SlowCo
1 MW
Nice project, I'll follow your build with interest.
Good luck and enjoy the process.
Good luck and enjoy the process.
1975 Honda CB 750 Conversion
- Thread starter BatteryManTakeMeByTh
- Start date
BatteryManTakeMeByTh
10 W
I totally agree, I don't think I can fit nearly that much. I was hoping for 28s12p at 336 cells, which would still be plenty of capacity for my commutes. The frame is 10ish inches deep (referencing the previous picture), so I could do 2 halves like you mentioned. The only problem is that I still would like to get fairly thick bus bars, and I'm not sure how I'd connect the 2 series halves like that. Seems like it'd be a nightmare to weld unless I could weld it flat and then fold it. That's what I've seen online, anyways, but I was thinking more like 0.3 or 0.4mm copper for the bus bars. Thoughts?
Thanks for the kind words. I need to stop dragging my feet. I'm trying to do at least half an hour of work on it every day. Lots of concerns at this point though.
Speaking of, I only have 330mm in each direction for printing space on the 3D printer I'm using. It's a good sized space, but it means I need to print in quarters of each side. I was wondering how I should secure the quarters together, or if I should just make a case to put it all in so I don't have to reinforce the spacers so much. I also feel like I probably need to smooth out the sides of the spacers so they can sit on the bottom and against the side of the bikes. That's just my rough ideas, though. Input would be great.
Here's what a quarter of the spacer side looks, for reference.
adsc
100 W
I would probably weld strips that overhang each side and then screw or weld the overhangs together once both halves have been fixed in relation to each other. I would worry when bending already welded strips that any lateral shift might impact the welds negatively. It might be possible to do it if you already have a spacer ready and do it very carefully (try to fix a broomhandle in place that you can bend the strips around) and can then immediately pack it all up.
How did you plan to mount the battery to the frame if you were not planning to build a case for it?
How did you plan to mount the battery to the frame if you were not planning to build a case for it?
BatteryManTakeMeByTh
10 W
Yeah, that makes good sense. I wanted to avoid bending the copper at all, preferably. Hence the large single-panel version. But, I like that overhanging piece idea. I'm thinking something like this, is that what you meant?
The black boxes are meant to be the halves of the battery, the orange is the copper bus bars on each half, and the red would be the copper connecting the two halves. I would assume that I'd need to screw the plates together and then solder them. Probably wouldn't want the screws actually over the cells like that either. But, just a rough sketch.
adsc
100 W
This is actually better than what I meant, which was more like this:
BatteryManTakeMeByTh
10 W
That does, in fact, make more sense. I thought about it more after drawing what I did and I figured that was a waste lol. I am very new to physical design, so I appreciate the help. Do you think I'd have to solder the plates together too once the screws are in?
If the plates have nice flat surfaces that have lots of contact area with each other, then no, provided your screws won't vibrate out and loosen
Tell ya right now, no electric you can put on that thing will outdo a Honda CB 750 engine.
They're pretty heavy, too.
I actually bored and balanced something like that.
Badass engine with a wet clutch?
Electric can't compare much to it.
0-80 in 4 seconds with electric? I doubt it.
They're pretty heavy, too.
I actually bored and balanced something like that.
Badass engine with a wet clutch?
Electric can't compare much to it.
0-80 in 4 seconds with electric? I doubt it.
BatteryManTakeMeByTh
10 W
Sounds like a good metric. Is there any downside to soldering them?
Why even comment this, lol? We're on a conversion forum. I am not doing this to make the fastest bike out there, or even a fast bike at all. I want a bike that I made, a fun project, and something to continue to work on. I'm happy to talk about aspects of the project, but if you're just here to promote ICE superiority, then all I have to say is cool, bro.
adsc
100 W
Well, if you solder them, you won't be able to easily separate the halves anymore. But maybe you don't have to be able to do that.
BatteryManTakeMeByTh
10 W
I don't know that that's something I'll want to do anyway, but that is a good point. I'll have to put that decision off until I have it built I think
It's not like that. You're gonna going to have to pack a lot of power into that to make it right.
The bigger motor, moar voltage, more amps.
I had a CB 750 that did 138 mph.
And got 50 miles to a gallon.
Don't get me wrong, I like electric stuff.
IMO you need a large QS fast motor.
Plan for 50% more amps and volts than you think you'll need.
No gears? On a motorcycle?
I go now.
I look back n see what you built later. Good luck on project.
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BatteryManTakeMeByTh
10 W
I see, my mistake. I apologize for my hasty interpretation. I know I need a big powertrain in there, and I have gotten some good advice here. Going up to 28s or ~104V nominal, aiming for 15HP, so looking for a 8-10kw rated QS motor right now. I imagine that's a lot less power than the original makes, but that's ok with me. I'm not looking to have a bike to really even take on the highway. Mostly a fun project, a commuter, and something to work on and upgrade over time. I feel no need to really go over 80mph on this thing for the near future. I expect that my designs for these specs are already overkill based on what I've seen elsewhere online.It's not like that. You're gonna going to have to pack a lot of power into that to make it right.
