Power inverters

SVcummins

Well-known Member
How do you size a power inverter ? I want to run a gasboy fuel pump and I don?t know how big of an inverter I need to run it
 
The motor on the gasboy should have a tag with the amp draw, that figure will be the current draw after the motor is running, Starting amperage will be cosiderably higher. The inverter you choose will need to be capable of meeting the starting amperage of the motor which will be 2 - 3 times the run amps. My guess is you will need an inverter capable of starting a 1500 watt load. Many inverters are labeled with intermittent load and continuous ratings. So an inverter with a 1500 watt intermittent rating should work fine.
 
(quoted from post at 22:53:59 05/14/19) How do you size a power inverter ? I want to run a gasboy fuel pump and I don?t know how big of an inverter I need to run it

For what an adequate inverter will cost you could probably darned near buy a 12 Volt field service tank pump, and have less battery draw as well.

Any time you invert or convert power with affordable devices there's a significant loss.

Or, how about a "previously owned" tank and 12 Volt pump?

Around here, all the real operators have gone to thousand-gallon factory-made fuel trailers, and you can't hardly give away a 250 or 500 gallon tank and 12 Volt pump.
 
What about buying an RV generator? I bought a Champion 3500w are around $300 a few years ago.

A 1500 w Power inverter will zap a battery.
 
The real answer is IT DEPENDS

SHORT ANSWER: You have to know the pumps running WATTS and then size an Inverter capable of supplying that (with wiggle room) PLUS has enough short term surge capacity to start the pump...??.

Starting and running current of the pump. The initial surge current when starting may be 4 to 6 times the run current so the Inverter needs that much short term surge capacity.

BATTERY POWER TO RUN THE PUMP VIA INVERTER

For every amp the pump draws at 120 VAC, a 12 Volt battery has to supply around 11 amps to the 12 VDC to 120 VAC Inverter and the energy required to run the pump for X hours is that 11 battery amps for X hours run time IE Amp Hours of energy.

EXAMPLE to make it easy if the pump drew lets use 5 amps at 120 VAC and you ran it lets use 10 minutes. That means the battery would have to supply 55 amps for 1/6 hour or 9 Amp Hours. If it drew 10 amps for 10 minutes that's 110 x 1/6 = 18 Amp hours. As an example lets say you had a 12 volt flooded lead acid battery rated for to make it easy lets use 100 Amp Hours and you shouldn't discharge it over 50% or 50 useable amp hours before recharging. If you ran a 5 amp pump 10 minutes and consumed 9 Amp hours you would get around 5 pumpings before the battery needs recharged

Not knowing the pump power requirements its a pure guess you may need a 1000 to 1500 watt or larger (subject to pump) Inverter. It has to have the capacity to supply running current and short term surge capacity to get it started. Then you need sufficient battery and/or charging capacity. If the pump draws much less you can get by with a smaller Inverter WELL DUH

Of course if the battery was on your pickup its alternator can be supplying charging current so theres less worry with the recharge discussion above.

Its more efficient if you had a 12 VDC pump so you avoid conversion and inverter inefficiency and heat losses.

NOTE the above is an approximation and NOT intended as accurate (no pump specs here) but ONLY an example so don't anyone have a calf now

John T Long retired n rusty Electrical Engineer so noooooooooo warranty
 
Larry I will look and see what I can find on the pump . I?ve got a good hand pump it will move as much fuel as the gasboy if you got arm enough to run it but operators don?t think it?s as fun to use as I do
 
You need to know the continuous rating of the inverter and if it makes a square-stepped modified sine-wave or a more correct rounded sine-wave. A "modified wave" inverter with square steps is cheap. Often $100 for a unit rated 2000 watts continuous and 4000 watts surge. It is poor for electric motor starting though. Inverters sold as "sine wave" cost more but start motors much better.

Gas pumps tend to have a start surge at 600 watts. So you need an inverter sizes around 1000 watts continuous rating.
 
I am not trying to spend your money for you but . . . This is one of the best fairly low priced inverters I have used when it comes to electric motor starting. I am sure there are others but I know this one is amazing. Xantrex is one of the oldest inveter makers around. I had a mod-wave 1000/2000 running a small 120 volt refrigerator and it struggled. Got this Xantrex and MUCH better.

