Electric Scooter Conversion - Polish WFM Osa M52

Hello all!

First a bit about me - my name is Filip and I live in Scotland. I am very passionate about classic motoring - cars, scooters, mopeds, motorcycles, everything really. I am originally from Poland and I've got a few old cars there that I love driving about - I try and tinker too but I am utterly useless at it, so try and leave it to professionals (bit embarrassing since I am a Mechanical Engineer by trade!).

I was thinking about converting a classic car for ages, but never really had the guts to pull the trigger on it - the cost just seemed to scary for something that may or may not pan out. That is when I realised I could do something that is cheaper but equally exciting - convert a two wheeler. I thought about simpler mopeds, bigger bikes etc. but with all of them I was really worried about space for the battery - this is when I thought that a scooter will be a perfect solution. And when scooters go, there is only one choice in Poland really, and it's the beauty of a WFM Osa.



So here I am - I pulled a trigger on what can only be described as a jigsaw version of the one above. I am very excited about it and mocked up a bit of a plan for this conversion:

1) The scooter has originally 14" wheels, with about 200mm clearance in the rear forks. This matches perfectly with a QS 273 rear wheel motor and that's my plan for this conversion. I think I'd go for a whole conversion kit from QS, including the controller, throttle and brake. Can't decide on the power though - the original bike had a 6kW ICE engine, but that's peak power. If I go for a 6kW electric, isn't it going to be a beast?
2) Battery - for range I was thinking 100km would be great. This is a heavy bike too, so I was thinking 72V but for the Ah I'll pretty much go with how much I can cram in it - 100Ah would be great. I was thinking to use EIG pouch cells, which are screw terminal - I'd need 100 of the 20Ah 3.7V cells.
3) BMS - Literally no idea on this one - I googled it for a bit and there is a great variety out there. Can anyone advise a suitable candidate?
4) Charger - not too fussed about rapid charging to be honest, a simple charger that doesn't take up too much space is what i am after.

I'd like to add tasteful mods to the bike too - replace the lights with an LED version (guessing a DC-DC converter will be needed for this), maybe add an RFID mechanism for starting the bike. I want to keep the looks but bring the mechanics into the XXI century.

One thing that keeps me up at night is making this road legal - the conversion will take place in Poland, but I have means of registering it in a few EU countries (family scattered all over Europe) - where is the best place to get this done?

I will try and keep this post up to date with progress that I am making - it might be slow at the start but hopefully once things get moving it will pick up the pace.

For the closing statement, I just wanted to highlight that I am a complete newbie to the electric conversions - if I made some gross errors of judgement please do let me know, I am here to learn and will listen to any and all advice you guys have

Looks like an awesome contender.

In the states, many people just register the bikes as their original vehicle class. I'm not sure if that's a viable option in Poland/EU.

7.2kWh should definitely get you to 100km, you might even need less if lower speed around town.

There are some decent Chinese chargers like the ones on BMSbattery.com that are air-breathing but pretty affordable and relatively lightweight. I have modded some for high vibe environments and moitsure-resistance. That's one place to look anyhow.

From my perspective it looks like you're definitely in the ballpark, and I love classic scooter designs like this, looking forward to it.

Thanks!

What is the typical solution people do with regards to speedos? I do not want to go with the digital one, is there an analog equivalent that takes hall sensor reading, but still has an old school needle?

Ideally I'd convert the original speedo to use a new mechanism, but maintain the old looks - is this a difficult job? Also, how are the universal meters calibrated - surely it matters whether it's a 14inch or a 20inch wheel for speed readings?

Thanks,

if you poke around arduino (or other mcu) forums, you'll find assorted projects to drive needle-type analog displays from digital signals.

whether they'll work on your specifc unit depends on it's design. if it's like many speedos, it uses a spinning cable from the wheel to drive a fluid-bearing (or similar) friction device inside the display, so the faster the cable spins the more it pushes on the intermediary device that moves the needle. to make one like that work you would need to take the digital speed signal and then run a motor that spins the input of the speedo at the correct rate to give the rigth speed for that input. would take experimentation to determine what that speed is, for a given speed signal input.


if yours are a regular current-driven needle like an ammeter or voltmeter, then you just have to output the correct current from the mcu to drive it, based on the speed signal coming from your wheel.

