as governmental Co2 reduction targets come into force ??? Who knows ?!
    Additionally, Low and Ultra-Low Emission Zones are on the increase. Two to three months riding in one of these zones would pay for the conversion.

    Finally, I put an OWL (energy power) meter on the charger last night. The 2 x packs were showing 67V at the start and were fully charged this morning (I think it should only take 4 to 5 hours tops from empty to full) and the meter displayed 1.7Kw of energy at 26cents (0.26 Euro) cost - for 34Kms !!!! Incredible.

    I can't help but get all fired up over this and think I could run for free if I had roof solar - and not much of it at that !! No cost to me, reduced noise, almost zero servicing costs and no Co2 emissions damaging the planet ! What's not to like ?
    Charge Socket (IEC)(250x188px).jpg
    Charger (Installed in SeatBox)(250x188px).jpg

    I guess now, it just remains for me to :
    do a lot more tests,
    make a video and You-Tube it,
    undertake the mods (when I've stopped grinning) and
    monitor how Scoot-ee performs over the next couple of hundred kilometres...

    RESULT ! Delighted, I think that says it all - I'm converted !!

  6. Likes Stevo liked this post
  7. #26
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    50cc Scooter conversion - Batteries revisited

    So, my original Panasonic 18650 cells, as a 20S4P pack in a 20 cells long x 4 cells wide configuration were, it transpired, simply too awkward a shape to remove and re-insert easily.

    I designed them this way so that the two packs would lie alongside each other just forward and above the motor in a GRP tray I'd made up. This was all to keep the centre of gravity as low as possible whilst enabling pack removal - to be charged indoors, for additional security and for piece of mind in extreme temperatures. The design should also have allowed the helmet to be stored in the remaining space - there is no helmet lock on this scoot.

    All looked good on paper and with mockups BUT, in reality / in use, with all the plastic panels and seat pod back in place, things were just that wee bit too tight; the batteries were very difficult to remove and the charger had to be removed first to enable the batteries to come out (and go back in)... And any helmet, apart for the most basic with no visor, didn't fit anyways (I really should have checked that first ! D'oh! ).
    In short, a real pain...

    So I looked at ways to re-jig the available space and decided to redesign the long and thin (20 cells long x 4 cells wide) packs into short and fat (10 cells long x 8 cells wide) packs.
    The idea here was to put the charger forward in the GRP tray and then the two battery packs, side-by-side, directly under the seat and easy to remove.
    Back to Sketchup and a re-design of the plastics that would be necessary for the second attempt (embarrassed face)...
    Once I had the design, I dug out the original foam template packs and modified them to represent the new 10x4 configuration I had in mind. I added some additional foam - just to make them slightly oversized / larger than my Sketchup designs indicated (just in case !! ).

    The new battery packs were then offered up left-to-right and forward-aft. I needed the charger to fit in as well and was keen to see if I could re-jig in such a way as to let me add a third pack at a later date, if I felt I needed to... As it turned out I fitted the charger in front and across the scoot. The two battery packs fitted neatly in a forward-aft configuration just behind this and... I think... I've just enough space to squeeze in a third pack later on - if required. That was lucky - I really didn't want to have to 're-invent' the GRP tray as well - it's not that difficult but it does take time and...

    As it turned out that was the easy part; modifying the existing battery pack configuration wasn't as easy as I had anticipated - mostly because I'd spot welded the packs together - preferring spot welds to solder and never thinking they'd need to come apart (D'Oh !).
    Anyways, once I'd opened up the packs and split them at the half way point (2 x 'sub-packs' of 10 x 4 cells) I realised I'd have to disconnected the BMS sense cabling, re-route and reconnect. In fact, as is often the case,, the thinking about doing this was more daunting than the actual doing ! Both packs were re-jigged within the day and ready for their new, 3D printed, enclosures.

    20S4P_10Lx8W Enclosure on Printer(500x375px).jpg

    The new design has just 3 parts (as opposed to original 5 parts) and is much sturdier; a top, a bottom and the slide in / out face-plate.

    Additionally, I decided to try out brass 4mm inserts for the 4 corner machine screws to land onto rather than my 'tried and tested' method of machine screw one side of an enclosure and a matching nut on the other.

