So it turns out most USB power banks won’t charge Exposure brand lights. They describe the mechanism that causes this on their FAQ page and have confirmed with me by email that this is the issue I’ve been having (multiple power banks and 2 different Exposure lights):
“Power banks have a boost converter to generate the 5V output. To save energy they will switch this off if there is no load. Some of them you have to press a button to start, others will test every second or so. We momentarily stop the charging every second to measure the battery voltage for the fuel gauge, some power banks can turn off during this.”
They said another customer reported successfully charging their lights from an Anker 737 Power Core.
Can anyone name any other makes/models they’ve had success with? I’d especially love to know if there are any smaller options in terms of size/weight - this thing is basically double the size/weight of my current ‘main’ power bank while only increasing battery capacity from 20,100 mAh to 24,000 mAh.
FURTHER NOTES:
- In the bikepacking race I’m prepping for I’ve heard multiple stories of people not being able to go fast enough for a dynamo to function. I also just don’t really want to go through the process of setting up a dynamo system right now. Would need to charge a power bank from it anyway since going direct to a lot of devices is problematic.
- I asked if I could charge a Support Cell (Exposure’s own backup batteries) from a powerbank and then use that to charge the lights. They said there’s a different technical problem that often gets in the way of charging support cells this way.
- I know there are even further challenges with powering Exposure lights while they are on. That’s not something I need to do in this situation - I can charge them when they are off.
- It would be OK if my ‘main’ powerbank couldn’t charge the Exposure light as long as I could use that power bank to charge a smaller one that does work with the lights.
- Once I started looking into this I opened up a whole other can of worms to do with charging rates. My 20,100 mAh Anker battery is a few years old and takes like 8 hours to charge via USB-A. I see now products like the model Exposure linked to above can charge in a fraction of the time, and choosing an appropriate modern Gallium-Nitride based wall-charger can have a big impact on this as well. Looks like with a carefully chosen setup I could potentially charge phone, bike computer, light, and backup batteries from a single wall outlet in 3 hours or less. This might make it worthwhile doing a big spend on all new top-of-the-line battery and charge parts and will still cost less than going to dynamo. Would be curious to hear anyone’s bikepacking-specific GaN charger experiences too. [EDIT: started a separate thread for this: GaN Chargers and High-Speed Power Banks - Device Charging For Bikepacking]