Voltron, the Electric RG!

Post up a thread for your EV. Progress pics, description and assorted alliteration
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woody
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Post by woody » Sun, 09 Jan 2011, 13:16

jonescg wrote:
However, I'm finding that my Dodgytech current clamp is giving strange results. The Cycle Analyst tells me that when I wind them up to almost full speed they are pulling 30 amps (no chain attached). Yet the current clamp is giving different results depending on whether it's AC od DC, and whether it's on the + or - battery leads, or the motor leads... Who do I trust?
the battery current should be measured in DC amps and will be approx proportional to motor power.
The motor current should be in AC (unless motor is *brushed* DC in which case use DC) amps and should be approx proportional to motor torque.
The currents won't match.
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

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Post by 7circle » Mon, 10 Jan 2011, 03:40

If you measuring big AC current from the battery it might be worth considering a bigger capacitor on the controller bus Pos and Neg.

7C

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Post by jonescg » Mon, 10 Jan 2011, 04:39

I can measure a decent (reliable) current on the battery positive before the contactor, but after the contactor I'm getting crazy currents because that's where armature positive heads over to the motors...

But hurrah!! Woohoo!

I am THIS >< close to finishing the bike! Image

Image

I mounted the BMS boards and they look pretty schmick. I had to drill into the frame, which I have tried to avoid doing, but a 3 mm hole isn't going to do much harm... I hope.

Image

They look great in the dark :D

So things that remain to be done:

Fibreglass tank cover
New (basic) seat
Fibreglass tail piece with sufficient air flow for the controller (thinking of a water jacket...)
Stiffer springs (friggin thing bottoms out)
Key switch wired up to axillary system, and lanyard / kill switches
Fit the speedo pickup somewhere... :shrug: I have a magnet epoxied into the sprocket, but it might be a pest to get at
Put the chain on...
and a you-beaut paint job Image

The sound on my camera isn't doing the twin-Agni beast any justice, but have a listen:

http://www.youtube.com/watch?v=6ukR2bwK ... r_embedded
Last edited by jonescg on Sun, 09 Jan 2011, 17:42, edited 1 time in total.
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jonescg
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Post by jonescg » Tue, 18 Jan 2011, 18:01

Thanks to a friends idea of putting the joining link on the other side, the chain moves freely.

And now the moment we've all been waiting for!!!

http://www.youtube.com/watch?v=nlmDPi01KSA
http://www.youtube.com/watch?v=_T9wiCa5G40
http://www.youtube.com/watch?v=5JVBjF_TXp0
http://www.youtube.com/watch?v=72iuHmRY-ew
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woody
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Post by woody » Tue, 18 Jan 2011, 18:29

Wrapped in TUBE /TUBE for the lazy like me:
jonescg wrote:


Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

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Johny
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Post by Johny » Tue, 18 Jan 2011, 18:50

Great stuff Chris. Well done.

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EV2Go
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Post by EV2Go » Tue, 18 Jan 2011, 19:59

Well done... Are you happy with it? any niggles to fix?

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Post by jonescg » Tue, 18 Jan 2011, 20:25

There are lots of things to finish, let alone fix Image

I MUST get stiffer forks as the original ones are already 90% compressed. I also need a tank cover and tail piece. The motor bolts are almost touching the chain as it flies past, so I would like to change them for button-heads, and while I'm in there I can put a side stand on the bike. I'd like to get a different sized sprocket in there just to test what it's low-speed current draw is like. Lots to do, and that's before it's test-worthy on a racetrack. Let alone getting it over to Wakefield Park for April 29th May 1st.
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Post by GRMarks » Thu, 20 Jan 2011, 04:30

I tried to post this coment a few days ago but it doesn't seem to be here so take 2
on my bike "My TZR 250 project" on the forum I used spacers in the top of the forks to lif them up a bit (about 40mm long) was fun getting the caps screwed back on but it works. Although my forks were at about 50% of travel. You can make then from some aluminium solid bar by just hacksawing them to length and filing smooth. You could use any thing just to test the idea. If it doesn't work for you then you can always get harder springs.
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Post by Thalass » Thu, 20 Jan 2011, 20:52

Awesome!
I'll drive an electric vehicle one day.

