G'day Pat, All
At 11:57 PM 22/05/2010, Pat wrote:
>After removing the 40 hp mercury engine <snip> Does anyone have any
>good ideas for using them in some useful way?
>
>The fuel gauge is next. I thought about recommissioning it as a
>volt meter for the 48 volt pack. I could create a set-up that
>causes it to go from empty to full as the battery bank goes from 48
>to 51 volts (or whatever the right numbers are).
Haven't got one yet, but I'm planning to use one of these (although I
see they're out of stock at the moment):
http://www.evworks.com.au/index.php?product=INS-EVW-FGD
to convert amp-hours used to a fuel gauge reading.
>The third gauge is a tach. It would be nice if it could measure
>prop rpm's, but I can't think of any easy way sense that.
IMHO prop revs are way down on the list of things to want to watch,
far more important to watch amp draw, however:
If the tach is suitable for 12V pulses, you could get a small
industrial inductive proximity switch, you can get 4mm, 6mm, 8mm
diameter and IP68 (immersible) with no problems.
Ebay has bucket loads of proximity switch hits, but most of them will
be too big, and many don't list the size, so you'll need to
cross-check the manufacturer's data. Examples are 150113878074 is a
4mm diameter one made by GE, 120553143319 is an 8mm one made by Micro Switch.
Inductive proximity is looking for a metal target, and a small one
will need to be close (like 1 to 2mm away), but most proximities will
be triggered by a permanent magnet a bit further away. This gives you
the possibility of glueing a small super magnet or two to the edge of
the prop, glue the prox switch to the drive body and be able to sense
the prop revs that way. Small size is important, as no point in adding drag.
Regards
[Technik] James
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