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Discussion Starter · #261 ·
Hi Guys

Motor is now back together using the front housing and brush holders from the old one
The armature, barrel and rear housing from the "new one"

I've drilled and tapped the barrel to get the same 8 degrees of brush advance

The brushes are the "new" ones that I was given

I'm giving it a gentle run in at 12v
I have an old battery from somewhere - it runs for literally two minutes - then I stick it back on the charger!

There is an event on Saturday - but I'm going to give it a miss
Instead I'm going to set it to my "grass track" setting - 20% throttle and drive it for a few weeks to bed the brushes in
 

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Discussion Starter · #262 ·
The Device is back on the road
-
Running the brushes in with the max current set to about 250 amps - and that would be full throttle

So far it seems to drive at traffic speeds with nowhere near that!

I will see how long I can do that before the power switches get moved up
 

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That's very cool! Do you think I could use one of your videos as an advertisement for the control/driver board? I'm getting some new ones made (surface mount) and populated professionally, and they'll be here around the 5th of May. I will be jobless starting in May, and would like to see if I could make working from home for myself a reality.
 

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Discussion Starter · #268 ·
Hi Guys

Not much on here until spring - still running the brushes in at low power

Anyway I got to thinking
When I blew up my old motor the brushes and com were not too bad

I have done 1/8th mile drags and avoided 1/4 mile drags because I was worried about the com at high rpm's

Now that I seem to have a supply of "spares" I'm thinking of going to play with the big boys at the 1/4 mile events next spring

So I had a look at what could fail - and I decided to worry about the
Volt "MANUAL SERVICE DISCONNECT - REMOVABLE PLUG"

Mine has the thumb bit broken off - but it works fine
Inside I believe is a 350 amp fuse

When I do a Drag - the battery current starts low - builds to somewhere about 1000 amps and drops off

So far I have not blown the 350 amp fuse - but holding the power on for another three or four seconds may just blow it

Are any of you guys near a Chevy dealer and would you be able to ask them about buying a spare?

My battery was out of a 2012 Chevy Volt

If I'm going to try a 1/4 mile having a spare "fuse" could save some embarrasment
 

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At that scale (I mean, technically at any scale) the "fuse" is just a chunk of wire.


You can (mechnically) measure it's dimensions and material, and just create a new one.


For racing, I would throw in something in the right ballpark and keep the factory one for normal driving.


The fuse is only there to protect your wiring from lighting on fire, so, "fusible links" are usually just 30-50% thinner than the main wiring, ensuring that it will melt at a level below where the main wiring melts.


I'd say start off with a chunk of thin wire, accelerate... and keep an eye on where you blow it up. Then use two wires, or heavier wire, then accelerate again. If you're watching the amps, you'll pretty easily mathematically determine the rough cross section you need. I.E. If a piece of 14g wire liquifies at 50 amps, and you want it to liquify at 350 amps, you'll need 7 of them, or one with the cross-section of 7 of them.


Keep it horizontal, DC will arc through a broken wire if vertical.


If you want to get fancy, take wire cutters and give it a pinch at either end. That gives a weak point for it to break. If it doesn't break at one end, and continues to arc, the opposite end will become the next weak point and it'll cut there and drop the whole wire out.
 

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"Hey, this fuse blew, it must need a heftier one which I don't seem to have. I know, I'll use this paperclip/ringnail/baking foil..."

I'd rather an encased fuse was used so if a piece of fusewire detatches it can't short anything else.
 

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So I had a look at what could fail - and I decided to worry about the
Volt "MANUAL SERVICE DISCONNECT - REMOVABLE PLUG"...
Are any of you guys near a Chevy dealer and would you be able to ask them about buying a spare?
My battery was out of a 2012 Chevy Volt
Better than that, pay the shipping and my fuse is yours...
PM me for details.
I will be pleased to be part of your future motor destruction at the drag strip :D;)
 

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Discussion Starter · #275 ·
Long past time for an update!

"New" motor - place, - need to run the brushes in - I gave it about two hours running on 12v - before starting to drive the car at 20% power (that would be full throttle - actually less)
It drove fine at that - didn't feel slow at all

So I drove for 120 km before going back to my usual 45%

While the motor was out
I fitted a new instrument panel with a neat GPS speedometer - looks a bit better and its easier to read when the sun is out

Also I got some padding for the seats! - just rectangular vinyl bags with foam inside held on with velcro

I have been invited to an EV event at Highlands MotorSport Park in Cromwell on the 9th of September

http://www.thenews.co.nz/community/open-day-will-pit-petrol-against-ev/

I had better do at least one test at full power before I go

I have just noticed the limits on picture file size are a lot larger now - I will have to re-set my camera again
 

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Discussion Starter · #277 ·
Long time since I last posted here - sorry

I haven't been doing much - just family stuff

But Today was the annual Gore 1/8th mile drag race!

We had three electric cars there today
My Device, Owen's Ute and Johnathan's wee BMW - i3

They put the BMW in the "European Cars" class - the other car in that class was a Supercharged Mercedes Sports Car

The BMW did a very creditable 10 seconds - and was only beaten by 1/10th of a second

I had a good day - no spray of molten copper this year!
And ended up the second fastest car there with 7.90 seconds and 93 mph!

There were six big bikes as well as about 30 cars - but I only beat two of the bikes

I started off doing a burnout to heat the tyres - seemed to work very well but on my last run I dropped the rear tyre pressure down from 19 psi to 15 psi
When I did my "burnout" they didn't spin!
And when I did my run I got no wheelspin and my fastest time

I may try dropping the pressure down even lower - or it may be that the track was well rubbered in by then
 
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