you could use analog electronics to do either of the above, too, but it's much simpler to experiment with different methods or ratios, etc., using the mcu and software (though i don't know how to do this myself, it's very common).


there are electronic (lcd, etc) display versions that work like the needle types, but look "modern"; if you don't want that but can't do the diy versions, there may be places that sell analog needle display versions that are driven electronically.

for calibration, you can calculate out how many rpm a specific tire will be at for a specific road speed, and hten how many pulses per rotation the wheel will generate, and thus how many pulses per distance unit over time (speed), and program (or design) your conversion electronics to display appropriately.

you will want to measure the actual diameter of the inflated tire on your specific wheel, if you want it to be perfectly accurate. you can get it close enough by using published specs for the tire you're going to use, if you don't want to wait till you have the wheel / tire built and there with you.


for registration and road legality...that's a complex pita in some places (maybe many). some don't care; if it meets the same safety specs it did originally, is all that matters for them. you will have to check in each place (country) you wish to use it what their regulations are. some require engineering tests and validation for various things, which may be complex and/or expensive to do. there are a number of conversion projects around the world (some posted here over the years, some found elsewhere on the web) that have been built but cannot actually be driven or ridden because they cannot be legalized for one reason or another where the builder lives.

so first check your local rules and regulations. then follow that specific process to get it legalized there. once that's done, you may be able to use those results to get it legalized other places, simplifying the process.



jeremy harris here on es has a thread about an rfid "ignition" for ebikes that would probably do what you're after.


there's a lot of chargers out there. if you are monitoring things (not just leaving it always plugged in when you're not riding it) you could use meanwell led psu, like the sealed and potted hlg-600h-xxa versions, where xx is the max voltage range of the unit. i use one built into the sb cruiser trike, so i can plug in wherever i am to get some charge. for my big trike pack it would take around four-five hours to get a full charge from empty with it, but if i'm home i can use the separate parallel set of them to get half that charge time, and if i really had to i could get it done in around an hour by paralleling four of them. they just don't have an automatic shutoff for the end of charge like a "real" charger would...but they are mountable on a bike or vehicle and weather/vibration proof.

chargers designed for the purpose also exist, but you need to get ones that are sealed and potted if you want to be sure they will resist weather and vibration. (ones that are sealed will resist weather, but if they're not potted then parts can shake around and either crack the pcb or solder if they're heavy, or break off and rattle around inside--not super common failure, but it does happen and sucks if you really needed to charge right then and have no other charger. if they are well-designed this is an uncommon issue, like the cycle satiator, etc., but many are not, and arent' really intended to be vehicle mounted).


lighting...commonly "12v" dc-dcs are used, run off your traction battery. make sure to get one that's actually more like 13.6-14v output, as that is what most of the automotive lights are meant to run from. and make sure it has enough amps to run all yoru lights, and the horn if you have one. horns take a lot of current when they first start to sound, and so do halogen (and hid) headlights--this can shutdown a dc-dc if it's not rated for that amount of current, and hten all your lights go off. (may stay off until the power is cycled to the dc-dc input, may just "blink").

FilipK said:

Thanks!

What is the typical solution people do with regards to speedos? I do not want to go with the digital one, is there an analog equivalent that takes hall sensor reading, but still has an old school needle?

Ideally I'd convert the original speedo to use a new mechanism, but maintain the old looks - is this a difficult job? Also, how are the universal meters calibrated - surely it matters whether it's a 14inch or a 20inch wheel for speed readings?

Thanks,

Click to expand...

Many modern speedos use very small stepper motors to actuate the needles, and these motors are available for personal projects. It depends on how comfortable you are with programming and taking apart the old cluster as to how hard that would be. I don't know if there's any open source projects out there for this, but stepper motors are not too difficult to drive with off the shelf bits and bobs, at which point you have complete control over your cluster and how it reacts to your inputs. You could even use the RPM gauge for power or similar.

Thanks a lot for the answers guys - these seems like far too much details for someone in such an early stage of the project - I'll make sure the bloody thing rides first

Any advice on sizing the motor appropriately, to slightly enhance against ICE performance?

How is the speedo driven now? If it is on the front wheel and you are only changing the rear, why not just keep it as it is?
I think you should look at the nucular controllers, they have a charge input for any dc lower than the pack. So you can use a psu of some sort, you dont really need a "charger".

