iPhone Battery Charging Protection Device

About iPhone's lithium-ion batteries

• Battery life: the amount of time a device runs before it needs to be recharged.
• Battery lifespan:  the amount of time a battery lasts until it needs to be replaced.

A battery’s lifespan is related to its 'chemical age', which is more than just the passage of time. It includes different factors, but the most important are the temperature and the number of charge cycles. On Apple's website, the instruction for how the device should be cared for are as follows:

• Avoid extreme ambient temperatures. The ideal range of ambient temperatures is between 16C ~ 22C (62F ~ 72F). Temperatures higher than 35C (95F) can permanently damage battery capacity. When temperatures are cold, there may be a noticeable temporary decrease in battery life but no damage to the battery.
• Avoid overcharge and over-discharge. The battery can be damaged when it is connected to a power source after being fully charged. When a battery is over-discharged, damage can be caused to the battery as well as the device's electronics components.
  ​The comfort zone for the battery stress is about 30% ~ 80%. (https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries, Figure 6)

The software solution from Apple
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• ​​Overcharge protection: Optimised Battery Charging. 
  With iOS 13 and later, Optimised Battery Charging is designed to reduce the wear on your battery and improve its lifespan by reducing the time your iPhone spends fully charged. When the feature is enabled, your iPhone will delay charging past 80% in certain situations. Your iPhone uses on-device machine learning to learn your daily charging routine so that only Optimised Battery Charging activates when your iPhone predicts it will be connected to a charger for an extended period of time. The algorithm aims to ensure that your iPhone is still fully charged when unplugged.
• Over-discharge protection: the power management system.
  The system determines the capability of the battery to supply needed power, and manages the loads in order to maintain operations. When the operations can no longer be supported with the full capabilities of the power management system, the system will perform a shutdown to preserve these electronic components. While this shutdown is intentional from the device's perspective, it may be unexpected by the user.

​What are the problems?
​

1. In our daily usage, when the charging source is around, the best way to prolong the battery's lifespan is to keep the battery charged level between 30% ~ 80%. This is almost impossible to achieve because there is no solution on the market to assist a user in doing so.
2. With the help of the common power bank, a user can prevent the situation of over-discharge the iPhone. However, there is still no solution for overcharging if the user leaves the iPhone to get fully charged.
3. Without a power bank, a user can risk permanently damaging the iPhone battery by completely exhaust battery.
4. Many users experience iPhones gets hot during wireless charging. This is potentially fatal to the battery lifespan.

Potential product solutions

​An iPhone battery protection device can be attached to the back of the iPhone by magsafe (or integrated into a phone case).

• Version 1 : Overcharge protection only - to limit a phone being charged over 80%
• Version 2 : version 1 + over-discharge protection. With build-in battery to limit the charging over 80% and output power to the phone when the phone battery level drops below 30%.
• Version 3:  version 2 + solar panel. With build-in solar panel to charge the build-in battery to extend the battery life a bit longer when an user is on the move.
• Version 4: version 2 + heatsink. Address the overheating issue during wireless charging.

* Photos are for concept illustration only.