I would like to set up a back up power system for times when city power is
down for extended periods. I need enough power to run our side-by-side ref
rigerator/freezer, a small fan, and charge a couple iPhones and a laptop co
mputer. The tag on the inside of the refrigerator says Full Load Amp: 6.5.
How much more will the motor draw at startup? Do I need to size for star
tup or normal operating conditions?
This model supposedly uses 617 kw-hours/year. Is this information relevant
in sizing a backup system? If so, how can I use it?
On 10/9/2013 1:20 PM, email@example.com wrote:
I need enough power to run our side-by-side refrigerator/freezer, a
small fan, and charge a couple iPhones and a laptop computer.
The tag on the inside of the refrigerator says Full Load Amp: 6.5. How
much more will the motor draw at startup? Do I need to size for startup
or normal operating conditions?
My generator says 5500 running watts and 7350 start-up watts.
I've had it running handling refrigerator, 2 small freezers, furnace and
well along with enough power for some lights, TV and computer.
You did not say what kind of system you want but I doubt battery would
handle your needs.
On 10/9/2013 12:20 PM, firstname.lastname@example.org wrote:
You may be able to get a high output true sine wave UPS and attach it to
several BFB's, "Big Freaking Batteries" that will run the fridge for a
while or find a 5kw contractor's genset you can roll out of the garage
or utility building so the exhaust fumes don't get into your home
and power thing with it. ^_^
6.5A * 120V = 780W
so you probably need at least a 1500-2000W UPS or generator because of
startup load (minimum)
Now if you go with a UPS keep in mind that let's say you want to run
this for 24 hours - even at a 50% duty cycle that's 6.5 * 12 = 30 Ah at
120V so 300Ah at 12V so that's six car battery sized lead-acid batteries
right there, without accounting for inverter losses and other
inefficiencies. Let's call it eight. Really, ten is probably a better
estimate - and that's just to run the fridge for one day with a little
A portable gas powered generator will take up less space, cost less,
etc... unless you already have a PV system or something in place I
don't see the benefit of going with batteries.
A typical tower or rack-mount UPS that just plugs into a 15A wall socket
may be rated at 1000-1500VA but that alone will be costly, and probably
comes with two 7-9.2Ah 12V SLA batteries. It "may" run a fridge but
it'd have to be an expensive true sine wave unit (~$4-500) to keep the
motor happy and that is really not what it's intended to do, so good
luck making a warranty claim if it fails. Many people think that
"clean" power is most important for PCs and other electronics, not true!
They can handle pretty dirty power as long as no voltage surges come
on the line that are too big for the built-in MOVs of the device's power
supply to handle. Electric motors, on the other hand, really don't like
dirty power. And even if your expensive true sine wave UPS works
flawlessly, the batteries supplied will be exhausted in a couple hours,
nowhere near an "extended power outage." You'd definitely be looking
for a $$$ commercial setup for your suggested usage, probably weighing
enough that it would have to be installed on the bottom floor (assuming
slab or foundation; if you have a crawl space fuhgeddaboutit) and as
large as your average refrigerator itself.
replace "roosters" with "cox" to reply.
On Wednesday, October 9, 2013 3:48:25 PM UTC-4, Nate Nagel wrote:
I doubt the typical refrigerator or freezer is running anywhere
near 50% of the time. Especially if you know it's on backup and
only open the doors as little as possible. The 617 Kwh per year
number would seem to support that it's running just a small
fraction of the time.
Let's call it eight. Really, ten is probably a better
I guess the benefits would be:
Someone doesn't need to be there to start it.
For the same money you could probably have a generator
with significantly more capacity
The inverter only lasts as long as the batteries.
A generator will run indefinitely as long as you put
gas in it.
The batteries don't last forever.
I would tend to go with about a 3000 - 3500W generator.
More than enough to run what he has so he can
plug in a TV, etc too.
But I'd also re-evaluate the need for one at all. The
typical fridge/freezer full of stuff will last a couple
of days without power, if you leave the doors closed.
You can have an ice chest available, open the fridge once
to get the stuff you're going to need for a couple days,
then leave the fridge closed. Also, if you know a
hurricane or something is coming, you can put extra
containers of water into a freezer 24hr or more in
advance. The more thermal masss, the longer it will last.
The lights, there are LED battery lanterns and such
available. The phone and laptop can be charged in the car.
I don't know about the motor in a refrigerator, but the motors where I
worked were driven from inverters that did not resemble pure sine waves.
The eairly inverters used stepped wave forms. Looked like a stair case gong
up 3 steps and down 3 steps for each half cycle. The later inverters put
out a waveform that looked like pure trash but were beter. You could
sometimes hear the motors 'sing' at high frequencies.
