ducktapeguy
Adventurer
I actually had the same idea a few years ago after the 2011 windstorm knocked out power for a week in my area. I was in the exact same situation also with a newborn baby. Before that incident I don't think I'd ever had a power outage in the last few decades last longer than an hour, so it got me researching quite a bit. Yes, the idea is feasible and although I don't have first hand experience doing it, but from what I remember it's not much of a problem. I actually had a generator capable of power my fridge during this time but I opted not to use it. In suburban CA the neighbors windows are probably no more than 30 ft away, so running a noisy generator isn't a practical solution. The only generator I'd consider using in a residential area is a EU2000 or equivalent which run close to $1k, but I'm not willing to spend that kind of money for something I might use every 30 years or so. A vehicle is not the most efficient way of powering a fridge, but in an short term emergency fuel consumption might not be that high of a priority. During that week long outage, my car inverter got a lot of use by running a long extension cord inside the house to charge up UPS's and other small items.
As other people have mentioned, the main thing you really have to worry about is making sure the inverter can handle the startup surge current. I think most fridges probably are in the 10-15 amp range, after all the circuit breaker powering that circuit it at most 20 amps, and in most older houses it's less than that. My old house had all the kitchen outlets and lights on one 15A circuit and the only time I had problems was running the microwave and fridge at the same time. So a 2000W inverter should be able to handle it. Actual running current is pretty low, I want to say in the 150W-250W range (I don't remember exact numbers on my fridge, but it was somewhere in the same league as a few incandescent lightbulbs) On top of that, the duty cycle is small, something like a 5-10 minutes every hour from what I remember. So really you don't need to have the engine or inverter running continuously, just enough to top off the battery every once in a while. As long as you don't open the refrigerator very often, you could probably get away just starting it up every couple hours or whenever you see the temps start rising. Which reminds me I was supposed to buy a remote temperature sensor to monitor the freezer temps during the next power outage, thanks for the reminder. I tend to keep all the extra space in my freezer full of water bottles, with all that thermal mass and a high efficiency refrigerator I think you could probably extend the intervals to a four hours or more, you'd just need to run the inverter longer to compensate and bring it back down to temp
There are a couple of issues that might cause problems. One, even if you have a hi output 100 amp alternator, most likely it doesn't put out that much current at idle, you'd need to be running the engine quite a bit higher to be able to get it in that range. Even then, I think the voltage regulator will limit the amount of current the batteries will take after a few minutes. Two, standard automotive alternators are not really designed to put out high currents continuously, you risk damaging the windings using it like this long term. You can get heavy duty alternators such as Leece-neville/prestolite have 100% duty cycle, but the prices of those are almost as much as a cheap generator and they probably won't fit under the hood of most modern cars without a lot of modification
Now after all is said and done, I should just tell you it's a lot easier to store powdered baby formula or uh, get it fresh from the source
As other people have mentioned, the main thing you really have to worry about is making sure the inverter can handle the startup surge current. I think most fridges probably are in the 10-15 amp range, after all the circuit breaker powering that circuit it at most 20 amps, and in most older houses it's less than that. My old house had all the kitchen outlets and lights on one 15A circuit and the only time I had problems was running the microwave and fridge at the same time. So a 2000W inverter should be able to handle it. Actual running current is pretty low, I want to say in the 150W-250W range (I don't remember exact numbers on my fridge, but it was somewhere in the same league as a few incandescent lightbulbs) On top of that, the duty cycle is small, something like a 5-10 minutes every hour from what I remember. So really you don't need to have the engine or inverter running continuously, just enough to top off the battery every once in a while. As long as you don't open the refrigerator very often, you could probably get away just starting it up every couple hours or whenever you see the temps start rising. Which reminds me I was supposed to buy a remote temperature sensor to monitor the freezer temps during the next power outage, thanks for the reminder. I tend to keep all the extra space in my freezer full of water bottles, with all that thermal mass and a high efficiency refrigerator I think you could probably extend the intervals to a four hours or more, you'd just need to run the inverter longer to compensate and bring it back down to temp
There are a couple of issues that might cause problems. One, even if you have a hi output 100 amp alternator, most likely it doesn't put out that much current at idle, you'd need to be running the engine quite a bit higher to be able to get it in that range. Even then, I think the voltage regulator will limit the amount of current the batteries will take after a few minutes. Two, standard automotive alternators are not really designed to put out high currents continuously, you risk damaging the windings using it like this long term. You can get heavy duty alternators such as Leece-neville/prestolite have 100% duty cycle, but the prices of those are almost as much as a cheap generator and they probably won't fit under the hood of most modern cars without a lot of modification
Now after all is said and done, I should just tell you it's a lot easier to store powdered baby formula or uh, get it fresh from the source
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