Legally converting a gas moped into electric?

[allu]

Hi all! First post on this forum, but I think I got this post in the right forum.

As title say I've had this idea for a long time. I've always been into mopeds, yes they're slow with max speed of 45 km/h but they're so convenient. Super cheap tax and the best part; you can park them as a bicycle meaning they're ideal for city use (also no one's going to steal your moped in broad daylight, lugging a vehicle weighing 100 kg around is going to attract attention unlike stealing a bicycle). What kills them though is the horrible restricted engines that produce pathetic amounts of torque and gearing good for speeds of +80 km/h. Also the noise levels are ridiculous for a vehicle with the given max speed. Most people run them derestricted (like me), but it's no fun to get in trouble after being caught. After seeing someone's project of converting a moped car, a terribly slow max 350 kg piece of plastic and aluminium causing traffic jams, to electric legally I got the idea to look up on the laws in my country and see what they say about mopeds. To be honest, the laws seem to allow fair deal of customization. For motorcycles they're a lot more strict, but for mopeds it only states: max 50cc gas engine or in case of electric engine max net power 4 kw. Top speed limit is 45 km/h. So to my understanding you should be able to swap gas engine to electric as long as it stays within those limits? I'll be emailing the ministry of transport (or whatever it's called, the only name I could come up for it in English) for clarification.

The sudden urge to build such a thing in the future is just a matter or living conditions changing. It's time to grow up and move out closer to my school but unfortunately the public transport is fairly terrible in that part of the city, so I need something else for transport. Cars are too expensive to maintain here, so a moped would be an ideal option. It helps that I'll be going to school to study engineering next Fall, aiming at the field of either designing or machining, so this could be a fun and teaching project to do or maybe even do as a part of project in school. I'm not planning on building this anytime soon, but now it's a good time to start planning and improving the initial idea and of course learn a lot about the secrets of electronics and metal working! I have very basic knowledge of electronics at the moment thanks to my background with RC-vehicles, but that was years ago so I'm sure my knowledge is in need of updating.

I have tons of question regarding the topic, but for everyone's sake I'm trying to be modest here

Regarding the engine:
-What kind of an engine would you guys (/or gals to that matter) recommend for powering roughly 100 kg enduro moped, keeping in mind the limit of 4 kw? Brushless engines are the way to go right now I think, but would you recommend outrunner or inrunner for this task? Would an RC engine be sufficient, or should I be looking for something else? I'm looking to hit the max power limit for maximum acceleration and torgue, but reliability is also an important factor.
-In my opinion a single speed setup should be sufficient considering the max speed of 45 km/h could be reached with fairly light gearing, or am I completely in the wrong here? A single speed setup would be dead simple, no clutch, no gears, nothing. Just the drive sprocket and the wheel sprocket. Given the power level, do you think an engine with 4 kw would have enough power for light offroad riding even with single gear set-up?
-How about engine breaking, is it bad for electric engines in the long run like it's for 2-strokes engines, or is it just fine like for 4-strokes?

Regarding the controller:
-Very little knowledge of this given topic, feel free to educate. What kind of a controller would be sufficient for this kind of setup? Will educate myself in the wiki for more knowledge, so pardon my newbie questions
-How easy is it to limit the top speed with controller to 45 km/h? 4 kw will definitely get me higher than that unrestricted, so something needs to slow things down a little bit.

Regarding the battery:
-What would be the ideal battery type for this kind of project. NI-CD batteries are pretty ancient nowadays I guess, so lipo's are the way to go I think. What battery type keeps it charge best in cold weather? Given the cold climate in my country this is an important factor. For winter usage would some sort of battery heater be beneficial? I've heard them being used in electric cars.
-I'm thinking of covering ranges up to 40 km on single charge with this setup, how many ampere-hours would be needed? is 20 ah enough or would I need more?
-How many volts should the battery have? I've always been confused with the amount of different voltages in batteries, I have seen at least 24,36,48,72 volt batteries, so which one should I be considering? I know the higher volt batteries run the engine at higher rmp, but how much would I need?
-If lipo's turn out to be the best option, what kind of discharge (c-) rating should I be looking for?

