# Adidas headphones have photocells and can be charged in any type of light – picture and sound – news

It’s much worse. The bright outside light on a summer day is about 100klux. The rule of thumb is that you then have an insolation of 1kW/m^2. The solar panels provide an efficiency of 10-15% and then about 100-150 W/m2 (I intentionally choose cautious values ​​here, as these are flexible panels). Or also 10-15mW/cm^2.
For reference, the linked JBL headphones have a 700mAh battery, which is good for 24 hours of playback time. Assuming a 3.5V cell voltage of the battery, this is equivalent to 700m * 3.5/24 = ~100 MW consumption. With 10mW/cm^2 it needs its 10cm2 solar panel to make it happen. It seems possible on headphones.

However, the illumination indoors is in the range of <50 lux in a darkened living room, up to 100-500 lux in an occupational health and safety workplace (from 1000 lux you can do operations), up to 50 thousand - 100 klux outside.

The previously mentioned energy/surface area can be linearly reduced by the amount of lux. Let’s say you enjoy headphones in a dim living room at around 50Lux (which is still brightly lit in my opinion), this solar cell only delivers 10-15uW/cm^2.

The article about JBL headphones states that they set “infinite” battery life at 50 klux. I don’t know how much margin there is, but assuming 50klux is the balance in terms of power supply/consumption, these headphones will have 100-1000 times longer charging time than the playing time they’re out of.

But ; Your mileage may vary. Imagine if you left those headphones on a sill (window) that catches an hour of sun every morning, you’d have a lot of fun with them. Of course you have to make sure that the solar panels are positioned correctly. But even if you only put these headphones in the shade, I wouldn’t expect you to be able to charge them for more than fifteen minutes of playtime a day.

[Reactie gewijzigd door Hans1990 op 16 augustus 2022 22:34]