Shaun:
You can go with a zero amp manual disconnect switch. Summit Racing has
about 5 different models of this type item for race cars etc. Dave and
Terry have a nice installation of this type on their aircraft.
Steve Hagar
A143
Mesa, AZ
> [Original Message]
> From: Shaun Simpkins <shauns@hevanet.com>
> Date: 1/11/03 4:16:43 AM
> Subject: Low-hold-current contactors and All-electric
panel examples
>
> All:
>
> Jim Nelson and a few others excepted, the XS cowl can't nicely fit a
standa> rd "big"
> front-mounted alternator, so past "all-electric airplane" threads on this
> the possibility of a B&C SD-8 or SD-20 on the vac. pad PTO as a secondary
> The Rotax-supplied alternator is of small capacity - 18A less
> whatever the fuel pumps and ECU computer draw - and the vac. pad RPM is
slo> wer than
> Lycoming standard, so an SD-8 is derated to about 5A and an SD-20 to
about > 12A. So good
> "amperage conservation" needs to be practiced.
>
> An annoyance is the 1A holding current of the battery contactor relay,
whic> h represents appx. 8%
> of the net Rotax alternator capacity. If you choose to implement a fully
r> edundant system, with
> dual batteries and alternators, you'll have at least 2 battery
contactors, > plus crossfeed contactors,
> so this drain can add up fast. Although one can use manual contactors (
as> Tony K. did for
> a while ) - possibly remotely activated via a Bowden cable - an
alternative> is a power-managed
> contactor, one example of which is the cii technologies EV-200
> http://www.ciitech.com/doc_generator.asp?doc_id1280
> This product was designed for battery-powered vehicles, can switch 200A
> and has a solenoid power-management circuit, which drops the hold current
> actuator to 130mA - an 8:1 reduction from a conventional contactor relay,
a> nd possibly low enough to be insignificant. It is highly reliable,
> lightweight, and an easy retrofit to a standard power system.
Unfortunatel> y, it is a lot more expensive
> than a conventional contactor relay - $75 instead of $15. But it may
make > sense if you don't want to go to
> heroic (Bowden cable) lengths to control alternator loads.
>
> I caution that this product has not been certified for the aircraft
market,> nor have I actually tested it. But
> it's a tantalizing idea for those builders who'd like to try something
>
> If you would like to see how the big boys do all-electric, check out the
SR> -22 Pilot's Operating Handbook
> on the Cirrus Design website
> http://www.cirrusdesign.com
> Page 3-28 and Page 7-39 et. seq. are very interesting reading and a neat
wa> y of implementing a dual-alt
> dual-bat dual-bus system without the need for a crossfeed switch. It's
got> Bob Nuckolls' name all over it,
> but I don't think he was a part of its design. Warning: the POH is 320+
p> ages and a 2.8MB download.
>
> Shaun Simpkins
> ...no longer building but still scheming...
--- Steve Hagar
--- hagargs@earthlink.net
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