[aprssig] Tesla Field Day mode (or any EV/Hybrid) FD load

[Robert Bruninga]

> ...and as for Field Day itself, is there an inverter on the market today
which will accept the high voltage DC input of today's hybrids and EVs,
...  In the ~10Kw range?  With US standard 240VAC Split-phase output?
That's my estimate of what it would take to run a 5 transmitter club FD
operation comfortably...  The Tesla's battery pack is about 75 KwH, right?
Or about 3 Kw average load for a 24 hour FD operation, so I'm guessing a
10Kw inverter would handle the peaks.

OK, Let's assume the FD 1kW PEP transmitter is only about 400W average
power, at a 20% TX duty cycle plus 10W on RX plus a pair of LED bulbs so
the average power per transmitter is only about 100W.  Five tents then
would only need 500W average total which is well within the capacity of a
1000 W pure-sine inverter connected to the 12v battery in an EV

At the FD site I powered with the Prius, each tent had a 12v battery for
local power and then the battery was charged from the central power system
with a 13.8V supply.

And since all of these 13.8V power supplies were modern DC switching
supplies, that ran directly on the 220 VDC from the Prius just fine.  At
that voltage it only took under 3 amps to provide the entire FD average
power and that could be run through hundreds and hundreds of feet of
standard #18 zip cord with no notable voltage drop.

The key to being able to use AVERAGE power so effectively is having 12v
battery at each tent for peak instantaneous current needs.  And most FD
sites prefer local DC so that they can power through the inevitable
generator problems...

PS, yes, you can find a 1 kW HVDC to 13.8V converter in every modern
hybrid.  In the Camry, it is a stand-along black box that you can get form
junkyards but price is high.  In the prius, that "converter" is embedded
in the HV system and cannot be dug out individually.  But again, why
bother.  Every Hybrid or EV is already doing that 1kW HVDC to 13.8v
conversion in its trunk, so you just connect to the 13.8v battery and then
invert to 60 Hz and you got it at 1 kW.

Bob