Buying an Inverter

[Mr. Spock]

One last worry..
Is it possible to have a pure sine inverter which cannot support an inductive load ?
When running , a pellet stove is surely just that ?

The possibility exist where the rating of the inverter can be exceeded by inductive loads such as motors. They will pull higher wattage on buld up to tourqe (surge load). To be safe use the wattage requirement of the appliance and double it. Use that value to size the inverter.

 

[tjnamtiw]

The possibility exist where the rating of the inverter can be exceeded by inductive loads such as motors. They will pull higher wattage on buld up to tourqe (surge load). To be safe use the wattage requirement of the appliance and double it. Use that value to size the inverter.

By my personal experience, the worst case scenario are refrigerators and freezers where the startup current can be as much as 10x the running current if the compressor is exactly at the wrong position to start.

 

[Mr. Spock]

By my personal experience, the worst case scenario are refrigerators and freezers where the startup current can be as much as 10x the running current if the compressor is exactly at the wrong position to start.

Most inverters provide surge current for brief periods of time and higher quality units will specify "how much" for " how long". I am not completely familiar with refrigerant compressor design but I know ac induction motors are used and split phase design comes to mind. In any event a motor behaves as a transformer with its seconday winding shorted when the rotor is not spinning. The surge current will be at maximum if the primary winding is connected at the instance of voltage zero crossing and the following voltage half cycle is in polarity with the remnance magnetism of the rotor core.
Not including any mechanical sticky spots of course

 

[Monica in France]

No – I was not thinking of start-up current as ventilateurs pose little problem here as apposed to compressors ( heat pumps = fridges / freezers etc ) where the load is immediate. ( I learnt all about this converting my car-lift to single phase ! )
A ventilateur builds up to its full load.

I was more concerned with the phase difference of the curent. I've noticed many square wave inverters are marked < not for inductive load >

All efforts to educate me will be gratefully received.

 

[SwineFlue]

I've noticed many square wave inverters are marked < not for inductive load >.

The square-wave output is extremely hard on inductive loads (motors and transformers) and will overheat the coils. They require a smooth, clean sine wave power source for proper operation. Do not use a square-wave inverter for a pellet stove.

 

[Mr. Spock]

As SwineFlu and wsar10 have explained stepped sine is not ideal for ac induction motors. It's not current phase per se, as much as the dead spots at voltage zero crossing assuming a 3 level modified square wave. As I have indicated, the RMS voltage for stepped sine is lower than pure sine and therefore the motor must draw more current to maintain torque so the motor runs hotter. Step sine induces pulsating tourqes. If you listen to an ac induction motor on modified sine, especially under load, it will sound quite different and not for the better.

 

[_CY_]

almost a waste of time fooling with an inverter backup ... runtimes are too short
go with a honda eu2000i very clean power

 

[tjnamtiw]

honda eu2000i

almost a waste of time fooling with an inverter backup ... runtimes are too short
go with a honda eu2000i very clean power

It better be very clean for a $1000!! That would buy 3 or 4 control boxes

Also when the SHTF and there's no more electricity to pump gas for that generator, the inverter running off of batteries and solar panels will be the ONLY way to go!

 

[tjnamtiw]

We have blown quite a few pcbs and transformers with owners going cheap. Wsar is right it must be pure. We only recommend 5kW+ and absolutely no auto ignition. Very murky water here as they should work in theory but they dont.

We have a simple rule of thumb,"if it wont run your toaster don't let it toast your stove!"

Hi Chickenman,
Interestingly enough, I pointed out earlier that Harman's recommended inverter that they sell is NOT pure sine wave by the admission of the company that makes them.

 

[wsar10]

Hi Chickenman,
Interestingly enough, I pointed out earlier that Harman's recommended inverter that they sell is NOT pure sine wave by the admission of the company that makes them.

Maybe they are using DC motors with some type of switching regulator setup.
I cant understand why ALL new pellet stoves or any new product does not use DC motors fro efficiency , you can spec a DC motor these days to meet any need.

 

[_CY_]

It better be very clean for a $1000!! That would buy 3 or 4 control boxes

Also when the SHTF and there's no more electricity to pump gas for that generator, the inverter running off of batteries and solar panels will be the ONLY way to go!

I'm using two sine wave inverters .. Trip Lite PV2000FC 2000 watt continuous, 3000 watt one hour, 4000 watt peak .. Maintains PWM sine wave output voltage of 120 V AC (+/-5%) Ideal for industrial power tools, window air conditioners, electric motors, pumps, desktop computers, laptops, portable electronics, etc.

other inverter is a Redi-Line which is really a rotating AC generator that puts out true sine wave .. it's got 1600 watt output ..