Well, if you are going for a 273 you can get a lot more power than the ice engine.. I wouldn't go smaller than the 24 fet nucular for that motor :wink:
They have bms coming, but it is unclear when. You probably need one to get it registered, it seems to be needed here anyway.
If you are registering it in poland you probably need to hurry. You guys are leaving eu for some reason :?

The speedo is unfortunately driven from the rear wheel, so that has to go.

I am not sure I understood your bit about nucular - is that a typo? My worry is that I oversize the engine and it's absolutely rapid to the point it's too fast - this is meant to be a cruiser with maybe a better acceleration, but by no means it is meant to break the speed record!

By the way, I live in Scotland (which technically have now left the EU) but not heard about Poland doing so, lol! Got some information that I am not aware of!?

FilipK said:

The speedo is unfortunately driven from the rear wheel, so that has to go.

I am not sure I understood your bit about nucular - is that a typo? My worry is that I oversize the engine and it's absolutely rapid to the point it's too fast - this is meant to be a cruiser with maybe a better acceleration, but by no means it is meant to break the speed record!

By the way, I live in Scotland (which technically have now left the EU) but not heard about Poland doing so, lol! Got some information that I am not aware of!?

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The nice thing about electric is you can always just turn your controller down and instantly have a more reasonable power level if you find yourself with too much power. Electric motors will only complain about being over powered, not under powered. "Nucular" refers to Vasili's line of motor controllers, which are garnering much deserved praise and usage from the ES community. The 24-FET version is capable of up to 10kW/13Hp continuous output with good cooling according to specs. This would pair well with the QS273 hub motor or 138 70H mid-drive motor. I'm partial to mid-drives, but hubs are unequivocally mechanically simpler to install and generally leave more room for batteries in the frame. Their weakness is specific power and unsprung weight.

Awesome - I will research Vasilis line of electronics. To be honest I'd prefer to have everything from the same supplier (controller + BMS), so that might be an option.

What's the consensus on the EIG cells (the 20ah pouches with screw terminals) - good/bad/ok?

I am definitely going with a hub motor - struggling for space and don't want to think about the complications in the build. Hub motor seems the easiest solution.

FilipK said:

What's the consensus on the EIG cells (the 20ah pouches with screw terminals) - good/bad/ok?

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depending on what you want out of them, they're great. they have their limitations, like any other cell.

a 1p pack can do 100a continuous, and 200a for 10 seconds, when new.

the ones i'm using on my sb cruiser trike are several years old and still work fine at the lower currents i'm using, peaks of around 80-100a (higher when experimenting with other controllers), and maybe 20a-ish continuous normally, higher when hauling heavy loads, etc. for range mine is a 2p pack, but 1p would handle the loads i've got. mine is 14s2p, and weighs almost 40lbs.

they're just bolt-together, easy to use busbars to do it, if you get the cell-holder hardware with the cells (like jimbob01 has in the thread in teh for sale section). so one of the easiest diy-able ev-grade cells. nissan leaf cells are usable this way, too, but i've only seen them available used, from totalled cars and the like.

they don't get unbalanced easily, unlike the typical 18650 packs, so they don't have to be balanced every time you charge them just to stay usable. even mine stay within hundredths of a volt, as old and used as they are. i don't have a bms on them, because i just monitor pack voltage while riding, and stop whenever the pack gets too low...and when i randomly check cell voltages, regardless of state-of-charge, they're still balanced.

(the one emergency time i ran them way down, one cell did go below what should be lvc for them, but they were ok, and they still work fine, though i would never normally do this https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1436423 ).

amberwolf said:

depending on what you want out of them, they're great. they have their limitations, like any other cell.

a 1p pack can do 100a continuous, and 200a for 10 seconds, when new.

the ones i'm using on my sb cruiser trike are several years old and still work fine at the lower currents i'm using, peaks of around 80-100a (higher when experimenting with other controllers), and maybe 20a-ish continuous normally, higher when hauling heavy loads, etc. for range mine is a 2p pack, but 1p would handle the loads i've got. mine is 14s2p, and weighs almost 40lbs.

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It's the last bit that worries me - by taking just the cell volume (ignoring any spacing between them), the 72V 100Ah pack like the one I am hoping for would be 29 litres (volume) for the EIG Cells, but only half that for 18650 (15 litres) and if I went for 21700 cells then this drops to less than 10 litres. Spaces comes at a premium because I have to contain everything underneath the bodywork.

