Ask the Cryptogonners: Run Freezer Off Van and 12v Inverter? [Confirmed: Yes.]
October 11th, 2015Update: Success!
I bought a NOMAD MOBILE 1500w pure sine wave inverter from waveinverter.co.nz (I have no affiliate relationship with them, I’m just a customer).
For testing, I unplugged the freezer (Westinghouse WCM5000WC) for a couple of hours and let it warm up a bit. Then I connected the inverter to our van’s battery terminals using jumper cables, plugged in the freezer (with 10 metres extension cord), started up the van and switched on the inverter.
It all worked perfectly.
The freezer ran for about 25 minutes, getting the temp down to normal, then it switched off and just reverted to its normal duty cycle. I have it set so that it ranges between -15.8C and -17.8C.
Running this freezer is a walk in the park for this inverter, which stayed cool to the touch after an hour. The fans were turning at very low RPM.
I was thinking that I’d sell this inverter in a couple of years, once we get our batteries for our solar system, but seeing the quality of this thing, I’m having other ideas…
I might build some sort of off grid shack (known as a “sleepout” in NZ) for our sons on our land and this inverter, plus a couple of cheap deep cycle batteries, solar panels and a charge controller could give them plenty of AC for lights, computers and a small fridge, chest-freezer-as-fridge or even a small fridge/freezer. Wi-Fi the network over to them… Easy! (I used gear from Ubiquiti Networks on a recent job and it’s fantastic.)
My guess is that parents don’t usually know what their young children will wind up doing later in life. If our boys find themselves in mainstream circles, suits and ties, etc. they’ll be able to tell hilarious stories about how they had an off grid sleepout in the wopwops and their freak parents.
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Update: Inefficiency of Using the Van + Inverter Method
Lots of people are pointing out that the van + inverter method is inefficient. Yep. I get it.
Here’s an email I wrote to one person that covers this topic:
Hello,
I bought a 1500 watt (3000 watt peak) pure sine wave inverter.
I get that the van is an inefficient way of going for this, but considering:
* that six days is the longest outage anyone alive around here can remember
* that most of the outages we experience, (over 90%) of them, are less than 12 hours
* that I just don’t want a piece of crap Chinese generator breaking and or leaking petrol and oil
* that I can easily re-sell that inverter once I no longer need it because lots of people around here are living in off grid shacks and house buses, etc.
* and keeping the freezer cold would only require idling the van for a couple of hours per day, max.
The inverter seems like the way to go.
Cheers,
Kevin
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Update: Lots of Responses
Thanks to everyone who responded. I have a lot of emails to go through!
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Yesterday, we were given a chest freezer!
In the past, we used to keep the meat from our homekills in a chest freezer at my mother and father in laws’ house. That freezer is now in our garage, so we will be keeping the meat over here.
Regular readers will know that we routinely experience power outages here in the Far North of New Zealand. (There was another one yesterday. Update: “The Far North district has the worst number of outages in the country.”)
The substation that serves my inlaws’ place has diesel backup, so they have much shorter outages over there because Top Energy just spins up the generators. We never worried about keeping the meat over there. Out where we are, though, we’re usually the first to lose power and the last to get it restored. The record length of a blackout at our place is six days.
Ok, it’s not an option to lose thousands of dollars worth of meat due to a blackout. The obvious way to make sure that doesn’t happen is with the use of a generator. (Or, in the event of an EMP attack/zombie apocalypse, 200 litre barrels and lots of salt. *grin*) Honda makes the best small generators, but they cost the most.
There are lots of cheap Chinese made lucky dragon generators out there that cost about 1/4 of what a Honda costs. There is also a middle-ground option that uses a Honda engine and lucky dragon everything else, but costs half as much as a Honda. That one has a system warranty of two years and coil warranty of five years. All the rest have one year, the minimum required in NZ.
The generators I’ve been looking at are in the 2kw to 2.6kw range.
I used a Kill-A-Watt type device and learned that my freezer needs 1450 watts to start the compressor. It uses about 100 watts while running. (If you don’t understand why the startup load is so high, see locked rotor current.)
I really don’t want to buy one of those bottom of the barrel generators.
Within about three years, we’ll buy a battery system for our house that will have backup functionality. So really, what I want is a bit of insurance against an extended blackout until we get our solar system batteries.
As bad as power reliability is here, most blackouts don’t last longer than 12 hours and wouldn’t have much impact on a chest freezer. Past a day, especially in summer, we’ll need a backup plan.
So:
How about a 12 volt inverter connected directly to the battery terminals of our van? (Don’t try this with the cigarette lighter plug.) There are lots of 1000 watt (2000 watt peak) units out there for under $100. They even come with the car battery clamps attached. They’re all lucky dragon, but at those prices, maybe buy a few. I mean, if they’re all tested and working ok beforehand, it would be really bad luck to smoke three of them on the big day (when only one needs to work).
I’d love to hear from someone who has actually tried this: Car/Inverter/Freezer. What I’m interested in is stories of success or failure by people who knew their fridge or freezer startup power requirement, used an appropriately sized inverter and kept the length of extension cord to a minimum.
My guess is that the fly in the ointment for this cunning plan could come down to whether or not the inverter is actually capable of peaking to 1450 watts for the fraction of a second it takes to get that compressor motor spinning.
What’s the verdict, Kevin? Been wondering about this myself.
I bought a much more expensive 12v inverter than what I was thinking about getting initially. I went with a pure sine wave 1500 watt (3000 watt peak) unit from a vendor in NZ. This is total overkill. It should easily do the job.
I should have it by Friday and I’ll test it out over the weekend.