jonescg's NEW electric racebike BUILD thread!

[wedge]

For a donor bike I think you are best off buying a complete running bike then selling the engine. The BEC (Bike Engined Car) guys are always looking for late model engines, especially 1000's. www.ozclubbies.com.au and www.racemagazine.com.au are probably the best way to get in touch with them. I think you could sell the engine and other bits (radiator, exhaust, ecu, loom, fuel pump etc.) for over half the cost of a good late model fireblade etc.. No problems with crash damage this way either.

[jonescg]

I have been thinking more and more about batteries. The greatest concern I have is the maximum and average currents passing through the terminations with a motor at full noise. I was wondering if taking advantage of the revised TTXGP rules was a good idea - bump my system voltage up to 700 V DC maximum (4.12 V per cell at charge)

Assuming the absolute worst-case scenario, my 150 kW peak motor would cause a current draw of about 240 amps (at 640 volts assuming ~3.8 V per cell under load). 240 amps isn't nearly as scary as 400 amps, and I was drawing 600 amps through my 50 mm2 cables on Voltron. So maybe a 170S 3P pack is a better way to go? Still gives me just over 9 kWh worth of juice.

Sure makes soldering tabs together a fair bit easier...

[jonescg]

OK so I decided to solder up 9 of my individual cells into a 3s3p arrangement and do a load test. Test rig was as before: a dead short


I found after being bent over a few times, they don't like being bent or soldered again. I figure a generous dose of flux would help things along. I decided to use some solderwick to parallel the cells first, then for the series connections. It looks absolutely hideous



But a dead short held for about 5 seconds (enough to make the PVC insulation on the jumperleads too hot to hold onto) made the cells warm up a lot. The current started at 270 amps and finished up at 220 amps. The terminations were still at ambient temperature. I wonder if the tabs just don't have enough copper to sink the heat out of the cells like I did last time with the 5 P setup Anyway, 250 amps on a 3P setup is 16C, which would render the cells dead flat after 3.5 minutes.

If I were to build a big pack this way, I'd try to use a slotted board of PCB underneath to prevent any solder from dripping onto the cells, as well as serving as a bit of thermal insulation. It would allow the tabs to be bent over more neatly too.

[c_a]

This looks so ugly

Should I build you a pack?

[jonescg]

As long as you use Turnigy's I should point out that I wouldn't use the thin solder wick for the actual pack, these are just my abused test cells.

My 80 W iron is too hot. It just burns the flux after leaving it on for more than 10 mins. After 30 mins it's glowing red hot Flux would help on the tabs for sure too.

[full-throttle]

That looks familiar

pack.jpg (190.94 KiB) Viewed 619 times

My 20 year old Weller died the day I was finishing my pack, so finished it off with a 200W chinese monster (courtesy of BenMoore) I invested over $500 in soldering equipment since..

Are you going to insulate each bank?

[jonescg]

So it was YOU who reduced hobbyking's stocks of 40C individual cells!

Dude, that pack looks frocking awesome! Well done! That's precicely what I'll be doing with my packs. I'll make them into magazines of about 66 volts and slide them into the pack. How did you find soldering the tabs? I think I need a better flux

I'll be pulling much higher currents so I need something a bit thicker than the ~8 mm2 wire you've used.

[full-throttle]

Nah, wasn't me - all those cells are from 4S packs.

I'm using a low-residue no-clean flux. It's really nice. A good soldering station with a quick recovery time makes the job easy. The Curie-point ones are the quickest (Pace, OKI, Metcal) Don't use the plumber flux

[E-racer]

Are those from the 4s hardcase packs? If so can you give me the actual cell dimensions.

[jonescg]

They are probably the same cells I'm using - Turnigy 5000 mAh, 40C. They are 50 mm wide, 140 mm long (including tabs) and 9 mm thick. The tabs are off to one side; about 3 mm in from the back of the cell. The tabs are 16 mm wide, barely 9 mm long, and 5 mm in from the edges, with a 4-6 mm gap between them.

[jonescg]

Some good news: I contacted the Hobbyking Wholesaler and shipping $5-6k worth of LiPo is no big deal. I just have to accept the > $700 customs fees As for pack sizes and formats, it really depends on what the motor needs and the inverter can supply, but generally higher voltages means less current through the terminations. I will have to use at least 1.6 mm copper plate soldered across the tabs to keep the heat out of the cells. Great thing about this is I can package the cells into a nice solid, waterproof, crash-proof unit with contactors, shunts, relays etc in the one box

Also, had a good chat to Neville at Evo, and it seems the AFM motors are good to go, all baring the money. I also heard back from Mr Rhineheart about their inverters and they look like a good option. He even offered to do some customisation and hot-rodding of the PM150 series to make it better suited for racing Awesome!