The bigger motor, moar voltage, more amps.
I had a CB 750 that did 138 mph.
And got 50 miles to a gallon.
Don't get me wrong, I like electric stuff.
IMO you need a large QS fast motor.
Plan for 50% more amps and volts than you think you'll need.
No gears? On a motorcycle?
I go now.
I look back n see what you built later. Good luck on project.
Thanks for the interest. What's wrong with no gears? I just want fewer points of failure, and especially to keep the points of failure as concentrated in the electrical systems as possible. I'm an electrical engineer, so that's what I'm most confident trying to fix. I definitely want to build up to be more mechanical though. I expect to learn a lot at my local maker space.
BatteryManTakeMeByTh
10 W
On a separate note, here's my current revision for the battery spacers.
14x6 cells and about 330mm x 180mm iirc. I'm planning on printing 4 of these and making 2 halves to attach together as per this drawing.
14x6 cells and about 330mm x 180mm iirc. I'm planning on printing 4 of these and making 2 halves to attach together as per this drawing.
I'd love final advice before I go ahead and model the bus bars so I can order them. Should be simple enough, but I'm also taking this opportunity to teach myself some CAD. Thanks for all the help so far.
adsc
100 W
Won't you need 8 of them? 2 for each 14s6p, 2x2 for 1x 14s12p, 2x2x2 for 2x 14s12p.
BatteryManTakeMeByTh
10 W
Mental math, my worst enemy. You are correct. I thought to myself, surely 14x6=84 and 84*2 is 336. Thank god I check with people before making stupid mistakes like that. I can't print bigger anyways, so it's not like I could have done it in 4 bigger prints anyways.
adsc
100 W
I guess instead of screwing them together, you could also bend both overhangs down to one side and then spot weld them together. Or maybe even bend them before you weld them to the cell terminals. Something like this:
BatteryManTakeMeByTh
10 W
I bet I can order them from Wellgo like this as well. I'll have to ask. I'd rather do as little of the bending myself if possible. It would be nice not to have it sticking out so much, though.
There's never anything wrong with less moving parts in my book.
You won't be dealing with 4 inline carburetors that have varnish in the bowls.
Slick 50 fuel treatment is good for that, btw. In case you ever need to clean a bowl full of varnish or jets on something.
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BatteryManTakeMeByTh
10 W
Exactly. I want to keep the learning as concentrated as I can so I can ease into the mechanical a bit more with future upgrades. I'm sure I'll be working on this thing forever, even once it's rideable.There's never anything wrong with less moving parts in my book.
You won't be dealing with 4 inline carburetors that have varnish in the bowls.
Slick 50 fuel treatment is good for that, btw. In case you ever need to clean a bowl full of varnish or jets on something.
I'll keep the slick 50 treatment in mind, since a few friends of mine have internal combustion motorcycles.
Returning to the bus bar and spacer design, I have a draft here finally:
and I'm starting to worry that the cells may be too close together to get enough copper in there for 100A. Since I'm up to 104V nominal, 100A gets me the 10kW number I'm aiming for. What do y'all think? I was hoping for 0.5mm copper bus bars, but at this spacing it seems they'd have to be thicker. Am I missing anything? It's not too big a deal to redesign them. A bit annoying at worst.
adsc
100 W
100 V is usually considered safe for a 1mm air gap between electrodes. So if you're wrapping the edges of the bus bars with electrical tape, you'll be golden.
BatteryManTakeMeByTh
10 W
Ok, well that's definitely good to know. I can definitely slap some electrical tape over the edges of the bus bars before the kapton tape layer. What about current capacity though, with how little copper there is in between the cell holes? It seemed like the bus bars have holds for the nickel strip that are nearly the diameter of the cells.
adsc
100 W
Kapton is a brand name, I think. I'm not sure what to call this tape that is not of the Kapton brand. Polymidtape maybe? That alone is good enough, you don't need anything else. I only wrote electrical tape, because I'm not sure what to call the 1 MOhm 220°C resistant tape. If you have brand name original Kapton, that will obviously also work.
As for current capacity, you can calculate it, there are lots of online calculators. You could also just screw everything together and do some load tests while you monitor for heat. Buy a couple 12 V DC heater units and clamp them over 3-4s.
As for current capacity, you can calculate it, there are lots of online calculators. You could also just screw everything together and do some load tests while you monitor for heat. Buy a couple 12 V DC heater units and clamp them over 3-4s.
BatteryManTakeMeByTh
10 W
Ah, gotcha. Good to know. I haven't done the research into that part of the battery yet, so that's good info.
I know I can calculate ampacity with cross-section, but I'm wondering about the volume too I guess. Load tests sound like a good idea, but anything I can do to measure thrice and cut once would be great. Copper is expensive.
I don't understand what you mean with the heater units. Could you expand? Thanks again.
adsc
100 W
Well, if you want to load test your battery, you have to discharge it somehow. Immersion heaters are just an easy and cheap way to do that in my opinion. I forgot you have a 96V battery, so you could also use 48 V solar immersion heaters and don't have to go down to 12 V models.
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