240v fridge - Samsung, F&P or Hisense?

[BruceS]

a watt is a watt.
It depends on what voltage to determine the Amps.
So a 100w is still a 100w but by converting/using a 12v inverter you will lose 'some' overhead.
So perhaps 108w ........ @ 12v will be 9A.
@ 24v will be 4.5A.
@ 48v will be 2.25A.
The efficiency of the inverter will vary. Old ones were a lot worse than the newer ones.
A lot of the time we can forget about Amps in our setups. Watts are a lot more relevant in my opinion.

[freechange]

Gotcha. I was starting to go in circles there for a minute.

[T1 Terry]

It is all only an average result as the real figures are constantly changing. The start up current depend on the head pressure remaining and this depends on how long since it cycled off. The max start up current is shown as the locked rotor current and this will be at the nominated operating voltage..... and that isn't always 240vac. So, if you use these figures as the extremes then you will be within normal operating limits in general operation. Start up current is locked rotor current x 240vac i.e. 7.5 amps x 240vac = 1800w. allow 10% for inverter losses and you would need an inverter with an output of better than 1980w. forget the peak figure advertised with these inverters, it is so short it may as well not exist, certainly not long enough to spin up an induction motor. The heavy weight inverters with the big transformers and the high $$ big brand names are in a different breed, the likes of the Projecta 2000w PSW can handle a 10% overload for a few mins, they squeal in protest but they will do it.

[freechange]

OK, heads spinning again. Who's on first...

Here I am talking in 100s of watts regarding inverter size when it should be in 1000s.

Now I see why George is using a 1000w 24v PS inverter for the Hisense. I didn't think the start up current would be so high.

If the Hisense power consumption says 100 watts then this means after startup it hums along drawing about 10amps (@ 12v ) through the inverter. But, I think you're saying the startup current can be nearly 20 times that, or 200amps?? If so I can't use AGMs if I want a 240v fridge.

And, how inefficient is drawing 10amps most of the time using a 2000w inverter? No option of course but what does the inverter use just sitting there on standby? I've only ever used a 300w PS in the past with almost zero standby.. Never had the need for anything larger. I used to see setups with 2000w inverters so they could run microwaves or hair dryers and thought, they're killing their AGMs. Different of course now Lithiums are on the scene.

[BruceS]

"""Start up current is locked rotor current x 240vac i.e. 7.5 amps x 240vac = 1800w. """

That was simply an example.
What is the "locked rotor current" on your choice of fridge?
Yesterday I used my WATTS CLEVER energy meter to test a friend's air conditioner system he recently installed in a poptop caravan.
I forget the brand but will check later.
After half an hour we checked the results. (Half an hour resulted in many cycles on/off)
The highest it got to was 1463w. He went to the Adelaide Caravan show & is looking at a Honda is2 but wasn't sure it'd run it.
Anyone with a Honda like to comment?

[T1 Terry]

Ok, the Fisher & Paykel advertises a current draw of 0.5 amps @ 220vac to 240vac. Locked rotor current can be 10 times that figure, 5 amps @ 240vac is 1200w, yet running this fridge draws between 7 amps and 5 amps @ 13v from the lithium pack. The simple solution is not to try and start up the compressor at full head pressure. If the power goes off while the fridge is close to the end of it's on cycle, the pressure will be high, wait 10 mins, then turn it back on, a much lower head pressure so a much lower power demand for that first few seconds getting the compressor up to speed. The inverter fridges don't have a big start up current at all, a 250 ltr will run on a 300w inverter without an issue, but the same size non inverter fridge will require a 600w inverter to cover the start up load.

T1 Terry

[nomads]

"""Start up current is locked rotor current x 240vac i.e. 7.5 amps x 240vac = 1800w. """

That was simply an example.
What is the "locked rotor current" on your choice of fridge?
Yesterday I used my WATTS CLEVER energy meter to test a friend's air conditioner system he recently installed in a poptop caravan.
I forget the brand but will check later.
After half an hour we checked the results. (Half an hour resulted in many cycles on/off)
The highest it got to was 1463w. He went to the Adelaide Caravan show & is looking at a Honda is2 but wasn't sure it'd run it.
Anyone with a Honda like to comment?

