Power Inverter

[shubox56]

Hi guys, I'm looking for a reliable but reasonably priced power inverter to operate household lights and a full size refrigerator in the event of a blackout. Any recommendations?

I'm looking at power inverters for the first time and need a little education. To set my expectations. How long would an inverter operate a full sized refrigerator on a fully charged car battery? Assume that the battery is not in the car. How long before the battery would be totally dead?

Thanks in advance.

 

[Sevenhills1952]

An inverter on battery wouldn't run a refrigerator for long! I'm guessing a couple hours? Look up inverters, check your refrigerator power demand and you could figure it out.
An inverter and battery may be ok for low power things, but anything like refrigerator, well pump, etc. you'd need a sufficient generator not inverter.

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[wyliesdiesels]

What is the size of the fridge and what is the amp rating on the nameplate?

as said above, a battery bank and inverter wont last long powering a fridge

 

[southalabama]

Home Depot has a EGO battery generator. $999.00

No experience with it. Check it’s output and your needs.

56-Volt 3000-Watt Nexus Portable Power Station Generator Powered with Two 7.5 Ah Batteries

 

[79firebird]

To run a normal size fridge going to need a min 2000 watt inverter as most are 1200+ watts, and a lot of batteries I have a bar fridge I ran off a 1000 watt on a battery from a cat and it would last a day and a half. a apartment size fridge at my uncles cabin was on a 3000 watt inverter with 4 6 volt batteries after 4 days they would be dead. . so probably better ti get a generator

 

[The Cobbler]

full size fridge on a car battery wont last long . I think you'd be lucky to get 2 hrs out of it

 

[dogdog]

Nope it won't start a full size fridge... I tried when there was the blackout... I think the one I have was the Cheap modified sine wave inverter 3000Watt... and it would make the motor buzz that is about it...

So... maybe more watt? or a good SPWM inverter ?

 

[Shiftless]

Nope it won't start a full size fridge... I tried when there was the blackout... I think the one I have was the Cheap modified sine wave inverter 3000Watt... and it would make the motor buzz that is about it...

So... maybe more watt? or a good SPWM inverter ?

What battery was that hooked up to and how many inches of what sized wire was used?

I’m pretty sure a 3000 watt inverter would have done it. I bet the battery or the wires were too small.

 

[dogdog]

It's the large marine deep cycle with 120RC.. Exide brand I think..
wire is what ever came with the unit... 4 or 6 gauge... short ones... 2ft or 3...

 

[slow]

I have a Xantrex ProSine 1000w True Sine Wave Power for my fridge backup plan. It's rated at 1000 watts but I have pulled 1500 for a couple minutes when testing with a heat gun. It has a digital display of power in and out.

Car battery is wrong choice, you want a deep cycle battery. I got around 4 hours during a hurricane using my setup and a new Group 65 battery from a diesel truck powering only the fridge. How long do you want to keep your system running for?

 

[rlitman]

To run a normal size fridge going to need a min 2000 watt inverter as most are 1200+ watts, and a lot of batteries I have a bar fridge I ran off a 1000 watt on a battery from a cat and it would last a day and a half. a apartment size fridge at my uncles cabin was on a 3000 watt inverter with 4 6 volt batteries after 4 days they would be dead. . so probably better ti get a generator

What fridges are 1200W? Mine are in the neighborhood of 700W, and I have had no trouble running one fridge at a time off my 1000W Honda inverter generator.

 

[dogdog]

The motor / compressor start up of the fridge will draws a lot more... maybe once it is running it will take less energy... the cheaper modified sine wave inverters actually have less power.... don't remember the technical mumbles about it....

 

[slow]

That is true, I did have issues starting my fridge on a 1500 watt modified sine inverter, but the pure since works like a champ, even at 1000 watts vs 1500 watt rating.

 

[rlitman]

The motor / compressor start up of the fridge will draws a lot more... maybe once it is running it will take less energy... the cheaper modified sine wave inverters actually have less power.... don't remember the technical mumbles about it....

You're talking about "subtransient reactance", and that is a property of the power supply. And yeah, "modified sine wave" (FYI even typing "sine" there that offends me, just as using the word "cheese" offends me when used in reference to "processed cheese product") power supplies will have crappy properties that can reduce motor starting ability.

