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Running Fridge/Lights from LEAF
Old 02-24-2019, 04:42 PM   #1
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Running Fridge/Lights from LEAF

I realized that maybe we should do this when the power goes out:



Summary: Use an inverter to get 110 V from the LEAF's 12 V battery. The driver battery recharges the 12 V.

I don't like the noise of a generator.

The specs on the fridge say 15A, so I guess I'd get a 2000 W inverter. Even if we ran the charge down, we'd just charge up when the power came back.
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Old 02-24-2019, 04:58 PM   #2
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Nifty.

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Originally Posted by TromboneAl View Post
I guess I'd get a 2000 W inverter.
But she says the DC-to-DC charger in the Leaf is 1kW, so...not sure the 2kW inverter would work as the 12V battery would have a net drain.
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Old 02-24-2019, 05:03 PM   #3
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Timely thread for us. As I write we are running off a Honda EX4500 generator, one of the older model "ultra quiet" ones, according to the specs, 65 dBA. I can hear it, but barely.

I bought the generator after we were without power for four days after an ice storm at the old house. This is the first time we've used it here in the 16 years we been living here, but I knew the day after I sold it we'd need it.

DW is happy we have the furnace (natural gas) running, some lights, and the refrigerator. And of course the computer.

Lots of high winds, our local utilities are all underground so it is rare for a sustained power outage. We've got fuel for overnight and then some but I might have to go out and forage for fuel tomorrow. I'd be surprised if this kept up for that long though.
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Old 02-24-2019, 05:05 PM   #4
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DW is happy we have the furnace (natural gas) running, some lights, and the refrigerator. And of course the computer.
...and internet, obviously.
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Old 02-24-2019, 05:14 PM   #5
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The 1 kW will work since the actual running power of the fridge is less than 1000W.
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Old 02-24-2019, 05:14 PM   #6
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Originally Posted by BigMoneyJim View Post
Nifty.



But she says the DC-to-DC charger in the Leaf is 1kW, so...not sure the 2kW inverter would work as the 12V battery would have a net drain.
Right, but only with a continuous drain of over 1 kW. Fridge probably uses much less most of the time.

I'll try thing out with my small inverter to see if the idea is practical (without fridge).
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Old 02-24-2019, 05:51 PM   #7
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Modern fridges today have all kinds of electronics that are sensitive to voltage/amperage changes and so on. I'd be careful.

We once had a minor power surge that fried the electronics on our fridge and killed it.
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Old 02-24-2019, 06:05 PM   #8
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Quote:
Originally Posted by Walt34 View Post
Timely thread for us. As I write we are running off a Honda EX4500 generator, one of the older model "ultra quiet" ones, according to the specs, 65 dBA. I can hear it, but barely.

I bought the generator after we were without power for four days after an ice storm at the old house. This is the first time we've used it here in the 16 years we been living here, but I knew the day after I sold it we'd need it.

DW is happy we have the furnace (natural gas) running, some lights, and the refrigerator. And of course the computer.

Lots of high winds, our local utilities are all underground so it is rare for a sustained power outage. We've got fuel for overnight and then some but I might have to go out and forage for fuel tomorrow. I'd be surprised if this kept up for that long though.
Glad you have heat, and I sure hope your power is restored soon. Good thing you have that generator!
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Old 02-24-2019, 06:13 PM   #9
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I did not know the LEAF has a DC/DC converter that can recharge the 12V battery from the propulsion battery, and that its capacity is as high as 1kW. Wonderful!

Now, to convert that 12VDC to 110V, may I suggest the Xantrex Prowatt SW2000? It outputs a true sine wave, not the crappy MSW (modified sine wave) that cheaper ones put out. Another thing that I like is its low idle power consumption of 6W. That testifies to its efficiency and low loss.

About the load, even a large fridge like my 30-c.f. only draws around 350W when running. However, the surge current when the compressor starts may be above 1kW, so the above Xantrex would be more than adequate, particularly if you also have other loads such as lighting on it.

