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[Bill822]

You're making a lot of progress quickly.

[3DRoboGuy]

Thanks for the encouragement, Bill. To be frank, it's all going pretty smoothly - almost too smoothly ! I'm working with baited breath...

I thought that before I start the main / primary EV electrics I should 'tidy up' a little bit first.
To be fair, at this precise time, given that I have serious doubts as to the effectiveness (and, therefore, finality) of the scoots gearing, I have decided to carry out the most basic of tunnel / cover modifications. All I did was to mark out the upper and lower limits of the chain drive between the motor sprocket and the, recently refitted, rear gearbox input sprocket

and then cut the marked area out with a hacksaw and file. A little sandpaper on the edges to finish and...

Once the marker pen is cleared off with some white-spirit then all will be well for a proper, chain-on test...

[3DRoboGuy]

These are to protect the internals form dirt, grit and water ingress as far as practically possible. In the case of my scoot, I have various cover / blank plates to design and fit :
[1] Oil pump blanks (I need to design one with a cable (motor) pass-through slot)
[2] Starter motor blank
[3] Crank shaft blanks
I reverted back to SketchUp again and then the 3D printer and came up with the various designs which I then printed in yellow ABS (just had a lot of yellow lying around  ) and then fitted.

It took two iterations of the square oil pump blank to take the motor cable... but all-in-all, no major issues.

[3DRoboGuy]

With most of the 'boring' stuff out of the way I started off trying to work out where to site the batteries I would be making. Once the site was chosen I'd have a better idea as to final available / required dimensions. I had already played about with weights etc and pre-set any pre-requirements I had :
[1] they must be removable for security, off-scoot charging and protection against extreme temperatures.
[2] being removable they need to be pretty light - around older laptop weights; 1Kg (plus or minus) would be great. For me 'lighter' not only means more easily carried about but less likely to be thumped around when placing them down etc and more manoeuvrable getting them on-off / in-out of the scoot.
[3] two (or more) smaller packs would tend to suit the previous requirements whilst benefitting from more spaces on board the scoot (there seems to me to be a lot of 'small' spaces available but few large ones) and also lends them more readily to be re-tasked between projects.
[4] maintain as-low-as-possible a centre of gravity; a top heavy scoot is horrible to handle both in traffic and whilst re-positioning/parking it by hand
[5] if at all possible, maintain the helmet area below the seat. Having said that, on this scoot any helmet would have to be a pretty small open face or half helmet if it were to fit at all !

Anyways, I had already selected 72V : 13-14AHr per pack equating to a 20S4P (1Kw) minimum pack power / size. Each pack was to be thermally protected and be able to be individually and / or group charged.

From the outset, I had hoped to build two 'long and slim' (20 cells long, 4 cells wide) packs and site them under the riders' feet, within the fairing area. Unfortunately, without massive frame mods, there simply wasn't enough space for this to be feasible.

Next I looked at using the space vacated by the recently removed fuel tank (although, in reality, too high - from a centre of gravity point of view.). The main (and pretty much insurmountable) problem here though, was that the seat lock bracket was in the way; the two packs would fit (side-by-side) but they'd not be removable. That coupled with the height 'issue' meant option 2 was, again without major grinding and welding work, a dead end too !!
Then I looked at designing and building two exhaust-style 'cans' - one for each of the battery packs and either side of the scoot... a wee bit drastic but definitely worth investigating. Maybe at a later date.
In the end I decided to fit them directly above the motor; in the area below the seat, at the very bottom of the seat 'box'. It would mean removing much of the base of the seat-box - so that they could be taken out (for in-house / external charging) and put back in again - but this was the most feasible of the options I'd looked at...
Once I had the location sorted it came time to make a bracket/shelf arrangement for the two battery packs to sit in above the motor. Initially, I made a mockup in cardboard then in some left-over 10mm EPA foam that was lying around. Once that seemed to be OK, I re-made the bracket so that the original would fit inside it, removed the original and fibreglassed up a shelf unit complete with side and fixing points to locate it securely on the scoot framework whilst, at the same time ensuring sufficient room for the motor to be rotated for chain tensioning... A bit for sanding and painting and...

With the battery mock-ups now fitting snugly in their new 'home' on board the scoot I gingerly cut, re-cut and cut again (and again - little by little) the base of the under-seat helmet / storage box to allow their insertion and removal. That all done, it was time to move on to making the battery packs.  After gathering together the parts; NCR18650GA batteries, SplitPort BMS, Thermal CB, Charge Plug/Socket & Anderson connector, etc... I began, with the help of the Spot Welder I built for these 18650 cells, SketchUp and my 3D Printer to build the battery packs.

