crf450r 45kw race bike build

[rivvs]

Started working on the battery box. Also After talking with someone who has first hand experience with immersion cooling I decided to not use that for the cooling because there is more negative than positive with it. Still not sure if I go air cooled like the stark Varg or water cooled.

 

[speedy1984]

What sort of battery amps are you hoping to reach peak and or maintain?What sort of tracks do you ride out there,sand or hard packed ect?Trying to understand why you think you would over heat the cells.The copper connections you are using and I used also all be it just a nickel strip overlay,helps definitely cool the pack when compared to my other pack that was just nickel.I know you want it to be 450 competitive and I would say it will anyway even if you don't try shooting for the moon.You know yourself there very easy to ride fast compared to a ice bike and in the right hands much quicker.

 

[rivvs]

What sort of battery amps are you hoping to reach peak and or maintain?What sort of tracks do you ride out there,sand or hard packed ect?Trying to understand why you think you would over heat the cells.The copper connections you are using and I used also all be it just a nickel strip overlay,helps definitely cool the pack when compared to my other pack that was just nickel.I know you want it to be 450 competitive and I would say it will anyway even if you don't try shooting for the moon.You know yourself there very easy to ride fast compared to a ice bike and in the right hands much quicker.

I will be ridding mainly deep sand tracks. Im fast to mid pack b class rider. I will use the bike for racing and also for practice day so I will be discharging and charging multiple time a day. And based on what I have read about the alta wich had about the same size battery as mine people were overheating the pack. The peak amp will be around 400 to 450 amp. But since I will ride deep sandy track the continuous power need to be higher.

 

[larsb]

It’s probably too late now but i’ll add that only a minimal amount of heat is created in the cell connections vs in the cells so with a given number of cells you’d be best off with a really low IR cell, something like the molicel p42b which is 15% lower dcir than even the p42a, maybe also forced air cooling of the cells if you ever ride slow but high power swamp or sand runs. But given the professional cell connections and overall build level you probably already know this.

 

[rivvs]

It’s probably too late now but i’ll add that only a minimal amount of heat is created in the cell connections vs in the cells so with a given number of cells you’d be best off with a really low IR cell, something like the molicel p42b which is 15% lower dcir than even the p42a, maybe also forced air cooling of the cells if you ever ride slow but high power swamp or sand runs. But given the professional cell connections and overall build level you probably already know this.

At first I wanted to use the p45b but the price I got from molicel was way too expensive. And they told they do not make the p42b this year. I thinking about using the whole case as a big heat sink with cooling fin.

 

[larsb]

Ok, i can imagine that, even the p45a is an expensive cell.
Great idea on the case cooling - i have seen some hybrid cells that cool the cell with the negative end transferring heat to a cooling block through a thermal (but insulating) pad of some kind. I’d guess positive end has a poor heat transfer due to that the vent is at this side. A lot harder with a mixed pos/neg cell layout i guess.. but which cells did the alta have, you might already have an edge through your cell choice?

 

[speedy1984]

I will be ridding mainly deep sand tracks. Im fast to mid pack b class rider. I will use the bike for racing and also for practice day so I will be discharging and charging multiple time a day. And based on what I have read about the alta wich had about the same size battery as mine people were overheating the pack. The peak amp will be around 400 to 450 amp. But since I will ride deep sandy track the continuous power need to be higher.

GotchaWell you defo picked the right motor for the job of deep sand tracks.Not sure how you would air cool it without letting dirt in tbh,i mean yeah you could use flaps but even then you could not wrap the pack in anything or air would not pass through the cells.Small rad fan pulling air out from the top would at least slow the build up of heat i guess.I mean if you are doing all the fab work yourself then i think i would still maybe try liquid cooling route myself.

 

[rivvs]

Ok, i can imagine that, even the p45a is an expensive cell.
Great idea on the case cooling - i have seen some hybrid cells that cool the cell with the negative end transferring heat to a cooling block through a thermal (but insulating) pad of some kind. I’d guess positive end has a poor heat transfer due to that the vent is at this side. A lot harder with a mixed pos/neg cell layout i guess.. but which cells did the alta have, you might already have an edge through your cell choice?

The Alta used 18650 Sony vtc6. the problem here is that I have mixed positive and negative. I could maybe have another plate in the middle of the two module as an heat sink too.

 

[larsb]

Don’t know if you already saw this but Pajda’s testing of high power cells posted here at ES have both vtc6 and moli p42. Seems you’ll get slightly less heating with your cells

 

[Eastwood]

I received my bussbar for the battery. I ordered them from Alibaba. 0.5 copper with copper plated nickel strip to spot weld on the battery.View attachment 331118

Can you please share your source for these busbars?
I”ll probably end up making something very similar to this because of cost, got some ideas I’m pondering on. Obviously it wouldn’t look as precise and clean with fabricating something like this by hand and not machine precision.

I’ve been reading and reading about all the different options of connecting the cell groups, As this will be my first battery build. This method seems like the most efficient way of by far!! Especially with using .5 copper
That thick copper is going to greatly reduce the heat buildup. Vey nice sir! Can’t wait to see some videos of your finished product, as this bike is going to be a performance beast!!

