"I hear used smartphones are a good deal, but I'm worried the battery will die quickly..."

Many people may feel this way and hesitate to buy a used smartphone. Especially for a device you use every day, battery life is a critical issue.

This article thoroughly explains, from an expert perspective, how to alleviate concerns about "battery life," which is the biggest worry when buying a used smartphone. We comprehensively cover everything from guidelines for battery degradation to checkpoints for making a successful purchase, and tips for extending battery life after purchase.

After reading this article, you will gain a deeper understanding of batteries and be able to find a reliable used smartphone that perfectly suits your needs. Please read until the end.

Used Smartphone Batteries: Common Concerns and Thorough Explanations!

Let's address the questions and concerns many people have about used smartphone batteries. Here, we'll explain in detail the degradation status of used smartphone batteries, the effects of degradation, and the possibility and cost of battery replacement. Unlike new smartphones, the condition of a used smartphone's battery can vary greatly depending on how the previous user handled it. Therefore, it is crucial to carefully check the battery's condition rather than simply choosing the cheapest option. This section will deepen your basic knowledge about used smartphone batteries, building a foundation for you to proceed with the purchase guide.

How much do used smartphone batteries degrade?

The degradation level of used smartphone batteries varies significantly from device to device. This is largely influenced by the previous owner's usage and charging habits. The most common indicator for battery degradation is the "Maximum Capacity" displayed on iPhones. This value indicates the battery's charging capability as a percentage of its capacity when new, and a lower value means more degradation. Generally, when the maximum battery capacity drops below 80%, users tend to notice a decrease in performance and shorter operating times. Therefore, when purchasing a used smartphone, this "Maximum Battery Capacity" is a crucial checkpoint. Many reputable used smartphone retailers specify this value, so be sure to check it before making a purchase.

What are the effects of battery degradation?

Battery degradation can have various effects on the usability of your smartphone. The most obvious is "poor battery life." You might find yourself needing to charge your phone by midday, even if it was fully charged in the morning. Additionally, a decrease in maximum battery capacity can affect the smartphone's processing power (performance). This is because the "performance management function" may activate, intentionally slowing down the CPU to prevent the phone from suddenly shutting down when the battery can't supply enough power. As a result, apps might launch slowly, or operations could become choppy, making the phone less comfortable to use. Furthermore, symptoms like longer charging times and increased heat generation can also occur. To avoid these issues, it's important to choose a used smartphone with a good battery condition.

Can the battery be replaced? What is the cost?

Since used smartphone batteries are consumables, they may eventually need to be replaced. Battery replacement is possible for most models, but the cost and effort involved can vary significantly depending on the model and the repair shop. Using a manufacturer's authorized repair service is often expensive, but non-authorized repair shops may offer more affordable options. However, opting for a non-authorized repair shop comes with risks, such as potentially voiding the manufacturer's warranty or uncertain repair quality. As a guideline, depending on the model, official manufacturer repairs typically cost around 10,000 to 15,000 yen, while non-authorized repairs range from 5,000 to 10,000 yen. PRODIG also offers repair consultations, so please feel free to contact us.

For affordable smartphone and tablet repairs, visit Smartphone Partner!
https://smart-partner.jp/

[Expert Tips] A Used Smartphone Buying Guide Focused on Battery Life to Avoid Mistakes!

What should you look out for when purchasing a used smartphone to alleviate concerns about the battery? Here, as used smartphone professionals, we will explain three specific checkpoints to ensure you don't make a mistake when focusing on battery life. By understanding these points, you can find a used smartphone that you can use with peace of mind for a long time, instead of just choosing based on price. Especially with used items, individual differences are significant, making pre-purchase checks extremely important.

Checkpoint 1: [Most Important] Aim for a Battery Maximum Capacity of "80% or more"

The "battery maximum capacity" is the most crucial indicator for judging the condition of a used smartphone's battery. This value shows how much charging capability remains compared to when it was new, and on iPhones, it can be easily checked from the Settings app. Many experts and used smartphone retailers recommend "80% or more" as a safe guideline for purchase. If this value falls below 80%, the battery life is likely to significantly worsen, and the smartphone's performance may decline. However, 80% is just a guideline, and depending on usage and model, even in the 70s might be perfectly usable. Nevertheless, if you want to use it comfortably for a longer period, it's ideal to choose a device with 85% or more, or preferably 90% or more. At PRODIG, we only handle products with a battery maximum capacity of 80% or more, so you can choose with confidence.

Checkpoint 2: Is the retailer's "warranty" comprehensive?

