Pure sine wave inverter

Help please:
Recently purchased a 2500W Pure Sine Wave Inverter and need to know the correct way of measuring output?
Using a multimeter set to 1000V AC I checked the output and the reading fluctuates between 580V/590V?
Several 240V appliances, 750W grinder, 1000W drill work faultlessly when plugged into device.
Can anyone explain the high reading?

The main reason for purchasing the inverter is to be able to run our caravan fridge on 240V while extended free camping in remote areas, to ease the gas usage.
The van batteries are currently charged with solar panels.

Any advice from our electronic gurus would be appreciated.

Peter

I hazard a guess you are reading across with out a load if you read the user manual it will give the readings you should get. with load and with out load accross the output. but more qualified than me will set you on right path.

It may be the inverter is producing a certain amount of radio frequency hash which is causing your multimeter to go haywire. I guess the multimeter is a digital one.

Cheaper digital multimeters don't have much in the way of r.f immunity. What brand of multimeter and sine wave inverter do you have ?

As for the fridge, personally I would get one that could be run of 12 v D.C direct from the battery or gas and save the bother of an inverter. As well there will be a power efficiency loss when using an inverter.

Direct d.c from the batteries when in non mains power areas would be the most efficient, an 32L Engel camping fridge which draws 2.5 amps of current of a battery is about 40 or so watts of power.

A larger 60L Engel fridge/freezer will draw from 0.5 to 4.5 amps at 12 volt supply, say 65 Watts of power max.

Hope the above is of use.

Lone Wolf,
Yes, the reading is no load.
The manual mentions 60/80VDC output?
Maybe I'm reading the multimeter wrong. 580V/590V could be 58.0V/59.0V
Although this reading is AC, get no readout if I select DC?

Mullockrubber,
Have a Power Inverter Model: HIP-2500
Multi meter: Beckman Industrial Digital - HD110

The van fridge is 150L X 3 way, however it draws 14amps when running 12V.
19kg gas services us for approx 2 weeks, depending on how many showers and in van cooking.
Have heard of success running the fridge on 240V via inverter and am willing to give it a go.
The main point here is how to check voltage ouput from this inverter.

Cheers
Peter

Hi Peter,
If you want to read the real voltage output, but you must be careful, put the plug in the socket but leave it out a couple of millimeters, just enough to be able to put the multimeter probes down and read across the two top terminals (not the straight earth terminal). Multimeter should be in the 1000vAC range as I believe you had it.
On the fridge note, my old 3-way used about 90w on 12v and 100w on 240v. Roughly the same, but you must add the inverter loss into account - but that's not the topic here....
Cheers

Hi Peter
I use an old university analogue meter for such situations or a true RMS meter at work.Keeping a good load on it as the guys said will help a lot a high wattage globe will do the trick.If you use a power board you can plug in your load and measure on another outlet.
Steve

That's a good idea deutran, why didn't I think of that? Peter, follow deutran's idea re the powerboard, it's much safer than mine....

The main point here is how to check voltage ouput from this inverter.

Just a side note....
Regardless of the meter readings, running the 3 way off an inverter will flatten your batteries very quickly.
If there is no charging system keeping your battery topped up while trying to run that fridge...your inverter will shut down as soon as it reaches the inverters LVD Low Voltage Disconnect. My guess is you'll get maybe a couple of hrs before that happens depending on the batteries SOC and overall well being. Those couple of hrs would do very little to the cooling of a heat exchange fridge.

Have heard of success running the fridge on 240V via inverter and am willing to give it a go.

Something to think about, if its was a viable option to run a 3 way off an inverter....everyone would have been doing it years ago.???

A while back had to measure the output of a generator at work and found it was difficult to get the multimeter probes to make good contact in the power socket slots.

Used a 3 pin plug without the cover and attached the multimeter probes to the lugs where the wires normally would go and then put the 3 pin plug into the socket.

Hasten to say this is rather dangerous and any exposed contacts should be well wrapped with insulation tape.

As an added precaution would disconnect the inverter from the battery whilst plugging in and out and not rely on the switch.

