Hardtail, On/Off-Road - 4.2KW - First Build

[Kyle201]

Well alright.

After many delays getting the parts I wanted, and just being busy... I REALLY want to start working on this again, however I'm going to need a lot of help. I'm about hitting the end of my length of knowledge, which is basically just the physical construction aspects... I can't quite wrap my head around how all the wiring is going to work yet.

So here's where I'm at with the build so far:


Here's the wire harness I was sold with my kit. It contains a 40A fuse, is that even enough for a 40A continuous setup??


BMS Diagram which is quite difficult for me to understand. It seems my BMS has two positive and two negative wires? For seperate connections to the battery and also the charger?


BMS itself


Grinfineon 40A Controller and Connectors



Cell Monitor and alarm.. I have 3 of these as they only support 8 cells each. These little units are the most confusing for me, next to the BMS. The support guy from hobbyking told me to get a few sets of those wiring units that came seperately, in order to use all 3 cell monitors? The connector on those wires doesn't seem to attach directly to the cell monitor.. though it can plug to them, there's more pins on the monitor than the wire connector.


I will have to change out at least 3 of my connectors I think. This is an extra sensor connector, the motor is using this, so I will swap the controller's to the same. Now I'm not sure swapping connectors is too difficult.. so, basically just cut the wires behind the connector... strip them back, and then feed them into each of these tiny holes and solder? But which colour wire into which hole is the question... will I have to remove the heat shrink from the motor's to figure out how they should go?? The other connectors seem a little more straight forward.


I also have these bullet connectors which should replace the anderson phase connector on the controller. So basically just solder the wires into the little tunnel at the back of the gold connections? I haven't actually soldered anything in probably 10 years since I did it in school. Soldering seems simple enough, but any soldering or connector swapping tips at all appreciated. I thought there was a third connection I had to change but maybe not.


Motor connections



Okay. And so just some info on my battery setup, I have the 24 cells being split up into 3 packs to distribute. 3 x 4 pack at rear of inner triangle box, 3 x 2 front of triangle and another 3 x 2 pack mounted below the bottom tube. Now I have some diagrams and info on how to set up the battery with the bus bars. But I don't have any examples of something like the 3 x 4 pack so I really have no idea how the bus bars would go on

Bus bars and ring terminals


So the ring terminals will be used to create 'daisy chain' connections between the packs.. and I was given a short length of 10AWG wire for this, is this thick enough for the power? 72v 40A continuous, and I plan to ride down to -20 degrees. Aaaaand... will I need to get a bunch more ring terminals, for each of the BMS to Cell connections? Basically just solder each BMS sense wire to a ring terminal and then sandwhich between bus bars and the bolts?

Bus bar setup
image_6_1.jpg

I was given a set of 12 images and texts to set up the battery which is fairly clear.. however none of the examples really show how the bus bars would work for my largest 4 x 3 battery. Any help there?


Sorry for being so needy on this project, it's just been sitting since I sort of felt a bit overwhelmed by it all. So some clarification to help me wrap my head around all of this will make me very happy!

Thanks again for all the patience and information from everyone here.

 

[Kyle201]

Okay, so... maybe too many things at once but first things first, I want to change the connectors.

The 5-pin "mini XLR" looks difficult to solder so I'll start with the XT150's for the phase connections. Now seems fairly straight forward, but I'm left wondering how I can tell how I'm matching the wires up properly with the connector already installed in the motor.



There's no colours or anything on the connector outers so... is there any way to tell without removing the shrinkwrap? Cause I'd rather not destroy it.

 

[diggler]

Don't know if this will help match your motor and controller wires, just trying to help one noob to another.
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=6241

I read this entire thread yesterday on the bus and sounds like you got some good quality parts and your not afraid to spend some money to get things done right.

I'm planning on using headways for my next build also, but no bms. I plan on bulk charging and balance charging while monitoring each cell with cell checkers at the end of the discharge. (because if there left on they will imbalance your pack)

I recommend trying to find answers to all your questions by reading this form a lot. As I read through yours I found myself saying O I read that on here somewhere.

