jonescg's NEW electric racebike BUILD thread!

[full-throttle]

I'd offer you my BMS - got 7 x 24cell and 7 x 16cell boards here. But The Seiko chips don't come in 3.5V LVC. The highest is 2.5V
Other than that the BMS works well for charging. Decided against LVC cut-off. The signal is still available of course.

 

[jonescg]

How big is the 24 cell unit? Would I be able to fit all 7 of the boards into such a small space? The 2.5 V low voltage point is a it too low for my liking... With the four DD-50 plugs I'd probably have about 200 mm by 200 mm to work with. They take up a bit of space.

I figure this is a good opportunity for a local BMS maker to try their hand at developing a solution. If miniaturisation and efficiency are the key aims, this surely presents a challenge for the keen.

 

[full-throttle]

Land area is 125 x 50mm incl terminals. Wires can be soldered directly of course. There will have to be a small junction board on top of that.
Thickness is 3mm at the very least, if no connectors and no balancing resistors are used. Otherwise is 15mm and active air cooling must be employed.
Balancing current is adjustable by selecting through-hole resistors up to 1.5A per cell. Up to 2 x 3W resistors per cell. A lot of heat

 

[jonescg]

Yes the heat generated during a balance charge has concerned me, and certainly makes a distributed BMS look rather unattractive. Even if it's only 1 W per cell, that's 168 watts that needs to go somewhere The BMS would be situated right at the top of the pack, so a fan could definitely be installed... Ideally the female DD-50 sockets could plug straight into a PCB-mounted plug, and this board then distributes power to the business end of the BMS.

Worth thinking about anyway.

 

[megacycle]

I'd offer you my BMS - got 7 x 24cell and 7 x 16cell boards here. But The Seiko chips don't come in 3.5V LVC. The highest is 2.5V

Is there a thread for this bms?
Must be in the hard to find section.

 

[full-throttle]

Pics are gone but it's there /viewtopic.php?f=22532
Search for Seiko

 

[megacycle]

The pic you posted is that just a led board for it!
Not really discussed im the posted link.

 

[jonescg]

I have started the battery pack!

No cells - that can wait till I have the money. But the jig to make them is ready!

The floor is just sitting on the bench, but the four sides go around it and screw in place with a screwdriver. Everything is remarkably square for my efforts... weird.

The idea is to start inserting cells while only the right side and back are in place (just to hold them upright). Then you start loading the next row of cells until it's packed with 126 cells. Then you screw the left side and front block in place to make it all tight and square.

Then I can bend, scuff, tin and solder the copper buss down! I have decided to get the copper cut to 16 mm instead of 18 mm. 18 was a bit too much, and given the whole lot stays ice cold during heavy discharge I can't see the reduced CSA being a problem. I also need to work out if I need to mount the bleeder boards directly to the copper blocks, or put them above a layer of G10-FR4 and connect them with wires. I'd trim the boards, obviously

 

[full-throttle]

The pic you posted is that just a led board for it!
Not really discussed im the posted link.

There was a pic of a couple assembled boards. The project didn't go ahead, those chips didn't satisfy the needs and I couldn't be bothered starting all over.

Still using the 16cell board charging twice a day for the last 2 years. The LEDs are on the BMS itself, not a separate board.

 

[jonescg]

I got these a while ago, but I thought I'd share





Friedrich. Friedifyoudon'tusethem I'd say :lol:

They weren't cheap but I think they will be well worth the money.

 

[jonescg]

Minor update, the battery pack is being constructed next week! It will of course, be sans cells, but all of the wiring, contactors, fuses and control box will be ready to go. Fortunately the cell packs are the last things to go in - safety first!

I'm getting it build from polycarbonate, but if I talk to the right people I might try to get a composite fibre box made down the track... That will have to be adequately insulated

 

[jonescg]

Major update!

Randy at Framecrafters has been busy putting my frame together!

He's got a mockup of the AFM140-4 motor and the battery box. The battery box will sit a tiny bit taller than this one (680 mm tall instead of 600). You can also see where the swingarm sits relative to the CNCd cradle and the motor. He's cleverly been able to use the motor mount as the other side to shear the swingarm. I should be able to drop the motor out fairly easily this way.

The motor will probably end up with the phase wire box at 10 o'clock and the coolant outlets at 7 o'clock.

Coming up very nice!

 

[Farfle]

Is he going to vertically trellis between those two booms on either side?

 

[jonescg]

Yeah, it will look a bit like the technique used to build this:

http://www.framecrafters.net/show-project.php?id=83

These internal struts will also allow the supports for the battery pack to be fixed to the frame.

Should be a fairly rigid bike.

 

[Farfle]

Looks good to me, do you know what tubing that is?

 

[EBJ]

Looks great!

I was wondering:
How is it that a motorcycle can get away with having the pivot-point of the swing arm at a slightly different location than the drive-sprocket? Is the whole point of chain-slack to allow for that? Seems to me that having a jack-shaft at the same pivot-point of the swing-arm would be a better option, but I don't think I've ever seen that on a motorcycle.

Why not?
Do you think it is just adding too-much complication to have a second drive-chain, or... does having the drive-sprocket at a different location than the swing-arm-pivot actually provide some sort of benefit?

 

[jonescg]

Farfle, I'm pretty sure it's 30 mm Chromoly. Or whatever the US equivalent is in inches - 1 and 1/4 inch or something.

EBJ - the concentric swingarm is an epic piece of engineering which really didn't offer much advantage over non concentric. I figure this is the best compromise in terms of fitting the motor in while leaving enough room for the battery pack. I recall Bimoto did that with one of their prototype bikes, but it never took off.

 

[jonescg]

Correction - trellis frame. This image hot off the workbench!

 

[voicecoils]

Incredible looking Chris. That's going to be one stiff mofo!

 

[AussieJester]

Very nice CHRiS, bet you got a little movement in the pants when you first opened that pic hrmzz...

KiM

 

[jonescg]

Yeah, I haven't even got it yet, but I'm recommending Randy to anyone who wants a custom bike frame. He's just so good at this stuff.

 

[Farfle]

I might have to copy that jig... it looks so much more simple and effective than chucking the headtube in the mill and clamping the frame to the mill table .

 

[jonescg]

Some more custom e-moto frame pr0n

 

[Farfle]

Doooooood. That is sooooooo shiny. Im drooling over here...

 

[Mike Edwards]

How is it that a motorcycle can get away with having the pivot-point of the swing arm at a slightly different location than the drive-sprocket? Is the whole point of chain-slack to allow for that? Seems to me that having a jack-shaft at the same pivot-point of the swing-arm would be a better option, but I don't think I've ever seen that on a motorcycle.

Why not?
Do you think it is just adding too-much complication to have a second drive-chain, or... does having the drive-sprocket at a different location than the swing-arm-pivot actually provide some sort of benefit?

Having the swing arm pivot in a different position to the chain drive has advantages and disadvantages. If you read up on squat and anti-squat with regards to the suspension you will get an idea of what I am referring to. Ultimately the pull of the chain operates at a different angle to the movement of the swing arm/suspension so it can have a positive affect but generally it is considered negative.

The only electric bikes I've seen that have had the motor drive on the same axis as the swing arm pivot are Kingston University and The Danish Future Electric guys (www.futureelectric.dk). In theory it is the most desirable solution but it relies an awful lot on the flexibility and stiffness of the rest of the chassis. In my opinion nobody has managed to get the balance of the two right so far.