Anyway, my true sine wave generator has merely a 900W rating (the 1000W rating is the "Max" and is more marketing BS than anything), and I've used it to run a single refrigerator for days on end. With three extension cords, I would switch between two fridges and a large freezer, giving enough hours to each to stay sufficiently cold (by carefully limiting door openings). It did not have enough power to run two simultaneously.

 

[dogdog]

You're talking about "subtransient reactance", and that is a property of the power supply. And yeah, "modified sine wave" (FYI even typing "sine" there that offends me, just as using the word "cheese" offends me when used in reference to "processed cheese product") power supplies will have crappy properties that can reduce motor starting ability.

Anyway, my true sine wave generator has merely a 900W rating (the 1000W rating is the "Max" and is more marketing BS than anything), and I've used it to run a single refrigerator for days on end. With three extension cords, I would switch between two fridges and a large freezer, giving enough hours to each to stay sufficiently cold (by carefully limiting door openings). It did not have enough power to run two simultaneously.

Pure sine wave inverters were priced out of reach normal Joes way back then... only recently past 2 or 3 years maybe it was priced right... but still a lot of "inverters" on the markets are still "modified" sine wave inverters.. a lot of people were not aware of the differences when buying these stuff including me way back then...

 

[theoldwizard1]

If some one really wants to pursue a decent battery backup solution, use 6V golf cart batteries. Best bang for your buck. Buy in pairs (obviously). How many you need depends on how long you want to run.

 

[shubox56]

Thanks guys. I'm reading through the numerous posts and trying to make heads or tails of it all. Just skimming through it, I'm still not certain which type to buy and weather it's worth the investment. Sounds like some have had reasonable success while many others --- WELL --- not so much. I'm definitely NOT going to spend a grand or more, that's for sure. And I'm not sure that I have interest in a generator. Lot to think about.

 

[Shiftless]

It's the large marine deep cycle with 120RC.. Exide brand I think..
wire is what ever came with the unit... 4 or 6 gauge... short ones... 2ft or 3...

I tried to use the wires that came with my 1000 watt inverter. I have a group 24 marine/ deep cycle battery running a 1/3 HP sump pump. With the 3 foot long 6ga. wires that came with the inverter, the motor just hummed even though the battery was brand new and fully charged. When I changed to 2 ga. wires one foot long, the motor ran fine and pumped out water just as quickly as when the pump was plugged into house current.
The voltage drop over 6 ga. wires 3 feet long was too much and the inverter couldn’t deliver enough to start the motor.

The surge through the battery cables is probably over 50 amps and might approach 100 amps. You need serious wire! I ran the numbers for voltage drop using 6 ga. and it was only 1-2 % in theory. But my real world experience seems to prove that thicker wire is better.

As was said earlier, for long term use the best bang for your buck is pairs of 6 volt golf cart batteries.

Here is a pic of my standby power unit for the sump pump. Storm related winter outages here are short. My pump needs to run for 15 seconds once every 20 minutes in the worst storms.

.

 

[shubox56]

Ok, so I'm hearing golf cart batteries repeated by a couple --- which reasonably priced inverter?

So a short run of 2g cable (something I have in the house) would work well from what I'm reading? Better to keep the inverter close to the battery and run an extension cord if needed?

I hope to order something this week IF I can narrow down a good unit for a price I can afford.

As for the fridge: I guess I could run the inverter in cycles to extend battery life. Maybe 30 minutes on 30 minutes off or something like that? And if push came to shove, what would prevent me from hooking the inverter to my car battery and occasionally start the car to recharge the battery to extend battery life in the event of a blackout?

 

[slow]

Nothing keeps you from connecting it to your vehicle to charge. I ran a fridge for 24 hours using 2 car batteries, and after they died, I then connected it to my duramax pickup, ran the truck for 15-30 minutes at a time to charge the 2 truck batteries, and the inverter battery using a pair of 2awg jumper cables to connect to the truck.

 

[shubox56]

Nothing keeps you from connecting it to your vehicle to charge. I ran a fridge for 24 hours using 2 car batteries, and after they died, I then connected it to my duramax pickup, ran the truck for 15-30 minutes at a time to charge the 2 truck batteries, and the inverter battery using a pair of 2awg jumper cables to connect to the truck.

