Kenric
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Inverter to power refrigerator during power outage

Sun Apr 15, 2018 6:00 pm

After a bad storm, we lost power and it wasn't predicted to come back on for 24 hours. I thought this would be a good opportunity to use my 2013 Leaf as a giant battery pack. I bought a 750W inverter, which should have been big enough to power my 5.1A fridge, but it wasn't able to power it. It did come on, the lights worked, the temperature readings worked, and if i turned off the cooling the fans would run. But not the compressor. I returned the 750W and bought the largest they had which was 1000W (2000W for 0.1 seconds) and it still wasn't able to run the refrigerator. Both were able to power a small 1A refrigerator. Luckily, the power came back on after 18ish hours, but I hope to learn what the correct solution is for next time. Any ideas? The 750W inverter never reported over current. The 1000W doesn't have any way to report that. I assume there is a large inrush when starting the motor, but not sure how I can easily measure it to know what size inverter I would need. I also thought about it later and the fridge must be sensing and not trying to turn on the compressor for some reason, since the rest of it worked fine.

LeftieBiker
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Re: Inverter to power refrigerator during power outage

Sun Apr 15, 2018 6:22 pm

Larger electric motors have a high startup power requirement. I would have thought a 1500 watt inverter would handle it, but if it's a large fridge, look for a good quality 2kw inverter with a 3kw surge capability. Remember, though, that the Leaf's DC-DC converter can only provide 1800 watts, and 1500 is safer for long periods. The car *must be* in Ready mode, with the yellow-green car icon lit, and remain in that mode. There is a topic on this. try searching 'Leaf to home'.
Last edited by LeftieBiker on Sun Apr 15, 2018 11:14 pm, edited 1 time in total.
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Nubo
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Re: Inverter to power refrigerator during power outage

Sun Apr 15, 2018 11:12 pm

Were you using a pure sine-wave inverter? Some appliances and/or motors do not like square waveforms. Especially newer stuff which is more likely to have fancy electronics and variable-speed motors. I'd bite the bullet and get a good pure sine-wave inverter. Especially if you ever intend to use it to power expensive electronics like computers, etc... And while some things may *work* with square waveforms, it can put unwanted stress on the components.

As for inrush current, the manufacturer's info plate on the unit may tell you what the starting draw is. I think you didn't exceed your inverter's capacity if it didn't trip. Furthermore, 2000W is in excess of 15A and unless you've got some huge commerical refrigerator I doubt it's pulling THAT much current. There's usually a capacitor that provides the starting kick.

One other thing to check was whether you had a proper ground.
I noticed you're still working with polymers.

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RegGuheert
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Re: Inverter to power refrigerator during power outage

Mon Apr 16, 2018 5:26 am

Kenric wrote:I bought a 750W inverter, which should have been big enough to power my 5.1A fridge, but it wasn't able to power it. It did come on, the lights worked, the temperature readings worked, and if i turned off the cooling the fans would run. But not the compressor. I returned the 750W and bought the largest they had which was 1000W (2000W for 0.1 seconds) and it still wasn't able to run the refrigerator.
Here are a few questions:

Q1) Was the LEAF in "READY" mode? This is the mode that you use for driving with the green car and bidirectional arrow showing on the dash. You need to use that mode to get the 12V battery to charge.
Q2) What is a "5.1A fridge"? My fridge consumes about 100W when running and draws about 1000W to start the compressor.
Q3) How old is your fridge?