When purchasing a used smartphone, a comprehensive "warranty" from the retailer is as important as the battery's maximum capacity. Unlike new products, used items carry the risk of unexpected malfunctions, so it's crucial to choose a retailer that will provide solid support in such cases. The battery, in particular, is a consumable item, and there's always a possibility of rapid degradation after purchase. Therefore, choosing a retailer with a comprehensive battery warranty will provide peace of mind after your purchase. For example, PRODIG offers a 1-year long-term warranty on all purchased used smartphones. This warranty provides free replacement if the battery's maximum capacity drops below 80% within one year of purchase, which is a rare and comprehensive offering in the industry. This is a testament to our strong desire to ensure our customers can use used smartphones with confidence. By checking such warranty details beforehand, you can purchase a used smartphone with peace of mind.

Learn more about PRODIG's安心保証 (Peace of Mind Warranty) 
https://prodig-shop.com/pages/guarantee

Checkpoint 3: Choose a model with a good reputation for battery performance.

When choosing a used smartphone battery, it's effective not only to consider individual differences but also to select a model that inherently has good battery performance. Generally, newer models tend to have improved battery efficiency and can be used for longer periods compared to older models. Also, within the same series, larger models like "Plus" or "Max" often feature higher capacity batteries, leading to better battery life. For example, among iPhone series, models from the iPhone 13 series onwards are known for excellent battery life. For Android, while it varies by model, high-end models like Galaxy and Xperia, or models that boast large capacity batteries like OPPO, are also good options. By researching the battery performance of each model according to your usage habits beforehand, you can achieve a more satisfying used smartphone purchase.

Why is PRODIG trustworthy? Our commitment to used smartphone batteries.

One of the reasons why "PRODIG" is chosen by so many customers is our thorough commitment to the quality of used smartphones. In particular, we have established our own strict standards for battery condition, which is the biggest concern for customers. Here, we will introduce how PRODIG provides customers with used smartphones they can use with peace of mind.

Thorough inspection system by specialized staff

At PRODIG, all incoming used smartphones undergo a meticulous inspection by specialized staff, one by one. This inspection process focuses not only on checking the exterior but also on thoroughly examining internal functions, especially the battery condition. Specifically, for iPhones, we always check the "maximum battery capacity" and only deal with devices that meet a certain standard (often 80% or more) as products. For Android devices, we also use specialized tools to check the battery health and confirm that there are no issues. This thorough inspection system allows customers to clearly understand the battery condition of the product before purchase, preventing situations where "the battery was more degraded than expected" upon arrival. 

Generous in the industry! 1-year long-term warranty after purchase.

One of the most important reassurances when purchasing a used smartphone is the "warranty." At PRODIG, we have established a generous warranty system to ensure our customers can use used smartphones with complete peace of mind. This is a long-term warranty covering 180 days from the purchase date. This warranty covers natural failures that occur during normal use. While battery degradation is inevitable for used items due to individual differences and age, please rest assured that PRODIG only sells devices with a maximum battery capacity of 80% or more at the time of inspection. This PRODIG warranty system is a manifestation of our unwavering commitment and confidence to fundamentally alleviate customer concerns. You can be prepared for any eventuality after purchase and continue to use your smartphone with peace of mind for a long time.

Learn more about PRODIG's peace of mind warranty
https://prodig-shop.com/pages/guarantee

You're all set after purchase! 5 tips to extend the life of your used smartphone battery.

Once you've got a reliable and affordable used smartphone, you'll want to use it comfortably for as long as possible. To do this, it's important to avoid putting stress on the battery with your daily usage. Here are 5 easy-to-follow tips to extend your battery's life.

Tip 1: Aim to keep the charge between "20% and 80%."

It is said that the lithium-ion batteries used in smartphones degrade faster when left at full charge (100%) or complete discharge (0%) for extended periods. Therefore, when charging, it is ideal to aim for the battery level to remain between 20% and 80%. "Overcharging" by leaving the charging cable plugged in overnight puts a significant strain on the battery and should be avoided. Many modern smartphones are equipped with features to prevent overcharging during sleep, so utilizing such functions is also recommended. Adopting this habit can help extend the battery's lifespan.

Tip 2: Avoid high-temperature environments.

Batteries are sensitive to heat, and using or charging them in high-temperature environments significantly accelerates degradation. Specifically, you should avoid using your smartphone in places where it can easily overheat, such as in a car during summer or in direct sunlight. Additionally, smartphones tend to heat up while charging, so it's effective to remove the phone case during charging or charge it in a well-ventilated area. If you feel it getting hot, it's important to stop using it and let it cool down. Especially in summer, when battery degradation is likely to accelerate, be mindful of heat countermeasures.

Tip 3: Review screen brightness and settings.