Thanks for confirming!

 

[shubox56]

So what inverter is reliable and a good value for the buck?

 

[TractorJeff]

I'm following with Interest!

 

[gtjunk]

I would recommend you check out some of the solar power forums before spending any cash.
My old place was off-grid, but I'm not normal and my expectations aren't in line with most.

It's important to note that when you size your battery bank, scale it so that not more than about 40% will be consumed for the time you expect to need it. If you drain a battery fully it will not recover and you will find your battery bank will degrade much quicker, which means less run time and increased operating/replacement costs.

 

[shubox56]

I would recommend you check out some of the solar power forums before spending any cash.
My old place was off-grid, but I'm not normal and my expectations aren't in line with most.

It's important to note that when you size your battery bank, scale it so that not more than about 40% will be consumed for the time you expect to need it. If you drain a battery fully it will not recover and you will find your battery bank will degrade much quicker, which means less run time and increased operating/replacement costs.

Funny you should mention solar -- I was JUST Googling that option. LOL

 

[shubox56]

I would recommend you check out some of the solar power forums before spending any cash.
My old place was off-grid, but I'm not normal and my expectations aren't in line with most.

It's important to note that when you size your battery bank, scale it so that not more than about 40% will be consumed for the time you expect to need it. If you drain a battery fully it will not recover and you will find your battery bank will degrade much quicker, which means less run time and increased operating/replacement costs.

Solar is very expensive and being in a townhouse, it's not a viable solution. Interesting to read about, though.

 

[dogdog]

IMO a small inverter generator would have fit your need better... and you don't have to deal with keeping the batteries charged so you have them ready when you needed it... a lot easier to just add a fuel stabilizer and run it once a year maintenance , and keep date on the fuel than all those other things.

 

[SGKent]

a typical refridge is around 700 - 800 watts.

To get 3 to 4 days on batteries you would need 4 to 5 fully charged 200 - 250 amp RV batteries. The battery will only let you use about 120 amps before the voltage goes too low to use.

To get 3 to 4 days cooling from a 2000 watt generator, you will need about 8 to 10 gallons of fuel if you run the generator 3 times a day for 1 hour each to cool the refridge back down. You don't need to run the generator 24/7. Just keep two gerry cans of gasoline ready to go. If you think power outages will be double this then use 4 gerry cans.

The optimal set up would be to have a RV battery or two, and inverter to charge phones, run a small stereo, recharge small flashlight batteries at will, run an extension cord to a LED light or two as needed, then fire up the generator to cool back down the refridge and recharge the RV batteries using a battery charger. I'd remove the inverter from the circuit when charging the batteries only to avoid voltage spikes taking it out.

 

[Bretny]

If some one really wants to pursue a decent battery backup solution, use 6V golf cart batteries. Best bang for your buck. Buy in pairs (obviously). How many you need depends on how long you want to run.

There are actually lithium batterys out there that are a far better value in the long run. FLA batterys only allow you to use about 30* of there capacity. Lithium is more like 60-80* of there capacity, no water to refill and are way smaller/lighter. FLA golf cart batterys do get your foot in the door very cheaply though.

On a side note I had a friend who had a 2,000w inverter hooked to a Toyota Corolla. It kept his food cold and heat working through Sandy or Irene a few years back. He just let the car run all night. Granted your alternator itsnt at optimal speed for the amps output but it worked.

 

[Bretny]

On a side note I bought a sportsman 900w inverter generator a few months back. It will start and run my 5cuft chest freezer. There are no evaporator thawing elements in a cheat freezer like every frost free fridge on the market. The defrost cycle is going to be the biggest draw. This can be over come easily with a plug in timer. The defrost cycle is ran off an internal timer and usually resets when the power goes out. But if your cycling generator run time u wouldn't need a timer.

 

[Sevenhills1952]

Here's some information...

2 Things to Know When Sizing a Battery Backup Unit for a Refrigerator:
https://www.mediproducts.net/blog/battery-backup-for-refrigerator

Years ago I spoke with a local power supply technician who said since most outages occur in the winter all you have to do is put perishables in a cooler with ice or if cold out just in a large box, the roof would be best, or in a car, etc.
An unopened refrigerator or freezer is ok without power for quite a few hours.

