The kit that matters is not the one with a hand-crank radio in a waterproof case. It is the small bag that keeps your router, your phone and your logins alive for six hours, and gets you back into your accounts when the phone holding your second factor is the thing that died. Everything below fits a 5-litre pouch and costs less than a mid-range phone.
Power: size it to the router, not to the fridge
A typical fibre router with its ONT draws 8–12 W. That number decides everything. A 20,000 mAh power bank is about 74 Wh of cells, and after converter losses you can realistically pull 60–63 Wh out of it, which is five to seven hours of internet. To use it you need a USB-C PD bank that can output 12 V and a USB-C to 12 V DC trigger cable matched to the router’s barrel jack — check the label on the router’s brick for voltage, polarity and jack size (5.5 mm outer / 2.1 mm inner is the common one; 5.5/2.5 also exists).
The tidier option is a small UPS: an APC Back-UPS BX600C (600 VA / 360 W) costs around $70 or BDT 8,000 and gives a router plus ONT roughly 45–90 minutes with no cables to hunt for. A 256 Wh portable power station such as the EcoFlow River 2 sits at the other end at about $200 and will run the router for a full day. The measurement method for all of this is the same one used to keep internet running through a power cut: measure the draw, then divide.
Charging bag: match wattage, ignore brands
One 65 W gallium-nitride charger with two USB-C ports and one USB-A replaces three drawer chargers and charges a laptop, phone and bank at once. Add a 2 m 100 W USB-C cable (the cable, not the charger, is what limits you to 60 W on cheap ones), a USB-C to Lightning cable if anyone in the house still uses one, and a 30 W car adapter for the 12 V socket.
Add a slim 10,000 mAh bank for a jacket pocket, so the bag’s big bank stays full. Add a three-prong to two-prong adapter: borrowed sockets are often unearthed and a chunky earth pin will not fit.
Recovery: two drives and one sheet of paper
Make a 128 GB USB drive (USB-A on one end, USB-C on the other, about $15) into the boring but decisive item in the bag. On it: a Windows 11 installer built with Microsoft’s Media Creation Tool, a macOS installer if the household has a Mac, an exported copy of the router configuration (Administration > Backup in most firmware), and PDFs of insurance, passport and warranty documents.
Then print the things that only exist inside a working computer. A single sheet, sealed in an envelope, with: the Wi-Fi network name and password, the router’s admin address and password (often still admin/admin on hardware nobody has touched since installation), the phone numbers of two people outside the household, and the backup codes for your email and bank accounts. That last item is the one people skip: if your authenticator lives on the phone that just fell in water, ten printed one-time codes are the difference between a two-minute recovery and a two-week identity queue.
Let someone else be able to get in
A password manager is excellent right up to the moment the only person who can open it is unavailable. Every major manager has an answer that has to be configured in advance. Bitwarden’s Emergency Access lets you nominate a trusted contact who can request access, with a waiting period you set (one hour to 30 days) during which you can decline; the contact gets view-only or takeover rights. 1Password issues a printed Emergency Kit PDF containing the Secret Key, which is the single thing you cannot recover from memory — keep it with the codes sheet, not in the bag’s cloud folder. Apple’s Legacy Contact is the third option and is deliberately slow (death certificate required), so it is not a weekend-outage tool.
Then test it: have the nominated person open the manager, sign in and close it. An emergency access path never exercised is a hope, not a plan, and the habits in password manager habits that stick apply here too. If you use passkeys on your phone, note the failure mode: they sync within an ecosystem, so a dead Android phone hands nothing to an iPad.
Storage and the twice-yearly check
Lithium cells hate two things: sitting at 100% in the heat, and sitting at 0%. Keep banks between 40% and 60% when stored, at room temperature, and never leave the pouch in a parked car — a Dhaka afternoon reaches 45°C inside, the fastest way to turn a good bank into a swollen one. Store batteries out of devices that will not be used for months; a leaking AA in a headlamp is a $40 replacement for a $2 part.
Every six months, do five things: charge each bank to full and discharge it to 60%; unplug the router and run it from the UPS for ten minutes to confirm the runtime you assumed; mount the USB drive on a computer and check the installer still opens; confirm the printed sheet still has working phone numbers on it; and check the dates on anything with an expiry, including the smoke alarm cells. Fifteen minutes in April and October, and the bag is worth carrying.