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Discussion Starter · #941 ·
Good move on the crash-readiness. I'm making sure my handlebar switchblocks come with molex or the like. Hey - I have changed my battery now so that I can has quick-swap batteries! Not that I can afford one battery, let alone two... but anyway, it's future proof :)
Great.
I've found some cieling winches on Ebay that I can build into the gantry and modify for 3 second lift.
65kg is about as much as I can lift but future packs will be heavier.
 

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Discussion Starter · #942 ·
If your Kilovac has a crack around this little vacuum nib, replace the unit.
This will allow air into the contact chamber, the contacts will burn and weld themselves closed so you wont have any precharge effect. Your controllers capacitors will cop a hiding every time you connect the mains battery to the system.
So every time I dropped my quick swap battery pack into the bike...BANG
small explosions at the tips of my aluminium blade contact caused scoring of the blade as particles of carbon, aluminium scraped down the blade.



Also dont like the way the copper anvil is too short, doesnt even come to the center point of the buttons.
Should go right out to the outer tangents of the buttons

 

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If your Kilovac has a crack around this little vacuum nib, replace the unit.
This will allow air into the contact chamber, the contacts will burn and weld themselves closed so you wont have any precharge effect.
Hi Rip,

You may have the cause and effect mixed around. I think it is more likely a failure to precharge caused the arc flash and weld and that caused the crack in the vacuum seal. Air doesn't cause the contacts to burn and weld. Many contactors are open frame, like the Albrights.

major
 

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Hi Ripperton. Is that an EV200? http://www.cafeelectric.com/downloads/ev200.pdf

Thanks for going to the trouble of cutting it open and sharing the photos. I always wondered what they looked like inside.

I'd like to point out that the plastic knob isn't the vacuum seal. But it does cover the crimped copper tube that is the real vacuum seal, as you can see here.



But if it's had a blow hard enough to crack the plastic, it may well have damaged the copper too, so your point still stands. I broke this one by dropping it, and so can't trust it, which is why it's marked "spare parts only".

I too am very surprised that the contact bar inside is so short. Were there magnets in those two pockets either side of the contact chamber?

Welding of the motor-controller's main contactor can occur if the precharge circuit isn't getting the voltage across the main contactor down low enough before it makes. As the datasheet implies, it needs to get down to 32 volts or less. This may be caused by insufficient precharge delay or by an unexpected load on the motor-controller side of the contactor.

Hi Major,
Atmospheric-pressure contactors can't handle voltages as high as vacuum contactors can. However I note that a vacuum contactor that has leaked but still has a pressure lower than atmospheric, can allow the arc to continue at even _lower_ volts per millimetre than an atmospheric contactor. Or coming at it from the other direction: As you pump the air out, they gradually get a lot worse before they suddenly get a lot better, according to Paschen's Law.
 

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I'd like to point out that the plastic knob isn't the vacuum seal. But it does cover the crimped copper tube that is the real vacuum seal, as you can see here.
<<<snip>>>
Hi Major,
Atmospheric-pressure contactors can't handle voltages as high as vacuum contactors can. However I note that a vacuum contactor that has leaked but still has a pressure lower than atmospheric, can allow the arc to continue at even _lower_ volts per millimetre than an atmospheric contactor. Or coming at it from the other direction: As you pump the air out, they gradually get a lot worse before they suddenly get a lot better, according to Paschen's Law.
Makes you wonder if Rip's contactor chamber was actually compromised. And thanks for the insight. For some reason I thought I'd heard that they actually pressurized the chamber with inert gas opposed to pulling a vacuum. These contactors are quite sensitive to precharge. One closure with the improper conditions can weld it shut. A good motor controller will check for the welded condition before initiating a turn-on sequence.
 

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Discussion Starter · #946 ·
Hi Rip,
You may have the cause and effect mixed around. I think it is more likely a failure to precharge caused the arc flash and weld and that caused the crack in the vacuum seal. Air doesn't cause the contacts to burn and weld. Many contactors are open frame, like the Albrights.
major
The plot thickens
Regarding what I said in my previous post about the plastic nib cracking, it doesnt cause the unit to fail so if yours is cracked, ignore it.

So the welding of these contacts was probably cause by capacitor flash as Major suggested or even overamping during use. I am running up to 400A through these over 20 second periods.

Yes Weber the magnets were in there and interesting point about the maximum voltage across the contacts when engaging (32v)
With all the testing I do I sometimes dont allow the precharge voltage to climb high enough before engaging the contactor so a little more patience when booting the beast might be needed.
 

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I know well these contactor and i have couples of these in various EV projects.

I think there is a reason why the short copper bar is not covering all the terminal stud and are just covering it half the surface. My guess is that it's for the arc blow out. The magnetic field generated by the high current is probably shaped by these half moon open area on the studs wich could help to blow out the arc.

These are rated 900VDC and are presurized with inert gas as well.

There is a great way to TEST THEM to know if they are damaged by arcing. Just measure the voltage across their two termninal with a voltmeter set to the mV scale and plug their terminal to a lab power supply or any regulated current and voltage source. Set to 1V or less and with couples of amp and measure the mV reading. divide the mV by the supply current and you will get the resistance of the contact.

To know if it was damaged just repeat this test few times and see if the resistance vary too much. If so, this mean the contact are not regular, meaning that the surface is not regular too = damaged.

Out of 5 used EV200 i bought on ebay last year there was only 1 good !!

Doc
 
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Discussion Starter · #949 ·
I know well these contactor and i have couples of these in various EV projects.
I think there is a reason why the short copper bar is not covering all the terminal stud and are just covering it half the surface. My guess is that it's for the arc blow out. The magnetic field generated by the high current is probably shaped by these half moon open area on the studs wich could help to blow out the arc.
These are rated 900VDC and are presurized with inert gas as well.
Doc
Hi Doc
good to have you here at DIY
Yes I though there would be a reason for the seemingly stupid design but what the heck, they work.

