Do not use Quick Chargers with Jooki
What is the problem?
Our ongoing testing has shown that it may be possible to damage Jooki with a USB Quick Charger. The symptoms are that Jooki no longer charges and may become warm.
So what is a Quick Charger?
Normal USB chargers provide 5V. To quickly recharge a cell phone, Quick Chargers can provide 9V or more in addition to the standard 5V mode. (Note: most USB devices, Jooki included, don't benefit from this)
The problematic chargers are usually shipped with high-end smartphones and marked with names like: quick charging, turbo charging, adaptive fast charging, rapid charging, and (Qualcomm) Quick-Charge.
How do I identify a Quick charger?
Look for 9V, 12V, 20V label on the charger. For example, this charger shows 9.0V which is not OK.
A charger marked 'fast' is OK if the label only shows 5V (and not 9V or higher).
Unsure? Please contact us.
What have you discovered so far?
Our preliminary investigations seem to point at an unwanted interaction between Jooki and the Quick-Charge charger that triggers the charger to provide a higher voltage than Jooki can handle. Jooki has protection circuits built in to deal with short overvoltage spikes, but these cannot deal with a sustained overvoltage condition as would be applied by the Quick-Charge chargers if they go into high-voltage mode.
We have not yet been able to reproduce this ourselves but we can envisage a scenario that might trigger this behavior. It also doesn’t happen every time a Quick-Charger is used.
What are you doing about this?
We are trying to reproduce the problem in our lab and exploring possible fixes with our hardware suppliers. We are determined to ensure that Jooki is a fun and reliable product.
What can I do?
Avoid using Quick Chargers with Jooki.