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Post by jonescg » Sun, 03 Apr 2011, 00:21

OK sorry about the hiatus, but things have been busy at work and in the shed. I spent a lot of time stripping the bike down and replacing the sprocket with a taller gear. Then I reassembled everything and upgraded the terminations. I should have next to no voltage drop now! Which might not be such a good thing since I'm already over-volting the motors.

I was supposed to be track testing the bike this weekend, but I simply couldn't get it finished in time. Hopefully it will be perfect in time for Wakefield Park in a month, and as good as ready for the Perth Sunfair. Fibreglassing is the slowest part, but I have recently struck a problem with the BMS: I fried it!

I have been balance charging each pack since they've sat for a long time. 4 of the 8 packs were out so much they needed about 12-16 Ah pumped into them and took 2-3 days to balance! WHile balance charging, I decided to start soldering the BMS loop up. In doing so, I noticed a little spark and a pop-fizzle. Unsure as to what was going on, I thought I'd test if there was a current through the soldering iron. Well it was like striking an arc on a welder!!! Needless to say the balance charger blew up.

I gave up and continued working on the BMS loop, but the master control unit won't reset because it's indicating one of the units isn't OK (normally indicating the cell isn't connected / low voltage or something). So I think I'm in line for a new BMS.

Frig, this is an expensive game.
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Richo
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Post by Richo » Mon, 04 Apr 2011, 06:29

Why is your BMS still in a panel?
So the short answer is NO but the long answer is YES.
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Post by GRMarks » Mon, 04 Apr 2011, 15:30

yep its expesive enough when everything goes right !

I will have to check my soldering iron befor I use it on my BMS.

One question on your build - is it going to be water proof ?

I have spent plenty of time on my design to make it water proof but its not so easy.

And congrats on a working project. I'm hoping to have mine at the test running stage this easter.
Last edited by GRMarks on Mon, 04 Apr 2011, 05:40, edited 1 time in total.
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Post by jonescg » Mon, 04 Apr 2011, 20:37

The BMS is in a panel because the A123 prismatic packs don't lend themselves to having BMS modules added to them. I need to have them remotely located, and two panels of 16 either side of the bike are perfect for the task. It turns out the high voltage capacitance effect I get on my bike (that is, I can measure ~100 V from the positive terminal and the chassis) was responsible for frying the BMS units. I need to put an in-line 100 mA fuse I think. The bike is not technically waterproof, no. But with some effort I might be able to get it splash-resistant.
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Post by jonescg » Mon, 02 May 2011, 00:21

Yeah, probably just as well I didn't make it to the eFX shakedown because I had a fairly serious problem with my twin Agni arrangement - catastrophic shaft failure Image

Image

Thankfully I just rolled to a stop and could push it home, but this doesn't look easy to fix. I'd say that the torque has ripped it out of the non-driven side because there wasn't enough coverage. I really need to come up with a better way of joining them... In any case I need a new drive sprocket and mid-shaft, and a new hub for the other side.

Dammit!

EDIT - I pulled it apart and had a look - I have bent the LHS motor shaft Image Image   That is another $1300 to replace :(
Last edited by jonescg on Sun, 01 May 2011, 15:16, edited 1 time in total.
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Post by Catavolt » Mon, 02 May 2011, 16:37

not good.
You need a flexible coupling between the two motors. you have an alignment problem.
Its not torque its alignment.

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Post by jonescg » Mon, 02 May 2011, 17:50

Either a flexible coupling that can withstand the loads I'm putting on it (unrealistic expectation I believe) or a solid shaft with solid, long keyway couplings that doesn't flex at all (effectively one long shaft between the two motors). I honestly can't see a lovejoy coupling being able to withstand the loads.
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Post by Catavolt » Mon, 02 May 2011, 18:12

You can also use two uni's. Love joy isnt the only one available.