That's all I can think of for now, will update my post if needed. While waiting for someone to answer I'll try to look for answers online and educate myself better, but hey I gotta start somewhere. Thanks for replies in advance!

-allu

 

[wineboyrider]

So you are going to use a moped frame?

 

[craiggor]

A guy called Sparta has just done this last week, see his thread "Honda MT50 road legal conversion" here is his bike

 

[allu]

So you are going to use a moped frame?

Yes I would be using a complete moped frame to make the paper work awfully lot easier. No chance getting a homemade frame registered, unfortunately :/

A guy called Sparta has just done this last week, see his thread "Honda MT50 road legal conversion" here is his bike

Thanks, will definitely look into that!

-allu

 

[Drunkskunk]

Welcome to the forum. Sounds like a fun project.

That Honda MT50 is awesome. the original bike has a very similar design to an MB5 that someone here converted with a massive rear hub motor. there's a thread about it here, too. Great bikes, but much bigger and heavier built than a moped. I've got an MB5, and keep dreaming about converting it.
We can probably help more if you tell us what moped you want to convert.

A chain drive motor would have the most potential torque per watt, but would also have more complexity and more points of failure. A hub motor would have less torque, but would be far more simple and reliable. The top speed potential would be the same. A hub motor at 4Kw would have dramatically more torque than a 50cc moped

The Honda motor used in the Ruckus/Metro is rated at: 4.9HP @ 8000 rpm, 3.35 lbs-ft torque @ 7000 rpm with a 3.5:1 final drive, meaning it has 11.7 foot-pounds of torque at the wheel. A rather basic 1000w Ebay bicycle motor has a peak torque of 60 foot-pounds at the wheel. This is why my Peugeot 103's motor has rusted solid since I discovered Ebikes

Lipo is dead tech. It's great for high power density, but also great for exploding and burning down things when used in large formats. Several members of this forum have lost bikes, garages, and even a house from lipo fires. They are also short lived with a low cycle life, and high maintenance. They latest tech is NCA and NMC cells. They are much safer, reliable, and longer lived.

Marketeers sell batteries by the Amp hour. But a battery's capacity is actually measured in Watt hours. Volts X Amp hours = Watt hours. That's useful to know because a 36 volt 30Ah battery has the exact same capacity and range as a 72 volt 15 AH battery.

As for range, we generally say you need 22watt hours of battery capacity for every kilometer of range at 30kph. Going faster uses more power. At 40KPH you use more than twice the power as you did at 30kph. So a 40km range at 40kph would need a battery with 1760 watt hours of capacity. Now you may often get further than 40KM on that capacity. Since it's bad to fully drain any battery more than once or twice, these figures include a built in reserve.

The controller you pick should match the motor. 4000 watts doesn't need any special controller, and there are several to chose from for each motor type. Pick the moped first, then pick the motor you want for it, then picking a controller will be easy.

 

[allu]

Welcome to the forum. Sounds like a fun project.

That Honda MT50 is awesome. the original bike has a very similar design to an MB5 that someone here converted with a massive rear hub motor. there's a thread about it here, too. Great bikes, but much bigger and heavier built than a moped. I've got an MB5, and keep dreaming about converting it.
We can probably help more if you tell us what moped you want to convert.

A chain drive motor would have the most potential torque per watt, but would also have more complexity and more points of failure. A hub motor would have less torque, but would be far more simple and reliable. The top speed potential would be the same. A hub motor at 4Kw would have dramatically more torque than a 50cc moped

The Honda motor used in the Ruckus/Metro is rated at: 4.9HP @ 8000 rpm, 3.35 lbs-ft torque @ 7000 rpm with a 3.5:1 final drive, meaning it has 11.7 foot-pounds of torque at the wheel. A rather basic 1000w Ebay bicycle motor has a peak torque of 60 foot-pounds at the wheel. This is why my Peugeot 103's motor has rusted solid since I discovered Ebikes

Lipo is dead tech. It's great for high power density, but also great for exploding and burning down things when used in large formats. Several members of this forum have lost bikes, garages, and even a house from lipo fires. They are also short lived with a low cycle life, and high maintenance. They latest tech is NCA and NMC cells. They are much safer, reliable, and longer lived.

