The washing machine problem

Deveak · June 2015

I've read over just about every thread on washing machines on this site and others. My problem is i can't find any information on the inrush current so i don't know how to size the inverter it runs on. I see lots of listings per load but I really need to know how large of an inverter it takes to run one. I looked at some of the smaller portable ones, they look nice like the panda portable washer or a pulsator type washing machine from sonya but i have no idea what the motor surge is. Pretty sure 12/24 volt models do not exist. Anyone have luck running them and if so how big and with what?

inetdog · June 2015

One thing that you need to be aware of is that in some cases, if the inverter does not cut out but just drops the voltage, the motor will start successfully with a lower current than the inrush and surge that it would draw from a stiff supply.
On the other hand, that same voltage drop could cause the electronic controls on a modern washer to shut down where a purely mechanical timer would have ridden through without problems.
I guess what I am saying is that just seeing the specifications will not be enough to tell you what will or won't work.

waynefromnscanada · June 2015

My sears front load has really no start surge. It starts slowly at perhaps 100 watts, them builds gradually to about 600 watts if in the spin cycle. If in wash cycle, it rarely uses more than a couple hundred watts, but always starts slowly with no surge at all. (Three phase inverter motor) In fact it would start, wash and drain (pump out) just fine on my Morningstar TS-300 inverter, and it would start to spin, but as the spin speed picked up, the draw would eventually reach the shut down point of the TS-300 and all would come to a stop.

oil pan 4 · June 2015

Same thing here. My Kenmore front loader slowly or soft starts.
I tested its peak current draw back when I first got my washer in 2006, I don't recall it being more than 500 or 600 watts.

zoneblue · June 2015

Yes depends on the washer. Anything with a direct drive permanent magnet motor will run on sub 1KW inverters. You can see our (run of the mill) machine complete cycle load graph here : http://forum.solar-electric.com/forum/solar-electric-power-wind-power-balance-of-system/off-grid-solar-battery-systems/21909-direct-drive-washing-machine-power-consumption

At that time the monitoring system i used was quite sensitve and captured surges and peaks pretty well.

2manytoyz · June 2015

You'll have difficulty finding any equipment that mentions In-Rush current. I had to buy a Fluke 334 to measure all my 120VAC loads. Then there's the issue of what your inverter can supply. The manufacturer will tell you the peak Watts for 'x' minutes, but they won't tell you the maximum spike it can supply to start a motor. In many cases, the start-up current can be 5x that of the running current.

My 600W 5000 BTU A/C unit measures 22.6 Amps during start-up. A Kill-A-Watt meter is far too slow to capture the reading.
A Dewalt Emglo air compressor, with a 1.2 HP 120VAC motor that easily runs from a 15A grid powered outlet, spikes at 53.8 Amps during start-up. Consequently, I can't run it from either of my inverters, or from a 2400 Watt (3KW peak) rated generator.

The testing I performed on a previous top loading washing machine can be seen here: http://www.alpharubicon.com/altenergy/altwashclothes2manytoyz.htm It ran easily from an 1800W inverter.

Our latest washer & dryer are front loaders. The washing machine does have a soft start feature, unlike the last one. It will be run from an inverter exclusively as soon as the weather cools down enough to run wire in the attic!

JoshK · July 2015

It will vary a lot between different washers. And knowing the spike is almost impossible. But in the hopes this helps you... My new washer runs for 42 minutes and uses 0.04kwh per run. The readings range from 5 watt to a momentary max of 420 watt.

SolarPowered · July 2015

Typical surge current is 12.5 amps for front or top load washers, 120V. That's the calculation for on grid and off grid independent branch circuit.
So you will need 1500watts, which will need a 12v DC/AC 2000watt inverter. I've installed these for 2 off grid homes.

JoshK · July 2015

SolarPowered wrote: »

you will need 1500watts, which will need a 12v DC/AC 2000watt inverter.

My 12v, 1600 watt inverter runs anything (110v) in my home, so I agree with SolarPowered. Chances are a 2000 watt will not disappoint you.

SolarPowered · July 2015

JoshK wrote: »

My 12v, 1600 watt inverter runs anything (110v) in my home, so I agree with SolarPowered. Chances are a 2000 watt will not disappoint you.

All inverters vary though, even with name plate. (I.E) I own a few of the sunforce 12V 2000watt peak surge/1000watt continous AC inverters, I've measured that they never meet the 2000watt peak.In my case the inverter peak surges at 1800watts, which is much less than the name plate surge, and the inverter heats up after a few minutes on continuous loads and can only deliver a consistent 900watts, not 1000watts.

Thats why the washer calculation summarizes that the surge current is 12.5 amp, even if you can find a washer that may have a surge peak of 8.5amp . 12.5amp is the average load calculation for the plethora of washers available on the market.

So if we calculate AC loads adjusted according to the 25% overcurrent protection, the inverter is always safe guarded and shouldn't (in theory) over heat no matter the physical demand VS the manufacturer name plate.

1500 X 1.25 =1875watts, in this case the inverter should never over heat unless the inverter is signifcantly under rated to the manufacturer name plate.

zoneblue · July 2015

You guys are still talking about conventional motors though. Direct drive (sometimes called inverter) models will reduce the peak by a significant margin. Here in NZ the leading brand of washers are all direct drive, have been since about the year 1990, so its easy for us to pick them up second hand for under $100. They never draw more than 500W peak.

And they go and go and go. Nothing to break. No belts, cluctches, gears nothing.