As for your torque arms. They look flimsy to me. I bought a set of DocBoss's and they worked great. I only used one because I was only running 60v 30A (your basic $250 1000W ebay 9c ebike kit), but my frame is aluminum too and I epoxied it. I didn't even use the dp420. I used the best jb weld there is but I did it right. (use a hair dryer) The good stuff will take 24hrs to cure like the db420, but Doc just used epoxy and he pulled a bus with his ebike using them. That's more than a good enough test for me. But just to be safe after 24hrs and it was cured, I drilled a hole the size of one of the holes on the torque arms through one of the holes in the torque arms into my aluminum drop out, then hammered a roll pin in flush with the inside of the drop out and cut the rest of the roll pin off with a wizzy wheel. It looks professional and if the epoxy doesn't crack after your drill and hammer then its probably good but just incase it did the TA is bolted on with your axle nut and has a roll pin so how is it going to spin? Unless the roll pin snapped too!

 

[Kyle201]

Thanks diggler. Yes I do want it to be done right, and as such with my high quality parts it's why I haven't made much progress yet as I'm afraid to wire something wrong and destroy something. But slowly gaining an understanding of it all and hoping to get some wiring done over my holiday break.

I have been reading around here a lot and I managed to find the pin number chart for the halls connector, but also learned my grinfineon controller auto-maps the halls! So I only need to get the ground and power pins correct and the rest will auto-sync!! Cool.

I've also been communicating with the knowledgable folks at ebikes.ca, as it seemed I wasn't getting much interest here.. but alas, according to Justin, the phase connections - all 9 combinations will "work", 3 spinning backwards and 3 forwards, so I guess I will just have to use alligator clips or something like that and test to see which way. I don't want to ruin the heat shrink to check on the colours, but he also told me that it would be likely the colours wouldn't even match between controller and motor... fun.

As for the torque arms, I think using two of the ones from ebikes.ca should be enough, Justin telling me that 1 would probably even work. My frame is steel as well. Doc's are cool too, and would have been my second choice but I was skeptical of an adhesive bond preffering a mechanical connection.. less easy to do wrong.

SO! I think I've got the halls and phase connections understood, now onto the battery, bms, and cell checker wiring. Complicated to my eyes o_o

Trying to find clear examples of how it's wired but it's confusing to me as some BMS have one P- wire, and one B- wire. Where mine has 2 wires for P-/C- and 2 for B-.

So I really need some help to understand the BMS wiring as this is an expensive unit and would love to get it right the first time.

Wiring diagram

BMS

Wire Harness I was sold with my kit


BMS connections, how I thought they might go...

Battery setup - Do the bus bars look correct on the largest main pack??


But then after looking at some other BMS setups it seems like the B- wires, both should be connected to the same place, the open negative on my battery pack. And then P- is for charge and C- for controller. But with my wire harness there's the single positive and single negative, which both go out to the charger AND controller. So would this mean, maybe my connections thoughts image is wrong. And both b- go to battery negative. Then both the blue wires (P-/C-) go to the negative of my harness. Then the positive harness connection will go straight to the battery?

Really need someone to help me understand all this ^^^

And so then for the sense wires. It starts with a black one (B-) which will connect to the same negative as the thick (B-) wires correct? Then I have to go sequentially across the pack to all the positive terminals.

And finally to further complicate things for my noob brain, I want to have cell monitors for each cell. So I got three 8cell monitors. They have 9 pins each, the first 8 will need to be matched up, and soldered into the same ring connectors as the BMS sense wires, correct? then the 9th pin is ground, which can share a single wire between all 3 monitor units.. but where will the ground connect to?

Thanks everyone.

 

[Kyle201]

Right on, don't everyone rush to reply at once

Anyway, I've been receiving much help from Jim at Headway HQ on these matters and now have a good understanding of almost all of the BMS aspects now.

Before I wire up the BMS sense harness can anyone quickly verify if I have the cells numbered correctly?