And here are a couple of comments:

C1) I find that I need to use a 1000-W inverter to start my large side-by-side fridge. Smaller sizes do not work.
C2) I used the same modified sine wave 1000-W inverter to start my neighbors fridge and it had a lot of trouble getting it going. That refrigerator was old and drew quite a bit more current to start. I *did* eventually get it to work, but I don't recall what the trick was.
C3) If I need to run multiple refrigerators during an outage, I typically connect multiple inverters to the battery.
C4) Note that a normal 15A plug is limited to about 1800 W, but the circuit breaker will allow a starting current much higher than that for a few seconds.
RegGuheert
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Kenric
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Re: Inverter to power refrigerator during power outage

Mon Apr 16, 2018 7:54 pm

Thanks for the replies. I know about the car needing to remain on in ready mode. I did have it that way. I measured the voltage and saw 14.4V but I think it went as low as 12.6 to 12.9V when the inverter was pulling power. It says "modified sine wave converter', but I don't know exactly what that means. Ground is something I didn't really think about. I am sure it wasn't properly grounded. There is an earth ground lug on the inverter but I didn't connect it to anything. I guess I should have connected that to the house ground somehow. The fridge is just a normal full size Samsung. The label doesn't have a startup max power, just lists 5.1 Amps which I assume is nominal max power. It is maybe 8 or 9 years old side by side.

So best guess by Nubo's comment is that it was the ground.

I guess it could have been voltage drop over the 25 feet of extension cord too, I didn't think about that either. I should have measured the voltage when plugging in the refrigerator.

Maybe I will give it another try this weekend to see if I can get it to work just in case I need to do it again in the future.

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Nubo
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Re: Inverter to power refrigerator during power outage

Mon Apr 16, 2018 8:36 pm

Kenric wrote:Thanks for the replies. I know about the car needing to remain on in ready mode. I did have it that way. I measured the voltage and saw 14.4V but I think it went as low as 12.6 to 12.9V when the inverter was pulling power. It says "modified sine wave converter', but I don't know exactly what that means...


https://www.altestore.com/blog/2015/10/ ... ifference/
I noticed you're still working with polymers.

Kenric
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Re: Inverter to power refrigerator during power outage

Mon Apr 16, 2018 8:46 pm

Nubo wrote:
Kenric wrote:Thanks for the replies. I know about the car needing to remain on in ready mode. I did have it that way. I measured the voltage and saw 14.4V but I think it went as low as 12.6 to 12.9V when the inverter was pulling power. It says "modified sine wave converter', but I don't know exactly what that means...


https://www.altestore.com/blog/2015/10/ ... ifference/


yeah, I was just reading about MSW vs PSW. So you think I would need a PSW inverter to run it?

Also read that the earth ground is connected to system ground for most of these, but I didn't check mine yet.

smkettner
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Re: Inverter to power refrigerator during power outage

Mon Apr 16, 2018 9:11 pm

Starting a full size home fridge needs a lot of good power. Yes you should have a sine wave inverter. Probably need 2000 watts rated and 3000+ watts surge performance. If the 12v wires are short you can probably get by with 2/0 wire (the size of a small garden hose). Next you need a larger 12v battery to even utilize the surge performance. Yes it is a bit of an ordeal to be prepared for an outage without running the generator.

Start current can be 5 to 10 times the rated current for these appliances. Once the compressor is running all becomes simple and the LEAF can supply the power.
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BrockWI
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Re: Inverter to power refrigerator during power outage

Tue Apr 17, 2018 5:57 am

I use a 2000w xantrex sine wave inverter and it will start anything you can plug in to a regular wall outlet.

What size cables did you have between the Leaf's 12v battery and the inverter? I ask becasue you need at least #4, I use #2/0 and it is only about 2 feet on each lead. Even #4 will sag voltage to the input side of the inverter quite a bit on motor startup, enough to put most 1000w inters in to low voltage shut down or fault. The more larger inverters won't mind the voltage sag as much, but smaller ones really need heavier wire to avoid voltage sag.

Also larger inverters tend to not care what the input voltage with regards to the output voltage, but less expensive inverters tend to just 10x the voltage. So say your input sags to 11vdc the output will be 110vac, where larger inverters will draw more power on the input side keeping the output voltage at close to 115 vac or so. As the output voltage dips it is less likely to start a motor.
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