They were used on everything from less than 1 HP to 300 HP motors.
The last time I was required to use a true sine wave UPS was when I
installed an Intertel phone system for a business. It's been years but I
don't think the phone system had a switching power supply so it needed
clean power to keep it from sounding like a buzz-saw. ^_^
I've seen them spec'd for CCTV, intrusion detection etc. systems... but
I'm not sure that it's really the true sine wave that's the driver, but
the requirement for a "true online" or double-conversion (e.g. not
line-interactive type) - most that are true online are also true sine
wave. Or it could be both. It's been a while since I've read one of
replace "roosters" with "cox" to reply.
Heck most of the electronic electronic equipment I've installed in the
past 25 years has had a switching power supply which didn't care WTF you
fed it with. One of these days you will be able to walk across a shag
carpet and use the static electricity to power your implanted link. ^_^
On Wednesday, October 9, 2013 10:14:47 PM UTC-4, The Daring Dufas wrote:
I understand what you're saying and agree with you, but it is very common f
or engineers, or at least spec-writers, to specify double conversion and/or
true sine wave UPSes for those uses, when it is a "mission critical" appli
cation. Nothing succeeds like massive overkill, I guess.
I actually have one of those units running my home theater and cable modem/
wireless router, I believe I've related that before, although there's actua
lly a reason for that - the APC line-interactive UPS that I had there befor
e made the TV (Samsung 46" LCD) hum/buzz alarmingly. And I got it used and
cheap. I did replace the cooling fan with an "ultra quiet" PC fan and ins
tall a thermostatic fan control to quiet it down though.
********************Trim Da Phat********************
About 30 minutes ago I put a new pair of 12 volt AGM batteries in an APC
Smart UPS 1000 that I may use on a surveillance camera job and it was a
scrap pile rescue that had absolutely nothing wrong with it except that
it needed a new pair of batteries. I get UPS units all the time that are
in the same shape needing only batteries and I'll never understand why
people throw the darn things in the trash. I sell the old batteries to a
recycler and have a good as new UPS to sell for a cost less than $35.00
in new batteries. I may get $250.00 for this one. ^_^
If that's all you want to run, something like a Honda EU2000 or the
Yamaha equivalent would work well and be quiet. There is also a Champion
equivalent that is cheaper and seems to get good reviews. On an EU2000
you'd likely get 8 hours on a fueling, and there are a number of
extended run fuel tank options available.
On 10/9/2013 1:20 PM, email@example.com wrote:
I don't know of a use. Have to chat with
your neighbors, see what works. Is the
natural gas available, and is it dependable?
You thinking permanant backup generator?
I'd like a wired in generator, but no money
for that. I do have a portable, which is
Christopher A. Young
Learn about Jesus
Spend some money on a Kill-A-Watt or functional equivalent and measure
Reason: startup requirements vary a great deal depending on how old a
refrigerator or freezer is and (I'm guessing) from make/model to
We have an old refrigerator in the kitchen that wants some ungodly
amount of watts - can't recall how many - and it tends to make our
automated transfer switch shed loads to allow startup by our little 2KW
OTOH, the new refrigerator and the new freezer in the garage don't pull
much more at startup than they do steady state - something under 150
How citified is "city"?.... i.e. do you have secure space to leave a
generator far enough from the house for safety fume-wise?
Do you have natural gas?
On Wednesday, October 9, 2013 4:04:06 PM UTC-4, (PeteCresswell) wrote:
is down for extended periods. I need enough power to run our side-by-side
refrigerator/freezer, a small fan, and charge a couple iPhones and a laptop
computer. The tag on the inside of the refrigerator says Full Load Amp: 6
.5. How much more will the motor draw at startup? Do I need to size for s
tartup or normal operating conditions?
ant in sizing a backup system? If so, how can I use it?
I second that observation, that new ones don't pull
much starting current. I monitored a 3 year old freezer running on a gener
ator during Sandy with a
Kill-a-Watt. It might have been 200 watts at most
at start-up, then quickly came down to under 100 watts.
That kill-a-watt is highly recommended for monitoring
how much load you putting on the generator during an
outage. I had it wired up so I measured the load
going to the generator. Actually the neighbor's
generator. I was shocked at how much we ran off that
puppy. And we had probably 150 ft of extension cord
between the generator and my house. And then another
100 ft of wire maybe to the furthest point in my house.
