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re: battery interconnect size
24 apr 2000
george ghio wrote:
>>>>you might wrap it around the battery connectors several times
>>>>to ensure a nice low-resistance wire contact.
>>>what a joke i suppose you would hold it in place with chewing gum.
>> no. i'd use a big washer under the screw, with the wire wrapped round
>> it in a pancake spiral, or fold the wire back and forth a few times
>> before inserting it in a crimp hole.
>sorry nick but the resistance is still only that of the wire used for the
>connection. the only way to decrease the resistance is to increase the size
>of the wire. the use of crimp lugs is the only way to go. they must be
>crimped according to specs. folding the wire over does nothing to reduce
>resistance unless you double the whole length of the link.
i disagree. the bulk resistance of the wire wastes less than 0.2% of
the pv power here, so that's not a problem. the point of folding the
wire at the connector is to increase the contact surface and lower
that contact resistance, which can be greater than the bulk resistance
of the wire. pressure helps too (to the 8th power, as i recall.)
nick
but why use wires or battery connectors at all? :-)
to: nick@ece.vill.edu, ronrosenfeld@spamcop.net
date: sun, 23 apr 2000 09:29:00 -0400
subject: re: battery interconnect size
from: richard j komp
dear nick,
i have found a simple way of making good, neat low resistance battery
connectors. i take "1/2 inch" soft copper tubing and crush the ends flat
in a vise, drill a hole for the post, then tin the ends with cheap
discount house 60/40 solder (that stuff is actually 60% lead and 40% tin
instead of the other way around like it is supposed to be and is quite
useless for ordinary copper plumbing work but perfect for this job).
the "tinning" is necessary to keep the copper ends from corroding when
connected to the battery posts (the positive post is the most
vulnerable). then i wrap the rest of the tube connector with electrical
tape so that dropped wrenches and such don't weld themselves to the
interconnects (that can be quite spectacular) you can also slit a garden
hose and slide it over the tube as an insulator.
by the way, "1/2" copper tubing is actually 16mm (a shade bigger than 5/8")
in od and is sold sometimes as 5/8" soft tubing for air conditioner work
(all plumbing is metric and always has been since the 19th century; it's
just that in this country, that would scare plumbers and engineers and
others afraid to use the metric system so somewhat arbitrary inch units
were given to the various parts.)
i don't have any resistance data for this type of interconnects, but
suspect that the resistance at the battery terminals is stil higher
than the copper tubing.
hope this helps,
richard j. komp, president
sunwatt corporation
rr 2 box 7751
jonesport me 04649
207-497-2204, e-mail: sunwatt@juno.com
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