Electric CRF Moto Build

Kinda just been doing this on the side but since my battery finally arrived really think I need to write this out more. I'm no e-moto builder, I'm just a motorcycle guy that feels confident enough with electrical things but the electric motor aspect/batteries/etc is all new to me.

Goal here isn't for some crazy bike that matches up to the original 450 engine, just looking to have fun building an e-moto and am purposefully setting my sights kinda low because I don't want to strive for perfection in this first try, would love 20kw of power, ain't going to happen right now. If I make something that can roll for 25 miles on it's own, I'm happy.

Started with a '03 CRF450 I got for $1200, it would...sorta run but it had 18 years of neglect as well so went through things. Figured since I have no plans to massively modify frame components, worst case, I throw the engine back in and it's back to it's old self.


Rebuilt stuff and started fitting electrical components, I kinda measured before-hand but also saw others do similar builds. For the motor I really was overthinking things, I was looking at way higher powered motors and ended up wanting to keep it simpler so I went with QS138v3 and Votol EM-200 controller. To me for what I want, 12-15kw is goal but not what's going to happen to start.


So the bike kinda sat in that form for about 1.5 months while I waited on a battery from China. Now since this is just a fun project I wasn't worried on shipping times and went with a cheap battery, 72v50ah BUT the main reason I went with it is because the business had them priced at $275 shipped. Unfortunately when I got the battery it was slightly damaged from shipping where it was cracked on the casing but that did allow me to see inside and see Liitokala Lii-50e batteries 20s10p configuration thus I figure....if nothing else, these are good supplies if I want to deconstruct this battery and build a new one.


Last few days been cutting some temporary engine mounts because I didn't really want the motor sitting free when it's powered on, worried it'd go flying or something.


And ensuring my sprocket is kinda lined up but I see with this setup the motor needs to move up and back just slightly, no worries since I need to make new mounts anyway, eventually going to make them out of something more durable than plastic but it's easy to work on at home.


Test fitting things and I might need to move my seat up an inch, I mean the seat plastic does bend and it'll just bend up in the front but need to fit this a little better. Think I'll try to raise the middle mount on the seat about 1".


So now I have a kinda good base I'd like to start wiring up to actually test my electric components. Gotta dig into some wiring diagrams and work one out, China does not like color coding wiring very well. I do have a feeling I only need like half these wires connected to test things like I just want to ensure the motor spins and controller is functional.


Next Steps:

• Charger for battery

• Connector for my battery leads

• Fuse/contactor/key switch/kill switch

• I'm sure about half a dozen other small items I'll find as I'm building

Anyway bit of a slow going project because I'm learning as I go but fun to do. I'll blame the Zero test-ride day for this whole endeavor, I gotta know how things work before I'll buy an entire bike pre-made. Welcome any input on things, as I said I'm learning but not striving for perfection here, really do want to see the motor spin though, that'll be fun.

Great project. I'll follow your progress. Good luck and have fun building :thumb:

Hohohoo,
my santa brought me a crf250r!
Still on the trailer, make room in the garage.

Also got the qs 138 70h v3 engine. Votol 150 controller, battery (for the time begin) surron. I have enough experience with the votol, with my surron tuning! It will be alright.
You have not (yet?) Attached the motor with the swing arm?
What power can your battery provide (continuous - great?) These cheap China batteries are often only built up to 50A current ... Unfortunately, a good battery is always expensive ...
It will be great fun

Have you checked your "damaged" battery exactly? A later short circuit (enduro / trial / cross-vibration) is no fun!

Paulflieg said:

Hohohoo,
my santa brought me a crf250r!
Still on the trailer, make room in the garage.

Also got the qs 138 70h v3 engine. Votol 150 controller, battery (for the time begin) surron. I have enough experience with the votol, with my surron tuning! It will be alright.
You have not (yet?) Attached the motor with the swing arm?
What power can your battery provide (continuous - great?) These cheap China batteries are often only built up to 50A current ... Unfortunately, a good battery is always expensive ...
It will be great fun

Click to expand...

I haven't yet mounted to the swingarm, both sides of the motor mounts don't look to line up so think I'll just attach from one side of the motor and bolt through. Should actually be a simple mount just a piece that goes from swingarm bolt to motor and then spacers on swingarm bolt to fill in so those seals are held. I do need to move the motor back just slightly and change my front mounts to go forward more to the front of the frame. Big reason I made this from plastic, some of this stuff I just need to see to be like, "oh yea that ain't right."