I think Ive won the eFXC championship twice this year.
I though I had it sewn up in October after winning on points but then the organizer added another race before the 9am noise curfew and that threw the whole championship open again.
It was also a sneaky way of getting another $1400 out of us and make sure we come back for the final round. There was no way we would have spent any money or effort to do 1 race when the result was already known.
Like Marquez all I had to do was finish one race in 1st or 2nd and the title was mine again.
Before the event Varley bit the bullet and fixed their battery by replacing a dodgy LiPo cell which was forcing them to run on greatly reduced power.
But then on Friday they found another cell went down and they were up untill 2.30 am on Saturday morning dismantling the entire pack. Cudos to Nick Tyson for his "never give up" attitude and Il think twice next time about helping them as I supplied them with some 6mm crimping lugs for the LiPo pack cables :(.
So Jason won both races but I got the 2013 eFXC title... again.

Heres the live feed and our race on a damp track.
Go to the second screen down and fast forward to 13 minutes.
Watch Jasons front tire slide going into turn 2 on lap 1 and he saves it.
http://new.livestream.com/itvl/events/2500918
 

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Nice work guys.

I see that Varley are building a custom frame too - It's the only way to go if you want to limit the compromise.

I hope to see you (and your rider) on track in 2014 Dan!
 

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Discussion Starter · #953 ·
Nice work guys.
I see that Varley are building a custom frame too - It's the only way to go if you want to limit the compromise.
I hope to see you (and your rider) on track in 2014 Dan!
Hope you get your bike running too Chris and good news for next year...
There are now 2 races per day as we have our first race before the 9am noise curfew so improved value for money there.
And the first race isnt until June in QLD so you will have more time to get ready.

Custom frame is a big ask if you want to retain all the original handling characteristics, steering head design is tricky stuff. Im going to just do a new swingarm first of all.

Midaz, my top speed was about 208kmh and Varley was about the same.
 

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Discussion Starter · #954 ·
Totally forgot about the regen thing.
I received the 200 and 300 psi transducers on Thursday and wired them up ready to install.
In Fridays test sessions I first tested the 150psi transducer and it felt perfect. I could feel the rear wheel locking when I pulled hard on the lever and it was perfectly usable for scrubbing off speed going up to the apex on a big angle. The amount of braking I got was spot on for the amount of tension my fingers were putting into the lever. I could use 1 finger for scrubbing speed in corners.
lock that one in :D

 

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Hope you get your bike running too Chris and good news for next year...
There are now 2 races per day as we have our first race before the 9am noise curfew so improved value for money there.
And the first race isnt until June in QLD so you will have more time to get ready.

Custom frame is a big ask if you want to retain all the original handling characteristics, steering head design is tricky stuff. Im going to just do a new swingarm first of all.

Midaz, my top speed was about 208kmh and Varley was about the same.
That's great news! I will definitely have my bike ready by then. I'll even put money on it :) 2 races per day is quite manageable, even if I only have one battery pack. More concerning is having enough battery to do all 5 practice sessions on the Friday. At Winton I could do a 6 kW charge and make all of the sessions, but a 9 kWh battery would leave me short each time since I can only charge at 4 kW. Still, that's great news and I will definitely be there, even if it's not me riding.

Custom frame is not a small undertaking, but if built by skilled hands they should offer all that a Jap bike has with the added benefit of fitting everything in.

I see they still seem to get something wrong at each race - Formula Oz rolling out when you were gridding up :rolleyes:
 

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Discussion Starter · #956 · (Edited)

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Discussion Starter · #957 ·
(Chris Jones prepare for jealousy attack)



Season roundup, fast and steady wins the championship.
The Ripperton bike was probably 6 seconds a lap faster than the Varley bike at SMP but Ripperton was probably 6 seconds a lap slower than Jason Morris.
Next year will hot up significantly with more bikes on track and those bikes will be faster and ridden by better riders.
 

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(Chris Jones prepare for jealousy attack)
Not jealous of the silverware mate, just jealous of the track time ;)

Indeed next year will be the big one. It takes 2-3 years to design and build a bike when you have half an income. But once it's rolling you can't stop it :D
 

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I think there is a reason why the short copper bar is not covering all the terminal stud and are just covering it half the surface. My guess is that it's for the arc blow out. The magnetic field generated by the high current is probably shaped by these half moon open area on the studs wich could help to blow out the arc.

These are rated 900VDC and are presurized with inert gas as well.
Hi Doc. I agree the bar not covering the stud may have something to do with arc blowout. I'm guessing the arcs are blown outward so they are running between the end of the bar and the unused part of the terminal, and thereby not damaging the contact areas.

We have to ensure we have the correct direction of current flow or the magnets will blow the arc the wrong way, which is more likely to damage the contact areas. The terminal markings relate to the _source_ of electrical power, so if it's switching the positive lead it will have + toward the battery and - toward the controller. If it's switching the negative lead it will have - toward the battery and + toward the controller. If it's switching somewhere within the pack then it's + to + and - to -. Opening under regenerative braking is bad, but not as bad as opening under drive current while connected the wrong way 'round.

Yes. Some sealed contactors use sulfur hexaflouride under pressure and some use vacuum. Among all inert gasses, SF6 is the best insulator purely because of the mass of its molecule -- about 5 times that of N2 or O2 (air). The manufacturer of the EV200 makes both types and I couldn't find anything that told me which type the EV200 is. But I found something that said you need to use "hard" contacts with SF6, not bare copper, because the SF6 does not remain inert when exposed to the arc. So it seems likely that EV200s are vacuum contactors.
 
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