What Portable Power Source Should You Get for Earthquakes?

Essential iItem for charging your smartphone during disasters!

Rumors have been circulating that a major disaster will occur in Japan in July, causing many people from China to avoid traveling to Japan, resulting in reduced flight services. Regardless of such rumors, it is essential in Japan to always be prepared for disasters such as earthquakes and heavy rains.

In today’s world, smartphones have become indispensable. During disasters, power outages can prevent you from charging your phone, cutting off communication and access to information—potentially leaving you isolated. Along with water and food, it’s important to have a portable power source ready as part of your emergency supplies.

A housewife in her 40s living in eastern Japan supports a household of four. In these unpredictable times, she not only prepares for emergencies but also uses a portable power station in her daily life. She first bought a small model, and later added a larger one as she found it useful.

“You don’t really understand a portable power station if you just store it away. By using it regularly, you get a sense of how long it takes to charge. You also learn things like needing an extension cord when using it outdoors—you wouldn’t know unless you try,” she says.

The first power station she purchased was about two years ago, a small model with a capacity of under 300Wh. During the day, she hung solar panels on her balcony drying rack to charge the station.

“At night, I’d bring the power station into the room and use it to charge my phone in places without an outlet, or keep a small lamp by my pillow on until I fell asleep. It also helped save electricity,” she says.

She later realized that the capacity wasn’t enough to run appliances like fans or dehumidifiers, so she purchased a larger model with over 1100Wh capacity. It came in a set with foldable solar panels. Having a large-capacity station on hand and using it regularly has given her a strong sense of security.

“Since COVID, more people are spending time at home, and demand for portable power has increased. Camping has also become more popular, and the need for power outdoors is growing,” says a spokesperson for EcoFlow Technology Japan, a portable power station manufacturer. They add that more families are camping with children these days.

“When camping with kids, some children don’t want to go somewhere without electricity because they want to play games,” the spokesperson explains. In such cases, portable power stations are essential for basic needs like lighting or boiling water with an electric kettle.

 

For home use with disaster preparedness in mind, around 2000Wh is recommended

There are various portable power stations available for disaster preparedness, each with different capacities. So how should one choose?

“A capacity of 1500Wh is recommended—it’s suitable for a one-night, two-day camping trip. For home use with disaster preparedness in mind, around 2000Wh is recommended,” says a spokesperson from EcoFlow (hereafter referred to as the same).

However, the larger the unit, the heavier and more expensive it becomes. On the other hand, if it’s small and lightweight, there are also models with capacities of 300, 600, or 800Wh.

What does it feel like to use one? For example, a product with a 600Wh capacity, when fully charged, can charge a smartphone about 14 to 18 times or a laptop about 3 to 4 times. Alternatively, it can power a 40W electric fan for around 4 to 5 hours or a 110W television for up to 2 hours.

“Compact models can be carried with one hand. It’s important to consider how much you’ll actually use it. It’s best if it’s convenient to use.”

To prepare for disasters, portable power stations need to be charged in advance using an external power source. If power outages occur and repeated use is necessary, having a solar panel can be helpful. Like the aforementioned housewife in her 40s, using a solar panel in daily life can give you a feel for its operation, so you won’t panic during emergencies.

When choosing a portable power station, battery capacity is the key criterion—but keep in mind that you can’t use 100% of the stated capacity. You should expect to use about 80–90% of the rated capacity. That’s because electricity is stored as DC (direct current) but household appliances use AC (alternating current), so an internal inverter must convert it, consuming some energy. Also, as the unit heats up during use, an internal cooling fan kicks in, using more power.

Portable power stations typically come with several outlets for plugging in appliances and other devices. If you plan to use multiple devices at once, having more outlets is better. Think ahead about how many devices you’ll be using and check compatibility.

For disaster preparedness, a built-in light is a convenient feature to have. While you might think connecting an external light will suffice, in an emergency, it’s far more useful to have a built-in lighting function.

Battery lifespan is also crucial. Most portable power stations use either nickel manganese cobalt (NMC) lithium-ion batteries or lithium iron phosphate (LiFePO₄) batteries. NMC batteries typically last 300–500 charge cycles, while LiFePO₄ batteries can last around 3,000 cycles. These also differ in price.

“LiFePO₄ models are the mainstream now,” says a spokesperson from EcoFlow. In general, batteries can swell due to heat and pose a fire risk, so LiFePO₄ batteries are considered safer.

When selecting a portable power station, it’s important to know these characteristics and choose a model with the right capacity for your usage needs. “It’s a good idea to actually pick one up at an electronics store or home center,” the EcoFlow spokesperson adds. The size and weight are best judged in person.

Rather than keeping your disaster-use portable power station tucked away, try to use it regularly. Familiarity ensures that you’ll know how to use it in an emergency. You might want to start with a small unit and, like the housewife mentioned earlier, consider buying a larger one later.

Prices vary by brand, model, and whether you buy in-store or online. According to the websites of major manufacturers, discounts of 10% or more—and sometimes even up to 50%—are available through special promotions. Once you know the kind of model you need, compare brands and purchasing options to make your best choice.