On 10/01/2013 05:10 PM, Fred Klein wrote:
> I should have given more detail w/ my question...my engine is a 140
> hp MPEFI engine by RAM Performance which is based on the Subaru...I
> have been using Fig. Z-19 from Bob Nuckolls' AeroElectric Connection,
> an electrical layout intended for a "Dual Battery, Single Alternator,
> Electronic Controlled Fuel Injection Engine", as a guide. Following
> it will build in the redundancy which Frans speaks of except for the
> single alternator...a shortcoming to be compensated for by using
> higher Amp/hr batteries which will be swapped out annually or
> bi-annually as Frans suggests.
Is it really not possible to get an additional alternator in it? EFI
tends to use quite some electrical power, and with batteries alone the
flight won't last very long.
> In my case, for weight and balance considerations, my batteries will
> be aft, and at this stage of the game, it appears that lightweight
> batteries would not necessarily be beneficial.
Don't worry about constructing weight aft. I have both batteries aft,
but also have the strobe unit behind the D-panel, the ELT-unit, the
Flarm/ADS-B/Wifi antenna's and transreceivers, I could also have put the
transponder in the tail (except for the control head), you can put a HID
landing light in the fin, etc. If you need to get more weight aft, there
are plenty of opportunities without having to resort to dead lead or
even lead acid batteries. ;-) And yes I like to have the CofG near the
aft limit. ;-)
Thinking about it, there is another possibility for having reserve
electrical power for single alternator setups. A non-rechargable battery
for just the EFI is also an option. Non-rechargable batteries are able
to hold much more power per weight unit than their rechargable cousins.
There exist alkaline power packs for remote electrical fences which hold
quite some amp/hours in a small package, but of course they lack
cranking power and rechargability. But they have a lot of power in the
package, just what you need if you need to keep the EFI going. It is
just a thought that this might be more weight efficient than lead acid
batteries.
Frans
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