Pass-Through Charging with Battery Packs

Are you looking to harness and store PedalCell's energy if your devices are fully charged? A battery pack equipped with "Pass-Through" charging may fit the bill.

What is Pass-Through Charging?

"Pass-Through" charging allows a device to be charged and discharged at the same time. In the case of a battery pack, pass-through allows a cyclist to plug their battery into an energy source, such as PedalCell, while simultaneously charging USB devices. The functionality can be game-changing for long-distance cyclists such as tourers and bikepackers. Not all battery packs are equipped with this pass-through. Manufacturers will typically list if their battery packs are equipped with pass-through in their specifications or FAQ.

The Benefits

Pass-through can result in a seamless, care-free, charging experience for cyclists:

  1. Prioritized Charging: Most battery packs will prioritize the charging of USB devices. This means that USB cycling devices, such as lights, will be fully charged before excess energy is dumped into the battery itself.
  2. Stored Power: Once USB devices are fully charged, a pass-through battery pack will automatically divert power into its internal battery for long-term energy storage.
  3. Energy Stability: USB devices will continue charging from the battery pack, even when stopped.

The Drawbacks

Pass-through charging does contain downsides that must be kept in-mind:

  1. Efficiency: Pass-through charging creates heat within battery packs, resulting in a 10-20% efficiency loss. This means that an additional 10-20% of power from the energy source (PedalCell) is lost compared to charging a USB device directly.
  2. Battery Lifespan: The extra stress and heat from pass-through charging typically result in a shortened lifespan for battery packs.
  3. Discharging Potential: Battery packs can discharge over time when used with a motion-based energy source such as PedalCell. For example, say a pass-through battery pack provides a constant 15W of power to 3X USB devices. Simultaneously, the rider is charging the battery pack from PedalCell at a speed of ~8 MPH, producing ~5W of power output. Since the net energy usage is negative, the battery will discharge, albeit slower, over time.


Battery packs equipped with pass-through charging can be popular with long-distance cyclists thanks to their ability to store energy on long trips while simultaneously charging USB devices. While the batteries do contain power and longevity limitations, they can be a great option for cyclists who want to make the most of PedalCell's charging capabilities. PedalCell provides up to 4X more power than other bicycle generators with leading industry-leading efficiency. These advantages make PedalCell a great fit for the power demands of a cyclist's pass-through charging setup.

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