Yet another CRF 250 Build but its my first so... ;)

[DonCox]

Dave, I tried some battery combinations in the Honda bike I have here. Just some test fittings. If you go back above, and look at IMG6656, the side view of the Honda. you can see the space below the battery in front of the motor, I can fit a 6 cell by 8 cell pack in there. Then I made another pack to go with that of a 8 cell by 14 cells. This would be the bottom pack, these 2 together, 6 x 8, and 14 x 8 for a 20S8P lower pack. Now the top pack would be a different shape but also 20S8P, but 2 rows of 10S8P side by side. Here is a sketch of the two packs. The top pack we would need to test the shape to see if it fits (7"wide, and 7.5" front to back, and 9 tall. We can come up with different shapes. (IMG 7293)
I have made a lot of batteries, but now I prefer having them built by Amorge. There is a lot of labor in building batteries, and the cases that Amorge makes are really a work of art, solid and watertight. But in building a battery, you want the cell groups to line up next to each other, or it gets real complex. Here is a pic of a battery I make for KX80-100 conversions. You can see the straight cell groups and then the weird shape cell groups. Those make it more complex. This is our fusible link battery packs that we make. (IMG5791)
Anyway just some ideas. Here are a couple more pics of the test fittings on this Honda.

 

[bananu7]

For reference, here's how the battery for my 250 is laid out:



It's 20s20p with 18650. Disclaimer: I haven't actually tried putting it in, as the design was made by the person I bought the project from mid-way. Supposedly the test cardboard model they tried did indeed fit. I want to make the case for it out of fiberglass and mold it as close as I can, but I expect there might be some "finessing" required to make it fit. I also need a way to build some kind of bottom support.

 

[DonCox]

Yes building the battery is tough. You make mockups and it all fits, and the final product is always a little too tight. I am finding that Amorge can build to very exact specs for the outside dimensions of the battery box. They can tell you how many cells will fit, and they make a nice aluminum box for the battery. I think the same shape battery could be built with 21700 cells (Molicel P42A) at a lot lower cost. I have built 18650 batteries out of Sony VTC6 cells and they are still in use, but the cells are more expensive and many more connections. Do you want to build the battery yourself, or have it made for you. Here are a couple custom Amorge battery's (20S12P P42A Molicel) they have made for me. If you read the label on these 2 batteries they show low Continous Discharge, but this is the BMS limit, but we have them made with Open Discharge, or no BMS control on Discharge , only Charge control. The Motor Controller has our low Voltage Slowdown and Shutoff. We can and do get 400A's out of these packs. I run most of the time at 300A. 72V at 400A give us a good 28KW. 28KW can keep up with the gas bikes, up the big hills at Glen Helen. This size batteries can run 6 lap races on that track with a half battery left.

 

[fmxxx666]

thanks to all of you who contributed knowledge and info

I guess I made my mind now.

not saying that I have decided on a specific battery yet but I have a plan now that I will follow

my absolute Dream Battery is this one:
EWATT 72v 76AH Pouch Cell Battery
Dimensions (mm):225mm x 177mm x 373mm
Dimensions (Inch):8.86″ x 6.97″ x 14.69″
300amp continuous power and 600amp peak
Capable of 42kW peak (21kW continuous)

there is even a 80v Variant of it same dimensions with:
300amp continuous power and 600amp peak
Capable of 48kW peak (24kW continous)

I made a Cardboard dummy to see if I can get it in somehow


Due to the dimensions putting it in from the top will not work.
Ill give it a try to take out the motor slide the battey in from the bottom and put the motor back in.
Thats then a more or less "permanent" battery but its huge and has a lot of juice plus it is capable of charging at astonishing 50A
So every brake from riding it can get charged up quick again (20A charger is included with the batt I guess thats plenty already don´t think its nessesary to go higher than that)


In case I cannot get the EWATT battery to fit I have to go the Amorge route.
72v, Metal Casing, QS10 Plugs, Open Discharge, and as much AH they can put in with Molicell P42A Cells overall min 300 amps continous

I have 2 Dimensions other dudes whare able to put inside their 2006-2009 CRF 250 Frame:

CRF 250 2007 Amorge 72v 44AH 330amps continous
25"x6.25"x6.25"
63,5cm 15,8cm 15,8cm
ran it up into the tank
Little surprised that he only got 44AH with this big boy battery.



Amorge 81V 60AH 220amps Continous Samsung 50s Cells
155mm x 165mm x 460mm (370mm on the short side)
6,1" x 6,4" x 18,1" (14,5" on the short side)
They are both for sale near by but I really dont wanna buy anthing with Samsung 50s Cells but Wondering what power Molicells in this dimensions would deliver.
Longer tip goes down in front of the QS motor.


sadly have to wait until the weekend after next to see my bike again and start testfitting....
but at least I have fun building cardboard dummys until xD

 

[bananu7]

> Little surprised that he only got 44AH with this big boy battery.

