I have two portable USB battery chargers. They are different brands. See the picture.
Both of them charge a cell phone fine, but they won't charge my hearing aids in the aids charger. When I plug them in, they charge for 10-15 seconds, then shut off. Both devices do approximately the same.
It occurs to me that those devices may have circuitry to detect if a load is plugged in. If not, they shut themselves down. I have a theory that the hearing aids current draw is so low that the device thinks "no load at all."
Might I be correct on that theory? or is there a better theory?