The generator was just 4KW, I think. Just one of those
cheapos. It supplied power for 4 fridge/freezers, two
gas furnaces, (actually 3 because I only put one on at
a time), some cfl lights, etc. The neighbor even had
a resistance heater running off it, that's the only
time I heard the thing surge. I showed him how to get
his gas furnace going, then he didn't need it.
And the whole time I was watching the kill-a-watt,
we had close to 120V all the time at the end of that
I previously would have thought like 7 or 8KW
was a good size. But now I'd say 5KW is plenty,
unless you need central airconditioning or some
other big load. Even the furnace was only like 300W.
And as I said before, for what he's talking about, how
critical is a generator? A fridge/freezer will easily
go through a 2 day outage if you don't open the doors.
Get what you need, put it in a small ice chest.
For lights you have LED lanterns now that last a long time. Phone/laptop yo
u can charge in the car. Not
sure how useful the laptop even is, with a big power
outage cable/internet is likely to be out too.
I got a week out of my freezer during Sandy. Some
stuff had just started to melt. I did put extra
jugs of water in to freeze a couple days before.
And on two days later in the week, I swapped those
out for new frozen ones from a friends freezer.
And then at the end of it all, it comes down to
probabilities. If there is only a very small
chance that you're gonna lose food in a freezer
from an outage that last many days, how often
does that happen? And if you lose $300 in food
if and when it does, is it worth the hassle of
having a generator and gas sitting around, etc?
Somebody in another group observed the distinction between "Lifeboat"
and "Cruise Ship" when it comes to choosing a generator.
I went the "Lifeboat" route with a Honda EU2000 and an APC UTS-6 smart
transfer switch. It serves most of the circuits in our house, but not
all.... but what it serves are sufficient for reasonable comfort given
that AC is not going to happen.
Fuel consumption was one concern. After that was the ability to pick
the thing up, throw it in a car, and use it somewhere else.
The neighbor gets about one hour out of his 5KW's 5-gallon tank. We get
more like five hours out of our EU2000's one-gallon tank.
But we also have natural gas. If I were doing it over, I'd have to
consider "Cruise Ship": a higher-capacity generator, maybe on a slab
somewhere in the yard, running on nat gas. No fuel storage issues, no
fuel availability concerns. Yes, it costs more per hour to run, but
how often do we get outages? Dunno what the cost would be, but I
suspect I might suffer some sticker shock...
But even if I stuck with gas, I would get a Honda EU3000 instead of the
2000. It's heavier, but still manageable given a hand truck and, if I
am to believe the numbers somebody posted somewhere, it's slightly more
economical at the 800-1200 watts that our house seems to run at much of
the time. Also, the to easily pick up the EU2000 cuts both ways
when/if one has the wrong kind of people wandering the neighborhood...
On Thursday, October 10, 2013 9:35:17 AM UTC-4, (PeteCresswell) wrote:
I'm not sure that's true. NG is fairly cheap. You'd
have to look at the fuel consumption specs and the cost
of the NG.
Dunno what the cost would be, but I
The big sticker shock is if you buy a whole house
standy unit and then have to have it professionally
installed, with transfer panel installed, gas lines
There are conversion kits available that will convert
common portable generator engines to nat gas. Some are permanent
and others allow switching back and forth. The kits
cost maybe $250.
And instead of running wiring to the appliances, like you
did, I would install an inlet at the panel and get one of
the lockout kits for the panel. It prevents the main and
the breaker that the inlet is connected to from both being
on at the same time. They are just a metal slide bracket,
but they are still charging $175 or so for them. Then
you use one heavy extension cord from the generator to the
inlet and use the breakers to manage which loads you want
on. I might consider
putting an ammeter between the inlet and the panel to
know exactly how much you're pulling too.
I have UPS's that keep my computers running...
That only presents one problem :
They would not be able to power my coffee maker!
In the 33 years I've been in my house all but two outages were less then
When I worked for the local electric company (Philadelphia Electric) I
was out walking the lines during a storm event - looking for downed
One of the residents came up to me to unload about how he had never seen
so many power outages in his life until he moved to the Philadelphia
"Where did you come from?"
"Got many trees there?
We just had a seven hour outage a couple of days ago.
Five hours from outage to somebody identifying the tree that fell down.
Two hours to clear the tree and get the wires back up.
A very tough and thankless job.
BTW: For the two ...long outages we had , I did have to go out and buy
some ice and put as much food from my refrigerator into a cooler.
We lost very little food. Certainly no where near what a generator cost.
One of the evenings was rather warm...but my industrial grade UPS with
over-sized batteries ran a fan all night with no trouble.
I do a lot of computer repair work and have at least 24 hours of backup
power...but not enough for a refrigerator.
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