Mine with Sanyo cells will be similar capacity. The easiest way to get decent kWh ratings regardless of voltage is to simply use better cells. With higher voltage the currents can drop slightly, so large pouch cells like e66a can often be enough for the target power. When you want really high currents, the 21700 cells from Molicel offer the best performance right now, but the price of a battery built with them can be easily double or even triple of a battery with a cheaper cells, for like +30-40% increase in capacity.

And then there's weight; while it's fairly easy to add more parallel cells to get more current and more capacity, especially when building a custom unit, adding extra 10kgs will be definitely felt in harder terrain. My current plan is to set the bike up with this relatively small ~3kWh battery, and see how much effective range I'm getting, as well as how much power I'll end up using. Then potentially plan for a second battery with more capacity and power (and likely voltage too) if needed. Even f I built the exact same shape with Molicel 18650 cells, I'd still get about +50% in capacity and similar power ratings.

 

[bayodome]

thanks to all of you who contributed knowledge and info

I guess I made my mind now.

not saying that I have decided on a specific battery yet but I have a plan now that I will follow

my absolute Dream Battery is this one:
EWATT 72v 76AH Pouch Cell Battery
Dimensions (mm):225mm x 177mm x 373mm
Dimensions (Inch):8.86″ x 6.97″ x 14.69″
300amp continuous power and 600amp peak
Capable of 42kW peak (21kW continuous)
View attachment 12142
there is even a 80v Variant of it same dimensions with:
300amp continuous power and 600amp peak
Capable of 48kW peak (24kW continous)

I made a Cardboard dummy to see if I can get it in somehow
View attachment 12143

Due to the dimensions putting it in from the top will not work.
Ill give it a try to take out the motor slide the battey in from the bottom and put the motor back in.
Thats then a more or less "permanent" battery but its huge and has a lot of juice plus it is capable of charging at astonishing 50A
So every brake from riding it can get charged up quick again (20A charger is included with the batt I guess thats plenty already don´t think its nessesary to go higher than that)


In case I cannot get the EWATT battery to fit I have to go the Amorge route.
72v, Metal Casing, QS10 Plugs, Open Discharge, and as much AH they can put in with Molicell P42A Cells overall min 300 amps continous

I have 2 Dimensions other dudes whare able to put inside their 2006-2009 CRF 250 Frame:

CRF 250 2007 Amorge 72v 44AH 330amps continous
25"x6.25"x6.25"
63,5cm 15,8cm 15,8cm
ran it up into the tank
Little surprised that he only got 44AH with this big boy battery.
View attachment 12144View attachment 12145


Amorge 81V 60AH 220amps Continous Samsung 50s Cells
155mm x 165mm x 460mm (370mm on the short side)
6,1" x 6,4" x 18,1" (14,5" on the short side)
They are both for sale near by but I really dont wanna buy anthing with Samsung 50s Cells but Wondering what power Molicells in this dimensions would deliver.
Longer tip goes down in front of the QS motor.
View attachment 12146View attachment 12147

sadly have to wait until the weekend after next to see my bike again and start testfitting....
but at least I have fun building cardboard dummys until xD

I've been looking at those same Ultra Bee batteries. The 80v 76ah from Ewatt. They also have an 88v option! Chi Battery Systems also has one coming out soon.

So, this is a question for Don (or anyone else in the know): What do you think of running these higher voltage batteries?

I guess it would be a matter of using the right controller with it. But I know the QS138 70h V3 motor can run higher voltage, so that would be more ideal, correct? Less heat build up, and would be able to run lower amps. If one were to go with a battery like this, what is the best controller to pair it with? EBMX maybe?

I love my YZ build, but would like to run a little more power for MX and have a little more range for off-road. The simple solution for me right now would be to just get a second battery. The problem is that the power drops significantly after about 15 min of hard MX riding with my 72V 51ah battery at 350a. That's closed to a full local amateur moto anyway, but I'd like to not have to worry about swapping batteries and would rather use, perhaps, 50% charge in those 15 min, then throw it on a charger back in the pits. I feel like that could be achieved with an 88v 76ah battery while running higher kw and lower temps.

Thoughts?

 

[fmxxx666]

@bayodome at least in my situation I have to stick to max 81v battery’s since my x-9000 controller can only handle up to 95v and a fully charged 88v ewatt battery has up to 104v so that crashes the limit there should be a 3sul something and a big fardriver controller that are capable of handling that much power

 

[bananu7]

Yeah, I second what fmxxx666 said; the only element that will limit your system voltage will practically be your controller. The QS138 will happily run at 110V or more.