I ended up :
...Building the packs - 20S4P configuration...
I decided to spot-weld (not solder) and fuse the cells (top and bottom / anode and cathode). I also decided to go with a split-port BMS and a thermal, 50A circuit breaker for output protection. I designed in 2 x thermistors and placed them 1/3 of the way / 6 cells rows in from each end-cap. The cables were routed to the CB end-cap and left insulated for a future date add-on project. The idea being to enable battery cooling / heating during charging and battery cooling when running and too hot. I haven't gotten round to this just yet but, when I need a break, I am programming and testing the AVR code.)
...Printing out, building and connecting up the end caps...
(I designed the end caps with three ridges - for the heat shrink to grip onto)
...and putting them all together before applying 3mm foam protective sheet and heatshrinking the lot...


NCR18650GA cells are 'C' rated at 3340mAHr. 'C' effectively equates to capacity (measured in AmpHours).
In the packs (designed & built above) there are 4 x NCR18650GA cells in parallel. That produces a total of (just over) 13AHr. They are rated at 3C continuous (10C max) discharge and 0.7C designed charge current which equates to a 9A charge current PER battery pack, therefore, a 10AHr charger would be fine (seeing as a 9Ahr charger isn't readily available and 1 additional AHr shouldn't cause an issue) for these packs.
Furthermore, whilst each pack has a 'C' rating of (just over) 9AHr, the PAIR of packs onboard the scoot will have a 'C' rating of (just over) 18AHr, so a 20A charger COULD be used IF the battery packs were to be charged as a pair (with a similar caution as per the 10AHr charger for a single pack).
I purchased (quite a while ago) a 72v 5AHr charger, however, should I wish to install an onboard (on the scoot) charger than to minimise charge time a 20AHr unit would quadruple the available charge current and (a little simplistically) speed up the re-charge time accordingly - if the room is available at the end of the project.
Either way, I don't foresee an immediate need to have 'high speed' charging and intend (at this point in time) to use the 5AHr charger for both onboard (dual / paired pack)and in-house (single pack) charging. As as 'aside' the 5A charger I purchased was $60 (USD) whereas a 20A version would be around $160 (USD) - not a huge increase for a far quicker re-charge - if required. The real 'downside' is :
the 5A charger comes in at around 1Kg and has dimensions around 200mm x 110mm x 60mm
whereas
the 20A version comes in at around 3+Kg and a ballpark size of 330mm x 175mm x 115mm.
Finding enough room for the 20A charger onboard the scoot would be much more difficult - in my case ! At some point I'll do a more in-depth study and comparison of 5A, 10A, 15A and 20A chargers... but not today... I'm still on a mission to finish this scoot !

[3DRoboGuy]

I'm only allowed 4 images per post so I have included the last image of a made-up battery pack here !
I make most of my updates there first and then copy'n'paste whan I can to the forum.  I hope that's all allowed / OK. There are a lot more images etc on the website : www.ianwatts.online.

[Bill822]

Again, I'm impressed by your pace with this project. Good info on your blog. I've only just started toying with the idea of my own EV conversion but I'm no stranger to designing and building new machines for the commercial market. Your project gives me encouragement.

I especially liked the idea of simulated exhaust cans for battery housings. On a larger bike that could work very well... and provide appropriate venting should I "let the smoke out."

[3DRoboGuy]

Hi Bill822,
Thanks ! To be totally fair, I'm probably a couple of days more advanced in reality than I am updating the forum... Having said that I have also had 6 months or so to plan this... so I do feel a little bit of a fraud in that  when I started the project some 5 to 6 weeks ago I already had a load of research notes, sketches and even some basic SketchUp designs in hand... BUT... I'm still very grateful for the support... I think 6 weeks in my son's world is a lifetime - he's almost stopped enquiring as to "Are we nearly there yet, Dad ?" 

I'm really hoping to have a 'dry' test by the end of the weekend... things are moving much faster now I have the basics pretty much finished.

As to the 'cans' for the batteries. I really like the idea but my printer doesn't go large enough, easily enough (without making a design in multiple
 clip / glue -together pieces) although I have seen that I can buy empty cycle battery pack 'enclosures' on eBay for 15-odd quid / 25-odd USD and with some modifications,... who knows ?... they might just look cool... it's on my list of 'possible future jobs/projects'...

