Recharging Power Banks with a Bicycle Dynamo Hub

I own three inexpensive Anker 10,000-mAh power banks, one model A1237 power bank (this model is no longer produced) and two 323 power banks. Each power bank weighs 9.5 ounces.

It requires about 55% of the capacity of one 10,000-mAh power bank to charge my iPhone 16 Pro and my Apple Series 10 Watch. Every few days I also need to recharge my tent lantern and my Blackburn bicycle lights; this uses only a few percent of the power bank’s charge. Without recharging, two power banks are sufficient for recharging these devices for three days, and three power banks are sufficient for five days. It takes about eight hours to charge one of these power banks using a 5-watt charger; using a higher power charger does not decrease the charging time.

I find it more flexible to carry two or three 10,000-mAh power banks than to carry a single power bank with larger capacity. If I have access to electricity, I can charge multiple power banks at a time.

For longer trips, I needed a way to efficiently recharge my power banks. I decided to use a dynamo hub. I had my local bicycle shop, Ace Wheelworks in Somerville, MA, install a Shimano Metrea Dynamo Hub and a Sinewave Cycles Reactor Dynamo Powered USB Charger on my Surly Disc Trucker. While I was at it, I also had them install a dynamo powered headlight. This was expensive, but I felt the convenience was worth the money.

Item	Price
Shimano Metrea Dynamo Front Hub, 12 x 100 mm Center Lock Black 36h	$241.49
Busch & Mueller Front Light IQ-X black 100 lux	$196.00
Sinewave Cycles Reactor Dynamo Powered USB Charger Top Stem Cap	$220.00
Labor and misc. parts	$203.00
Sales Tax	$44.47
Total	$904.96

On my recent eight-day tour on Cape Cod, I had a good opportunity experiment with recharging my power banks using the dynamo hub. I spent the first four days and nights at a campground that provided charging ports in their recreation room, so it wasn’t until the sixth day that I needed to charge a power bank. The A1237 power bank has a percent charged readout, so I could obtain fairly precise numbers for charging. The results were variable, and I found that riding one mile increased the charge about 1%.

Start	End	Increase	Miles
4%	36%	32%	21
36%	67%	31%	35
6%	56%	50%	45

This means if I ride about 55 miles each day, I can keep my power banks charged. If I carry two or three power banks on a long tour, I can rely on charging with my dynamo hub with an occasional recharge from an electrical outlet.