 

[rivvs]

Can you please share your source for these busbars?
I”ll probably end up making something very similar to this because of cost, got some ideas I’m pondering on. Obviously it wouldn’t look as precise and clean with fabricating something like this by hand and not machine precision.

I’ve been reading and reading about all the different options of connecting the cell groups, As this will be my first battery build. This method seems like the most efficient way of by far!! Especially with using .5 copper
That thick copper is going to greatly reduce the heat buildup. Vey nice sir! Can’t wait to see some videos of your finished product, as this bike is going to be a performance beast!!

I sent my file to WELLGO store on alibaba. Thanks!

 

[larsb]

I've got to recommend this strip calculator made by user ludwig_bre on the efoil forum. It gives an calculation of strip losses in relation to battery losses, temp increase in strip and so on.

I think it calculates too high temperature increase in strips as they are thermally connected to the cells but overall it's a nice tool to show the relatively less heating and lesser importance of the interconnections when compared to the cell heating.

https://lbre.de/hp/BPC/BPC.html

Battery Pack Nickel Strip Calculator

Hi together, Everybody here needs battery packs for foiling. Many build these packs their own, wondering how thick the nickel strips need to be, how hot they will get, and if they even need nickel or if maybe steel is enough. From my perspective, many people go way overboard on the thickness...

foil.zone

 

[rivvs]

Update on the bike. I almost finished welding the battery and also started working on the mounting point. And I 3D printed the conver for the chaincase.

 

[SlowCo]

Great progress!
Why still a foot brake pedal and not go with a lever for the rear brake on the handle bar?

 

[rivvs]

Because I prefer foot brake. And in case I get arm pump on the track I can still brake and correct Trajectory in the air.

Great progress!
Why still a foot brake pedal and not go with a lever for the rear brake on the handle bar?

 

[SlowCo]

Because I prefer foot brake. And in case I get arm pump on the track I can still brake and correct Trajectory in the air.

Maybe get a left side brake lever on the handle bar as well that does progressive regenerative braking through the controller/motor?

 

[Eastwood]

Great progress!
Why still a foot brake pedal and not go with a lever for the rear brake on the handle bar?

Yeah, I agree Rear handbrake, especially with the torque output from electric. Most people, loop out their gas bikes, because they need to put their right foot down and then they have no access to the rear brake. I mean, that’s more with off-road like Enduro riding, but I suppose it could happen on an MX track as well. They do make a rear handbrake that works in conjunction with the footbrake.

LEFT HAND REAR BRAKE KIT | Rekluse

The perfect complement to a Rekluse auto clutch, the left hand rear brake kit allows riders to fully operate the rear brake using only their left hand. The rear foot pedal is still operational at any point in time.

rekluse.com

 

[rivvs]

If I ever go for hand rear brake I think it will be full on regenerative brake. And I will delete the rear brake completely but this will need some testing before I do that.

 

[Eastwood]

I went with the cl700 because that is the biggest I could fit in there without having to a parralel group of battery. And I do not have the cl700 but cl700tp. The tp has toll mosfet so I can have more amp than the regular.

Was reading back through your thread about the 3Shul controllers as I just ordered one. The newest versions of the CL700 and CL1000 are the same size. Maybe your CL700tp is smaller?

They sent me the new manual with dimensions yesterday.

CL700-CL1000.pdf

drive.google.com

They also confirmed the CL700 and CL1000 are the same size just the capacitor and mosfets are different.

 

[rivvs]

Was reading back through your thread about the 3Shul controllers as I just ordered one. The newest versions of the CL700 and CL1000 are the same size. Maybe your CL700tp is smaller?

They sent me the new manual with dimensions yesterday.

CL700-CL1000.pdf

drive.google.com

They also confirmed the CL700 and CL1000 are the same size just the capacitor and mosfets are different.

Well when I ordered they were not the same size. Guess if the 700 it not powerfull enought I will upgrade to the 1000

 

[Eastwood]

Update on the bike. I almost finished welding the battery and also started working on the mounting point.

Have you started assembling the battery yet? 26s 14p right? When you said “welding the battery" I guess you’re referring to the battery box.

 

[rivvs]

Have you started assembling the battery yet? 26s 14p right? When you said “welding the battery" I guess you’re referring to the battery box.

Yes finished welding the battery box. I will start printing the battery cells holder this week. Yes 26s14p. This build is taking a lot longer than I had planned.

 

[JRP3]

This build is taking a lot longer than I had planned.

Don't they always?

 

[speedy1984]

What do you think the auw will be when finishedWith that many cells and reduction it may or may not end up on the chubby side.

 

[rivvs]

What do you think the auw will be when finishedWith that many cells and reduction it may or may not end up on the chubby side.

It weight 206lbs right now without the batteries. When finished it will be close to 270lbs. the Stark varg weight 263lbs ant the alta mxr weight 268lbs. So not that bad for something built in my garage!