Marketeers sell batteries by the Amp hour. But a battery's capacity is actually measured in Watt hours. Volts X Amp hours = Watt hours. That's useful to know because a 36 volt 30Ah battery has the exact same capacity and range as a 72 volt 15 AH battery.

As for range, we generally say you need 22watt hours of battery capacity for every kilometer of range at 30kph. Going faster uses more power. At 40KPH you use more than twice the power as you did at 30kph. So a 40km range at 40kph would need a battery with 1760 watt hours of capacity. Now you may often get further than 40KM on that capacity. Since it's bad to fully drain any battery more than once or twice, these figures include a built in reserve.

The controller you pick should match the motor. 4000 watts doesn't need any special controller, and there are several to chose from for each motor type. Pick the moped first, then pick the motor you want for it, then picking a controller will be easy.

Thanks for your helpful answer!

Yeah that Honda is very nicely built indeed! I've been thinking about converting one of these enduro/supermoto mopeds with Minarelli AM6 engine. I'm familiar with them since I still own one (Peugeot XPS 2008) which could be used for this project. It's too modified and so much money had been put into it that I would never get satisfying amount of money out of it if I sold it. Also it has a frame design kind of similar to these commercial e-bikes (stealth h-52 etc.), so battery could be fitted fairly easily.

To me a chain drive is the way to go. Finnish laws and regulations are not strict when it comes to modifying a moped, unless you're modifying the wheels, breaks, or doing major modifications to the frame (and risking losing structural strength). Also couldn't find any hub motors that would fit an 18-inch enduro tire, so unless someone finds one it'll be a chain drive. Hub motors would make it so simple though, not hard to see why many people prefer using them over mid-drives.

Interesting info on the batteries. Any idea where could I get those cells? I've been having hard time deciding how large of a battery I want. I seem to be deciding between 48 v and 72 v batteries, but I can't decide how many volts I need. I know a higher voltage results in higher top speed, but that's not what I need really. So I have a feeling that I would be better off with a 48 v 20-30 ah battery (960-1440 wh), rather than paying a lot more extra for 72 v 20 ah battery. What kind of discharge should I be looking for with this kind of setup? Would 40 amps at 48 volts get me anywhere? My math says that would equal to 1920 W, which seems kinda low compared to the 2880 W I'd get with 72 v battery. Or should I just increase the amps drawn from the battery? I know drawing higher amps decreases the lifespan of the battery, but how large is this effect? Of course I'd never go super high, but would be helpful to know the safe limits. It's hard to choose the battery when you don't know how much performance you really need :lol:

I kind of overestimated the range I'd need in my original post. I'd say 30 km is the absolute maximum I could ever end up using it, but more often I'd use it for max 20 km (distance between my apartment and home). Besides, if I ever needed to continue somewhere after driving that 20 km home, I could charge it up for at least a few hours before departing, making the extra range pointless. Extra range is handy, but a few hundred extra bucks is a salty price for something you wouldn't pretty much never need. Unless someone comes up with some super cheap cells/packs of course I'm planning on keeping my budget for battery at around 500-600€ after looking at the prices.

So many questions to ask, but I think these are enough for now

-allu

 

[Scottydog]

I did my scooter by conversion, though I imagine every country has it's own set of rules! :?

http://www.royalgazette.com/news/article/20160609/bermudian-fulfils-his-electric-dream

 

[Scottydog]

Video of it in action

[youtube]BX27rcRwl-U[/youtube]