The place to connect the multimeter probes are the active and neutral lugs, i.e the two angled ones.

just stick ya finger in there pete--if it goes zzzzzzzz u know u r on a winner--if nothin happens then get the mrs to have a go and smile--

I hate electricity at any time.

regards
oneday69

Thanks for all the hints fellas, will do a test again today under load using a spare socket on a power board.(Very handy hint Deutron)
Have solar panels on the van keeping the batteries topped up, will do some home trials to check what amperage the fridge draws and see if the batteries can cope this function.
Maybe swap the fridge to gas overnight?
Narrawa your point is valid however there are many one off simple ideas that have become the common. Nothing ventured nothing gained mate.


Peter

Let us know your results Peter, I too think Narrawa might be right, but I'm holding by breath in anticipation..

My van was built 2004 with solar system put in by a professional outfit bought in to do the job by Royal Flair. I had a 100 amp aux line put in when the Electric brakes and Towing kit was fitted. The 2 by 100 amp Deep cycle batteries only get charged via 240v ac or the solar cells.
The 3 way fridge run on 12 v only from the tow vehicle. If I leave the fridge on with the 4WD not running it's battery will be flat in less than 2 hours. I have checked the current rating on the fridge it is 47 amps. On gas it will do 3 weeks with daily uses of the gas hot plate. NB this is a fairly large fridge and has no problems with hot tropical weather.

Deutron, Can you please explain a little more about the RMS (Root Mean Square)
Have been doing some Googling and they mention multiplying the voltage by 0.707.
Could this mean the no load outlet voltage 580 X 0.707 = 410VAC?

Cheers
Peter

G'day Peter just googled is this yours...




View Larger Image
2.5kw Inverter
Model: HIP-2500
Approvals: None
Capable: None
Brand Name: HONGHUI
Region: Ningbo Zhejiang
Brief Description: 1.CE ROHS E-MARK CERTIFICATION2.Low and high input voltage protection3.Over loading protection4.Over temperature protection5.Pure sine wave
Continuous power:2500w: Peak power:5000w
Input voltage:12v/24v: Output voltage:100-120/220-240v
CE ROHS E-MARK CERTIFICATION: Overloading protection
Over temperature protection: Low and high input voltage protection
Short circuit protection: Packing:1pc/color box,4pcs/ctn

Offline
Product Details
Key Specification
2.5kw inverter

Continuous power:2500w
Peak power:5000w
Input voltage:12/24v
Output voltage and frequency:100-120v 60Hz
220-240v 50Hz
Pure sine wave
CE ROHS E-MARK CERTIFICATION
Low and high input voltage protection
Overloading protection
Over temperature protection
Short circuit protection
Packing:1pc/color box,4pcs/ctn
G.W/N.W:30/28KGS
Meas:49*48*28cm


We were running a 3 way fridge for five years, but found that having to get a bottle of gas every 21 days, was a pain. Not to mention expensive.
So when we updated our caravan, brought one with all the mods cons, we also got them to add a waeco compressor 12 volt fridge..150 litre.. Have two 110 amp hour batteries. A smart charger, plus one 120 watt solar panel on top of van.. Now fridge keeps everything cold. Never have to worry about gas running out.. One nine kilo bottle last easy two months or more, we use gas cooking and a gas hot water service..
Solar panel keeps up with it all day even when there isn't much sun.
Run a 20i geny at night, for a couple of hours, we were told the smart charger would charge batteries up within 20 minutes, which it does. But mainly run the geny to run the microwave, and aircon.
Batteries are usually fully charge by 9:30 am by the solar. On sunny days.
We also have 12 volt lights, which I replaced with led lights,
They don't use hardly any power, and the van is lit up really well. We worked out that in 1 year the solar has payed for itself just on gas only... We live permanent in our van...


Cheers.

Mike.