Anyways, thanks again.
Good luck with your Zero.
I'm off to start the controller electrics. Hopefully, no smoke !! 

[3DRoboGuy]

This week I've been busy with the last major part of the conversion: siting the controller and associated components.
The original ICE kit has been removed.
The original wiring has been serviced / repaired / updated to remove no-longer required cabling and modified to re-task cabling to suit the new electrics and add any new / additional cabling for the imminent electric conversion.
The 3Kw BLDC electric motor has been fitted on a custom, adjustable, aluminium bracket and the cabling routed aft and up to the intended controller position.
The belt driven vari-drive has been modified for a chain drive with rear sprocket and the clutch has been left insitu (to start off with but I have my doubts here...).
All lighting has been switched to LED.
The battery pack tray has been built and installed.
The 2 x 72V, 1KW battery backs have been built, charged and tested.
The fuel filler cap has been replaced with a 3D printed charge point complete with waterproof cap (still need to update here with pics etc).

The next step was to design and build the controller 'tray' and then mount the controller before adding a 2nd tier shelf arrangement on which to mount the other electrical / electronic components (fuses, relays, DCDC convertor, 12V battery etc) and connecting the systems up prior to testing. Now it's becoming exciting...

Controller tray
Now that the batteries were sited directly above the motor, there was enough space (with a little modification) to site the controller (and ancillary parts) in lieu of the petrol tank / aft of the rider's seat. This are is a quite 'unforgiving' space in that the rear wheel is directly below (don't go too deep) and the fairings are immediately above (don't come too high). To boot, access to the rear / brake light is from this area too (don't go too far aft) and the front end is limited by the seat-lock bracket (don't come too fare forward)... BUT... all-in-all this is controller space !! Dry and well cooled...
Having decided all would be well, I set to designing and fabricating the tray. This was no job for SketchUp or the 3D printer - just cardboard, scissors and tape before moving on to foam and then fabrication with fibreglass...

It quickly became apparent that no matter how much I dislike cutting holes where not absolutely necessary and no matter how much I 'squeezed' or moved the controller or how I oriented it (within the constraints that I had) I HAD to cut two holes in the seat support bracket to enable the cables to pass through and, thereby, allow the controller to move far enough forward to facilitate access to the tail lights. In this case though I couldn't see how the holes would weaken the overall structure so... I cut the holes, rust proofed them, glossed over and trial fitted the controller...

All looked good so the next step was to mount the controller and the two SSRs with their heatsinks. I guess the 'norm' here is to use HV contactors / relays but Solid State Relays use so little power when 'On' and have the advantage of being so very flexible with their energising voltage that I thought I'd give them a go. They have worked great in other projects (like my Spot Welder) so they deserved a chance here too... especially as, having no moving parts, there can be no contact bounce / accidental disconnect due to the higher vibration of the scooter... Anyways, I gave them a go !
Two of them, one for the low voltage (12V) / controller energising and one for the high voltage, (72V) motor.

The recently removed fuel tank had been through-bolted at four points - top and bottom left and right of the recently-fitted controller tray. These were to be re-tasked to locate the "ancillary components shelf" which (because it allows me to see the controller & SSRs below and because (I think) it looks super cool - not that, when all the fairings are back in place, it will be visible !) was to be made form 8mm clear Acrylic sheet...

After test fitting the controller tray and acrylic 'shelf' it was time to drill 2 additional (corner) holes in the tray for drainage (there's just bound to be some water ingress) and finally fix it to the scoot frame.


I ended up with the painted black, GRP tray housing the controller, the 2 x SSRs and their heat sinks. The tray is angled down toward the front of the scoot (towards the bottom of the image); this is where the 2 x 10mm drain holes are situated. 

The SSRs screw to their (black) heat sinks and the heatsinks are through-screwed into the base of the controller tray. The two holes previously drilled in the seat-lock bracket enable the controller HV input (thick red and black) and motor phase cables (thick blue, yellow and green) - both right hand lower corner, together with the control cables (thinner, multi-coloured) - left hand lower corner, to exit the controller tray without chafing etc...

Now, things began to move really quickly !
This was the part I'd been really looking forward to !!
The first job was to finish siting the SSRs and connect the 2 x battery hook-up cables (terminated with Anderson connectors) The DCDC convertor was fitted next, followed by the Li-Ion 12V battery, the shunt (I think I'm going to want to know charge / discharge current and voltage etc) and then fuse holders. I added a pair of (red / black) banana connector sockets to measure the battery / DCDC convertor voltage and to connect an external 12V source / charger in case of 'flat battery'.