Prices are still high, but I can't do much about that. ~$8000 for a motor and $10,500 for a controller is steep man

Still, my friend Dan is keen to do a high-end build with me, so watch out 2013, there will be two >150 kW e-motos to beat

[Hugues]

hi there,

i'm keeping an eye on your thread, i'm learning a lot with your extremen requirements.


My idea is to build a nice chopper, but power requirements should be 10-15 kw i guess. I'll get my pre-build thread started soon.

thanks for keeping us posted.

[jonescg]

Hi Hughes,

Great to see your pre-build thread up and running. I'll offer a few suggestions in a bit.

I attempted to solder 2 mm copper plate over the top of the cell tabs and it seemed to work OK, but the 80 W iron took a bit of time to get stuff hot. I think this taking so long is not good, as the cells were hot, like over 40'C when I'd finished.



I'll try to do a better job on the next set of cells next week when they arrive, as well as put some PCB material under the tabs to insulate things a bit better.

Hope the heat hasn't damaged the cells

[Nuts&Volts]

That heat may degrade the seals around the tabs and top of the cells making it easier for the cell to swell and burst. I have seen a large number of LiPo cells (Blue LiPo 25C cells) soldered together this way with large chunks of copper. We have over 10 cells fail by swelling and bursting at the top of the cells (no fires only cells dying). Capacity loss has also been experienced, but could be from a lack . I believe soldering can damage the cell and the poor electrical connector at this joint can waste a lot of energy through heat. I think if you can limit the heat into the cell then soldering will work, but in our case it has turned into a unsafe battery pack because we dont know how much we hurt each cell and dont know which ones will start to fail. We also welded a few cells when we could and have not had any of those cells (which werent soldered too) fail. Food for thought.

I didn't personally design or build this pack, but I am working with it now and have had to fix a lot of this pack.

[jonescg]

Thanks for the advice, Kyle.

When you say welded - what did you do? I can't see any practical means of spot welding these things together; not in this format anyway.

I just did another dead short test and it pulled 300-250 amps for a good 5 seconds, and NONE of the terminations were hot, none of the tabs or cells were even warm, but the jumper leads were in a bad way

So I think this is the way to go, I just need to find a way of getting a lot of heat into the plate as quickly as possible, then letting it cool. I think some internal resistance tests before and after would probably help here.

[jonescg]

OK so I have looked at getting some PCBs made up for holding the cells in place. A Melbourne based firm can do it for me, but alas, they need me to supply the board drawings in Gerber 274-x format. OK, so I downloaded Eagle Layout Editor... Holy smokes! Can you come up with a more complicated way of doing a simple task??

Basically I want it to look something like this:


Does anyone know how to draw something as simple as this in Eagle??

Cheers,
CHRIS

[full-throttle]

Done

10s3p PCB created (the one above is 9s3p)

[jonescg]

Awesome

I owe you one! Next time you're on your way over to South Africa, drop in to Perth and I'll shout you a beer Nah seriously, name your price, that's awesome.

Leeanne will get back to me with a price for routing the boards. My cells have arrived so I can start putting together a 10S3P battery pack for my non-specific e-bike project

[Gordo]

......, but the jumper leads were in a bad way

I think you will find the heat comes from the jumper clamps. You might try a spring clamp off a welding cable. They don't get hot like those plated steel automotive clamps.

[jonescg]

They are actually copper ones, just rather flimsy at the business end. The only time a termination got hot was when the connection was poor and the heat generated was sunk buy the 2 mm copper plate. Even then it wasn't that bad.

Provided every connection I do is a solid one, there shouldn't be any overheating worth mentioning under hard use.

[Hillhater]

Probably a little late for you jonescg, but i thought this may interest you..
http://vimeo.com/34702692
..Any idea who "mic ofOz" may be ?

[Gordo]

From Rickard;
"The second (battery) was originally described somewhat vaguely by Celso Menai of Portugal. Celso IS kind of the battery guy with a small OEM that is developing a kind of tricycle car that is really quite captivating in the video he showed us at EVCCON. This theme was expanded by Mic of Oz - an Australian who provided an animation of it on Vimeo that I rather liked."

[Hugues]

Probably a little late for you jonescg, but i thought this may interest you..
http://vimeo.com/34702692
..Any idea who "mic ofOz" may be ?

interesting idea, wonder if the guy has actually tried it.
thanks for the link

[Malcolm]

I nearly posted that video myself, but if I've understood right it means that all the clamping force has to come from a pair of threaded plastic rods. Plastics tend to creep under load, so the clamping force will gradually decrease with time. One possibility would be to use steel threaded rod with a series of insulating sleeves around it. The total length of the sleeves would have to be slightly less than the clamped length of the rod. The spacers would also have to be incompressible, so plastic is out again.

[full-throttle]

I owe you one! Next time you're on your way over to South Africa, drop in to Perth and I'll shout you a beer Nah seriously, name your price, that's awesome.

It's all good, but thanks for the offer! I'll try and come to one of the races in Victoria this year.