Why am I not seeing more 18650 packs in here - they seem fairly cost effective, do they require cooling to work properly? I'd imagine a good BMS plus a smart charger and the issues with balancing that you mention are not a concern.

I think the reason you don't see more 18650, 20700, or 21700 packs are because of the spot welding, and it might also have to do with the fluctuating prices also. It is hard to come by great deals on cylindrical cells when shopping for just 1 pack worth of cells. Especially when a lot of es people only shop from cells from known vendors to avoid fakes, quality control failures etc. If you can find the right cells for a price you can afford you still need to tackle the battery pack build. And most likely you will end up spot welding. For batteries, the old saying if something is too good to be true, most like it ain't. Avoid random vendors, of "great prices" from China. Lot of fake cells floating around.

The ideal way to connect cylindrical cells would be to do it like tesla does using fuse wire, to avoid heat damage to any single cell and it is also a fail safe for individual cells. But the diy crowd don't have the needed setup to make those connections. So spotwelding, soldering or other clever ways to connect cells are what we are left with. And even people with several build packs behind them sometimes go to hot and too heavy when spot welding and damage one or more cells. And likely you won''t notice before way down the line....not ideal but that how it is for now.

But if you take your time building your pack, don't rush the build and keep you current as low as possible and as low as possible while still getting a solid connection spot welding is doable and will give you a great pack, at fairly low volume so you don't require as much real estate. Lots of great threads about building and spot welding a battery pack here. Use the search function at the forum, or google search with "site endless-sphere.com" at the end of your search string and you shall see.

Tesla way of connecting:


DIY spot welding going pear shape:



But if you search the battery section you will see a lot of 18650 packs engineered in many clever ways, even without soldering or spot welding so I am sure you can find a way to works well for you.

FilipK said:

It's the last bit that worries me - by taking just the cell volume (ignoring any spacing between them), the 72V 100Ah pack like the one I am hoping for would be 29 litres (volume) for the EIG Cells, but only half that for 18650 (15 litres) and if I went for 21700 cells then this drops to less than 10 litres. Spaces comes at a premium because I have to contain everything underneath the bodywork.

Click to expand...

it does seem large, but since it is including the cell protection casings and the mounting hardware / busbars / etc., it's not really that big.

if you use other (cylindrical) cells, you're going to need a case around them for stiffening to keep spotwelds from breaking, and to protect against shorts across the cell faces, etc. you have to allow for padding or insulation between the main and balance / sense wires and the cells *and* the casing, so they don't get pinched and short or break, as well. then space for whatever bms you use, and allow for cooling of the bms, so space for airflow too. (you can also use a bms on the eig pack, but it's not really optional on 18650/etc packs because there is more cell variation than with the large-cell ev packs).

the one advantage to cylindrical cells is that since each cell contains it's own compression mechanism, they can be distributed in groups wherever they will fit in a vehicle or bike. a large-format-cell pack is harder (or impossible) to do that with, since the cells are supposed to be compressed (though i don't do this with mine and don't have cell problems because of it, it's supposed to be done and should increase capability/lifespan when it is--some cells can actually be destroyed by not doing it; they puff up and fail).

there are other easy-to-assemble large-format cells, too, including used nissan leaf cell modules out of totalled cars, etc. i don't have direct experience with any other than the eig cells, though.

Why am I not seeing more 18650 packs in here

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in where?

on es in general, id' say almost all of the packs used are 18650 of one type or another, though some are generic cheap pouch cells (including rc lipo). only a few are ev-grade large-format cells of whatever type.

- they seem fairly cost effective, do they require cooling to work properly?

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cost of cells themselves may be higher than you're expecting, from sellers that actually test their cells and that sell them in relatively matched sets. most of the cheap places may not even sell you stuff that's from the same batch of cells (and may even just have random recycled garbage cells that have been rewrapped as "better" cells).

like any other cell type, it depends on which cell you use and what it is capable of relative to your demands on it.

for instance, i have an 18650 pack here that is "rated" for something like 30a or more, but it's only 4p, so each cell has to handle 7.5a+ at those currents. i forget which cell model is in it, but if it's used anywhere near that rate, the pack gets hot--much hotter in the center than the outside, and the outside, even in cold weather, is hot to the touch. it also unbalances very quickly used at those rates. iirc, the cells are actually being used within their "spec sheet limits", but this is still very hard on them.