    20S4P_10L8W End Panel(500x667px).jpg

    The face-plate houses :
    the Circuit breaker,
    the 2-pin Anderson Controller connector and
    the 4-pin Charge socket.

    20S4P_10Lx8W End Panel with Components(500x667px).jpg

    It simply slides into slots on the two enclosure halves which makes wiring it all up really simple.

    Luckily, both the Controller cable and the Charger cable were sufficiently long so there were no more mods to be done. I just had to wait for the 3D printer...

    So, putting it all together :

    20S4P_10Wx8L pre-CloseUp(500x375px).jpg
    20S4p_10Lx8W Insert fitting(500x375px).jpg
    20S4(_10Lx8W Open(500x667px).jpg

    I found the best way of inserting the brass threaded 'inserts' was to simply heat them with a soldering iron whilst applying slight downward force. Speaking from my experience, attention has to be paid :
    1: not to overheat the insert - it's very easy to loose control of its direction and depth if it's too hot !
    2: to maintain as vertical a pressure as possible - again, it's really easy to mis-align the insert and, as such, have difficulty screwing up the machine screw later. To be fair, a misaligned insert can be re-aligned later after some heating but it does take some time and weaken the structure / insert's grip on the surrounding plastic (PLA or ABS).

    TIP: I found it best to apply gentle pressure with the soldering iron until the insert was around 1/3 depth and then replace the iron with a flat faced tool (like an overlarge allen key) to continue the downward pressure and ensure a flat face on the surrounding plastic mating surface. This way it's not as easy to push the insert in too deep, it's easier to maintain verticality. and the colder mass of the allen key allows the insert to cool faster, thereby minimising insert 'drift'...

    Anyways, the finished battery packs look like:

    20S4P_10Lx8W ReadyToUse-1(250x500px).jpg
    20S4P_10Lx8W ReadyToUse-2(250x500px).jpg
    20S4P_10Lx8W ReadyToUse-3(350x500px).jpg

    I noted that I was not going to have enough of the one colour to complete printing the packs so decided to print one side of each in silver and the opposing side in black ! Seems to work !! I also wanted to ensure as little 'stress' on the inserts as possible, so taped up the packs (over the insert area) at each end. If I was printing the packs again, I'd most likely have 6 inserts / matching M4 x 35mm machine screws but...

    The new packs dropped back into Scoot-ee without any issues at all. All-in-all a successful rescue from my first poor design. That was a bit of luck.
    The downside ? Whilst there appears to be sufficient room for a 3rd battery pack (just) there is no longer room for my lunchbox !!

    Anyways, new batteries complete. Onto the other mods / improvements...
    Last edited by 3DRoboGuy; 12 August 2019 at 0535. Reason: image change

  8. #27
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    50cc Scooter conversion - after 500+ electric kilometers & VIDEO !

    Well... I thought I should make a quick update.

    Scoot-ee has now completed more than 500km since going back on the road after the conversion to electric.
    Nothing major to report (except the previous battery re-configuration work).

    A video can be found here : https://youtu.be/4QgF20aDRrw
    This was my first foray into forums, my first scoot conversion and now this is my first YouTube video (needless to say, I'm extremely anxious ! ) Be gentle folks !!
    It does go a long way to proving though - if I can do it in my garage, so too can anyone else with a mind to do so !

    Anyways, on a not so great a note, some of the in-use problems I had :

    1: SSRs : I decided to use SSRs (Solid State Relays) to handle the power switching on Scoot-ee. I encountered a few issues here :
    SSR's dislike back EMFs and spikes and, like any other 'switch' they can't control inrush current (like when connecting the battery to the controller). There are also tons and tons of el-cheapo Chinese copies that are simply not up to spec / masquerading as 60A units when, in fact, they're only 25A or 30A internally !! I'm not making this stuff up, I actually stripped the third failure down - one 25A FET... That was it !! VERY annoying. (If I get time, I'll make a post about my work with this too).
    The inrush current is handled in many different ways. For me, being an electronics sort of chap, I decided to go down the NTC / PTC thermistor route. I contacted those really nice guys at Ametherm (Canada) and was re-directed to their European (UK) office. To cut a long story short I found (thanks to Tony Chedester - Canada and Eleonore Hofmann - UK and some formulae they supplied me with) that the AS32 5R020 does a great job providing inrush current limiting across the Hi-V (Controller) SSR as did a chunky 100v, 6A diode in reverse across the SSR to deal with back EMFs to the battery. Between these two components and a 'real' (not cheap Chinese copy) 100A DCDC SSR I have had no more inoperative SSRs for over 400Km now. Result !!
    Ametherm AS32 5R020(250x388px).jpg
    Diode 6A 100v(500x400px).jpg