G'day Bruce,

We have the Air command Ibis air con and this will run happily off the Projecta Intellicharge 2000w psw inverter.

The maximum watts I have seen on the remote panel meter is 1550w and that was last week when outside temp was 39 deg C and it bought inside temp down to 26 deg C in approx 30 mins.

We also used the Honda 2.0, to power the air con, a couple of days ago. Outside temp was 39 deg C, c'van was in full sunlight, Honda was located approx 15 metres from c'van and both air con & generator operated with no problems.

The c'van was in full sun as the couple we were camped with were walking 600 head of cattle and they had the nice shady spot.

In fact, when inside temp had dropped to 26 deg C, I turned the Projecta battery charger on (although I did wind it back from 50amp to 12.5amp) and this did not worry the generator or the air con.

The generator ran for approx 5 hrs on a tank under the above conditions and I refilled it once, so was running for over 8 hrs.

I have done the above on numerous occasions and have never had a problem.

Obviously the Honda is working above "Eco" power, but as we don't use it that often, it is good to give it a bit of hard work when we do!

Regards,

Ian

[freechange]

"""Start up current is locked rotor current x 240vac i.e. 7.5 amps x 240vac = 1800w. """

That was simply an example.
What is the "locked rotor current" on your choice of fridge?
Yesterday I used my WATTS CLEVER energy meter to test a friend's air conditioner system he recently installed in a poptop caravan.
I forget the brand but will check later.
After half an hour we checked the results. (Half an hour resulted in many cycles on/off)
The highest it got to was 1463w. He went to the Adelaide Caravan show & is looking at a Honda is2 but wasn't sure it'd run it.
Anyone with a Honda like to comment?

My Honda 2 ran a Dometic B3000, if the genny was kept cool in the shade. Although at about +38C ambient, when it was really needed, it gave up the ghost. The Honda 2 is rated to a constant 1600w so should be fine. Problem is it had to run full bore constantly to cover the air con stopping/starting. Eco mode was not possible so fuel usage was high.

[freechange]

Ok, the Fisher & Paykel advertises a current draw of 0.5 amps @ 220vac to 240vac. Locked rotor current can be 10 times that figure, 5 amps @ 240vac is 1200w, yet running this fridge draws between 7 amps and 5 amps @ 13v from the lithium pack. The simple solution is not to try and start up the compressor at full head pressure. If the power goes off while the fridge is close to the end of it's on cycle, the pressure will be high, wait 10 mins, then turn it back on, a much lower head pressure so a much lower power demand for that first few seconds getting the compressor up to speed. The inverter fridges don't have a big start up current at all, a 250 ltr will run on a 300w inverter without an issue, but the same size non inverter fridge will require a 600w inverter to cover the start up load.

T1 Terry

Sounds like I should be able to get away with the Victron 700w 12v PS for the Hisense. Not having a microwave so can't see the need for a 2000w inverter. If I go Lithium I may up the inverter size to run a split system domestic air con, if I can squeeze one into the layout.

[T1 Terry]

I like the idea of an inverter dedicated to powering the fridge and a second inverter for the big loads like air con and microwave etc that is only one when needed. This adds the redundancy factor that will cover a failure of the fridge inverter till a replacement inverter is found. By using a slightly over sized inverter the over load strain is removed and the opportunity to add a power point dedicated to phone/laptop/table charging a well.
$$ would be the only reason not to consider lithium as the first choice. If the unit is only going to have occasional use and rarely used for free camping, lithium would not really be an economical choice, but a live in with regular freedom camping the lithium would pay for itself very quickly, so it's a matter of deciding where the use pattern fits between these two options.