This build as it stands should be 50a from the battery and they claim 100a burst but that's probably BMS shutdown or something. It's nothing fancy, I figure I'm going big enough with a 'full size' bike as my real first electric build I wasn't going to over-do the battery and if that's the sole limiting factor creates for a simple upgrade. I knew I overbuilt the controller but figured that's more of less brains of things so no reason to overload it and kinda underbuilt the motor because I just didn't want to try to squeeze a big motor in and have no space for battery. Truthfully if I ever got 15kw of power out of this motor/build that'd impress me but I believe at 3kw power I can be a registered electric scooter (with some lights).

I almost went with an expensive battery that claimed upwards of 300a output but was close to $1k and power complicates the build. I'm willing to spend $1k to get a nice battery on this once I prove I can build it hah.

Paulflieg said:

Have you checked your "damaged" battery exactly? A later short circuit (enduro / trial / cross-vibration) is no fun!

Click to expand...

I'll admit not a deep dive like removing all the wrapping and the battery does live under a fireproof welding blanket for now. The external blue wrapping is ripped so you can see the batteries but I did not see any damage to any connections/batteries. I did see that post and thought long and hard on batteries, definitely doing things slowly because I'm trying to be safe like I haven't even charged the battery or tested anything just yet but think I have things mostly setup to see if the motor spins/battery works.

Honestly I got this battery because they mis-priced it and I didn't think I'd get it so $270 for 72v50ah. I don't expect to thrash hard and this is kinda a proof of concept for me still. As I build the bike I get the feeling I'll either have to build my own battery or figure out a contact to build one. This may become in a few weeks me tearing off all the blue wrapping on the battery though just to inspect and really see quality of the battery, who knows, maybe it's decently made just with a cheap BMS.

This battery if anyone interested but $550 now and damaged the same way the 2nd to last review showed:
https://www.aliexpress.com/item/1005002768350847.html

Hi there,im also building a 2010 crf450 r and will be watching your build along the way.Motor position wise undo the lower shock/linkage bolt so the swing arm moves freely and have it sit nice and flat/horizontal and both the top and bottom part of the chain should not touch or if a small sprocket is used both equally touching the chain guide.Ill be running the same motor on 26s and 315 dc amps on my build.

Which battery? Homemade? Which dimensions? And cells?

speedy1984 said:

Hi there,im also building a 2010 crf450 r and will be watching your build along the way.Motor position wise undo the lower shock/linkage bolt so the swing arm moves freely and have it sit nice and flat/horizontal and both the top and bottom part of the chain should not touch or if a small sprocket is used both equally touching the chain guide.Ill be running the same motor on 26s and 315 dc amps on my build.

Click to expand...

Great info man!! I knew there was a reason I didn't torque down my linkage bolts yet!

Today aim to finish up engine mounts, start charging the battery and dig into simple wiring to test motor, think I still need a few pieces before I hookup like I want a robust switch for the battery just to be sure I can control it's power draw. Man if I could get this working and build up to maxing out the EM-200 controller for power, 15-20kw would make for a really nice trail bike in my mind, what you're talking would make a CRF250R blush .

Paulflieg said:

Which battery? Homemade? Which dimensions? And cells?

Click to expand...

Posted a link to it above, bought battery, it's kinda big like 15-16" tall, 200 Lii-50 21700 cells and since it's a cheaper battery just 50-100a discharge so nothing crazy. I wanted cheaper and with cheaper comes less power which I'm accepting for now as this is my first build. Motor can handle more, controller can handle more and building parts around the bike like fuses/wiring to support higher amperage not the 50-100a range I have now.

Was a bit lost without this diagram that I just got from Siaecosys for the wiring harness. Some of the wires are labeled but many aren't:


Officially connected the battery to a charger. Charger came with 3-pin XLR connector and battery had a DC adapter on it so I had to make a XLR->DC adapter (I didn't want to cut wires on stuff). So far it appears as though the battery is fully charged as the charger stayed green for the LED, never went red for charging which kinda makes sense to me from the factory.

Next up is wiring an XT90 on the battery since it's bare leads and then going over my wiring harness connections to ensure I have everything like I think I need a 12v relay and some other pieces, gotta read through that diagram above more.

Edit: And I was mistaken thinking the spot in the harness was for a +12v relay....that's actually a 72v relay which I assume they wired this for instead of a contactor since it's more complicated and for higher power.

