But a battery has a VERY limited capacity 100AH out of a 60 lb lump
- while a generator keeps providing power as long as you can feed it.
Having a battery and inverter for low power short term loads to avaid
running the generator full time can make sense - as long as the
battery is charged by the generator when the generator is running.
I considered this for my furnace, but decided a generator would be
more cost effective for the few times the power goes out for periods
longer than the thermal time constant of the house. The batteries won't
run that long anyway.
What happens when the batteries are low, the furnace kicks on and
preheats...later, the air handler starts, dropping the battery voltage
below the cutout threshold and shuts it down...until it restarts.
I just don't like gas on fire in the midst of electronics that's
surging on and off.
Sure, it's all protected so that can never happen.
Until it does.
My experience is that the gas valve and ignitor (well,
my old furnace had pilot light) were fine. The air
handler blower would not power. So, all that heat and
no where to blow with it. That didn't seem safe.
I did get a two stroke ETQ generator. it doesn't start
very well, needs ether if it's been sitting. But, the
generator provides a few hours of run time. An hour of
furnace before bed time is enough to keep the place
over night. Let the generator cool, and bring it indoors.
Less likely to be stolen.
My forced Air fan takes 720 watts maximum to run.
The Xantrex-802-1500 is not a UPS. I can not be plugged
in (charging) while it is discharging. One of the other.
AC output power (continuous): 1350 W
AC output surge capacity (peak): 3000 W
AC output voltage: 120 Vac
AC output frequency: 60 Hz
AC output waveform: Modified Sine Wave
Inverter no-load current: 0.30 amps
Internal battery capacity: 51 amp hours
Sump pump 1/2 hp 300W 1 h 18 min
Microwave 1000W 19 min
Or about 32 or 26 minutes. Not a lot of time.
the riddle wrapped in an enigma wrapped
On Monday, December 30, 2013 2:24:53 AM UTC-5, Todd wrote:
If it will only run a 300W load for 78 mins,
why are you even considering it as a backup power source for
a furnace? If it's reasonably cold, the furnace will
be running 25 - 50% of the time. That would give you
2 1/2 to 5 hours of heat, assuming it uses 300W. In a
power outage, IDK anyone that's looking for 5 hours of
heat. You either don't need it if the outage is a matter
of hours or you need it for days.
What is wrong with parallel batteries? More batteries longer runtime. If desired, get the mondo non-venting
types and parallel them.
Used UPS for small server farms are cheap, too. These
allow for adding more capacity at your own leisure. Plus,
the unit will give you seemless transition while you wait
for power, or to start up the new generator that you get. :-)
Strange. I have never seen a problem with rack-mounted battery
banks in parallel. A bad battery will cause problems regardless
of series/parallel connection. One would have to have some messed
up wiring for there to be an issue with charge, or drain. Keep the
links the same and the battery will not know the difference. Close
enough and you will have to nit pick to find something wrong.
In fact, unless shorted, a bad battery in parallel will not hamper
the function of the circuit. A bad battery in series will. If one
battery is drawing too much on charge cycle it is weak and needs to
be replaced, the same as in series. In series you will not know
until you use the batteries, in parallel, you might not know at
all. That is why there is such a thing as maintenance.
Many off-grid and industrial applications require that both a series
and parallel set-up be implemented to obtain the desired voltage.
The only fault one would notice in the parallel portion would be
less run time per bank. Something one would not observe under
normal usage other than an overall underperformance of the system
as a whole.
Sure, but the "problems" are quite different. Parallel batteries will
get "interesting" if a cell shorts or if there is a big difference in
the age/size. A shorted or weak cell in a series connection will just
limit the utility of the battery. A battery isolator will solve the
problems with parallel batteries but it also wastes significant power.
A shorted cell certainly will hamper the function of the circuit.
Without a battery isolator, it will draw *significant* power (as in:
fire) and discharge the other battery. The voltages will equalize and
that power is lost as heat.
In a series connection the, no power is lost to heating. The voltage
drops by that cell but otherwise, little happens.
If you mean that you won't have a fire to tell you that something's
GENERALLY SPEAKING, connecting batteries in series is better than in
parallel - as a "battery" is a "series" of cells. Get 2 big-assed 6
volt batteries and put them in series rather than 2 smaller 12 volts
in parallel for the same capacity.
Bigger batteries, and parallel batteries for the sake of more current, will
last longer, since discharge will be less in. Given time. I started out
with two 120 amp hour batteries on the boat with isolator. It worked better
with batteries in direct parallel with the trolling motor.
Yep. Want more trolling time, add another battery in parallel. The amp
hours are additive. Can't do that with a series set-up. Well, not for
the same cost. Ever priced a 6-volt Trojan battery? Daaaammmmn!
On Monday, December 30, 2013 1:27:30 PM UTC-5, Irreverent Maximus wrote:
The problems are that the more batteries, the more cost, the
more space they take, more replacement cost, etc. The battery
pack/inverter the OP was looking at was $425. That gives him
300W for an hour and 15 mins. That's in the price range of a generator,
which, IMO, and apparently most of the rest of homeowners, is
a better, more practical solution. And if it's portable, it's
also available for other use, anywhere you need temporary power
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