Hello John,
In our electrical work, this is a common practice to use several smaller
wires then one large wire. Instead of using one 500 mcm wire that is rated
for 400 amps, we may use two each 3/0 wires or two 4/0 wires if there is
more than three bundle together.
We use circuit breakers and terminal lugs that are design for multiple
wires. I have calculated using my Electrical Engineering Handbook, that it
would take 12.82 each No. 10 AWG 19 strand copper wire that is rated for 90C
to be equal in a cross section circular mills and resistance to a No. 2/0
AWG wire with a minimum of 126 strands
It is best to use a heavy duty barrel that ix zinc plated copper that is a
non-solder type. The solder type have a hole at the connection end. The
barrel should be long enough and diameter opening so some of the insulation
of the wire is inserted into the barrel. There heavy duty sire barrels may
either be a two crimp or three crimp type.
If it's a two crimp type, then first crimp at the wire end and then at the
connector end. If you crimp at the connector end first, the taper barrel
could push back the wire. If it's a three crimp wire connector, then crimp
in the middle, then the wire end and then at the connector end.
Apply a heavy duty heat shrink with adhesive in it to seal the connection
and reinforce the wire ends.
A 2/0 cable has cross section of 133,100 circular mils at a 0.07793 ohms
resistance per 1000 feet.
A No. 10 AWG wire has a cross section of 10,380 circular mils at a 0.9989
ohms resistance per 1000 feet.
Therefore: 133.100 / 10.380 = 12.82 no 10 AWG wires all space in air.
Bundling the 12.82 or 13 wires will have a de-rating factor of about 0.76 on
the amount of continues current you can draw at the maximum temperature
rating of the wire.
Therefore: If the bundling of No. 10 AWG wire 19 strand copper wire that is
rated for 90 C and is equal to the 2/0 current rating of 215 amps continues,
then 215 x 0.76 = 163.4 amps.
This de-rating factor is normally use on insulated wires, so the maximum
current will not melt the insulation.
In my EV, I have one connection that runs from one of my safety contactors
to a shunt that is only 2 inches away at a 90 degree angle. I am using a
large brass 4/0 set screw terminal lug that is connected directly to the
contactor and the other one connected to the shunt. I have bundle seven No.
6 AWG bare copper wires that is bent at a 90 degree.
The rating of this type of connection for this distance is 553 amps. If
these wire were insulated, than its de-rated to 445 amps.
Roland
----- Original Message -----
From: "John O'Connor" <
[email protected]>
To: "Electric Vehicle Discussion List" <
[email protected]>
Sent: Sunday, December 12, 2010 5:56 AM
Subject: [EVDL] battery interconnect idea
> Someone please tell me what I am missing.
>
> I am thinking of using multiple pieces of multi-strand 10 awg wire as
> battery interconnects.
>
> I have a 144 volt pack of floodies, with a zilla 1k and ADC 9 inch
> motor. I don't think I ever pull more than 300 amps from them long
> enough to register my ammeter and for me to notice. Current
> interconnects are a mix of 2/0 cable and copper bar stock with bends.
>
> Assuming I get the right cross section of copper, is there any reason
> I should not just strip the ends, bunch them up and put some lugs on?
>
> John
>
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