the eig cells don't even get noticeably warm at currents near "spec sheet limits", most likely those limits are very conservative compared to the 18650 spec sheets' limits. (meaning, the 18650 makers are specing them for the worst-case usage, while the others are spec'd for the average usage). i'm not using htem near those limits very long, so it's possible that if i was, they'd get warmer than they do--but the 18650 pack i have heats up very very rapidly.

there are several people here on es that do battery testing, and there's dedicated threads for a number of 18650 cell types if you want to poke around to see what they can actually do.


as far as cost effective....are you including the costs of the interconnect materials, of the spare cells in case you get duds, of the significant extra labor you'll spend building them vs large-format cells, the spot welder and power source for that, time and materials spent learning how to use it and make good welds every time without damaging your cells, etc?

(or the cost of the no-weld interconnect system, and time spent configuring and assembling that, and troubleshooting and testing all the connections for equal pressure and resistance, etc)

and including the time spent on testing each cell to ensure all the ones you use are well-matched, or at least that the mismatches are distributed among the groups evenly, and the cost of the test equipment to do this?

I'd venture it takes me, slowly, around an hour, maybe two with any complications, to build a 14s2p eig cell pack. (more if i were to build an outer casing for it, depending on what i started with; i used a 50-cal ammocan for the 14s1p version, which took about 20 minutes to prep and install the pack into). if i had to cut busbars for it myself id' probably have to add a few hours for that, but mine came with them (and they can be designed and ordered from anywhere that does laser or waterjet cutting easily enough).

I'd imagine a good BMS plus a smart charger and the issues with balancing that you mention are not a concern.

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that depends.

many of the 18650 cells, if used at the rates we use on evs, especially if used for their entire capacity range, become mismatched in characteristics much more rapidly than the large-format ev cells. so they then *require* balancing, and longer and longer balancing times, as they age (while the large-format ev cells may not do so for many more cycles).

if cells require balancing, it is primarily because they're losing capacity at different rates, and the rate of change increases over time--more rapidly with some types of cells than others. this means you get less capacity from the pack as a whole, because once any cell in the pack is lower than others, it'll hit bottom sooner--and as soon as that cell hits bottom, the entire pack discharge must be stopped, so the capacity of that lowest cell (or the group it is in) *is* your pack capacity. meaning, if there's one cell that has only 80% of the capacity of the rest of them, then in a 1p pack that would mean you can only use 80% of your entire battery capacity (or else you damage that cell even more by discharging it further and further below it's actual capacity, and eventually make it a fire risk). (the math gets more complex the more parallel cells, but also the more likely that you will have multiple low-capacity cells, or broken interconnects within a group that actually take cells completely out of the pack, lowering that group's capacity by an entire cell (or more).

if cells don't require balancing, it's becuase they're all the same capacity, so you're not "leaving it on the table" for the cells that don't have a problem, which is what happens in the above situation.


if your pack is large enough that you don't use its' entire capacity anyway, and say use only the middle 60-80% of it, locking the rest out by setting up a bms to only charge to 80-90% of full, and to shutoff discharge when it's still got 10-20% left, and also don't use the pack near it's current limits, the cells (of any type) will last longer (probably by quite a lot).

but then you're carrying around significant "extra" weight and volume....

that's how some of the evs get by with using 18650 and other small-format cells, and generally also what they do with large-format cells. they can guarantee a certain capacity and pack lifespan by locking out some of the capacity and capability, using a pack that's capable of much more means that even when it's old it'll still be able to do *at least* what they said it could. (sometimes by "unlocking" some of that previously untapped ability, but mostly by simply not using them very hard, so they don't age as fast as they would if used at or near their limits).


anyway....there are advantages and disadvantages to every way of making battery packs. if there were one with no disadvantages, then most packs would be made that way.

Do you have a trust worthy source for the EIG pouches? Seems they are not as common in EU anymore.

jimbob01 in the for sale section?

Wow, there really is a wealth of knowledge on these forums - thanks a lot again for your guidance guys!

I think you've successfully pushed me away from the idea of 18650 battery pack. I checked the mass as well as volume and the 18650 does a bit worse than an EIG pack (45 kg vs 41 kg), and that's just the cells whereas the EIG already has some sort of framework around it (but it would still need a small case).