 

[Kyle201]

The bike is READY!

Everything is working veerrry well so far, though only 1 test ride it seems to be meeting my expectations quite perfectly

Some ride stats..

Max current 71A
Min current -17A (Regen)

5100W Peaks! Lots of GO!

This thing pulls up the hills pretty hard really felt great.

Some observations / improvements that will need to be made:

-Throttle has a moderate dead zone at the beginning, (though not convinced this is such a bad thing yet, in terms of safety..) and also ramps up quite quickly, also seeming to have a bit of lag in the response.

-Modulated regen using the throttle is SO COOL. However I had a couple jolts where I release the brake lever before the throttle, or even at the exact same time. Definitely have to get in the habit of releasing the lever first always.

-Upside down handlebars very effective for getting the weight forward in low traction such as deep and heavy snow, and also great for aerodynamic body position, however seems to cause some wrist discomfort riding more upright... but feels perfect when getting low and aero.

-Some rattling noise over bumpy terrain, pretty sure it's the battery blocks having some movement.. will need more padding or some such.

- Wire management is a touch sloppy but overall very happy with how it all looks and performs right now.

PICS !!

 

[Kyle201]

Hey ES folks!

About time for a little update on this bike I suppose.

I've done about 4000km on this bike now, and commute with it every day that isn't raining hard! My quality of life has greatly improved. No more sitting in traffic, inside a closed box staring at other boxes. I zoom down the bike path in the open air, getting some exercise and adrenaline every trip to work or elsewhere! I commuted all winter as well down to -20C without problems running studs on just the front wheel. I stored the bike outside once in the winter and the battery was very upset after that. Now I keep it in a heated garage/shop all the time, and add insulation during the winter months.

No major issues so far! Only a few minor crashes, but I ride fairly aggressively. I've done 2-3 foot flat drops without breaking anything yet! Works pretty well for off-road... but dual suspension would be wayy better as this thing is a pig at 90lbs. Good thing I'm a light rider.
Suspension seat post is awesome! Add comfort AND control as I can stay seated which prevents the rear wheel from bouncing off things as much.

Some issues, modifications, or thoughts so far:

- Power slides are the shit! I can 2 wheel drift this thing on the gravel so hard. The weight balance with the triangle batteries is awesome. I can do tight pavement and even gravel corners near top speed no problem. Upside down riser bars help for this. Still riding with them upside down! Sometimes on a long ride and trying to sit too upright, the wrists get a tiny bit uncomfortable. But I'm used to it now, and it's not really an issue.

-No flats yet!!!! While riding, at least. I've acquired some slow leaks (on the rear), but always made it home before losing all pressure. Added some sealant inside my downhill tube now. Front is tubeless 120tpi, and never had a front flat.

- Shunt modded the 40A Grin controller to 62A! Voltage sags down to about 68v at the lowest for a few seconds when pulling full power... but this thing accelerates quick! And the controller gets warm but rarely hot.

- Only ONE walk of shame so far. I thought my BMS died, but it turned out one of my BMS power connections had just exploded. Perhaps poorly soldered. There was yellowing around some of the BMS wires where they go into the PCB. So I disconnected the BMS thinking it was the issue, only to have cutting out issues. Fixed the bad wire, and left the BMS disconnected for now.... dozens of cycles since then and working great.

- My sidecover bolts stuck out too far and always frocked up my knees. So I replaced the bolts around the knee area with washers/magnets. Works great.

- Stock shitty 14ga wiring and motor get pretty hot! Lots of hills here. So, I did a lazy wire change outside of the motor/controller and just spliced on some nice silicone high strand 10ga to the existing phase wires on controller and motor.

- Added heat sinks to the side covers of motor! I've noticed a fairly significant thermal improvement watching my temp sensor readings. Lower overall temperatures, always, and it takes longer to heat up, and cools down quicker! I used to hit 110c+ on an agressive hilly ride, now it barely gets over 95 ever! Temps drop twice as quick as before. I'll probably try to add more heat sinks between the spoke flanges as well, to help cool the magnets.