Two SSRs :
... both energised by the Li-Ion battery via its fuse, the ignition switch and the kill switch.
One 10A SSR (left hand side) for the low voltage (12V). This unit feeds 72V to the DCDC convertor.
One 60A SSR (right hand side) for the high voltage (72V, motor / controller). This unit feeds battery pack 72V to the LV / 10A SSR (which feeds the DCDC convertor) and the controller.
One DCDC Convertor :
Connections to the HV SSR output, shunt ground and the 12V fused rail.
One diode :
In-line between the fused 12V rail and the Li-Ion battery The purpose of the diode is to enable Li-Ion battery pack charging whilst preventing back-flow from the battery to any on-board items - except the DCDC convertor (for charging)
Three fuses :
DCDC convertor (all onboard 12V)
Ignition / controller enable (basically, kill switch OFF and Ignition switch ON puts 12V onto the  'power lock' / controller enable.
Onboard lighting / horn electrics
One shunt :
One side of the shunt was connected to both battery -ves, whilst the other side was connected to motor controller -ve, DCDC convertor -ve and chassis ground.
Final steps : the motor cables (green, blue & yellow) were connected via a 50A terminal block to the controller. The controller / motor hall sensor connections were made (plug'n'play)...

... and then onto the throttle, brake, reverse and power lock cables... but those are for tomorrow... (mostly because it's late and I note that the throttle cable is terminated with a different plug-type to the controller socket !

To be frank, I also have :
the High / Low speed connector to make (naturally I only need the HIGH !) but (if only for testing) i'd better make a PAIR of connectors - one for Hi and another for Lo speed - or I could add a Hi/Lo switch...

the 'fuel filler' / charge port to connect. I have designed it (SketchUp) printed it (3D Printer), fitted the matching 72V charge connector into it and test fitted it on the scoot but I need to add the diode protection, connect up and fit it...

dry test the lot...

reassemble the scoot and let my son test it for me... receive his 'review' / critique and...

and... probably, a load of other small jobs I haven't remembered to write down here...

[3DRoboGuy]

Again, the fourth, last, most interesting (in my mind) image wasn't accepted - I'd hit my 600kb limit. Here's the one I wasn't allowed to post :

as with all previous posts I've more info on my web blog: https://www.ianwatts.online/blog

[3DRoboGuy]

This was some fun ! I took some measurements and started designing (SketchUp, again) a replacement fuel filler neck & cap some weeks ago.

First I thought I'd use the same Anderson connector as was on the batteries I intended to build (and have since completed). I can't, right now, remember why but I changed my mind and used the XLR 4-pin socket to match the plug that arrived with the charger... the same sockets in fact as I fitted to the two batteries for charging - keeps the parts list simple

During first fit though, I decided to change the design (again) to a 3pin IEC mains 110/220V AC socket - as per the mains cable between the wall outlet and the charger input. This was mostly because, having a drink at the bar, discussing charging one night, we all agreed that the charger would always be required to charge the scoot (obviously). My idea was that the charger should be carried in a back-pack / ruck-sack or, if space wasn't too important, under the seat ! It was pointed out to me that the charger would then need to be connected to both an available wall outlet and the charge socket, behind the seat. Seemed pretty obvious to me... what wasn't so obvious was that everyone agreed it would be simpler just to connect the bike to the wall socket - no charger to play about with or fall off the seat (or wherever else it had been balanced) and break. Seems reasonable ! In addition the space under the seat (on this scoot) is pretty poor anyways (I think I've already mentioned that somewhere along the line...) so... why not use it for the charger ? ? ? As a bonus, the charger is always dry under the seat - it wouldn't necessarily be so, balanced on the seat / next to the scoot during charing...So... why not indeed ? !
And, as it transpires, there's still some space left over for documents, tools and gloves etc...

The 'downside' to this approach is that the scoot will have a fixed / permanent mains AC item wired in at all times and although it won't (obviously) be live at all times, I'm unsure as to any safety regulations with this approach. Having said that, the IEC connector could always be swapped out for the XLR connector in around 10 minutes... so... What's not to like with this approach ?

The final connector, fitted on the scoot with the fairings back in place, looked pretty cool / not totally out of place... almost as if it was part of the original Chinese scoot...

