The iPhone and Cell Phone Battery Guide

Tech Tips

The Battery Guide Introduction


Like many modern portable electronic devices, iPhones and cell phones rely on a Lithium Ion battery as their source of power. Lithium Ion batteries offer many advantages over the previous Nickel cadmium batteries, although there are some limitations.  A brief education on the Lithium Ion batteries used in the iPhone, iPod, iPad and other modern cell phones and tablets and how they work is beneficial, so that you can better maintain your battery over time.  Many modern smartphone users are unknowingly shortening the life of their battery due to bad practices. In this guide we will discuss ways to improve the life and maintain the capacity of your cell phone battery. We will also discuss common ways that batteries are damaged. But first, let’s look at the major differences between the Lithium ion battery used in the iPhone and other modern cell phones and the Nickel cadmium batteries of the past.

The battery used in the iPhone 3GS

Lithium Ion Vs Nickel Cadmium

Although Lithium Ion batteries are presently the norm for small portable devices like the iPhone, Nickel cadmium once ruled the mobile industry. So what makes the Lithium Ion battery better suited for modern devices? The Lithium Ion battery has a much higher energy and power density than the Nickel Cadmium battery. This makes it ideal for small portable devices like the iPhone. A one cell nickel cadmium battery (NiCad for short) rates at 1.25 volts, whereas a one cell lithium ion battery rates at 3.6 volts. This means that it would take three NiCad cells connected in series to match the voltage rating of a Lithium Ion battery. This makes for a smaller and lighter weight battery which is ideal for the iPhone and  modern cell phone.

Furthermore, the Lithium-ion battery does not suffer from the infamous “memory affect” that has plagued NiCad batteries. The memory affect refers to the loss of capacity in a NiCad battery if the battery is repeatedly recharged without being allowed to fully discharge. When this happens, the battery seems to develop a memory for a smaller capacity. Fortunately, lithium-ion batteries do not suffer from the “memory effect”.

There are two major drawbacks to Lithium Ion batteries. First, lithium Ion batteries are fragile. Each Lithuim-Ion battery has a protection circuit built in to ensure safe operation. This protection circuit ensures that the voltage of the battery does not drop too low during discharge or peak too high during charging. Either voltage extreme can seriously damage the battery, making  this protection circuit a necessity.  Unfortunately, this protections circuit adds to the cost of the battery, and is a component that is susceptible to damage during impact. This makes an iPhone or smartphone battery another fragile component in the device that can be damaged during a drop or fall.

Small circuit board on the bottom of the iPhone 3GS and limits the batteries charge and discharge.

A Modern Cell Phone Batteries Life Span

The Lithium-ion life span issue is somewhat subjective and is an issue that manufacturers have often avoided discussing. What is known, is that the iPhone and cell phones batteries lasts for only a finite number of cycles. Apple claims that “A properly maintained iPhone battery is designed to retain up to 80% of its original capacity at 400 full charge and discharge cycles.” However, this claim is based on ideal scenarios with proper maintenance.  In reality, the effective life of the iPhone battery falls somewhere between 300 and 500 full cycles.  A full battery cycle is defined as a complete charge and discharge of the battery.  Therefore,  discharging the battery to 50% and recharging it equals a half cycle and repeating the process would make one full cycle.

iPhone Battery Indicator

The fact that remains relatively unknown about the lithium ion batteries found in the iPhone and other devices is how much power  the battery retains,  regardless of whether it is in use or not. This means that even if your cell phone sits in a closet for a year without use, odds are the battery capacity has deteriorated to some extent.

So how much does an lithium ion battery deteriorate over time?  The exact number is widely debated, but some estimates claim as high as a 25% capacity loss per year and others  as low as 10%.  According to, “Some capacity deterioration is noticeable after one year, whether the battery is in use or not. The battery frequently fails after two or three years.” The bottom line is that the  cell phone batteries do not last forever, and if your battery is more than a year old and showing signs of reduced capacity, you may need a battery replacement.

A Modern Cell Phone Batteries Capacity

The capacity of an iPhone or smartphone battery is defined as the amount of time the battery can sustain the device. According to Apple, a full charged new or well maintained iPhone battery should yield roughly 8 hours of talk time on 3G or 225 hours in standby mode. The lithium ion batteries found in call phones are rated in mah (milliamp hours).  The iPhone 5 battery is rated at 1450 mah. The replacement batteries provided by uBreakiFix are rated for the same capacities as the original battery.

Lithium Ion iPhone batteries should be kept at room temperature as often as possible. Extreme heat and cold can ruin a lithium ion battery. Avoid leaving your device in a hot car or exposed to direct sunlight for too long as this overheating can severely limit the batteries capacity. The protection circuit built into the battery also helps guard against overheating. If for any reason the battery attempts to operate outside of a safe temperature range, many devices will display a temperature warning on the screen. The temperature warning displayed on the iPhone is shown below.


Modern Cell Phone Battery Maintenance

There are some simple maintenance steps to follow that can maximize your iPhone or cell phone batteries lifespan and capacity.

  1. Avoid allowing the battery to fully discharge too often. The built in protection circuit will prevent the battery from draining to the point of irreversible damage. However,  repeatedly allowing the battery to fully discharge causes unnecessary strain on the battery.
  2. Avoid charging your iPhone  or cell phone in particularly constrictive cases. Some cases do not allow for proper heat dissipation and can cause the battery to overheat while charging which can limit the batteries capacity over time.
  3. Avoid high temperatures. As mentioned previously, high temperatures can severely limit battery life and capacity. Try not to allow your iPhone or cell phone to remain in an environment above 100 Degrees F for any length of time
  4. If you are planning to store your device for any length of time, charge the battery to roughly 50%. This avoids letting the battery sit at full charged or discharged levels which can produce unwanted strain on the battery. Since lithium Ion batteries continue to discharge over time, even without use, storing your device with a dead battery will allow the battery to continue to drain. This continued drain can result in serious and even fatal damage to the battery
  5. Watch for any signs of reduced battery capacity after one year of use or 300-500 charge cycles, whichever comes first. If you notice signs of reduced capacity, consider replacing the battery.

If you are in need of a battery replacement, stop by our of our many retail locations. We offer battery replacements for many popular devices including: iPhone, iPod, iPad, smartphones, tablets, and computers.

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