Emergency Power For Your Home

Emergency Power. In the aftermath of one of the largest power outages in BC history, where more than 700,000 people lost their connection to the BC Hydro grid, many for up to 5 days, I decided to write this blog article to outline what a normal person can do to mitigate their electricity supply problem during such events. The focus is on back-up power via battery, but inevitably I suggest ways to actually generate your own power too (when appropriate or even feasible)

Define ‘Inconvenience’

First, let’s consider the short, intermitted blackout. The ones that happen in November storms when a tree knocks out power to your neighbourhood. Or a transformer quits outside your apartment building. These are the 1-3 hour blackouts that we get once or twice a year. More of a nuisance than a real problem. For these, you might need a flashlight or lantern, a radio for news & entertainment, plus the ability to charge a cell phone. Even if the outage happens in January, and it’s minus 20 outside, you should be able to carry on.

However, these outages are not always that simple for people that rely on grid power at all times. Example: medical equipment. Someone living with muscular dystrophy might have a ventilator and absolutely must have power at all times. Similarly, I consult with dozens of people who want portable or emergency power for CPAP machines. Many home medical devices offer back-up batteries of their own, or power alarms, but these rarely address a long-term outage of more than a few hours.

Now, let’s consider the big event. Earthquakes, ice storms, tornados, hurricanes, tsunamis, etc. These types of events can knock out power for days or even weeks.
We are told by various public safety agencies that 72 hours (3 days) is an important number when it comes to emergency preparedness. In practical terms, being self-sufficient for 72 hours likely covers well over 95% of the emergency situations we might face in our lifetimes. So, in the analysis that follows, I will consider that 3 days forms the upper limit of power independence for most people. Of course there are ways of building-in expandability if longer time frames are desired.

How Much Emergency Power Do You Really Need?

Let’s start with the basics, and work our way up.


Provided that the cell network hasn’t gone down with the grid, your cell phone or smartphone is an important communication tool. There are many back-up battery packs to extent your phone’s operational time. A solar charger in combination with a battery back-up will go further, but better yet, use a dynamo charger so always have a power source, even in the depths of winter when the sun isn’t around.

Remember: plug-in land line telephones draw power from the phone lines themselves. So while your cordless phone is helpless in a power outage, and your cell phone battery will drain even if it can’t connect to the cell ntowork, the good ‘ol corded countertop phone set may be the only phone system that works!

We are talking battery-powered radios here. Multiband radios are the best choice, providing the ability to scan AM, FM, Weather Band, and even Shortwave Bands for news & information. Make sure you have a set of batteries available for your radio, so it doesn’t quit after an hour or two! A better idea would be to have a self-powered radio in your house. One that charges from solar and/or dynamo hand crank. These are not expensive, and avoid the concern over batteries.


If we consider the worst-case scenario, and plan for emergencies happening in the dark of winter, then we naturally need to have a reliable light source on hand. Most people have a flashlight in their utility drawer or garage, but chances are good that the battery condition is unknown at best. So, like the radio, it is a good idea to have a flashlight that can power itself.
Same thing goes with lanterns, especially those that use expensive ‘D’ cells. Better to have a rechargeable lantern that provides a way to charge itself.


This is a common question with a simple answer: Forget using an electrical back-up power source for heat.
The problem is that generating heat from electricity requires quite a bit of power. I like to use a hairdryer as an example… a typical hair dryer would drain power equivalent to a laptop battery in less than 2 minutes. So, for heat, you are best to use wool blankets, foil blankets, wood fireplaces, wall tent heaters (it sits outside & requires a duct for the warm air to enter your house), or hide out in your car. Apartment & condo owners have an advantage of rising heat from the floors below.
Warning! Do not use any propane heater indoors… the exhaust fumes are toxic and potentially fatal. Not to mention the fire hazard.


For many people, power outages are particularly scary. If you rely on a ventilator, CPAP machine, or any other medical device, you will no doubt have researched back-up power option. I will use a ResMed S9 Elite CPAP machine as an example in this section (feel free to email me with any particular model you would like a calculation for)…

Power consumption of this ResMed model is in the 13 Watt range when using a median pressure setting & no humidifiers or other features requiring heat. This translates to an SLA (sealed lead-acid) battery size of approximately 18 Amp-Hours to support the machine over an 8-hour sleep (allowing for a maximum 50% depth of discharge recommended for SLA batteries). If you use an AC inverter to plug the CPAP into the battery, you will lose approximately 25% of your power in the conversion from DC to AC and back again, meaning a larger battery pack of 24 Amp-Hours. Using a more efficient DC converter or car cigarette plug accessory for your CPAP will save you that power.
Batteries in this size range are relatively small, and weight in the 15 lb range. Very common to have people attach a solar panel for charging the battery during the day, especially while camping.

