Polyfuse for KX3 external battery

[KD0GLS]

Wondering if anyone here has made use of a polyfuse between an external SLA battery and a KX3.  I'm interested in your experiences with these devices and in any specific hold and/or trip current values you've tried and had good (or bad) luck with.

72,
Brent, KD0GLS, Minneapolis

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[WB4SON]

Try this reference:
http://www.littelfuse.com/data/en/Product_Brochures/EC327-E_Polyfuse_PTC.pdf

Be aware that the polyfuse is a thermal device and reacts rather slowly.
 LiPo/LiFePO4 batteries are VERY low impedance and can put out hundreds of
amps into a short circuit.  That can easily exceed the ratings of standard
polyfuses.  Those designed for battery service, like the VT series, are
somewhat more robust but can be physically larger.

Personally I rely on standard ATC fuses in series with the power leads.

73, Bob, WB4SON


On Tue, Aug 13, 2013 at 2:43 PM, KD0GLS <[hidden email]> wrote:

> Wondering if anyone here has made use of a polyfuse between an external
> SLA battery and a KX3.  I'm interested in your experiences with these
> devices and in any specific hold and/or trip current values you've tried
> and had good (or bad) luck with.
>
> 72,
> Brent, KD0GLS, Minneapolis
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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[Don Wilhelm-4]

Brent,

I recommend fusing *any* battery cable near the battery (or power
supply) with a fast-blow fuse whose rating is matched to the size of the
wire.  #10, 30 or 35 amps, #12, 20 or 25 amps, #14 15 or 20 amps, #16 or
#18 10 amps.  I like the in-line ATC fuses or use a rigrunner or other
fused DC distribution box.

If a short at the cable plug occurs the fuse will blow and protect the
wire from making molten metal and possibly fire.

That fuse is not intended to protect the equipment.  Most equipment (the
KX3 included) has internal protection for overcurrent.

73,
Don W3FPR

On 8/13/2013 2:43 PM, KD0GLS wrote:
> Wondering if anyone here has made use of a polyfuse between an external SLA battery and a KX3.  I'm interested in your experiences with these devices and in any specific hold and/or trip current values you've tried and had good (or bad) luck with.
>
>

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