REFLECTOR: 24 volt electrical system

[Douglas Holub]

Have you tried that circuit? It doesn't look like it will work to me. Two of the diodes will always be reverse biased, and there will always be 24 volts on the load, imho.

There's only one thing I haven't been able to get for 24 volts, and that's the P-Mags. But they only draw around 20 mA during normal operation, so I think it will be ok if I run them off the bottom battery, and then every year at the condition inspection, swap the batteries around. (Schematic attached.)

Doug Holub
  ----- Original Message ----- 
  From: Joe Ewen 
  To: Velocity Aircraft Owners and Builders list 
  Sent: Wednesday, September 27, 2006 7:54 PM
  Subject: Re: REFLECTOR: 24 volt electrical system


  The duty cycle for the 30 amp load is very low.  If one is practicing takeoffs and landings, there are maybe 8 - 15 second cycles.  If the load imbalance is an issue the circuit could be accomplished by using schottky diodes and paralleling the load off both batteries.  See attached.  A converter for that size load is likely to be rather expensive and bulky.

  Joe
    ----- Original Message ----- 
    From: Jim 
    To: Velocity Aircraft Owners and Builders list 
    Sent: Wednesday, September 27, 2006 7:26 PM
    Subject: Re: REFLECTOR: 24 volt electrical system


    jewen at comporium.net wrote: 
Andy,

Use 2 12 volt batteries in series (24v.)  For the 12 volt circuit(s),
center tap between the two batteries. See attached drawing.

Joe




On Wed, September 27, 2006 10:27 am, Andrew Ellzey wrote:
  I would have liked to use a 24 volt electrical system on my aircraft, the
problem is the hydraulic gear pump system being 12 volt @ 30 amp. Has
anyone flying an XLRG found a way around this issue?

Andy Ellzey_______________________________________________
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    It is not a good idea to use the circuit and set up the batteries as you have indicated you are better off to use a converter to lower the voltage.  By following the circuit as discribed  you will over charge the battery located at the location 12 V to 24 Volts, what happens is the altenator or generator supplies a current  (Amps) to operate the equipment installed in the aircraft or other device.  Both batteries receive say 50 amps or so the battery located at 0 to 12 Volts receives 50 anps - the current required to operate the equipment associated with it let's say 30 amps for the equipment so 20 amps is charge for the 0 - 12 Volt battery.  The battery located at the 12V -24 Volt location also receives 50 Amps but only 5 amps is required to maintain / operate the equipment in its circuit.  The battery located at 12 Volts to 24 Volts will receive an extra 45 amps and will boil or dry out in short order and there will be very low capacity in this battery and you will be repl;acing it on a regular basis and not understand why it is failing as it has no load and it should not be the one that is failing.  

    Regards
    Jim Greening



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