1000 watts continuous and 1800 watt surge rating. Your gas pump likely surges at 600 watts.
cvphoto23166.jpg
 

All good advice so far .
As it appears that your estate could use a generator to operate the fridge, freezer, sump pump , microwave , C-pap machine etc .
This is a whisper quiet machine that will operate on either gasoline or propane . Light enough to pickup and set in the truck bed.
The general rule of thumb when purchasing an invertor or "small" generator . Is to calculate all the required loads , figure the size of the generator required and then double it .
Anyone thinking they can operate a 12.5amp load continuous on a 1500W generator is overly optimistic.
https://www.championpowerequipment.com/product/100264-3500-watt-dual-fuel-inverter/
 
I am not disagreeing with you but . . . Much depends on the actual ratings of the draw and whatever is making the power.

For example, a so-called Honda 2000 watt inverter-generator is only rated to make 1600 watts continuous.

Some high-end power makers give actual output in time-frames. Some over-rate in the advertising and a few under-rate (kind of rare now
adays).

Here is one example. Xantrex 2400 watt inverter.
Rated for 9200 watts for 1 millisecond.
Rated for 6600 watts for 100 milliseconds.
Rated for 4200 watts for 5 seconds.
Rated for 2400 watts forever.
 
All I know is years ago I bought a rated at 300 watt unit to try to run a dorm size refrigerator in camper that called for way less power than the invertor was rated at. would not do it so tried with a standard incandesincant light bulb of 75 Wats and that bulb would kick the unit off. Unit was rated for 4 tomes what the bulb should have taken. Think it went to scrap.
 
Obviously you bought something that was misrepresented.

Many RV and marine refrigerators made my Norcold for 12 volts DC use had AC powered compressors. Norcold used a small built-in inverter to power them. I have one sitting in my shop right now. Inverter from the factory that is hard-wired is about 4" square. Pretty small unit that obviously does the job.

One of my RVs has a dorm refrigerator that is powered by a 800/1600 watt inverter. It has worked fine for many years.
 
I've owned RV's for 49 years and in later years owned a bunch of different size n shape and brands of Inverters and based on my experience I will say this:

While they cost more, if you end up buying an Inverter I highly recommend you purchase a PURE SINE WAVE (PSW). Sure some equipment works with a cheaper MODIFIED SINE WAVE (MSW) but I have seen equipment problems when using them HOWEVER I've never seen equipment problems due to the use of a proper Pure Sine Wave PSW Inverter. All that's left is see how many actual watts the pump requires so you can easily size the Inverter ALLOWING FOR THE FACT START UP REQUIRES MORE AMPS THEN RUNNING AMPS. That's where an Inverters SURGE rating can come into play but beware that can be a bunch of HYPERBOLE lol NOTE that's NOT to say a good MSW cant still "work", your money your choice not ours

A few among several brands you might take a look at are Magnum and Victron and Xantrex

HOWEVER its more efficient and no Inverter required if you go with a 12 volt DC powered pump if available.

Post back any Inverter or Battery type questions

Hope this helps

John T
 
Leroy I bought a little 100 watt at Christmas time cheap one time it would charge my phone but wouldn?t run anything else
 
AS I recall, the people at Xantrex had one of the first consumer-grade portable inverters - back when they called the company "Trace." Heart and Trace/Xantrex supposedly got their start making inverters for small boats - and for marijuana farmers living off grid and hiding out in desert areas of the southwest. Believe it or not, Mr. Heart wrote a small book on the history of such inverters. I found it kind of interesting. Most of the companies that sold them in the USA were started by disgruntled employees who set off on their own. Like Outback. Now - seems things have changed since the market is flooded with stuff from Asia.

Xantrax (Trace) got bought out and is now a Canadian company. Still, they are still making good equipment. Very few consumer-grade inverters sold as "sine-wave" make a true sine-wave, but some come surprisingly close.

I have been using inverters since the 50s models that ran on vacuum tubes and a 150 watt inverter was the size of a suit-case. Things have really changed. I will also note that there are some very cheap so-called "sine-wave" inverters being direct-marketed from China and show a really nice sine-wave on my scope.