    2: Charger : I found the charger (much like the controller) really didn't 'like' the instant it was connected to the on board batteries. Each time a connection was made a noticeable electrical 'crack' could be heard. A temporary way around this issue was to ensure the charger was connected to the mains and 'On' before connecting it to the batteries but... that was 'fiddly' and prone to error (forgetfulness). Anyways, once again, Ametherm and their formulas and data sheets came to the rescue. Once I'd fitted a suitable, in-line, inrush current limiter between the charger output and the batteries, the problem went away - permanently. Another Result !!

    3: Batteries : I had initially designed my batteries to be 'long and thin, siting them above the motor (low centre of gravity etc), 20 x 18650 cells long and 4 cells wide (as per the previous posts). In fact, by the time I'd refitted all the fairings / seat panels, I found it almost impossible to remove and refit the battery packs. A redesign was required !! I redesigned (Sketchup) the packs to be 10 cells long by 8 cells wide. No mean feat re-jigging the packs / spot-welded connections... but... a days work and two days 3D printing time later, I now have new 2 x re-jigged packs. MUCH better. An additional unexpected 'plus' - the battery pack re-design would appear to enable me to fit 3 (as opposed to the designed-for 2) battery packs within the available area below the seat, the shorter / squarer batteries fit best further aft... which means I used the now 'spare' space ahead of them for the charger which no longer sits on a shelf above them. I've discussed all this in a previous post.
    All the above is neat and really works out well - day-to-day charger access isn't really needed - however, to the 'negative' bit - relocating the charger forward of the batteries basically 'hides' it away which means the red (charging) and green (charged / finished) LEDS are no longer visible ! So... I now need to add a remote / more visible Red/Green charging/charged LED. I'm currently thinking about a suitable site / method of doing this...

    4: Range : There are two 20S4P packs fitted. Range though is (depending upon use) between 25km and 38km. 25km when driven REALLY hard, two up. Much better, up to 38km without any run-out-of-juice dramas, if my wife is in control or I select the 'Lo' Speed setting (you may remember, I wasn't sure why I would need 'Lo' but... I added the Hi/Lo switch some weeks ago) !!! I'm sure this could be bettered still BUT youngsters feel the need for speed and it doesn't really matter how often I tell them, the throttle grip appears to be a two stage switch for them (with no in-between) off / stopped and on / full speed !!!

    5: Coulomb counter / Volt/Amp meter : We've learned to 'take it real-easy' and 'limp' home when the displayed voltage drops below 68V on the level and with no (or very little) acceleration ... Still 30plus Km for a 2Kw pack (around 30cents a re-charge) is brilliant ! I really do need to get onto that coulomb-counter... My logic here is to design an Atmel microprocessor based board that monitors voltage and input (charging) / output (motor / lights etc) current. I'm thinking a small micro-processor based board (once programmed / configured) should be able to display remaining Amps and, therefore, remaining Km. Either on a dedicated display or, this summer's job (if nothing else more urgent pops up) on the existing fuel gauge. When the gauge drops into the red, it's time to head for a recharge !!

    Anyway, like I said above, I did create that Scoot-ee video (my first ever video) and it's here : https://youtu.be/4QgF20aDRrw
    I have thought of doing a few more, based on each of the major steps during the conversion but the vid took me a day all-in and, whilst I'm willing to spend time creating and posting them, I'd only really feel comfortable doing so if someone feels that they may be useful... so... I'll wait and see what the responses to the video are like.

  9. #28
    Senior Member Stevo's Avatar
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    Nice job!
    Now ride and enjoy your work
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
    Current builds: eVOR.v3.4

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