Oh, this package comes with a wiring harness ... Nice!
Is the dc / dc (72v / 12v) converter also included?
Is the controller already configured correctly for the 138 h70v3?
Would you save the configuration without making any changes !?
That would be nice. I would love to see the config.

When connecting the controller for the first time, it is good to precharge with a resistor ...

Paulflieg said:

Oh, this package comes with a wiring harness ... Nice!
Is the dc / dc (72v / 12v) converter also included?
Is the controller already configured correctly for the 138 h70v3?
Would you save the configuration without making any changes !?
That would be nice. I would love to see the config.

When connecting the controller for the first time, it is good to precharge with a resistor ...

Click to expand...

I paid extra for the harness/DC converter because....well, Keep It Simple Stupid and it was like $30 more. But you can order it all from Siaecosys so it all comes in one box. The only things I don't see that I need are a 72v relay and ignition switch (as well as pre-charge).

The controller should be configured for the motor since it was all bought as a kit from them. I would surely save the OEM configs for reference, love doing that stuff, I do it with my ECU's which is just a controller for gas engines.

Great info on the controller, I need to lookup more with that and confirm the connections before I connect any power to it. May wait for contactor/resistor until I even connect the controller. Was looking at this thread on pre-charge since you mentioned:
https://www.diyelectriccar.com/threads/precharge-what-is-it-why-do-i-need-it-how-do-i-do-it.25419/

Thinking I have most necessary connections done, there are added connections for lights/turn signals/horn/etc that aren't connected:


Officially connected my first 72v battery to a charger and didn't get an explosion or sparks, was happy about that hah:


While I wait on switch/relay can aim to finish up mounting the motor in a better spot and possibly find better way to mount the battery. Gotta laugh at myself I still haven't even tested my battery with multimeter yet but we rolling now, I plan to get a better battery if this build works anyway.

Plugged in charger, battery just stayed green, went through things and found the DC adapter for the charge port I couldn't see voltage. Spliced in an XLR plug to the charge port after confirming I got voltage on the bare wires from the battery and NOW my charger is red which is charging.

Was a bit worried because my battery leads were showing 70.1V but when I was testing the charge port I got nothing. Was more worried that it was a problem with the battery pack from the case damage, something I didn't see but so far 30 minutes on the charger, voltage has gone up to 71.3V and everything is cool to touch, charger is lightly warm but the fan is running as expected, nothing hot, feeling successful.

Now back to reading up on making a pre-charge circuit while I wait on few other parts that'll take a few weeks.

Thinking of keeping pre-charge circuit rather simple since this setup is really limited to 100A max, I'm not sure if that's where BMS shuts off but I'm going to set that since manufacturer parameters and kinda sorta trust this battery. Thinking make a connector with a breaker/fuse/resistor and momentary NO switch:


If I decide that I want more power or something this is easy enough to re-think but this setup would mean breaker OFF when connecting battery. Connect battery, press button for pre-charge and then flip breaker. I might not really need the 10a fuse, might be useless there.

Broke my ankle (riding) so this kinda took a back seat to other things the last few months but I was also waiting for some parts. Finally got it all together and my motor spins! How well it spins, how well everything is working is not a concern but alls I know is I got it all to turn on including the LCD and spins as expected with throttle.

Oh and no explosions/fire/smoke/sparks/heat buildup, all nice and....really uneventful....except me being giddy that the motor is spinning.


Really thankful they've programmed the controller in some way from the factory because that'd be another hurdle if I had to do it now, have not logged into the controller yet, think I'll try that tomorrow to see settings.

And successfully got into the software for the controller. I did have to use the drivers from Prolific instead of the ones Siaecosys has listed on their website:
http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=223&pcid=126

Then ensure you select "CAN Enable" on the program.











Not changing anything in here since I dunno what I'm doing and it's working enough right now. Thankful this was all pre-programmed for things. Now it's turning to mounting things back on the bike in some kinda way.

I'd be happy for you if the battery delivers those amps. I will test these settings (original from qs?) on the Em150....

Paulflieg said:

I'd be happy for you if the battery delivers those amps. I will test these settings (original from qs?) on the Em150....

Click to expand...

Nah it won't, I need to edit that but these are completely OEM settings for things. My breaker should blow at 100amps so I have things limited, I doubt my battery can go over 100amps in current state. Wanted to capture this info since I don't see it listed anywhere.