First Electric Motorcycle Conversion Advice (1974 Honda CB360)

[RealPolarBear]

Hello everyone!

I am relatively new to this community and am super excited to learn about electric motorcycle conversions. I have been lurking for a bit to compile a parts list of my own to start my first build. I have done smaller projects with RC cars and electric skateboards so I am familiar with some of the main components that go into a build, but I am looking for more advice.

The motorcycle I’m converting is a 1974 Honda CB360 which came mostly complete (with a non-running motor). The frame, wheels, tires, fork, and swingarm weigh roughly 150-175 lbs (68 - 79 kg). I myself am a 6’ 3” 190 lbs (190.5 cm 86 kg) rider. I would like to be able to cruise at ~55 mph (~88 kph) and do short (<30s) bursts quicker. This bike will be a road commuter where the speed limit doesn’t exceed 45 mph around town. That being said, it would be nice to be able to have some overhead to ride back roads where the speed limit increases to 55 mph. It should be noted that around town, the roads are relatively flat, but outside of town, it can get hilly with inclines at 5-6 degrees (8-11%). These hills are 1 mile long at the VERY most. Usually, they are about half a mile. I would like to have at least 20 miles (32 km) of range around town. Likely, I am probably just going to get a battery that fills the frame well (capacity-wise), so the exact numbers on range are not too important to me. 20 miles just seems like a reasonable minimum.

From snooping around the forums for a bit, I have learned an enormous amount and have started to compile a parts list. I would be very grateful to anyone who can offer any criticism to this list as this is a new experience for me.

Parts:

Motor: QSMOTOR 138 4000W V3 Mid Drive Motor With Gearbox
Controller: SiAECOSYS/VOTOL Programmable EM200-2sp 72V 600A Controller
Battery: Amorge Custom 72v 40ah 200A battery pack with charge indicator

Of course there will be accessories and smaller parts here and there, but currently, I am more concerned with the big expenditures. My budget for the three of these items is about $1700 but I have some wiggle room.

My main questions are:

Controller: Is the VOTOL EM200-2sp a reasonable controller for this build? It is rated at 72 v (which is what I will be running at) and 200 A with boosts capable of 600 A. I am also considering a Fardriver. Would this be a better option? If so, are there any recommendations for a specific controller?

Battery: The Ah are not too important to be right now, I’m more concerned with amps. I believe I should be looking at a battery rated at 200 A with boosts of 240 A. Will this be able to push me up to speed of 50 mph (80 kph) in a reasonable time (<15s)? Or should I be looking to get a battery with higher discharge than this? If so, what are some recommendations that I can ask Amorge for that will be safe on the VOTOL or Fardriver recommendations?

Any feedback and advice y’all have to offer would be extremely appreciated. Thank you in advance

 

[jetpackjbd]

I don’t know enough about controller brands or models to help you out with decisions on what to buy, but 72v with 600 amp max load will be far more than enough for a little 4kw motorcycle. Even at the continuous load of 200 amps, it’s capable of 14kw. It’ll still work fine with a lower power motor but it’s just a bit of a waste of money and space unless you plan on upgrading the motor later. I would go for a higher power motor but it might not be necessary. Currently your motor is only a bit over 5 (electric) horsepower, which may get you up to 60 but it’ll be a struggle.

 

[harrisonpatm]

Your parts list looks quite close for what you want to accomplish, I don't have major suggestions, as all of the components you suggest are capable of what you're asking from them. You even have a reasonable range expectation of 20 miles, which most newcomers aren't able to expect, as they usually want a lot more than what's reasonable. Also, I'll note that your bike frame is rather similar to mine in many ways, so check out my build if you haven't already for similar expectations. Main difference would be that I used a hub motor, you are looking at a middrive. On that note:

Battery: The Ah are not too important to be right now, I’m more concerned with amps. I believe I should be looking at a battery rated at 200 A with boosts of 240 A. Will this be able to push me up to speed of 50 mph (80 kph) in a reasonable time

Yes, in fact, my frame of a similar weight really only ever sees bursts of 150 amps, maybe 175, so if you build it to handle 200-240, you should be all set, with headroom.

 

[harrisonpatm]

I don’t know enough about controller brands or models to help you out with decisions on what to buy, but 72v with 600 amp max load will be far more than enough for a little 4kw motorcycle. Even at the continuous load of 200 amps, it’s capable of 14kw. It’ll still work fine with a lower power motor but it’s just a bit of a waste of money and space unless you plan on upgrading the motor later. I would go for a higher power motor but it might not be necessary. Currently your motor is only a bit over 5 (electric) horsepower, which may get you up to 60 but it’ll be a struggle.

