Message text written by Graham Singleton
>Check with Bob Nuckolls but I think you will need 4 gauge or even 2.
Either
way the resistance of each connection will have a noticeable effect so
these must be good.<
I would say that, particularly with the lower current draw of a Rotax
starter, 4 guage should be ample. 2 guage would be more appropriate with
the much larger starter currents required by Lycoming/Continental engines.
I agree that the quality of the connections is every bit as important. Even
with rear mounted batteries and a mid sized engine (ie the Subaru) 4 guage
has proved sufficient. The weight saving between 4 and 6 gauge even with a
rear mounted battery is not worth considering as it may cause problems
later when the battery is a little low on capacity.
There was an article about copper v aluminium battery cables in Kitplanes
some years back. Although aluminium has a slightly greater resistance it is
possible to compensate by greater cross sectional area and still win out on
overall weight. Also solid strips of it can be glassed into the sides of
the fuselage if a long length is required making a neat installation. Make
sure that there is adequate glass to ensure good insulation otherwise you
could end up with a nasty electrical fire.
Nigel Charles
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