Backup Power Options - Computers / Tech on modified / pure sine wave inverters?

I know we’ve talked about having backup power available for various things, and I’m wondering whether there’s a significant benefit to having a pure sine wave vs. a modified sine wave for doing things like charging devices, running computers, etc.

Basically looking at something that could provide emergency power for some tech, run a small chest freezer if there was an extended outage, etc. And “pure” is significantly more expensive than modified.

Anybody have any thoughts?

There are a couple of different time spans here.

~0-20 minutes, intermittent use

Catch power dips. Time to shutdown computers, charge phones if an extended outage. This is ups territory.

hours, days

If well stocked, your freezer should be good for a day or two with no/limited opening. Beyond that, you’re looking at deep-cycle batteries and an inverter, or a small generator. I bought a duel-fuel generator that can run on propane so I don’t have to worry about gasoline sitting around and going bad, and for safety. Also a consideration if you have refrigerated medications.

sine/modified sine

Can’t really speak to this, other than to say I have this CyberPower (simulated sine) and it gives me about 6-8 minutes to power down my iMac Pro, 2 monitors, half dozen external drives, Synology NAS, cable modem, and Synology router.

Most of the things you want to run off a UPS are fine with modern modified sine waves. Certain types of motors and resistance circuits don’t like it.

I have multiple UPSs on computer equipment and a backup generator. The UPSs handle the outage until the generator kicks in. Recent storm knocked power out for 3 hours and all worked well.

Yeah - I’m looking at this category, with enough power to keep phones topped off, the chest freezer / fridge running, etc. And output would need to be high enough to catch the initial surge load from the compressor in the chest freezer / fridge.

Since we’re in an apartment, I was looking at 1 or 2 large deep-cycles and a 1500W inverter (again, surge load) from someplace like Harbor Freight or Amazon. Getting a pure sine wave would almost double the inverter cost, hence the question.

Any experience running a fridge/freezer on a modified sine?

What kind of computer(s)? I went with sine based on this information as I have an iMac.

I think motors are more efficient on sine waves, which would increase battery run time. I don’t use a UPS for anything motorized, though, so I have looked into this minimally.

As for the freezer, you can keep things frozen during a short term power loss if you leave the door shut. Food will stay frozen for days if the freezer is well stocked with frozen food/blocks of ice (field tested by a family member during a multi-day unplanned/unexpected power outage). One strategy is to keep bottles of frozen water in the freezer when it begins to empty of food. Barring a catastrophic regional power outage, you can also just buy bags of ice to pop in the freezer if your neighbourhood is experiencing an extended power loss. I suspect this method will preserve your food for longer than an affordable UPS could.

I should also add that I occasionally get too excited about deals at Costco and buy more food than can fit in my fridge (I can’t say no to a big bag or three of Koru apples!). I put the extra food (not meat) in a cooler with an ice pack. The food can keep least a week in there easily. I’d use the same strategy during a long power outage: I’d put a bunch of ice in the fridge and keep it closed as much as possible. In a pinch I’d sacrifice bags of frozen veg to keep the fridge cold. You can used the thawed veg to make soup stock after, so no waste.

Yes, I have a MSW inverter in my motorhome and it runs a KitchenAid reefer, an induction cooktop, and a microwave. The microwave doesn’t produce as much output so it takes about 20% longer cook time. TVs, satellite receiver, usb chargers all work fine.

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