How often do I need to recharge a power bank if I am not using it regularly?

The obvious key point is, if not in regular use.
Firstly, a good power bank should be able to retain charge for well over a year and perhaps well over 2 years, if not in use and stored safely according to the user manual.

A good quality power bank can’t be overcharged. It should have smart internal control circuit (ICC) that should cut the power when fully charged or if the heat gets over a prescribed level. 

In order to conserve the stored power, the ICC will auto switch off power output when the device you are charging becomes full. All you’ll need to do for instance, is to unplug your device being charged. 

Secondly, if you won’t use it for a long time then there’s probably no need charging it because batteries tend to discharge over time. Therefore it seems a futile effort to charge it at all. So, might be best not to charge it until needed. Also, batteries can be a fire hazard if not properly stored. Best to avoid that risk if the power bank isn’t in regular use.

However, it is important to note that you can charge your powerbank whenever you like - especially if a solar power bank; in which case you just need to expose it to direct sunlight. You don’t have to wait for it to be fully discharged before you charge it up. You just need to keep it safe.

Dave Ebi is a Most Viewed Power Bank Writer on Quora. Join HetoGrow on Facebook, Twitter, Instagram, G+ or LinkedIn