To estimate the battery capacity required for 3 nights, without any charging source like solar or vehicle, simply multiply by 3. In the above example, 3 nights would be covered by a 54 Amp-Hour battery pack (72 if using an AC inverter). This level of capacity is in the range of what is called a “Group 24” lead-acid battery. These are about the same size & weight as a car battery (50 lbs). Be sure to select a “Deep-Cycle” model, and not one that also touts starting ability. Only deep-cycle batteries are designed for this type of charge/discharge use.

Need a humidifier or other feature involving heat? Your CPAP power consumption will quadruple.

Lithium battery packs are also an option, but tend to have very strict power output limits & may not work for your unit if you use humidifiers or heated hoses. Lithium packs also do not support AC inverters (at least not above 50-60 Watts), and are very expensive. I suggest looking at these only if you need the ultimate in portability.

Emergency Power Technology

In the event that you need to use a computer or tablet during a power outage, despite the fact that the internet in your area will likely be down along with it, you have quite a few options available.
To double the 2-3 hour realistic runtime of a typical laptop requires a back-up battery of at least 60 Watt-Hours. External lithium battery packs for laptops are available, but once you get into day-long computer use, you will be looking at the larger SLA batteries described above & an AC inverter to go with it.
Far more energy efficient than laptops, tablets have modest back-up power needs. In fact, in many cases, they will only demand about twice the power of a smartphone. In the case of an iPad, a 50% battery drain each day amounts to 12-15 Watt-Hours… it will likely be even better while internet access is down & YouTube cat videos unavailable.
Look for external tablet USB batteries like the V44Jumpr Slate, or Jumpr Prime to extend your tablet beyond 2-3 days with modest use.

A Quick Word About AC Inverters…
Standard ‘Modified Sinewave‘ inverters will usually work fine for most laptops & medical equipment. But for the best performance, and longevity of your computers & medical equipment, I recommend a Pure Sinewave inverter. The cleaner power is easier on your equipment, and won’t create noise on sensitive equipment or audio/video equipment. 250 Watts to 350 Watts is usually sufficient for CPAPs, while 800 Watt models or larger should be used with fridges & freezers (see below). See the compact 120W model for camera chargers & other small electronics.


Every time the power goes out, the question pops into your head: “Do I eat all the ice cream now, or wait an hour until it starts melting?” Forget the leftovers, what about the eggs in the fridge, or the meat in the freezer?
Like the problems of generating heat from electricity, cooling can be almost as costly in terms of electrons. A 16cu-ft fridge/freezer can draw over 400 Watts for more than 12 hours total each day. What does it take to back-up this level of power consumption?
400 Watts for 12 hours a day amounts to 4,800 watt-hours per day.
For comparison, there is approximately 1,400 watt-hours of useable power in a pair of deep cycle golf cart batteries. If you were to connect an AC inverter to such a battery bank, you could operate your fridge for around 6 hours. Not bad for the short outages, but not so good for the big ones.

To handle a power outage of more than a day, you could purchase a generator, but this gets tricky since the fridge is not always ‘on’, thus wasting fuel. Not to mention that you would need to keep enough fuel on hand. Gen sets are not an option for apartment or condo dwellers of course.

Solar? Well, to offset just the fridge described above would require a 1KW system in most parts of Canada in the summer months. Winter? Get a big battery bank! Again, this is not an option for apartment or condo dwellers.

The solution? Think small & efficient. Use a small chest freezer on a low setting to keep things from spoiling. Chest freezers are more efficient than upright fridge/freezers, and on a ‘low’ setting you could double or triple your battery life support time.

In Conclusion

There was life in the universe before the power utility, and just because they experience a glitch, or get rattled for a few days doesn’t mean you can’t enjoy a few 21st century amenities.

Take time to make an inventory of the equipment you absolutely must have operational during a power outage, and how many hours or days this involves. Use this article to locate the power equipment that will get you there.

Need help?
I am happy to assist with the number crunching.
Send me your priority list via email, and I’ll let you know what it will take to meet your specific needs.

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