jonescg's NEW electric racebike BUILD thread!

[jonescg]

I've decided to move the contents of the main control box to the inside of the main battery enclosure. This way the current shunt, pre-charge and discharge resistors, HV relay and main contactor (and fuse) will all be inside the battery enclosure.
It means designing a more compact PCB to mount stuff on, but this is no big deal. Then I can replace the current (slightly dodgy) Anderson connector with a more appropriate Amphenol HVIL connector.
There's still room for the BMS boards above this shelf, but it's going to be tight.

 

[jonescg]

Much more compact layout for this PCB. Hope I can get it fabricated in a couple of weeks...

The hand-drawn lines indicate where the leads and ring-lugs go.

 

[jonescg]

Enclosure is mostly taking shape too. I will probably put a low current HVIL connector just above the big one so I can charge the bike.

 

[jonescg]

Model looks OK. Just have to wait and see how the polycarb fabrication goes.
I also have to find a solution for charging the battery when it's in the bike. I don't want the main contactor needing to be closed when the bike is on charge, but I also don't want live pins on a connector either. So there's the option of a small contactor inside the battery pack, where I have virtually no room left. I'll probably end up using another low current HVIL connector, but even they are so bulky.

 

[Frank]

Why do you like the HVIL connectors better than the Anderson's? I've always used Anderson's and have zero experience with the HVIL system.

 

[jonescg]

Why do you like the HVIL connectors better than the Anderson's? I've always used Anderson's and have zero experience with the HVIL system.

Because I'm running a system voltage which exceed the Anderson's limit of 600 V DC.
Plus I also teach HV battery safety, and I don't want to be a hypocrite, even though I'm sure the Anderson would work just fine.
The benefit of the HVIL connectors is that I can arrange it so no power is available on either the main connector OR the charge connector unless something is plugged into it. Considering the charge port will only be accessible with the tank cover off, and the bike is unrideable in that state, I'm not too worried about ride-offs.

 

[hallkbrdz]

That makes perfect sense and is something all racing organizations should require for HV systems to ensure worker safety to the greatest extent possible.

 

[jonescg]

End cover PCB's finally arrived. I'm not leaving myself much room...
The balance wires have clearance but I will try and use some of that non-adhesive epoxy to settle everything down.

 

[jonescg]

Starting to take shape. It's not the most elegant solution, but it does appear to work.

 

[jonescg]

Portholes are for squeezing potting compound into. Unfortunately, there's about 2 kg worth of FR4 sheet here already! The potting compound will no doubt add at least 5 kg to each module if I got too carried away, but the main purpose for potting the sides is to secure the balance wires, and preventing them from rubbing or fretting where they shouldn't.
And yeah, Ideally I'd use female headers for the balance wire connections, but this was the most compact option available at short notice. All female PCB mounted headers were really tall and bulky.
Next up, once I have glued the sides on, spotwelding both sides. Sparkletime!

 

[SlowCo]

Wow, that must have been a lot of work!

 

[jonescg]

Wow, that must have been a lot of work!

It is and it isn't. I only work on this over the weekends, and I've got plenty of experience building them now, so I know what to expect. The slow part is spotwelding these tabs, which will take a bit longer since each pulse is longer and the hand piece will get quite hot.
Then the joys of gluing it all together within the tolerances I've set myself.
The polycarb enclosure is being CNCd at the moment, and it should come together fairly quickly. Perhaps not in time for the expo (Nov 4th and 5th).

 

[Cowardlyduck]

What spot welder are you using?

 

[jonescg]

Just a Sunkko 709 transformer welder. Seems to do a pretty good job.

 

[jonescg]

Busy day welding a module up. A friend came and lent a hand with his welder too. Duty cycle was famously poor, hance the ventilation. Next step is to glue the covers on.
Shame it won't be rolling in time for the expo, but that's okay. The bike will still be there.

 

[Cowardlyduck]

Can tell you really do teach HV stuff with that one handed probe

 

[jonescg]

Glued the first side on - keeping it secure with about 40 kg of cobalt sulphate solution.

 

[jonescg]

Just a quick update - I've spotwelded all four modules and have glued the sides onto three of them. I fear I will only have enough thermally conductive epoxy resin to glue half a module together. This black stuff from U-sheen is a great adhesive, and the new stuff I got from Electrolube (still laugh at that name) simply doesn't stick to anything. I might be able to put the last of the adhesive around the perimeter of the surface and use the not-so-sticky stuff in the middle? Not keen on mixing them in case they behave weird.
Anyway, the polycarb enclosure should be done this week so I can start to put all the other parts together.

 

[jonescg]

12 kWh complete. All up it's 68 kg for these four modules, and the enclosure + hardware will probably add another 7 kg at least.
I can build the battery pack and have it operational, minus the BMS which is yet to be devised. Next weekend will be a productive one!
Tonight when it cools down a bit I might put some of the expanding foam in all the port holes to secure the balance wires. Fully potting it would add at least another 3 or 4 kg, so I'll avoid that if I can. For a road-going EV, sure. But not a racer.

 

[jonescg]

It's an inline 4!

Minus the enclosure and other hardware...

 

[SlowCo]

It's an inline 4!

Awesome!

 

[jonescg]

Bit of progress on the battery today. Rather warm in the shed though. 42'C in November is a record broken.
Test fit of the enclosure went well. Bit tight at the base, but I can make adjustments if needs must.

The charge HVIL and discharge HVIL are mounted, while the modules themselves fit snugly in the space provided.

I'm not sure if the fans will fit now that everything is coming together. I might proceed with some covers and see how we go.

 

[jonescg]

HVIL contactor and fan logic sorted:

 

[jonescg]

Every day is like a puzzle... once it's done I'll devise a better way of doing it.

 

[jonescg]

Pack fixings in place. Most of the HV wiring is done, but there's still a few bits to finish.