Morning Mike,
The details you have posted are similiar however we bought our inverter from an Australian supplier. Maxkon has identical markings.
Your setup sounds ideal, we only get two weeks from a 9kg bottle.
As has already been mentioned if run on 12V the power draw is excessive, 14amps.
If run on 240V amperage draw is approx 1amp however am trying to establsh what is the actual combined amperage using an inverter?
This is all a learning curve and any info is appreciated.
Looks like an actual trial is required to prove one way or the other if this method is practical and power saving and end result saving gas.
In the mean time can not fathom out how to read inverter voltage output.

Peter

Peter, I think the actual formula for working out power in voltage by amperage. So 12Vx14A= 168W and if you are right and it draws 1A at 240V then that is 240Vx1A=240W. So if the inverter is needing to supply 240W output, then it will need more than 240W input to compensate of internal usage and losses, therefore the very least it will use is 240 / 12 = 20A for the input from the battery.
Anyway it will be interesting to see you final results...
Cheers

Or you could simply put a large Amp meter in series with the inverter at the battery end while its running the fridge. This will convince you in the simplest of tests. I did this some time ago and did what others have done, put a 12v fridge in place and use the old fridge as a pantry.

You get nothing for free using an inverter, pure sign wave or not.

G'day Nightjar

Good luck with your experiment, but trust me with a big inverter like that, we did the same thing 2400w 4800w peak, trying to do what you are doing, amongst a few other things, and the big sudden drain on the battries, 2 x 100ah AGM deep cycle. They are now dead and buried.

We have now replace the battries with new 130ah AGM battries (same as Ted Topcat has) and now treat them with a little more respect, in that we don't let them drop down to low, try and not let then go below 12.2v to 12 .4v and if you take out 80 amps for the day then you have to put back in 80 amps, if you don't then it's just a cumulative gradual loss.

These battries should stay at 12.6v for hours on end running what ever it is your using appliance wise, TV and light etc etc.

If you try running your fridge at night along with these other things just make sure that you don't drop your battry voltage down too low.

If running your fridge during the day and it takes most if not all of the solar you can generate being consumed immediatley, then your battry will slowly but surely deterioate.

Anyhow good luck with your experiment, but keep in the back of your mind big power draw from battries = not good.

cheers dave

mmmm not looking good, saving some gas by using an inverter.
Is there a formula for calculating actual amperage?
As you all are saying unless the solar replaces the used amps the batteries are going to take a knock.

Cheers
Peter

You need be exremly carefull on usage as you never get the battrys fully charged they only get back to about 80 to 90 % so you need put more in than take out or a very short life for those poor battrys.Inverters are good for short use small appliences low draw on power, other wise as stated by all the other posts we would all be running our houses on them. but good luck with the experiment we all wait on the eventual outcome .

G'day Nightjar

The amps have to be replace somehow, either by extra solar panels or a generator or by 240v power when your near it, the last option if used should not be delayed to long and let the battries get to drained.

You just need to be sure how many amps you are going to use continually, and make sure you have enough solar to replace that amount, or genny that can be used incase of bad weather/cloudy. And enough battery/amps to store the excess power made during the day to be used at night, without over draining the battries.

You have probably already looked up these conversion calculators, but here is a link to one.
http://www.powerstream.com/Amps-Watts.htm

cheers dave

The whole thing is sort of do-able, but with a 2-way fridge as they draw approx 4 amps when the compressor is running (roughly 50% of the time), roughly using about 48Amps/day. A 3-way uses over 10Amps 100% of the time, roughly using 240Amps/day. If you got a 2-way to supplement your 3-way, you could run the 3-way on gas and the 2-way on 12v while you still had a lot of supplies, and after 2 or 3 weeks turn it off the 3-way and just use the 2-way only as the stocks get lower.
3-ways are the best for minimal LPG usage over the time but 2-ways are the best for 12v & 240v usage. Anyway, it's just an idea....

You can pump thousands of $$ into solar gear for just a few weeks away...and it will fail sooner or latter due to cloudy periods. Imagine a week of just cloud and rain??.. while your appliances keep pulling the juice out that your panels cant quite replace, the system is slowly running down. Answer ---> spend more money, add more weight, take up more room ect.
Save yourself big $$ and opt for a small generator and run it for a few hrs each night if need be.
Have on hand a good 240v battery charger to do the major charging...15-25 Amp charger will put back in a very short time what your trying to achieve with thousands of $$ worth of solar gear that weighs a tonne.