I agree with this, that your current weak point seems to be your motor, but really, only by a little bit. You'll see others on the thread able to regularly get a bit more out of the 138 than it's specs, but you'll have to ask them. I do think you should stick with the controller you have picked out, as in my opinion, it's not always great to be pushing your controller to its max rated specs on a regular basis. I have a 400-amp continuous controller, 600 peak, and as a result it basically never gets more than slightly warm, even where I mounted it with little to no airflow. Overkill, yes, but also equipment safety, in my opinion.

 

[jetpackjbd]

I agree with this, that your current weak point seems to be your motor, but really, only by a little bit. You'll see others on the thread able to regularly get a bit more out of the 138 than it's specs, but you'll have to ask them. I do think you should stick with the controller you have picked out, as in my opinion, it's not always great to be pushing your controller to its max rated specs on a regular basis. I have a 400-amp continuous controller, 600 peak, and as a result it basically never gets more than slightly warm, even where I mounted it with little to no airflow. Overkill, yes, but also equipment safety, in my opinion.

Yeah, definitely better to go much higher than you need. Even if the motor is able to produce more power than stock, the original engine on the motorcycle made 30 (peak gasoline) horsepower. Currently the motor planned to be used has the same power as my push mower. Even if you could double the power it would make about as much as a smaller riding mower.
Only way to see if it’ll have enough power is to try it though. I’ve got a 500w (2/3rds HP) scooter that goes 15MPH with ease, and should do 25MPH with a sprocket change. A gas motor with that little power would struggle hard, the lowest you really see on gas scooters is 2 horsepower. So who knows.

 

[Eastwood]

Sounds like you’re on the right track. The QS138 4k v3 is a great motor. Cruising at 50 mph will drain your battery quickly at those speeds, just keep that in mind when calculating for range. The VOTOL should work just fine. You could always change controllers after the fact, if you don’t like the functions.

 

[RealPolarBear]

Thank you all for the quick responses! It's thrilling to see this helpful community engagement. From what I understand, my current limitation is my choice of motor. I originally chose this motor due to its (relatively) compact form factor compared to the next step up qs165 v2 5000w mid drive motor. I seems that the qs138 motor has good power for its size and price. I'm not shy of upgrading in the future, but this is my first entry-level build and I want to keep my goals (and expectations) reasonable. Likewise, I do think it'd be nice to be able to fit a bigger battery (72v 56-60ah 200/240a) battery but I'm going to have to get some more measurements before I consult with Amorge to have it made to fit. I'm no speed demon so having good acceleration and torque in the low range would be preferred, but it would still be nice to top out at ~60 mph (~100 kph) on straight flat roads. To clarify, most of my commuter riding will be at around 35-45 mph (56-72kph), but having the ability to go above that for leisurely rides is preferable.

I've found that the qs138 seems to be a be a good middle ground between power and range tradeoffs, is this generally true? I'd like to be able to get up to my cruising speed (even if it takes a little longer) on the weekends, but it would be a bummer to get to a hill in my area and not have the torque to be able to get up it at 10-15 mph (16-24 kph).

I really appreciate all the feedback!

 

[RealPolarBear]

Your parts list looks quite close for what you want to accomplish, I don't have major suggestions, as all of the components you suggest are capable of what you're asking from them. You even have a reasonable range expectation of 20 miles, which most newcomers aren't able to expect, as they usually want a lot more than what's reasonable. Also, I'll note that your bike frame is rather similar to mine in many ways, so check out my build if you haven't already for similar expectations. Main difference would be that I used a hub motor, you are looking at a middrive. On that note:

Yes, in fact, my frame of a similar weight really only ever sees bursts of 150 amps, maybe 175, so if you build it to handle 200-240, you should be all set, with headroom.

Coincidentally, your bike was one of the first builds that I came across during my research. It's a super sweet bike and has defiantly inspired me to what's out there and what can be done. Your 8000w qs273 is quite the beast paired with that monster battery and controller!

 

[harrisonpatm]

Coincidentally, your bike was one of the first builds that I came across during my research. It's a super sweet bike and has defiantly inspired me to what's out there and what can be done. Your 8000w qs273 is quite the beast paired with that monster battery and controller!

Thanks for the compliments. I'd say you're on the right track, you can probably go ahead and get started with your plans. I think you may find you won't be able to hit the top speeds of 50-60mph, for as long as you'd like to sustain it, but I could be wrong. Haven't used that motor.