The LEAF propulsion battery is large enough (24kWh for the 1st gen) that it should sustain the fridge and light loads over 24 hours. I measured my fridge at less than 5 kWh/day, and we opened it all the time.

Even when you have sustained outages, recharging the LEAF with a generator will require running the latter only a few hours each day and not continuously. That helps tremendously with the noise, and the care/feeding of the generator.
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Old 02-24-2019, 06:19 PM   #10
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An important note about wiring:

Forget about attaching a large inverter of 1kW or 2kW like the Xantrex to the battery with chintzy alligator clamps. The current drawn will be more than 100A, and can reach 200A during surge load.

You want solid bolted-on lugs. And use at least 0-AWG cables. Smaller 2-AWG cables may be used if you keep the cables short, like less than 2 ft.
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Old 02-24-2019, 06:30 PM   #11
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The Xantrex I talked about earlier has a good efficiency, such that its internal fan does not turn on with a 1kW sustained load (because it does not get hot). As mentioned earlier, when there's no load, it consumes only 6W.

I have not seen an inverter that boasts a lower idle consumption. Some do, but they do that by the inverter powering down when there's no load, then turning on periodically to see if there's a load out there. When the fridge is not running, its electronics present such a low load that it would be missed by such inverters. You would be pulsing your fridge, and it won't like it. Small LED lights would also be pulsing. Totally uncool!
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Old 02-24-2019, 06:58 PM   #12
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Originally Posted by TromboneAl View Post
The specs on the fridge say 15A, so I guess I'd get a 2000 W inverter.

15A seems high. Our large LG side by side shows 3.85A on the label inside the fridge compartment.

During the four day power outage last week it ran fine on a 1500/3000W (running/surge) MSW inverter. The pure sine wave type will be more efficient and nicer to electronics as noted by NW-Bound.
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Old 02-24-2019, 09:35 PM   #13
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Originally Posted by NW-Bound View Post
An important note about wiring:

Forget about attaching a large inverter of 1kW or 2kW like the Xantrex to the battery with chintzy alligator clamps. The current drawn will be more than 100A, and can reach 200A during surge load.

You want solid bolted-on lugs. And use at least 0-AWG cables. Smaller 2-AWG cables may be used if you keep the cables short, like less than 2 ft.
Yes, I powered the freezer for a few hours during an extended outage a few years back, and even though I know that you need really, really good connections on the battery side to handle the surge current, I still underestimated it, and the inverter kept shutting down and cycling on start up. I had to start the engine to boost the voltage to at least get past the start up surge.

You need extremely good connections on the battery to inverter. No messing around.

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15A seems high. Our large LG side by side shows 3.85A on the label inside the fridge compartment. ....
The 15A would be a start up surge. No way a fridge will draw 15A continuous. That would require a 20A outlet anyhow (15A are rated at 80% for continuous).

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Old 02-24-2019, 11:20 PM   #14
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The 15A would be a start up surge. No way a fridge will draw 15A continuous. That would require a 20A outlet anyhow (15A are rated at 80% for continuous).
-ERD50

Yes, I know there will be a surge when starting.
I was suggesting a smaller than 2000W inverter would suffice - i.e. there will be a running/surge rating for the inverter to account for the start up.
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Old 02-25-2019, 06:58 AM   #15
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Yes, I know there will be a surge when starting.
I was suggesting a smaller than 2000W inverter would suffice - i.e. there will be a running/surge rating for the inverter to account for the start up.
Yes, but be careful. You can find 1000/2000W ( cont/surge) inverters. But the peak is a hard limit. Semiconductors can't take an over-current situation in the same way copper wires and iron armatures can. Iron/copper heats relatively slowly, and can withstand fairly high temperatures. The silicon die can be damaged by lower heat much quicker.

