With every charge cycle your phone battery degrades slightly. A charge cycle is a full discharge and charge of the battery, from 0% to 100%. Partial charges count as a fraction of a cycle. Charging your phone from 50% to 100%, for example, would be half a charge cycle. Do that twice and it’s a full charge cycle. Some phone owners use more than a full charge cycle a day, others use less. It depends on how much you use your phone and what you do with it.
2. Avoid extremes of heat and cold.
If your phone gets very hot or cold it can strain the battery and shorten its lifespan. Leaving it in your car would probably be the worst culprit, if it’s hot and sunny outside or below freezing in winter.
3. Avoid fast charging.
Charging your phone quickly stresses the battery. Unless you really need it, avoid using fast charging.
In fact, the slower you charge your battery the better, so if you don’t mind slow charging overnight, go for it. Charging your phone from your computer as well as certain smart plugs can limit the voltage going into your phone, slowing its charge rate. Some external battery packs might slow the speed of charging, but I’m not sure about that.
4. Avoid draining your phone battery all the way to 0% or charging it all the way to 100%.
Older types of rechargeable batteries had ‘battery memory’. If you didn’t charge them to full and discharge them to zero battery they ‘remembered’ and reduced their useful range. It was better for their lifespan if you always drained and charged the battery completely.
Newer phone batteries work in a different way. It stresses the battery to drain it completely or charge it completely. Phone batteries are happiest if you keep them above 20% capacity and below 90%. To be extremely precise, they’re happiest around 50% capacity
5. Charge your phone to 50% for long-term storage
The healthiest charge for a lithium ion battery seems to be about 50%. If you are going to store your phone for an extended period, charge it to 50% before turning it off and storing it. This is easier on the battery than charging it to 100% or letting it drain to 0% before storage.
Thanks for reading. 1. No as long as the power bank voltage offered is between 5.1V to 5.4V. 2. If your power bank voltage is lesser than 5.1V never use it with your device as it will end up drawing power from your device and not charging your device or will end up drawing very little power. Now if your power bank usb voltage is greater than 5.4V one thing you can do is try to charge your mobile or tablet till the battery percentage reaches 80-85% Hope that answers your questions.