Re: [EVDL] fusewires for 18650 cells

2019-01-02 Thread Lee Hart via EV

ken via EV wrote:

  Thou my cells are rather close in capity, I'm still thinkng of using fuse
wire as in the telsa pack .  If i used the phone cable 2 pair cable that
runs around houses and used 3/4 inch form cell to bus bar  would my 10
amp cells be protected ?


As mentioned, phone wire is not of consistent size or quality. As a 
result, its performace as a "fuse" is likely to be inconsistent. Maybe 
that's good enough; maybe not. You'll have to test it carefully to be sure.


A few background details on fuses might help. A fuse "blows" when the 
metal reaches its melting temperature. That is a function of current, 
time, and ambient temperature.


Onderdonk's equation provides a ROUGH approximation of the fusing 
current of a round uninsulated wire in still air. For copper, it is I = 
0.148 A/T^0.5, where I = current in amps, A = cross sectional area in 
mils, and T = seconds.


Any insulation on the wire drastically lowers the fusing current.

Any airflow around the wire drastically increases the fusing current.

Most metals have a high enough melting point that they can set fire to 
surronding materials. When the fuse opens, there may also be an arc. 
This is especially dangerous on high voltage DC, because the arc will 
not self-extinguish until it is very long! That's why commercial fuses 
are always in some fireproof package.


Whatever you do, test, Test, TEST!
--
The belief that there is only one truth, and that oneself is in
possession of it, is the root of all evil in the world. (Max Born)
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] fusewires for 18650 cells

2019-01-02 Thread Robert Bruninga via EV
Best thing would be to just test them and be sure.
But don't test with a 3" piece of the wire from end of battery to the
other end, because that is not the same as testing a 3/4" piece.  You will
need a 3" piece of heavy wire and then just the 3/4" of the "fuse" wire to
get a valid test.

But trivial to do the test.


Bob

-Original Message-
From: EV  On Behalf Of ken via EV
Sent: Wednesday, January 2, 2019 4:26 PM
To: Electric Vehicle Discussion List 
Cc: ken 
Subject: [EVDL] fusewires for 18650 cells

 Thou my cells are rather close in capity, I'm still thinkng of using fuse
wire as in the telsa pack .  If i used the phone cable 2 pair cable that
runs around houses and used 3/4 inch form cell to bus bar  would my 10 amp
cells be protected ?

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[EVDL] fusewires for 18650 cells

2019-01-02 Thread ken via EV
 Thou my cells are rather close in capity, I'm still thinkng of using fuse
wire as in the telsa pack .  If i used the phone cable 2 pair cable that
runs around houses and used 3/4 inch form cell to bus bar  would my 10
amp cells be protected ?

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