 

[RealPolarBear]

Thanks for the compliments. I'd say you're on the right track, you can probably go ahead and get started with your plans. I think you may find you won't be able to hit the top speeds of 50-60mph, for as long as you'd like to sustain it, but I could be wrong. Haven't used that motor.

Yeah, I think the conclusion I've come to is that a burst of 50-60 mph (80-100 kph) would suffice for me. Any more than that for an extended period of time would drain my battery quick. If my normal riding style is around 45 mph (72 kph) on flat terrain, I think the qs138 4000w v3 is a solid choice to balance power and range. I'll have to report back on the actual speeds I'm able to reach and sustain

 

[RealPolarBear]

Also realizing now this thread may have been better suited for the builds thread. Can any admins help with moving this?

 

[Jordan325ic]

I used a QS138v3 with an EM150, 60v 150A on my ‘74 Yamaha build. On the flat it did 55-60mph. Put 2000 miles on it, mostly at top speed. Rebuilding now for 70mph. The motor should be fine!

 

[RealPolarBear]

I used a QS138v3 with an EM150, 60v 150A on my ‘74 Yamaha build. On the flat it did 55-60mph. Put 2000 miles on it, mostly at top speed. Rebuilding now for 70mph. The motor should be fine!

That's super sweet! It's nice to have the input from some more similar setups. I'd love to see a picture of that build

 

[amberwolf]

Also realizing now this thread may have been better suited for the builds thread. Can any admins help with moving this?

done.

 

[RealPolarBear]

Hi Sphere!

I've been hard at work fabricating a lot of the parts I've needed for my build and I am now at the point where I need to worry about electrical. For background, I have:

Controller: SiAECOSYS/VOTOL Programmable EM200-2sp 72V 600A Controller
Motor: QSMOTOR 138 4000W V3 Mid Drive Motor With Gearbox
Battery: Amorge Custom 72v 75.6ah Molicel P42a battery pack (in shipping)

My controller will have a maximum current of 200A continuous and 250A boost. I am looking for some advice regarding a contactor, precharge circuit, circuit breaker, and key switch. I was wondering if anyone had any luck wiring these components with the EM200-2sp. I am having trouble drawing a circuit diagram and understanding how these components will connect and work together. Likewise, if anyone has recommendations for any of the components listed above (besides the key switch, I already have that!), any input would be highly appreciated!

Thank you for your help and please feel free to reach out if there is any more helpful information I can provide!

 

[harrisonpatm]

Hi Sphere!

I've been hard at work fabricating a lot of the parts I've needed for my build and I am now at the point where I need to worry about electrical. For background, I have:

Controller: SiAECOSYS/VOTOL Programmable EM200-2sp 72V 600A Controller
Motor: QSMOTOR 138 4000W V3 Mid Drive Motor With Gearbox
Battery: Amorge Custom 72v 75.6ah Molicel P42a battery pack (in shipping)

My controller will have a maximum current of 200A continuous and 250A boost. I am looking for some advice regarding a contactor, precharge circuit, circuit breaker, and key switch. I was wondering if anyone had any luck wiring these components with the EM200-2sp. I am having trouble drawing a circuit diagram and understanding how these components will connect and work together. Likewise, if anyone has recommendations for any of the components listed above (besides the key switch, I already have that!), any input would be highly appreciated!

Thank you for your help and please feel free to reach out if there is any more helpful information I can provide!

This is my advice, you don't have to follow it, just suggestions.

Contactor

Precharge: wire a 1-2kohm resistor to both posts on the contactor, leave it there all the time. No switch or circuit needed. Controller will always stay precharged.

Breaker: typically, the breaker is there so that you can turn off the battery output manually and service the wiring without worrying about a shock. And it can trip if your controller happens to pull too much. It rarely, if ever, will be use to disconnect the controller from the battery while under load. If that happens on a regular basis, then either your controller is drawing too much current from your battery, your battery is underrated for your application, or you sized your fuse wrong. With that in mind, I use something similar to this. You'll want a 200 amp breaker, since that's your controller's max battery current rating. Perhaps 250 amp.

Notice that this breaker is only rated for up to 48v. A breaker is rated for a voltage so that it can safely open a circuit without the risk of a spark bridging open contacts. Since you won't typically be using this to disconnect under load, it's possible that this might work for you application. Also, while 72v is higher than 48v, it could possibly still safely disconnect it at your voltage.