Some specs/stats:


Using a 24x3.0" rear tire at low pressures (18-20psi)

Top speed:
- 55kph on flat with a light headwind and no pedaling
- With pedaling: Up to 57kph and even a moderate headwind
- Uphill with a moderate headwind, or flat ground with a strong headwind this thing will still do ~48kph without pedaling, and over 50 with pedaling.

I can decrease the controller wattage by 500-600 watts pedaling at top speed, while increasing top speed by 3-5kph!! (short bursts for this much effort, 10-20 seconds at a time) All with just a 48t / 16t gearing. Very high cadence, but that's okay with me as I probably can't even fit much larger of a chain ring.

Max range:
I could definitely get about 100km of range if I didn't WOT most of the time. Usually only up to 80km of range pedaling a lot while still traveling at about double the average speed a road bicyclist will do at half the human effort. I've drained the battery in about 45km as well, doing a lot of hills, fast accelerations and not pedaling.

Power usage for commute:
My commute is 15km each way, and I generally use about 4.5Ah of my 15Ah per way. WOT 90% of the time. Sometimes as low as 4Ah if I pedal more, sometimes 6+Ah with strong winds or not pedaling. About 5Ah if I don't really pedal at all with average winds. Sometimes I'm lazy early in the morning...

Love this thing!!! 100000x more enjoyable than driving a car to work, and can still get the blood pumping really good.

Anyway, here's a current pic!

 

[Ellou]

I'm currently building my first e bike and hope I have at least half the fun you are.lol

Nice build. Stay safe.

 

[Kyle201]

Thanks Ellou... I hope you have at least half as much fun as I'm having, cause that'll still be a lot!

Made a video! Here's the machine in action: https://www.youtube.com/watch?v=HWre2IkoOFM&feature=youtu.be

 

[rider95]

Why such a powerful kit for a first build????? with that frame ??? running that kinda of power you are making things a lot more complex and expense , this is you first build keep it simple and cheaper . With that bike you should be using a geared hub motor pushing up to 2000w this would make a great all around get around E bike even light trail riding 30mph plus a very fun easy and simple and a whole lot cheaper to build . You need to gain experience and knowledge this you will get starting with a simpler build and will save you a lot of frustration and money . Buy a complete kit so it all will be plug n play try to deal buy from the same vender EMV3 or dogman or one of the other shops that is respected on here .

 

[Kyle201]

Hey rider. What's the problem exactly? I ride mountain bikes extensively, do a lot of extreme off-roading and downhilling. I also have a 250cc KTM 2 stroke dirt bike. So I have a lot of experience even with a motorized bike already before I built this. I also have a lot of experience building and maintaining my own bikes... and after seeing the 10kw + bikes here, I thought a few KW would be easy. I started out with only 2.6kw, but then shunt modded the controller to 4.2kw.

Pretty happy with the power so far, in fact... I wish it was more powerful already as I am used to it... and completely comfortable riding at top speed (55kph) but I realize it's dangerous to go much faster sooooo I am content right now. This bike is fun as hell, and I wanted to be scared by it at least a little bit... adrenaline, fun, etc.

Did you see the video I just posted? This bike is perfect for me. I commute on it almost every day to work, and I've only had to do ONE walk of shame due to a single poor connector solder, that blew up. Anyway, I got this thing all up and running no problem almost a year ago now, and nothing major has failed. 4000+km and it's quite reliable. Never even had any flats out on rides, despite the fact I've bottomed out the tire a dozen times on curbs. ]

This thing handles light trails, and rough roads at top speed flawlessly. Smooth and controlled. The frame is a pretty beefy steel MTB frame. Much higher quality than the many walmart frames I've seen motorized here at even higher power levels... Dual torque arms so the axle hasn't twisted into the dropouts much yet even at 62A output and 20A regen. Frame dropouts DID get a touch looser at some point, probably my lack of re-tightening at one point. But still perfectly good to use.

Thanks for the input anyway...