And even if it says 2000 'peak' - how long is that? Do they say? It might be 1/60th of a second (one cycle, limited by capacitors?). What if the fridge draws > 1000W for 1 or 2 seconds?

And it's possible that 15 A may not be the actual peak, that may be integrated over time, with a higher current, shorter pulse. I'm just suggesting to be conservative, and go with a larger inverter than you think you might need. A refrigerator is a tough load. Read reviews to make sure it works with most fridges of that size.

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Old 02-25-2019, 07:25 AM   #16
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Inverter quality is all over the map. I just returned 2 this week. While they may claim to handle 2kw steady with a higher surge, its not uncommon to see them trip out at 1500w steady resistive loads. Some inverter data sheets (if you can read Chinglish) suggest 10x (!!) higher ratings to handle in-rush currents from inductive loads on compressor motors. One of my professors once sneered at then modern mass produced electric motors as "they don't design them any more, they just build them" (and that was nevermind how many decades ago before plastic parts were invovled)... a well designed motor will have about 3x startup loads, so 7-10x for todays motors might be appropriate.


Start with buying or borrowing a kill-a-watt meter however it will not display start-up loads. If nothing else its eye-opening to see how much some electronics draw even when "off".
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Old 02-25-2019, 08:12 AM   #17
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Originally Posted by ERD50 View Post
Yes, but be careful. You can find 1000/2000W ( cont/surge) inverters. But the peak is a hard limit. Semiconductors can't take an over-current situation in the same way copper wires and iron armatures can. Iron/copper heats relatively slowly, and can withstand fairly high temperatures. The silicon die can be damaged by lower heat much quicker.

And even if it says 2000 'peak' - how long is that? Do they say? It might be 1/60th of a second (one cycle, limited by capacitors?). What if the fridge draws > 1000W for 1 or 2 seconds?

And it's possible that 15 A may not be the actual peak, that may be integrated over time, with a higher current, shorter pulse. I'm just suggesting to be conservative, and go with a larger inverter than you think you might need. A refrigerator is a tough load. Read reviews to make sure it works with most fridges of that size.
-ERD50

Good information, thanks.
P.S - Ditto @ NW-Bound
In my real world example given above, I used a Harbor Freight Jupiter 1500/3000W modified sine wave inverter to power the fridge, some CFT lighting (4 15W bulbs), the blower to the propane fireplace, and the tankless water heater simultaneously. I unplugged the fridge and switched on the TV (25" CRT) and the Dish receiver for evening entertainment. The Dish box did not 'like' the quality of the electricity but everything else worked fine. Probably 15+ hours of use and many fridge start cycles.
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Old 02-25-2019, 08:20 AM   #18
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FWIW, I have cheap little 300 W inverter for my car to charge electronics that have no USB charge-input and a 115 V plug such as a laptop. It works. But this cheap inverter does not produce what I would call a good sine wave. But the laptop AC adapter takes care of it.

Anyways, you go first and try this with your fridge and tell us how it went. Thanks!
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Old 02-25-2019, 08:40 AM   #19
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Interesting thread. I have a c-max hybrid and it appears it would also work this way. It has a 2 kW dc-dc converter powering its 12-V system, so I will probably try this out.
Tell me about the C-Max HV battery and hybrid electrical system - General Discussion - Ford C-MAX Hybrid Forum
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Old 02-25-2019, 08:40 AM   #20
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Another twist. There is a sub-culture of people that hack their EVs to use in place of something like Tesla Powerwalls to power their whole house with off-peak power. They charge the batt on off-peak and then use the batt to power the house during peak hours. They do this full time, not just during power outages.
The trade off is "what if I need to go somewhere but my car is down to 20% charge after running my house during the day".


If you want to take steps for something like this, skip the cheap "car inverters" and buy building blocks for whole house inverters used in solar installs.



Then you can take it a step farther and recycle old laptop batteries to build your own powerwall-like house batt.
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