 

[Monica in France]

That is a bit of an overkill for a stove isn't it ?
Mine is rated at 100 Watts.

 

[Monica in France]

Chickenman : I hate to mention this but you don't need pure sine to run any toaster I've come across !

 

[bondo]

That is a bit of an overkill for a stove isn't it ?
Mine is rated at 100 Watts.

The manufacturer of my stove recommends 1000 watts. You want overkill for the just in case. They are also consider the auto ignition I assume.

 

[wsar10]

Chickenman : I hate to mention this but you don't need pure sine to run any toaster I've come across !

this is true a toatster is resistive load.

 

[rick31797]

I bought a pure sine 1000 watt inverter today.. and still need to get some cables to hook it to my battery...

(broken image removed)

 

[chken]

I'm using two sine wave inverters .. Trip Lite PV2000FC 2000 watt continuous, 3000 watt one hour, 4000 watt peak .. Maintains PWM sine wave output voltage of 120 V AC (+/-5%) Ideal for industrial power tools, window air conditioners, electric motors, pumps, desktop computers, laptops, portable electronics, etc.

other inverter is a Redi-Line which is really a rotating AC generator that puts out true sine wave .. it's got 1600 watt output ..

That tripp lite inverter looks handy for camping too. If I were to hook that up to a Prius, would the car come on automatically to keep the battery charged? I'm talking the regular battery not the traction battery.

 

[TimfromMA]

I built my own battery backup using a 1500W APC and a pair of 90AH Marine Batteries. It cost me about $500 in parts and will run my stove for about 8 hours.

 

[Mr. Spock]

The setup you invest in will depend on your requirements and budget. After the nor eastern of 2011 I learned quickly just how dependent one is on electrical power. There was no grid for 7 days and gas unavailable for several until stations brought in backup generators. I immediately prioritized needs verses wants. The first priority was keeping the family warm. To meet that requirement I installed a solar system that can run the pellet stove well into 5 days or more without sun. The stove runs on the system all winter. The inverter I choose was a Magnum which is used in rv's. Very dependable. In the summer the system has other benefits such as powering the air conditioning. It can also run the well pump if needed.

 

[_CY_]

That tripp lite inverter looks handy for camping too. If I were to hook that up to a Prius, would the car come on automatically to keep the battery charged? I'm talking the regular battery not the traction battery.

sorry no intelligent features for auto start .. even though I've got a really good inverter .. choice for portable power is really Honda EU2000i
inverter is for my 8hp diesel powered generator with 200 amp 12v output .. plans was to mate diesel genset to a 12v battery bank powered with solar.
like a lot of projects it's stalled .. solar panels and control box has been sitting ..

exiting news on solar cells .. efficiency just doubled to high as 50% by using solar cells with several layers. with each layer absorbing a different wavelength .. http://www.economist.com/news/scien...ency-solar-cells-about-go-mainstream-stacking

 

[TCZON]

Looking at the inverter that rick31797 posted, as it's on sale at Crappy Tire this week. We already have 6 6V golf cart batteries just sitting in the basement, ready for a new job, since the golf cart has gone to scrap yard heaven. Hoping we can get a battery backup system going before fall at the latest! With 6 batteries, I'm hoping we can get something set up to give us 24hrs plus of backup power. We do have access to some power during a power outtage, but it requires us running heavy duty extension cords over 275' to the barn with the generator backup on our property. The first priorty for this power is our sump pump though, everything else becomes secondary, including heat, unfortunately.

 

[rick31797]

So i get my new inverter hooked up and plug the stove in and i get an error,, it says

Inverted polarity in power outlet....

Now i see on the back of the convertor a ground screw..says nothing in the manual about it.. do i run a small ground wire from the convertor and attach it to the black negative cable attached to the battery..

 

[Owen1508]

I was just looking at this one. A little overkill but it's a all in one unit. Just need marine battery and cables.

(broken link removed to http://www.sell.com/271W8G)

 

[TimfromMA]

Check out this thread about the battery back up I made out of an APC and a couple of marine batteries.

https://www.hearth.com/talk/index.php?threads/Homemade-Battery-Backup.125698/

 

[gfreek]

Inverted polarity in power outlet....

I would check the wires in the outlet and make sure black and white wires are on proper terminals..
http://www.ehow.com/how_2313797_fix-reverse-polarity-receptacles.html