I say might, and possibly. Take my suggestions with a grain of salt. Just because its what i do and it's worked so far for me, doesn't mean it's the best idea. If you want a breaker that will 100% work at a higher voltage than 48v, you'll want to look at solar disconnect breakers like this one, which are usually good up to 200v, since solar panel voltage can be quite high. These will be more difficult for you to find a mounting place on your bike, and not waterproof, but they'll work well.

Key switch: someone more familiar with your controller should chime in, but your controller will have an on-off wire, usually a single wire that needs to connect to B+ in order to turn on the controller itself. You can put a switch on this line, needs to be rated for your battery voltage, but will carry very low current. Or, you can put your key switch on the contactor's coil 12v power supply, and any automotive ignition switch will be rated for 12v. Or, do both: keyed ignition switch for the contactor, simple toggle switch for the controller. Or vice versa. Imagine how to turn on a regular IC motorcycle, you need to turn the key, as well as toggle the engine's red kill switch on the right handlebar. So choose one of those to turn on the contactor, and the other one to turn on the controller.

 

[RealPolarBear]

This is my advice, you don't have to follow it, just suggestions.

Contactor

Precharge: wire a 1-2kohm resistor to both posts on the contactor, leave it there all the time. No switch or circuit needed. Controller will always stay precharged.

Breaker: typically, the breaker is there so that you can turn off the battery output manually and service the wiring without worrying about a shock. And it can trip if your controller happens to pull too much. It rarely, if ever, will be use to disconnect the controller from the battery while under load. If that happens on a regular basis, then either your controller is drawing too much current from your battery, your battery is underrated for your application, or you sized your fuse wrong. With that in mind, I use something similar to this. You'll want a 200 amp breaker, since that's your controller's max battery current rating. Perhaps 250 amp.

Notice that this breaker is only rated for up to 48v. A breaker is rated for a voltage so that it can safely open a circuit without the risk of a spark bridging open contacts. Since you won't typically be using this to disconnect under load, it's possible that this might work for you application. Also, while 72v is higher than 48v, it could possibly still safely disconnect it at your voltage.

I say might, and possibly. Take my suggestions with a grain of salt. Just because its what i do and it's worked so far for me, doesn't mean it's the best idea. If you want a breaker that will 100% work at a higher voltage than 48v, you'll want to look at solar disconnect breakers like this one, which are usually good up to 200v, since solar panel voltage can be quite high. These will be more difficult for you to find a mounting place on your bike, and not waterproof, but they'll work well.

Key switch: someone more familiar with your controller should chime in, but your controller will have an on-off wire, usually a single wire that needs to connect to B+ in order to turn on the controller itself. You can put a switch on this line, needs to be rated for your battery voltage, but will carry very low current. Or, you can put your key switch on the contactor's coil 12v power supply, and any automotive ignition switch will be rated for 12v. Or, do both: keyed ignition switch for the contactor, simple toggle switch for the controller. Or vice versa. Imagine how to turn on a regular IC motorcycle, you need to turn the key, as well as toggle the engine's red kill switch on the right handlebar. So choose one of those to turn on the contactor, and the other one to turn on the controller.

Wow thank you for the descriptive response! I really appreciate you taking the time to help me understand some of these concepts. I think one of the main reasons I'm confused is because of the contactor. I don't quite get how I would trigger the contactor. I'm confused where the 12v power comes from for this trigger. Further, I do not think the wiring diagrams provided by QSMotor are very helpful. I'm trying to figure out how and why there are three different ignition connectors. I emailed a representative to see if they have any input.

 

[harrisonpatm]

Again, I can't knowledgeably answer regarding your specific controller, I haven't used it. But it's possible that your controller has a 12v line that you can use to fire the contactor. If it doesn't, you should be able to provide your own: a dc/dc converter off your battery. You may need to get a converter anyway, if you haven't already, to power all your accessories.

 

[RealPolarBear]

Gotcha, I have a DC/DC converter which is already apart of the wiring harness that was provided with my shipment from QS. It is hard to be able to test if it actually works without having the full 72V battery so it may be wise to wait for that before I continue more testing. Thank you for all the useful info!

 

[j bjork]

The controller is a little on the small side if you want as much as possible out of the motor. Most that run votol go for the em260.

 

[RealPolarBear]

The controller is a little on the small side if you want as much as possible out of the motor. Most that run votol go for the em260.

Yeah I realize that. I’m hoping that it will suffice for my requirements. I figure I can always upgrade it later if I am not satisfied. I think the em260s uses the same wiring harness too which would be convenient.

