Message text written by "Ron Jones"
>Donald, I had installed the heavy (dash2) cable from front to back as per
the Good Book but had not yet made up a battery carrier when I telephoned
Neville Eyre on another matter. ".. bye the way," he said, " when you come
to install the battery, put it under the cowling to avoid the voltage-drop
that the rear position will cause." "You will also save some weight and a
lot of expense." !!
After some thought I did this and the cable I saved weighed 7 1/2 lbs. This
would, of course, be divided fairly evenly either side of the c of g and
would not have affected to any great extent the ballast needed later - so
it is the better position IMHO.<
Dash 4 gauge cable is quite sufficient for a Rotax starter motor (600W)
even in the rear position. My Europa starts no problem at all with it and I
have a rear mounted battery. What is more critical is ensuring you have a
battery that can deliver the current without too much voltage drop. The
internal battery resistance is every bit as important as the resistance of
the wiring to it. I started with a ordinary sealed lead acid battery. This
was no good. The batteries sold by Gerry Davis can easily cope. Remember
that after a few years the battery capacity will drop so a bit of initial
overcapacity is a good thing. Also as hand propping a Rotax is at the best
difficult I would recommend some form of external power connection. This
enables you to get an easy jump start on a landaway if your battery cannot
cope and also saves your aircraft battery if it is used for the first start
of the day in cold weather. If you opt for a forward battery position think
carefully about how you are going to arrange an external power connection.
Fiddling around with battery connections in the front cowl with the engine
running is not the safest occupation.
Nigel Charles
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