Im not saying dont have any solar, but do the figures and work out for your setup a happy medium.
The fuel efficiency of the Honda EU20i is remarkable...and id have to probs saying this for the Yamaha or similar brand.
I run mine this season gone near on 9 out of 10 nights in WA and it cost only a couple of hundred dollars. I could have opted for the smaller model but went with the general consensus with my selection.
Electric blankets...15Amp inteli charger...bread maker every night, lights, phone/detector/and assorted electrical chargers and goods including laptops, TV, DVD player, electric kettle, two fridges while batteries were being topped up...aircon early in the season both day and night till it was not needed. Electric heater Halogen type.
There were many nights one could not be bothered to get up and turn it off, and depending on how much fuel was put in that arvo, it was still running when we woke the next morning.
The beauty of the generator is...low weight, low running costs, low maintenance, and runs everything. Works both day and night to charge batteries if need be...including the main vehicle start battery if idiocy takes place due to human error.

Those who have big $$ tied up in their solar systems...still have a geny...that should tell you something.??

A small 1KVA would have run much of what i have in our van effortlessly....including halogen heater 2x500W bars using one bar only... aircon 500W cold only..... Bread maker 600W max in bake mode.

Very interesting, thanks to all of you who have contributed.
It certainly has become obvious that the 8 amp input from current solar panels are not going to keep up with the drain from the fridge.
Back to the drawing board.
One point that jumped out at me was Narrawa's mention of bread maker!
Are you saying your bread maker runs off your generator power without any interuptions to the cycle? Have often thought about fresh bread every other day but was informed (looks like misinformed) bread makers and generators don't mix.
No question we can learn something new every day.

Peter

G'day Peter

One point that jumped out at me was Narrawa's mention of bread maker!

Our Yamaha ef2800i runs our breadmaker, right through from start to finish, 3 hours, and I know Narrawa's Honda EU20i does the same as I've been camped with em when they use it for the breadmaker.

cheers dave

Without a problem..... they pull 600W when in bake mode and much less while kneading the dough, and the smaller generators would have no problem as long as you dont interrupt the process for more than 5 minutes. (eg...run out of fuel due to not topping the geny up ) Like Dave said...its a 3 hr process.....and its absolutely mess free.
You can also use it to knead damper mix.... Bacon and cheese mixed in with both damper and bread mixes along with the multiple recipes available. The smell of fresh bread cooking is mouth watering. We have on occasions scoffed the first loaf while it was steaming hot and put another mix on for tomorrows sandwiches.
The 600Watts is intermittent, the heating element is never on for more than a few seconds at a time during the bake cycle, which from memory is about the last hr of the 3 hr cycle. In that time the batteries and anything else is being taken care of while we watch the news on TV or hang out by the fire sipping a red or having a beer with friends.

Great replies guys! I'm thinking of setting up a solar panel/ battery / gennie . I will be buying the panels and battery first as I have a small gen set ,750w -650 draw , so it will do for the moment until I ca afford a inverter gen . Thanks again , love the idea of a bread maker ,

Your spot on narrawa I have a kimberly kamper and it has 210 hr batt supply and a constant solar panel feeding them also a 80 watt fold out panel, But i still carry a 20I honda and sometimes need run it for about 2 hours at night,And as you say look about and you will see 90 % of campers and vans have a geny of some sort .BETTER SAFE THAN SORRY.

Very interesting thread, especially to someone like me that's in the throws of tackling camp power production, I see the Honda 20I gets a good wrap, I have seen them working first hand and they seem to be brilliant and so quiet!!! are there any of the cheaper models worthwhile that people have had experience with?, I'm not expecting to get a Honda for the price of a lesser known name, just curious as to how they stack up.. if at all? what would the expected life hours of a Honda20I or similar machine be?, if that's known?.

Wayne.