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Post by jonescg » Mon, 02 May 2011, 18:18

That still presents me with two weak points. Even if I used a universal joint, I need to fix it to the motor on the right, and have a drive sprocket on the left. I still think a solid shaft joining them would be stronger. Something like this?

Image
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Post by Catavolt » Mon, 02 May 2011, 18:24

Can you rubber mount the motors at all.

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Post by EV2Go » Mon, 02 May 2011, 23:48

Leave the motors solid mounted and go with a flexable coupling in between. Even the smallest amount of miss alignment is either going to wreck the bearings or break the shaft like it has done.

You could do what Anthony has been suggesting I do with my trike(similar arangement motor and diff fixed in line with each other via a torque tube, yours are fixed in line via the frame cradle)

He suggested getting a double ended taper lock sprockets. The taper locks bind the sprocket to to each of the shafts, and a double row chain locks the two sprockets together.

Which gives you a tiny bit of movement for shaft missalignment and plenty of strength for transmitting the power between shafts.

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Post by EV2Go » Mon, 02 May 2011, 23:52

Image

Unfortunately this won't work fo me as I need to have to torque tube over the top and couldn't get the link pin in place, but it would work for you where it's not enclosed.
Last edited by EV2Go on Mon, 02 May 2011, 13:54, edited 1 time in total.

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Post by jonescg » Tue, 03 May 2011, 00:06

Hmm, seems overly complex. Every other TTX-GP entrant who uses dual Agni motors has fixed them with no flexible elements in the drive shaft whatsoever. My problem with any amount of flex in the system is that it simply creates a weak point. For the record, my shaft didn't break - it just popped out of the hub. This was probably due to the vibration associated with the unavoidable misalignment of the two motors. There are two ways of dealing with vibrations in my opinion. Fix them solid so they can't vibrate, or allow tolerance for the vibration. The latter means leaving slack in the system somewhere.

Now, shoot me down in flames cause I'm a plant scientist, not an engineer or an electrician, but I still think a solid bar joining them will do a better job. Current setup - 2 hubs creating 4 weak points = fail. Spider / universal joint - 3 joints = 6 weak points = fail. Solid bar - one massive hub = only 2 weak points = less fail Image
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Post by EV2Go » Tue, 03 May 2011, 00:21

Well it was my intention to do exactly what you are suggesting with mine.

Put a flange on the diff that had a flat plate with 4 holes, and put a taper lock on the motor shaft with hub, join the hub to the flange with bolts allowing zero movement.

The flange on the diff should be true being that it is machined off the same axis and the taper lock hub should also be off the same axis. In theory both parts should have no run out and all should be well.

But and here is the but... what if there is the most tiniest bit of run out on the taper lock hub if the taperlock doesn't sit absolutely perfect in the hub. It might be bearly measurable but lets say it has a pooftenth of run out, that means either the shaft has to flex that bit or the bearing have to try absorb it.

After careful consideration I decided even though I will try get it perfectly aligned, I still have to account for my X-Ray vision being slightly out.

Edit:
Some other considerations. What if when both your motors are running they cause a slight harmonic destortion in the mounting plate... think tapezoid and parallelogram, you have a situation where both motors are moving the joining shaft off it's centreline.

So even if you get the shaft alignment perfect any plate distortion will result in the same effect as if the shafts were missaligned.

Also torque twist or deflection will cause some alignment issues too.
Last edited by EV2Go on Mon, 02 May 2011, 14:36, edited 1 time in total.

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Post by EV2Go » Tue, 03 May 2011, 00:44

From a weak point perspective, being that the chain on the two sprockets are not actually moving they are less likely to fail than the bike chain. The bike chain is constantly changing the sprocket tooth position with the chain links.

At best if your front and rear sprockets are well matched teeth wise, any link on the main chain will only touch the same tooth on the sprocket every couple of cycles (there are calculators out there to determine best sprocket combos). So because the chain is not meshing with the same tooth every time this increase the wear rate on the chain.

Now let’s go back to the coupler... the same tooth stay with the same link constantly and because it is all rotating as one fixture the chain is barely operating as a chain it is merely there as a strong link between two sprockets.

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