So it will be an EIG pack with 72V, as many sets of 20Ah as I can fit it (hoping for 5 but might be problematic).

For BMS, I was thinking of going to China - IC GOGOGO seems to be a respected manufacturer and quite popular on this forum.

That would leave an on-board charger - is it worth it though? I understand it would have to be an Automotive grade one to deal with the weather and vibration, I'd imagine it would be quite pricey, whereas I can pick up a standalone one quite cheap.

Ancillaries like DC-DC Converter will be picked up later as I get an idea of space limitations. Anything major I am missing or is it time to spend some cash?

FilipK said:

That would leave an on-board charger - is it worth it though? I understand it would have to be an Automotive grade one to deal with the weather and vibration, I'd imagine it would be quite pricey, whereas I can pick up a standalone one quite cheap.

Click to expand...

you can charge with meanwell hlg (or maybe elg) led psus, since you will have a bms to shut off charge when the pack is full.

a listing of some of the ones you can use (ignore the -b versions, just use teh -a); they can be had cheaper than what you see here, sometimes they're available used on ebay/etc for a lot less.
https://www.mouser.com/Power/Power-Supplies/LED-Power-Supplies/_/N-axgjt?P=1y92d4aZ1y92da8Z1yxt5gx&Keyword=meanwell+hlg-600h&FS=True

the versions i ahve, the hlg-600h, 600w or so output, are sealed and potted (so a bit heavy but vibration/weatherproof), and about the size of three or four eig cells stacked. 7lbs, iirc.

i use a single hlg-600h-54a built into the sb cruiser trike for onboard charging of my eig 14s2p (or the older 14s1p version) 52v pack. that gives me around 57.7v full charge at about 12a charging rate. (which is a hair over the 0.5c (two-hour) rate recommended for 1p, but only a bit more than 0.25c (four-hour) charging rate for 2p).

but because they're isolated, they can be paralleled and seriesed, so a 72v pack could use two hlg-600h-42a in series, for 14a+ of charging. they're adjsutable current and voltage (the a versions), this one from 21v to 42v output, so adjust each one to give you a total of the 82v full charge (4.1v/cell) the 72v pack would need.

(you can go up to 4.15v/cell if you like, but there's not much capacity in that last bit; i think mine ends up 4.12v/cell)

for double the charging current, you can parallel a second seriesed pair of them, for 28a+ charging rate.

you can adjust the current down if you prefer a slower charging rate.

if you have a 2p pack, 40ah, using one seriesed pair, it would take around 3 hours to charge from empty.

a 5p pack, 100ah, would take around 8 hours.

if you only need slow charging when out and about, you could just have one pair onboard, and have a second pair (or more than that) at home that plug in parallel to the onboard ones for much faster charging (though usually at-home charging doesn't need to be as fast as onboard charging).

if you wanted to have onboard charging as fast as possible, 0.5c rate, then for a 5p 100ah pack, that would be 50a. 50/14 is 3.6, so using four sets, with the current on them turned down just a bit to 12.5a each, would give you the max charging rate for 5p, for a two hour (ish) charge. (it actually takes more like 2.5+ hours because the charging rate slows as the cells fill up).

a 4p 80ah pack max rate is 40a, so 3 pairs would do that, each turned down to 13.4a.

etc.




the elg series is lower wattage per unit, so takes more in parallel for the same charging rates as the hlg series. but they also come in higher voltage units, so you wouldn't have to series them. at the voltages your pack would be,
https://www.mouser.com/Power/Power-Supplies/LED-Power-Supplies/_/N-axgjt?P=1z0wc4uZ1y91agaZ1y91ag8Z1y8cove&Keyword=meanwell+elg&FS=True
or
https://www.mouser.com/Power/Power-Supplies/LED-Power-Supplies/_/N-axgjt?P=1z0wc4uZ1y91agaZ1yqhw1fZ1y92d38&Keyword=meanwell+elg&FS=True

ELGC-300-M-A is 58-116V 2.8A, so it would take only one in series, but would take more than four in parallel to equal the two hlg-600h-42a units in series.

but if you only need long overnight or longer charging, just one of the units would provide 82v at almost 3a, and it'd be like half of the width and about thickness of three-four eig cells in size, around four pounds.

a 100ah pack would take a day and a half to recharge with one of those from empty...but if you don't acutally run it empty most of the time, and use only say a quarter of the capacity most of the time, simple overnight (about 9 hours) charging would work with just one of these.

