CRF #2 - 250R - LGX P41A 20s1p - EM200

[bananu7]

Despite my best efforts, the build is moving slowly. I've printed prototype cell covers in two variants; one going into separator slits (with a clip) and another gripping the threads. The first broke almost immediately; the shape is good, but the way it's printed means it gets ripped layer-wise, so no go. The thread-catching one is tricky to put in but with some hot glue should hold well. Step by step closer.

In other news, I decided to buy another controller, a smaller Fardriver 72680 for it, because they appeared in the PL warehouse on Aliexpress. Because of the slight error in the box shape (from the post above), i couldn't fit the Votol EM200 with the radiator sticking out as I originally planned, because it would hit the rear shock. Fitting it inside of the box would require cutting out a lot of the radiator which, while possible, would take time and effort. In comparison, the fardriver drops in there sight unseen. This means i just need to finish the box (cut flash lines and paint, drill holes) and the rear end of the bike will be pretty much done. The battery remains the biggest risk point.

 

[dominik h]

If you need more phase amps, I bought a few months ago a ND961000 with the same heat sink size as my older ND72680, except that it is 1 cm taller and the plastic housing uses the full size of the heat sink.

 

[bananu7]

I think 680 is gonna be more than enough, my Votol has what, 590? and is positively powerful.

Anyway, some updates. I've decided to call the battery design finished and asked for CNC quote. What I got was a bit more expensive than planned, but I decided to just go for it - for scaled production, I'll buy raw material and arrange cutting myself, but now I want it all quickly. The plates remained 3 and 6mm thick as in original design.

I've bought a lot of stainless bolts to hold everything together - cells to themselves, busbars, enclosure lid etc., as well as main compression rods - going with just 4mm to save weight, since they really need to produce a minuscule amount of force related to their capabilities.

I've also realized i bought only half of the stainless bar i need for the electrode clamps; after all I need 2 50mm plates per connector, meaning 40 plates or 2m in total + cut waste, and I only bought 1.5m of bar. This time I decided to buy it slightly thinner (10x3mm), and use the thinner one right on the 3mm fiberglass - again, saving weight and giving me slight adjustment in electrode length. I already cut the 10x4mm sections and now need to drill, deburr and lap them flat. It goes relatively quickly and shouldn't all take more than two evenings.

I need to finally run the main print series of the covers, as I only have the prototype now - need to confirm what grabbing diameter will work best in the end, since I'm afraid that even 4.1mm might require a bit too much force. If you don't understand what I'm talking about, it'll become much clearer once i have the assembly photos.

I also bought a few more busbars, since I realized I'll need more than 0.5m in total; opted to go for 15x3mm instead of 10x5, as that should be much easier to bend with almost the same cross-section. 45mm2 of raw copper should be more than enough for occasional peaks of 380A this battery can produce.

This leaves me with an enclosure to make. I'll 3d-print a plug directly and laminate directly on top of it, pulling vacuum over it, in two pieces - forming the cover with a lip. Effectively it's exactly the same process as if I was making a negative mould, except I'm actually interested in the negative part and thus will consolidate it under vacuum. This will give me perfect internal dimensions to fit the internal construction. I'm planning to leave at most 1mm of clearance (maybe even 0 - I'll cover the print in a layer of pattern coat which should form a fraction of a mm) to reduce the possibility of chaffing and vibrations. If all goes well, the internal construction should perfectly slide into the case and remain there solid without any need for padding.

I've also been slowly chipping at the 2nd controller enclosure - it requires a bit more sanding, a finishing coat, polish and drilling holes. Maybe two more evenings in total here as well.

We're getting closer.