Norcold AC/DC refrigerators in the 80s used AC compressors with small, hard-wired mod-wave inverters built in. They did, and some still do - work very well. Not much step-up windings needed though. As I recall the AC compressor runs on 40 volts, so the inverter only has to have windings to step up 12 volts to 40 volts.
 
I've owned Xantrex products that were okay but owned a Xantrex Charger that crapped out after only a few months grrrrrrrrrrr

I like Magnum and Victron and Xantrex Inverters but there are also other good brands out there

John T
 
Like I said, most of these companies were started by ticked off ex-employees of other inverter companies. Magnum was started by people who had formerly worked for Trace/Xantrex. Same goes for Outback.
 
Great history lesson, thanks. Regardless who started them or who works or did work for whomever, I still like Victron and Magnum and Xantrex. To each their own preferences and I'm sure different users can report different experiences. And there are other vendors also but I have less knowledge concerning many of the others.

Nice chatting with you

John T
 
A generator can be a temporary power back up. Portable power where an extension cord can reach. I have mine mounted in a lawn cart. My second generator is easily put in truck.

A generator is more practical than an inverter.
 
I have a big generator welder I guess I could throw
it on the truck and power the fuel pump with that
then I?d have fuel and a welder / power in one spot
wouldn?t be a bad idea
 

Remember gasoline is highly flammable. Just don't setup the inverter too close to the gas pump, and put a long cord on the pump. Also seal the cord where it enters the pump.

Dusty
 

Remember gasoline is highly flammable. Just don't setup the inverter too close to the gas pump, and put a long cord on the pump. Also seal the cord where it enters the pump.

Dusty
 
I plan on using a long cord this is diesel I?ll be
pumping so it?s not nearly as flammable as gas I?ve
used the pump at home on the diesel tank for years
I?m just wanting to make it mobile
 
Friend and I about 10 yrs ago bought Inverters from Harbor Freight. Think they are 1800 3600. Mine will run a 120 gasboy easily. It ran another friends refrigerator, tv, and lamp. For a week during a Ice storm. Ran it from a new Ford Taurus, He was handicapped, and wife could drive car to station and get gas and groceries. Then alligator clip inverter to battery and let car idle all day and night. They had a wood stove. Think inverter was $99. Bargain!
 
That?s the story I wanted to hear . I?ve got big enough batteries available to feed one and the gasboy will pump 30 gallon of diesel in about 5 minutes so the truck could idle
 
I have two inverters from Harbor Freight. Both are rated 2000 watts continuous and 4000 watts surge. One I bought 14 years ago and the other 2 years ago. Both have been fine. The one that is 14 years old cost me $79 on sale. I have used it to build several off grid cabins and ran a small air compressor (for a nail gun) and a 13 amp circular saw. Only slight complaint about either is they do a lousy job running a cordless-drill battery charger. Also make GFCIs buzz if any get plugged in. Ran my tools fine. The older HF unit has a thermal-fan that almost never comes on. On the newer one, they cheaped out and the fan is hard-wired to run all the time. If you use it inside a small building or RV the fan noise can drive you nuts.
 
Acording to figures on the refrigerator I figured what unit was advertised as it would have plenty of capacity, When it would just trip out I decided it was just overloaded due to figuring things differently but them when I tried it with just a simple trouble light with that 75 watt bulb and it would trip out I gave up on it. Something like the frige I could understand if it was just a over starting load but a bulb does not have that. Now this was back in the 90's so not that much information avaible on things. I had seen them working on the power line service troucks so I figured it would be good for that little fridge in camper when on the road.
 

Got a couple of 2000 watt inverters in a garage sale. Put one on my kawasaki mule and use it with the pole saw for cutting tree limbs. works very very well but the mule was to be running or the inverter will shut off after about 3 cuts, due to low voltage alarm. Also run the sawsall and other tools. Since I have a heavy duty cord coming from the mule battery with a 200 amp plug on it,,, I can plug in my jumper cables for jumping tractors and stuff, or plug in the inverter, so its a great setup for around the farm. Generators are bigger and too heavy for small jobs when the inverter does fine.

The inverter also can be plugged into ac power and doubles as a heavy battery 100 amp charger with the 200 amp plug with the jumper cables mentioned earlier.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top