How Many Times Does 20000mAh Charge a Garmin Edge 1040 Plus Bike Computer?
Updated 2026-08-17 · Power Bank Guide
When you're deep into a bikepacking trip or a multi-day festival, your bike computer is your lifeline for navigation and performance tracking. If you are wondering how many times a 20000mAh charge can power a Garmin Edge 1040 Plus, the answer isn't as simple as dividing two numbers. To get an accurate estimate, we have to look at battery capacity, voltage conversion, and real-world efficiency.
The Math: Calculating 20000mAh Charge for Garmin Edge 1040 Plus
To find the actual capacity, we first convert milliamp-hours (mAh) to Watt-hours (Wh), because that is how energy is truly measured across different voltages. Most power banks use internal 3.7V lithium-ion cells. The formula is: Watt-hours = mAh Ă· 1000 Ă— voltage.
For a 20,000mAh bank: 20,000 Ă· 1000 Ă— 3.7V = 74Wh. The Garmin Edge 1040 Plus has a highly efficient battery designed for long-haul rides, but for the sake of calculation, its capacity is roughly 6,000mAh (approx. 22.2Wh).
On paper, 74Wh divided by 22.2Wh suggests 3.3 full charges. However, power banks lose energy during the conversion from 3.7V (internal) to 5V (USB output) and then back down to the device's battery voltage. In the real world, you should expect a 60% to 70% efficiency rate. This means a 20,000mAh bank provides roughly 12,000 to 14,000mAh of usable energy. For the Garmin Edge 1040 Plus, this translates to approximately 2 to 2.3 full charges.
Choosing the Right Power Bank for Camping & Outdoors
When you are off-grid—whether for van life, backpacking, or cycling—you need a bank that balances capacity with portability. A 20,000mAh capacity is generally the "sweet spot." It provides enough juice to keep a bike computer and a smartphone alive for several days without adding excessive weight to your saddlebag or pack.
For those heading into the wild, the INIU 20000mAh Portable Charger (Flight-Safe) is an excellent choice. It delivers 22.5W fast charging, which is more than enough to top off a Garmin device quickly. Its compact size makes it easy to stow in a jersey pocket or a small frame bag, and the included flashlight is a practical addition for midnight camp repairs or navigating a dark festival campsite.
Understanding 22.5W Fast Charging and USB-C PD
Not all power banks deliver energy at the same speed. The Garmin Edge 1040 Plus supports USB charging, and utilizing a Power Delivery (PD) capable bank can reduce the time your device spends tethered to a cable. A 22.5W output, like that found in the INIU 20000mAh Portable Charger, is versatile. While the Garmin may not pull the full 22.5W, this overhead allows the bank to charge other gear—like an iPhone 17, Samsung, or Google Pixel—at significantly faster speeds than a standard 5W or 10W brick.
If you are incorporating solar top-ups into your off-grid setup, remember that solar panels charge the power bank, which then charges your device. This "buffer" method is far more efficient and safer for your electronics than plugging a Garmin directly into a fluctuating solar current.
Travel Safety: TSA and FAA Regulations
If your cycling adventure involves flying to a new destination, you must be mindful of battery regulations. The TSA and FAA generally prohibit large lithium batteries in checked luggage due to fire risks; they must be carried in your hand luggage.
Most airlines follow a limit of 100Wh per battery. As we calculated earlier, a 20,000mAh bank is approximately 74Wh, putting it well under that 100Wh threshold. While the INIU 20000mAh Portable Charger is designed to be flight-safe, always confirm the specific regulations with your airline before departing, as rules can vary by carrier and country.
Tips for Maximizing Battery Life Off-Grid
To make that 20,000mAh charge last even longer during your trip, implement these power-saving strategies:
- Optimize Garmin Settings: Turn off Bluetooth or ANT+ sensors you aren't using, and lower the screen backlight brightness.
- Avoid Extreme Temperatures: Keep your power bank and Garmin inside your clothing or a padded bag; extreme cold can cause voltage drops and reduce effective capacity.
- Charge During the Day: If using a solar panel, charge your power bank during peak sunlight hours so you have a full reservoir for overnight charging.
- Charge in Increments: It is often more efficient to top off a battery from 20% to 80% than to let it die completely and charge to 100%.
FAQ
Will a 20000mAh power bank overcharge my Garmin?
No. Modern devices and reputable power banks have built-in charge controllers. Once the Garmin Edge 1040 Plus reaches 100%, the device will stop drawing current, preventing overcharging.
How long does it take to charge a 20000mAh bank?
Depending on the input wattage, it can take anywhere from 5 to 12 hours. Using a high-wattage USB-C wall charger will significantly speed up the recharging process compared to a standard USB-A port.
Can I use this power bank for other camping gear?
Yes. A 20,000mAh bank is ideal for charging headlamps, GPS watches, and smartphones. Depending on the device's battery size, you can typically expect 3-4 full charges for a standard modern smartphone.