People worry about losing power. They don't realize 99.97% of the time they have power.

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[HOTFR8]

An inverter on battery wouldn't run a refrigerator for long! I'm guessing a couple hours? Look up inverters, check your refrigerator power demand and you could figure it out.
An inverter and battery may be ok for low power things, but anything like refrigerator, well pump, etc. you'd need a sufficient generator not inverter.

Sent from my SM-S320VL using Tapatalk

I run my whole property on an inverter. Had the power off here and have all fridges and essentials run for hours. If you look into a decent system and have it set up the right way many items can work with an inverter with Solar and a decent battery back up.

 

[Sevenhills1952]

I run my whole property on an inverter. Had the power off here and have all fridges and essentials run for hours. If you look into a decent system and have it set up the right way many items can work with an inverter with Solar and a decent battery back up.

$?
Certainly with solar and batteries you can run your whole house, even sell back excess (I assume you can), but everything has a cost/benefit factor.
If I lived in Palm Springs I would be very interested in solar...but it seems like here near the Blue Ridge it's cloudy a lot and rains quite a bit.
I finally broke down last year and have a 10kW gas generator. Our neighbors just put in a nice Generac system with 500 gallon L.P. tank. It cycles once a week (testing).
We've been here 40 years and the total outages have been about 12 days. Once power was off a full week...but we were in Florida so we missed that one.

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[HOTFR8]

$?
Certainly with solar and batteries you can run your whole house, even sell back excess (I assume you can), but everything has a cost/benefit factor.
If I lived in Palm Springs I would be very interested in solar...but it seems like here near the Blue Ridge it's cloudy a lot and rains quite a bit.
I finally broke down last year and have a 10kW gas generator. Our neighbors just put in a nice Generac system with 500 gallon L.P. tank. It cycles once a week (testing).
We've been here 40 years and the total outages have been about 12 days. Once power was off a full week...but we were in Florida so we missed that one.

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Location can be an issue and yes you do have to weigh up the $. For me it was a good move as our power is out often on the hottest of days. We can and do export power and even in the middle of winter on a cloudy day my system can be exporting. All depends on how you set it up and how it all works.

 

[HOTFR8]

I have removed a couple of off topic posts and perhaps a dormant spammer.

Ok, so I'm hearing golf cart batteries repeated by a couple --- which reasonably priced inverter?

My smaller system that is my UPS supply for my office has two 6 volt Batteries formerly used in a communication system. Any Solar supplier or battery firm will have a battery you can use.

 

[dcg9381]

So what inverter is reliable and a good value for the buck?

I don't have an answer...Ask over on 5th wheel RV forum (Jayco, Grand Design, others) - lots of them have inverters for residential refrigerators.

 

[dcg9381]

$?
Certainly with solar and batteries you can run your whole house, even sell back excess (I assume you can), but everything has a cost/benefit factor.

You can. It's expensive.

Consider the Tesla Power wall 2.
It's max output is 30A and/or 5.8 kW - basically, lets say you have 25A to play with.... Being conservative, your home has 200A service, probably pulls less than 100A at full load.

To cover it, you'd need 4 x Tesla Power Wall 2's. 4 x $7000 = $28k - and that's just for the hardware, not the installation.

You'll need an inverter/Solar system to charge them that is capable of charging in "grid down" situations (these aren't normal inverters). I'd say, estimate starting price installed at $17k.

You're at $45k "to start" plus the Tesla installation (could be another $4k-$10k), assuming your house was designed or can be reconfigured to use the Tesla batteries.

This system is capable of selling back to the grid, yes.

It'll also last (on battery power) for as little as 3 hours, depending on how much power you're pulling..

Yes, there are other inverters that can do batteries - cost less than tesla, but covering the "whole house" with batteries is challenging.


Lower bar:
Install a whole house Propane LPG generator for under $10k - easily. Will run for days/weeks with a residential propane tank and easily power the whole house.

Install a 6KW PV system in addition - maybe $15k - it feeds the grid excess. Won't work with grid down, but you've got the generator.