 

[DaLanMan]

Mine isn't as simple as a single word.. but hey it has a remote.... I use that to make the initial connection, with a briding circuit, Hit the remote and start the process, it kicks on and allows the lines to come up to equilibrium, and then closes it's circuit pulling the resistor out of the circuit so there is no on-going charge except the few milliamps that this thing has while in stand by mode. I could write up the circuit, but if you look at The german youtube Great scott I think his name is, I stole the idea from him...

 

[RealPolarBear]

Mine isn't as simple as a single word.. but hey it has a remote.... I use that to make the initial connection, with a briding circuit, Hit the remote and start the process, it kicks on and allows the lines to come up to equilibrium, and then closes it's circuit pulling the resistor out of the circuit so there is no on-going charge except the few milliamps that this thing has while in stand by mode. I could write up the circuit, but if you look at The german youtube Great scott I think his name is, I stole the idea from him...

Gotcha, the remote idea is definitely worth looking into. Likewise for “Great Scott” haha. Thank you!

 

[Dui ni shuo de dui]

Controller: Is the VOTOL EM200-2sp a reasonable controller for this build? It is rated at 72 v (which is what I will be running at) and 200 A with boosts capable of 600 A. I am also considering a Fardriver. Would this be a better option? If so, are there any recommendations for a specific controller?

The Votol is very good, it has plenty of power.
I have an EM-150 and it's running at 280 Battery amps, I don't know how many phase amps since you can't really set it in the programming interface. It's pulling like crazy, it litterally destroys my old sabvoton that I was running at 250 battery amps and almost 600ph amps. It's one of the most powerful controllers I ever tried. I don't know if the newer versions of Votol are as good as the old ones though nor if they are still unlocked.

So I must say I'm abit confused by j bjork's comment, as I think this controller choice is maybe a bit overkill given the fact that your bike isn't really designed to be a fast bike (relatively weak frame, drum brakes at the front, etc).
In my opinion you'll have plenty of power already. But that's just my opinion.

The biggest problem of the votol is really the programming interface, it is by far the worst interface I've ever worked with. Nothing makes sense, the documentation is catastrophic, it's an absolute nightmare to work with it.
That's too bad because otherwise it's a very good controller.

The fardrivers are probably a better choice, they have similar power, they are reliable, they work well, there are many people using them nowadays so you are likely to find someone who can help you troubleshoot it. The programming interface is a lot better than the votol even though it could be improved, the documentation is crap but still ten times better than the votol's.

I'd go with a fardriver if I were you, but the votol is still a good choice if you're willing to put time and effort into deciphering its interface.

Also, I have to say that your bike seems like a good candidate for a hub motor. Is there any particular reason why you'd like to go for an onboard unit?

As for precharge, breaker and all that stuff, I suggest not bothering yourself with it.

It only will add more weight, more complexity and more failure points, for no added value. A smart BMS will do all of that already, because a BMS is basically a breaker (it monitors current and you can tell it to cut power if it goes over any level of your choice) and a contactor (the BMS can cut off the power completely either with a long press on a physical button, or in the phone app by clicking on a button), and smart BMSs include a precharge system which even allows you to set and change the precharge current to whatever value you want in just a few clicks in the app.
Also if something is damaged the BMS can detect it and it will cut power/beep at you.

So there's really no need to double down on this. In my opinion the only thing you should really add to a BMS is a good fuse between the BMS and the battery. In case the BMS goes wrong the fuse will be there to cut the power and it'll protect the battery from damage.
All that contactor/precharge/breaker stuff made sense a long time ago, but theyre completely outdated now that we got decent and cheap smart BMS.

Keep it simple.

 

[j bjork]

The Votol is very good, it has plenty of power.
I have an EM-150 and it's running at 280 Battery amps, I don't know how many phase amps since you can't really set it in the programming interface. It's pulling like crazy, it litterally destroys my old sabvoton that I was running at 250 battery amps and almost 600ph amps. It's one of the most powerful controllers I ever tried. I don't know if the newer versions of Votol are as good as the old ones though nor if they are still unlocked.

So I must say I'm abit confused by j bjork's comment, as I think this controller choice is maybe a bit overkill given the fact that your bike isn't really designed to be a fast bike (relatively weak frame, drum brakes at the front, etc).
In my opinion you'll have plenty of power already. But that's just my opinion.



Keep it simple.

My comment was just about the controller in relation to the motor, as some seem to suggest that it was to much already. As you say it is probably a lot already on this bike.
These motors can take a lot in bursts at least, I dont know when it comes to high power for longer times.

(I think the votol em150 does 540pA on maxed settings. I havent mesured myself, but someone else did. I think I saw 370bA in short peaks on mine, but I am not sure. Something like 31kw on the logs.)