Friday, June 25, 2021

Powering your Router with your Power Bank

With the work from home setup we all have to rely on our routers for a reliable connection throughout the day. If you live in a region like me where power failures are common, you need to plug the router to a UPS to maintain uninterrupted internet (specially useful for long meetings). UPS ensures the router is powered by external power when power is available and switch over to UPS battery when no power.

In addition to a UPS, you can also use your Power Bank which you may have already purchased for your phone to power the router. 

You can consider this approach if:

- You don't want to purchase a bulky UPS just for the router.

- You are fed up with unreliable/broken UPS switch-over delays and battery quality.

- You already have an unutilized power bank with you.

What you need:

- A router

- A power bank

- Step-up voltage convertor cable (Can be purchased at a very low cost compared to a UPS)

Verify your router power consumption:

Take a look at the bottom and it should mention something like this:

V means Voltage and A means Amperes. In my example it's 9V and 0.6A. Some routers might mention the current in milli-amperes (eg. 600mA). This allows us to estimate the power consumption of the router.

9V X 0.6A X 1hour = 5.4Wh

That means if we keep our router running for 1 hour it will consume 5.4Wh of energy from your electricity supply. (Wh means Watt Hours)

Another example: Router says 12V / 1000mA
1000mA = 1A. That means:
12V X 1A X 1hour = 12Wh

Verify Power Bank energy output:

The output energy of the power bank effects how long can your router run from the power bank before you have to recharge your power bank. There are 2 factors to this:
- Power bank battery capacity. Usually power banks mention their capacity in milli-ampere-hours (eg. 40000mAh
- USB output voltage. Usually this is 5V.

Calculating energy output of a 40000mAh power bank with 5V output:
40000mAh = 40Ah
40Ah X 5V = 200Wh

Another example: 10000mAh power bank with 5V output:
10Ah X 5V = 50Wh

Estimating how long your router can run:

Run time = Power bank output energy / Router power consumption

According to my examples, to run my TP-LINK router with a 10000mAh/5V power bank:
Run time = 50Wh / 5.4Wh = 9.2 hours (theoretical maximum)

Keep in mind this is the maximum runtime if there's no energy loss during power transmission. Assume the efficiency is 70%, then the practical run time is 9.2 hours X 70% = 6.4 hours.

By that estimate, if I use a 40000mAh/5V power bank, I can run my TP-LINK router for nearly 24 hours continuously before I have to recharge the power bank.

"Passthrough" power banks

If your power bank supports "passthrough" feature, then it can charge while providing battery power to your router. Then you don't have to worry about router power consumption and having to unplug and recharge. Refer to your power bank manual to find this out.

Purchase a matching step-up converter cable

Last thing you need to do is find a step-up voltage converter cable to match the power bank output voltage and router input voltage. The convertor cable provides a USB jack to plug to power bank USB output. Also please verify when purchasing whether it provides the matching power jack for your router power socket.

Here are some step-up cable search results from and

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