SolarPowered · July 2015

zoneblue wrote: »

You guys are still talking about conventional motors though. Direct drive (sometimes called inverter) models will reduce the peak by a significant margin. Here in NZ the leading brand of washers are all direct drive, have been since about the year 1990, so its easy for us to pick them up second hand for under $100. They never draw more than 500W peak.

And they go and go and go. Nothing to break. No belts, cluctches, gears nothing.

For Grid Systems the Branch circuit for washer is calculated at 12.5amps ( for both motor 8amps, and pump 4.5 amps), thats just how its calculated. Its just a measurement for over current protection.
If it was just the motor which the circuits for gas dreyers are rated at 8 amps, it would be better descriptive, but there are times between cycles with washers where even for maybe 10 seconds there could be a peak surge of 1200watts, even with direct drive systems, that work in combination with a pump.

The calculation doesn't change for off grid because inverters requiring over 10 amps require some sort of over current protection device inline.

Also following these calculations equipment tends to last longer from the washer/inverter, etc. Building to the bare minimums equipment does tend to fail sooner.

Ethan Brush · July 2015

SolarPowered wrote: »

For Grid Systems the Branch circuit for washer is calculated at 12.5amps ( for both motor 8amps, and pump 4.5 amps), thats just how its calculated. Its just a measurement for over current protection.

Not really. what you presumably are referring to is the 1500 VA for the laundry receptacle which is used to calculate service and feeder load. This is added to the general lighting loads and small appliance loads, and then demand factors are added in. This is just for the "laundry receptacle" required by 210.52(F) and isnt necessarily for the washing machine. This may sound nit picky, but the point is that this figure isnt meant to say anything about the specific amp or watt draw of the washing machine.

SolarPowered · July 2015

Ethan Brush wrote: »

Not really. what you presumably are referring to is the 1500 VA for the laundry receptacle which is used to calculate service and feeder load. This is added to the general lighting loads and small appliance loads, and then demand factors are added in. This is just for the "laundry receptacle" required by 210.52(F) and isnt necessarily for the washing machine. This may sound nit picky, but the point is that this figure isnt meant to say anything about the specific amp or watt draw of the washing machine.

Thank you for the clarification, I concur with that statement.
However lighting loads, are seperate branch circuits from, appliance circuit loads.

Differences corresponding to NM-B(white 15amp), NM-B( yellow 20amp), NM-B (orange 30amp)

Calculating VA for laundry/washing loads would mean no more than 1junction/recep boxes a dedicated for washing machine (technically it should be a dedicated 1 pole circuit, no different than a 2 pole 30amp for electric dreyers, (or dedicated circuits for fridges, micro waves, and garbage disposals greater than 1/2hp).

So if I'm not misconstruing NEC laundry/washer circuit should infact be dedicated.

zoneblue · July 2015

Mate all im saying is that our 1000W inverter will run the washer, our base loads, the water pump, AND the slow cooker on high without the fan even kicking in. You can see the actual power trace in the link above. Theres no major surges to speak of. That monitoring is sensitive enough to capture the fridge compressor surge, so it should show washer surges. Mr Argumentitive

petertearai · July 2015

Yes I settled on a fisher & pykel smart washer . washes at around 100 watts , slowly ramps up to 300 watts briefly at the beginning of spin cycle .. no surge currents, motor is i think essentially a big direct drive stepping motor.Very economical , and no way expensive .

BB. · July 2015

I have a Fisher&Paykel washer and (natural gas) drier. They are very nice units (dc servo motors and no surge current). My units use about 0.25 kWH per load.

Mine are about 10+ years old and I turn of the electrical power to them when not used... They use something like 9+ watts when "off"--And use almost as much turned off as doing a couple washes a week (9 watt load is 1.5 kWH per week vs ~1.0 kWH per week for two wash/dry loads).

-Bill

SolarPowered · July 2015

zoneblue wrote: »

Mate all im saying is that our 1000W inverter will run the washer, our base loads, the water pump, AND the slow cooker on high without the fan even kicking in. You can see the actual power trace in the link above. Theres no major surges to speak of. That monitoring is sensitive enough to capture the fridge compressor surge, so it should show washer surges. Mr Argumentitive

I'm not argueing I'm agreeing with you. For a branch circuit appliance, I have to calculate for the maximum an appliance can use on that branch circuit.
There is a lot to account for. Much of the larger washers for grid are up to 5cu/ft of volume with large barrel drums. Over 5cu/ft its considered commercial grade, and those calculations are much higher than what we see in residential applications.

I do agree that your unit is highly efficient. I just calculate for the maximum allowable. Thats all I am saying, if there is room for additional loads on a 2000watt inverter..Great, good investment.

petertearai · July 2015

Hi Bill . Thanks for alerting me to the stand by draw . I do keep it switched off when not in use but didn't realize the it had such a standby load .

zoneblue · July 2015

NZ is kinda lucky that F&P pioneered (or at least been early adopters) of direct drive technology. F&P manufactured in NZ until around late 1990s i think, before going off shore. I gather F&P get a bit a premium price markup when exported overseas, but they are a dime a dozen here. Around NZD700 new.
F&P is also famous for its "dish drawer" dishwashers.

But i get the impression that many more companies are going that route, so id just be doing a little research on the brands available near you.

Deveak · July 2015

hmm, i did not expect to get so many replies. Interesting. I will look into direct drive washing machines. I was considering the gravity fed portable units like the panda portable washing machine. I would only be doing clothes for myself and something small is ideal for my camper. Still, if its more efficient for a full size that may be worth it.

The washing machine problem

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