Alubukhara said:
Everybody knows you dont run heavy loads (Iron, AC etc) on batteries but
why?
A normal one ton Air Conditionar (AC) requires 1500 Watts so the current
(amps) required if the mains voltage is 220 should be 1500/220 = 6.8 Amp
A 100 Amp hour battery can provide 100 amperes for 1 hour right?
That means it should be able to run about 14 AC's (100/6.8) for one
hour??????????
I know its nonsense but what am I missing here?
Wrong calculation.
What was not addressed so far is that 6.8 amps at 220 V is "equivalent" to
125 A at 12 V. Iow, A = P / V.
So, you would need an even *bigger* battery than your already very very
large 100 A-hr battery.
And, a pretty expensive inverter. Altho an inverter providing 6.8 A at 220
may not seem like a big deal, the ability to handle much larger in-rush
currents upon start up *is* a big deal.
And these are paper calculations, as well. Everything gets worse off paper,
such as the voltage drop of batteries with discharge, IR drop, etc.
Now, if this were a car A/C, you proly would need *far less* than a ton of
A/C, AND you probably wouldn't need it to be on for a solid hour, so you
could make do with a smaller (separate) battery. But still a
battery-demanding proposition, which is why the battery should be separate
from the rest of the system, lest you become stranded.
If for an apt/ house, you'd proly need a pile of batteries -- but then,
you'd proly have the room for this.
Fortunately, the newer inverter technology for A/C (mini-splits or ductless)
seems to be pretty power-miserly, altho it is still a motor, but a much less
gluttonous motor.
EERs for minisplits can push 20+, so you get much more bang for your A/C
buck -- but a lot of bucks: these high-end A/Cs (fujitsu, mitsubishi) are
perty pricey.
Inverter mini-splits can have net *triple* the EER of an old clunker, in
particular old sleeve (thru the wall) units, which have notoriously low
EER's -- they claim 8, but proly pushing 6.
If you were actually considering trying this, I'd get the smallest units
possible in multiples, and "stage" them, to be kind to the batteries.
Inverter technology in newer A/Cs already has a kind of built-in staging,
but I'd still go with multiples of the smallest units -- which I think might
be 9,000 btu (3/4 ton), but poss. less.
Oh yeah, and *lots* of batteries.
--
Mr. PV'd
Mae West (yer fav Congressman) to the Gangster (yer fav Lobbyist):
Hey, Big Boy, is that a wad (of cash) in yer pocket, or are you just
glad to see me??