Ancillaries like DC-DC Converter will be picked up later as I get an idea of space limitations.

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if your pack voltage was significantly lower or higher, you could use a meanwell led psu for that, too, but there aren't any dc-input versions in your pack voltage range.

but there's lots of cheap automotive-level-output dc-dc units out there, from $20-$50 or so, depending on the amount of current you end up needing for the lights/etc.

Awesome, I think the decision is closer and closer. The shopping list looks like that for now:

1) Motor

https://www.alibaba.com/product-detail/QS-Motor-14inch-6000W-273-45H_62061247799.html?spm=a2747.manage.0.0.2cd071d29mj6vY

2) Controller

This is the only one where still have doubts. Three options here really

a) Sabvoton, QS suggested this but it's only 4000W (they said it's ok for my top speed, but I struggle to understand that), it's $330.

https://www.alibaba.com/product-detail/Sabvoton-SVMC-72200-E-bike-Controller_62090503423.html?spm=a2747.manage.0.0.2cd071d2iJcbyO

b) Kelly Controller, again suggested by QS but with a higher wattage, it's $350.

https://www.alibaba.com/product-detail/Kelly-controller-DC-motor-controller-KLS7245H_62120105494.html?spm=a2747.manage.0.0.2cd071d21keEPy

c) Nucular Tech.

I am guessing I'll have to go with 24F (6kW Nominal power), this is quite expensive at $465 + potting.

3) Batteries

Eig cells, 3.7V @ 20Ah. A hundred of those will be used to make a 72V 100Ah (if I can fit it). That would make 20 in series to get it up to 72V and then 5 of those paralleled.

4) BMS

Am I going to need a separate BMS per each 72V 20Ah pack? I will probably use something from this store

https://www.aliexpress.com/item/33014476298.html?spm=2114.12010612.8148356.58.92ed3de2RRrZxQ

5) Charger

Two off those in series. I am still researching but this is the fallback plan.

https://eu.mouser.com/ProductDetail/MEAN-WELL/HLG-600H-48A?qs=sGAEpiMZZMt5PRBMPTWcadpJaJ00SD0W9cEkFLB%2FnV60w2hRdpzfFw%3D%3D

I think that covers the major expenses - the smaller things will be bought as the bike shapes - am I missing anything important?

How about this controller? Check the dimensions to see if you can fit it somewhere in your scoot, it's a big controller.
https://qsmotor.en.alibaba.com/product/60255817584-801784612/APT_Programmable_Sine_Wave_FOC_AE96600_72V_96V_8kW_PM_Motor_Driver_Controller.html?spm=a2700.icbuShop.41413.11.746a7768FPxzAL.

This looks good and it support regen, unsure why QS has not suggested that - I will ask.

Yes, you're probably right on the rim, I've not selected one yet. Original tyre was 3.25 X 14 - I think these aren't produced anymore, so if I cannot get them I will go for 90/90 14.

Looking at the motors again, it looks like you have to go for a 2.75'' rim to get the highest wattage.

When it comes to chargers, I've seen these on a few websites - is anyone using it? Looks compact, it's potted and IP67, can't see any downsides to be honest!
https://a.aliexpress.com/_dZgJtLz

I went back to double check the rim - below is the comparison between the original rim (measuring in at about 74mm) and the QS Motor Rim (measuring in at 94mm). The 10mm either side I am hoping won't look too different.





Things have completely stopped on the orders tho, for the known reasons. So I am trying to progress with the restorations.

I received the cells from jimbob, not had a chance to open them yet but the shipping was rapid!

Hi Gents,

Restoration is ongoing, albeit significantly slowed down due to obvious reasons.

I am now spending majority of my time reading up and buying all the necessary items to finish off the conversion.

One big outstanding question is wire sizing - I get that bigger is better and for the quantity of wires needed I will probably oversize them dramatically, however, one thing that is fixed are the wires on the BMS. I do not know exactly what sizes they are, but they are tiny (it's an IC GOGOGO BMS, 100A continous, 200A peak).

When I went on an IC GOGOGO shop page, they also sell 8 AWG wire and state that the allowable load current is 190A - way higher than any value I can find online.

Is there a consensus among the community on how to size the wires? Can I trust the IC GOGOGO wires or should I replace them with something bulkier?

Thanks,

Filip