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POWER POLE CONNECTORS
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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There are charts around on the web to tell you, but I go with 40A as a conservative rating. I tried 12g running my Mag motor and at 80A it get REALLY hot in around 20 seconds. It would have melted the insulation off if I had kept going...

You can run the fan directly off the battery. The current going to other devices will not affect it.
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Post Mon Sep 20, 2004 9:39 pm 
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timmeh
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Joined: 20 Jul 2004
Posts: 2523
Location: Victoria


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Thanks nick i guess i will be useing 8g running to my ev then hey Very Happy
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Post Mon Sep 20, 2004 9:41 pm 
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JohnMuchow



Joined: 25 Aug 2004
Posts: 21
Location: New York City, USA


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quote:
Originally posted by Team Hell Bent!:
How many amps contin can 12g wire handle?


You can pull 40A without melting the standard plastic insulations (PVC, etc.) but you can pull a lot more current if you use silicone-insulated wiring. It has a temperature rating of 150-degrees C (occasionally 200-degrees C.) vs. a max. of 105-degrees C. for the plastic insulations.

In addition, silicone insulation may be thicker than THHN and the other very thin insulations, but it takes a lot of abuse.

But, the voltage drop in 12AWG wiring might be a problem, even if the insulation isn't melting. Be sure to check the resistance of the wiring you're considering using and calculate the voltage drop (current times resistance). Whatever this value is, it's not getting to your motors. It's just being dissipated as heat. If you have a lot of connectors, you may need to factor in any voltage drop across them too. Typically, this is only a concern at really high current levels though.

An example:
12AWG = 1.71 ohms/1000ft. (depending on the stranding)
8AWG = 0.752 ohms/1000ft. (depending on the stranding)

If you have 3ft. of 12AWG wiring (18 inches out to your motors and 18" back to the batteries), then the total resistance is .00171 x 3 = .00513 ohms. With a current level of 40A, the voltage drop thru the wiring is 40 x .00513 = 0.21V. Not too bad. But at higher current levels, lets say 80A, the voltage drop is 0.42V and this doesn't even take into account the voltage drop of any connectors, the battery's internal resistance voltage drop, and any drops caused by the battery bars or inter-battery braid. It adds up quick and can easily cause enough of a voltage drop to really affect the max. speed of your motors.

Using the above example, at 40A, 8AWG wiring only has a voltage drop of .09V, almost nothing.

If you have room for the larger cable and can afford the extra weight (and cost), I always recommend going to 10AWG or 8AWG for a typical LW. The cable runs cooler, last longer (more durable), and the voltage drop is lower.
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Post Tue Sep 21, 2004 6:21 pm 
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timmeh
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Joined: 20 Jul 2004
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Location: Victoria


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I mwill be using 1 foot of 8g wire running to my ev then Very Happy

My ww motors will only need 12g wire as they only pull about 10max each contin.
Eaven if they pulled 20amps contin which a doubt 12g will still be fine.
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Post Tue Sep 21, 2004 6:28 pm 
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timmeh
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Joined: 20 Jul 2004
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Location: Victoria


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The 45 amp power pole connectors have 525 micro ohms resistance how much lotage drop would i get?
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Post Tue Sep 21, 2004 6:51 pm 
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Glen
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Joined: 16 Jun 2004
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lol you can get away with far less for your drive motors. i had screwy/screwed/cobra running off 18g wire for ages and i dare say it had more than a pair of ww motors could ever dream of drawing.

can i ask why you went with ww motors btw being so slow and heavy?
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Post Tue Sep 21, 2004 7:04 pm 
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timmeh
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Joined: 20 Jul 2004
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Location: Victoria


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my ww motors are actully actuator motors from am equipment and they are 1.2kgs each and at 18v they are 150 min rpm and very powerfull allso they are smaller than ww motors about 2/3rds the size and all metall parts no nylon gears in there Wink
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Post Tue Sep 21, 2004 7:14 pm 
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Philip
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Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane


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Tim, you may find that 150 rpm is a little slow. You could get two dill motor and gearbox combinations for 1.2 kg.

On the other hand. Your all metal gears and craploads of torque will be very reliable. You may find that for your design you don't need the speed and you certainly want need the extra power used by a drill.

It will be interesting to see how the completed robot performs.

Post Wed Sep 22, 2004 6:31 am 
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3Faze



Joined: 26 Jun 2004
Posts: 99
Location: Lincolnshire, UK


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13A two-core mains on my EV.... gets a bit warm Confused

Post Wed Sep 22, 2004 8:41 am 
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