The design incorporates an 'O' ring on the lid / cap and a large overhang to reduce the chances of water ingress. It has two large drain slots built in (semi-circular, forward and aft of the raised, central, IEC socket, to prevent water build-up if any gets in.

The mains cables (L, N & Earth) are soldered and heatshrunk before being liquid silicone sealed. The cable terminates in the under-seat area with the original IEC plug for the charger. The charger output (XLR connector) connects to the, now redundant, original XLR socket thereby keeping it all fully removable for service etc...

A little smear of silicon grease on the 'O' ring and the lid / cap is a simple friction twist fit !

[Bill822]

Zero uses the IEC socket for charging so it should be OK as far as regulations. Not so sure about the IEC into the charger under the seat. Make sure there is an earth connection through the IEC/charger housing to the chassis.

[3DRoboGuy]

Hi Bill,
Thanks for that - No, I haven't !
I hadn't given an earth point too much thought and stopped thinking about it completely when I tried to work out where to connect the cable on the charger !     (and the scoot) !
I will though !
It'll go onto my list of things to finish. Before I do though... is there an earth wire from the charger itself on the Zero or could I simply 'tap into' the earth cable where I soldered it at the socket ? Pedantic possibly... but I only ask because
[1] there is no dedicated earth point/stud/screw on the charger (I could quite easily add one though) and
[2] whilst the charger is now 'on board' I haven't screwed it down / fitted it permanently as it's above the batteries (and they're removable) in the seat box and I only have the one, so wanted it to remain removable... (not that I plan on removing the batteries much !
[3] I guess there's no 'issue' with having HV (72V) -ve, LV (12V) -ve and mains 240V ground all connected ? That IS how it would have been done on warships, yachts and commercial ferries etc but... apart from anything else that was quite a while ago now... and either the rules may have been updated or my brain is more befuddled that it used to be...
...probably a stupid question.

The charger should though, I guess, be screwed down with a visible earth cable linking it to chassis ?...
Just hadn't planned it that way...

It's quite amazing really... at first glance, there appears to be loads of space on these scoots but when it comes down to it, there's really very little... 

[Bill822]

First, I am not familiar with UK/European regulations which I have heard can be very specific. I am also not an electrician by trade.

I would expect the earth (we say ground) pin on the IEC connector in the charger to be connected to the metal housing of the charger. You can verify this with a multimeter. If so, a wire attached to the housing and the frame would provide a current path in a fault. This is what I would do myself but may well not meet code. On industrial (mining) machines I built for worldwide use I always connected an earthing cable directly from the power connection point to the frame of the machine and never heard of a problem with compliance.

Yes, it should be fine to share an earth between AC and DC components. You have a connection to earth through the kickstand anyway, though unreliable. I did it all the time back before I sold my company. Where you can have issues is if you have two separate plug-in power supplies both providing DC. Even then problems are rare.

With Chinese designed Ebay sourced components, of course, all bets are off. It sounds as if you used quality parts though.

EDIT: I should add- the most likely cause of a ground fault on your scoot would be chafing through the insulation of the mains cable since it will be subject to considerable vibration in use. Exposure to moisture should also be controlled.

[3DRoboGuy]

Thanks,
I think we're both on the same page here...

I always connected an earthing cable directly from the power connection point to the frame of the machine and never heard of a problem with compliance.

That's my current plan too. It does mean removing the fairings again but... I could do with a few other tweaks in there while I'm at it so I'll get onto that later this week (I'm away 'til Friday but...)

On another note, I did manage to do a dry-test / get the rear wheel spinning last night so WooHoo !!

Everything looks pretty good at the moment but I did notice some 'stutter' at high(e)r revs... Having no 'load' (wheel off the ground) I'm unsure if this is a phase / hall sensor or some kind of rev-limiter issue. I'd also say that the clutch (original as-fitted kit on the input shaft to the rear-wheel gearbox) needs to come off... I'll do a load more tests later in the week but you really do need the motor to spin up before the clutch engages and moves the rear wheel. Maybe that's a good thing but...

Anyways, like I say, I'm away til Friday so will content myself (with frustration) to giving these 'issues' some thought and wait til I return. Probably, first check would be with a tacho-gun on the motor gear / rear wheel to see what the actual revs are... Apparently this motor spins up to 5000rpm (with 5900 as maximum).

[Bill822]

I was thinking about the clutch and gear ratios. I was surprised you left the clutch in place but it might allow you to run a higher gear (lower ratio) to reach higher top speed while still having enough torque to move away from a stop without overloading the motor. Just a guess on my part.