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#21
07-13-2012, 03:28 PM
 dougingraham Senior Member Join Date: Jul 2011 Location: Rapid City, SD USA Posts: 537
Re: Warp Factor III is now Alive!

If the resistance is 0.1 you are in trouble. The average resistance would be half that meaning 0.05 so the losses in a single connector block will be 3000^2 * 0.05 = 450000 watts of waste heat in every connector block. (Note: It is impossible to have this much resistance and still get to 3000 amps. If the resistance was actually 0.1 ohms per cell then you would be limited to a short circuit current of only 37 amps average) The resistance better be closer to 0.0001 which would give 900 watts of waste heat per side or 1800 watts per cell. Still too much as this is more than a space heater on every cell.

You need to run current from one side of your connector block to the other and measure the voltage drop from a point different than the connection. Divide the voltage drop by the current to get the resistance. Example. You pass 50 amps through the block and read a voltage of 0.005 then the resistance will be 0.0001 ohms. You may have to pass quite a lot of current if your meter doesnt have a millivolt range. The effective resistance will be about half of this because of the way the cells are paralleled.
__________________
Doug Ingraham
Rapid City, SD
1985 Mazda RX-7 GSL (1400+ EV miles)
Now on the road but still under construction.

Last edited by dougingraham; 07-13-2012 at 03:31 PM.
#22
07-13-2012, 07:30 PM
 LithiumaniacsEVRacing Senior Member Join Date: Oct 2010 Location: Lyme, CT Posts: 1,964
Re: Warp Factor III is now Alive!

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President of The NEMRS
www.NEMRS.net
Enzo Ferrari "Horsepower sells cars, torque wins races".
#23
07-13-2012, 07:39 PM
 LithiumaniacsEVRacing Senior Member Join Date: Oct 2010 Location: Lyme, CT Posts: 1,964
Re: Warp Factor III is now Alive!

Finishing touches before hitting the track on the July 21st.
* EMUS BMS installed working properly.
* All tin complete and sealed.
* Water pump connected.
* Line-Lock connected.
* OD unit installed and wired.
* Seating brushes everyday.
* Installing rear window tomorrow.
* Gauges coming soon!
* Paint coming soon!

I see no problem racing on July 21st.
__________________
President of The NEMRS
www.NEMRS.net
Enzo Ferrari "Horsepower sells cars, torque wins races".
#24
07-13-2012, 07:47 PM
 LithiumaniacsEVRacing Senior Member Join Date: Oct 2010 Location: Lyme, CT Posts: 1,964
Re: Warp Factor III is now Alive!

Quote:
 Originally Posted by Semper Vivus Don't trust the last digit of a digital multimeter, even if it is a Fluke . With this setup, your measurement includes the contact resistances between the busbars and the probes. Draw a constant current of for example 10A through it and measure the voltagedrop. This will give you a much more accurate result! Kind regards Tom
Okay, I took a charge pack of 3.77V discharged at 10amps and the pack dropped to 3.62V ???
__________________
President of The NEMRS
www.NEMRS.net
Enzo Ferrari "Horsepower sells cars, torque wins races".
#25
07-13-2012, 07:54 PM
 LithiumaniacsEVRacing Senior Member Join Date: Oct 2010 Location: Lyme, CT Posts: 1,964
Re: Warp Factor III is now Alive!

Quote:
 Originally Posted by LithiumaniacsEVRacing Okay, I took a charge pack of 3.77V discharged at 10amps and the pack dropped to 3.62V ???
I test just one single 3.88v lipo cell and discharged at 10amps on a icharge, the 3.88v dropped to 3.66v ???
__________________
President of The NEMRS
www.NEMRS.net
Enzo Ferrari "Horsepower sells cars, torque wins races".
#26
07-14-2012, 06:31 AM
 etischer Senior Member Join Date: Jun 2008 Location: San Francisco bay area Posts: 982
Re: Warp Factor III is now Alive!

Quote:
 Originally Posted by Semper Vivus Don't trust the last digit of a digital multimeter, even if it is a Fluke . With this setup, your measurement includes the contact resistances between the busbars and the probes.
... and the tiny 20awg wire connecting the probes to the meter. If the resistance really was 0.1 ohms, you'd have a 200 volt drop across that connection at 2000 amps.

Looking forward to seeing it run.

Why are the battery hold downs so loose, is there something that still needs to be installed?

Last edited by etischer; 07-14-2012 at 06:38 AM.
#27
07-14-2012, 07:02 AM
 LithiumaniacsEVRacing Senior Member Join Date: Oct 2010 Location: Lyme, CT Posts: 1,964
Re: Warp Factor III is now Alive!

Quote:
 Originally Posted by etischer ... and the tiny 20awg wire connecting the probes to the meter. If the resistance really was 0.1 ohms, you'd have a 200 volt drop across that connection at 2000 amps. Think it's just the meter, I test a solid piece of copper bar, then a solid piece of aluminum bar and received the same resistance number, I am not worried. Looking forward to seeing it run. Why are the battery hold downs so loose, is there something that still needs to be installed?
Yes, tube are being installed today. The packs are also glued together, so consider then one solid pack.
__________________
President of The NEMRS
www.NEMRS.net
Enzo Ferrari "Horsepower sells cars, torque wins races".
#28
07-14-2012, 06:54 PM
 LithiumaniacsEVRacing Senior Member Join Date: Oct 2010 Location: Lyme, CT Posts: 1,964
Re: Warp Factor III is now Alive!

__________________
President of The NEMRS
www.NEMRS.net
Enzo Ferrari "Horsepower sells cars, torque wins races".
#29
07-15-2012, 11:46 AM
 albano Senior Member Join Date: Jan 2009 Location: Pretoria, South Africa Posts: 213
Re: Warp Factor III is now Alive!

Looking GREAT!!!!! Can't wait to hear what does this beast does on track.......
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Albano dos Santos
#30
07-15-2012, 01:30 PM
 Ace_bridger Senior Member Join Date: Nov 2011 Location: UK Posts: 486 Blog Entries: 1
Re: Warp Factor III is now Alive!

One word, WOW!!!!

Good luck, l;ooks awesome!!
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1993 VW Golf Mk2, 9'' ADC, Open Revolt, Trojan 150Ah 12x12V batteries, 2.5KW Elcon charger, motorsport hall effect throttle.

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