One of the biggest consumers of smartphone battery is the screen display. The brighter the screen, the more power it consumes. By avoiding excessively high screen brightness and utilizing automatic adjustment features, you can reduce battery consumption. Also, features like Wi-Fi, Bluetooth, and GPS continuously consume power if always left on. You can improve battery life by turning them off when not in use, or by limiting location services to only essential apps.

Tip 4: Turn off unnecessary notifications and background updates.

Push notifications from apps and background app updates also subtly contribute to battery consumption. Especially if you have many apps installed, these features may be constantly draining your battery. By turning off notifications for unnecessary apps and restricting background app updates, you can reduce wasted battery consumption. Apps like social media and games that send frequent notifications often show a significant improvement, so be sure to check your settings.

Tip 5: Smartly utilize low power (power-saving) mode.

Many smartphones feature a "low power mode" or "power-saving mode" designed to conserve battery when the charge is low. Activating this mode restricts background app updates and visual effects, helping to save battery. While this mode is typically used when the battery is already low, it's also recommended to actively use it when you still have charge, for instance, on days when you'll be out all day and want to conserve battery.

[2025 Edition] PRODIG's Recommended Used Smartphone Models Based on Battery Performance

When choosing a used smartphone, good battery life is an important factor. Here, we will pick out and introduce recommended models from both iPhone and Android categories that excel in battery performance and are popular in the used market.

[iPhone Edition] Models with good battery life and excellent cost-performance

The iPhone series has significantly improved battery efficiency with each new model. In particular, the iPhone 13 series and later are known for their excellent battery life.

• iPhone 13: With a significantly increased battery capacity compared to the iPhone 12, it offers battery life that can reliably last all day. It's also a readily available model in the used market.

• iPhone 14 Plus: Among the iPhone 14 series, this model stands out for its particularly large battery capacity and excellent battery life. With its large screen size, it's recommended for those who enjoy watching videos or gaming.

• iPhone SE (3rd generation): Despite its compact size, it features the same A15 Bionic chip as the iPhone 13, leading to improved battery efficiency. It's especially recommended for those upgrading from an iPhone 8.
  

Click here for PRODIG's used iPhone 13 series lineup 
https://prodig-shop.com/collections/iphone-13series

Click here for PRODIG's used iPhone 14 Plus product list 
https://prodig-shop.com/collections/iphone14-plus

Click here for PRODIG's used iPhone SE3 product list 
https://prodig-shop.com/collections/iphone-se3

[Android Edition] Recommended Models with Large Capacity Batteries

Android smartphones vary greatly in battery capacity and performance depending on the model. Choosing a model equipped with a large capacity battery will allow you to go through the day without worrying about charging.

• Google Pixel Series: The Pixel 7 and Pixel 8 series are known for good battery life due to the excellent power efficiency of their proprietary "Tensor" chip.

• Galaxy S Series: Samsung's flagship Galaxy S series offers both a large screen and a high-capacity battery, providing high performance and excellent battery life.

• OPPO Reno Series: Many mid-range models in this series are equipped with large-capacity batteries exceeding 5,000mAh, making them highly recommended for those who prioritize battery life above all else. When choosing a used smartphone, it's a good idea to check actual battery life by referring to hands-on reviews, not just specs.

Click here for PRODIG's Android product list
https://prodig-shop.com/collections/android

PRODIG will buy your unwanted smartphone! Make a smart switch.

When upgrading to a new smartphone, many people wonder what to do with their old one. It's a waste to just leave an unused smartphone at home. PRODIG offers a buyback service for unwanted smartphones, allowing you to use the funds towards your new purchase, making for a smart and economical upgrade.

Why is PRODIG's buyback service convenient and cost-effective?

PRODIG's buyback service offers many convenient and cost-effective benefits for customers. First, you can check the estimated buyback price online on our buyback site, allowing you to get an idea of the value from home. Additionally, since PRODIG also handles sales in-house, we can reduce intermediate margins, meaning you can expect a high buyback price. Regarding data erasure, which is a concern when selling a smartphone, we use specialized tools to completely erase your data, so you don't have to worry about personal information leakage, and you can use our service with peace of mind. Please note that PRODIG does not offer online appraisals or mail-in buybacks; we only provide in-store buybacks at our Akihabara location. When visiting, please remember to bring your identification documents.

Can you buy back a smartphone with a degraded battery?

You might be worried that a smartphone with a degraded battery won't be eligible for buyback. Rest assured, PRODIG does buy back smartphones with degraded batteries. While a better battery condition will naturally result in a higher appraisal value, even if the battery is degraded, as long as other functions are fine, we will properly assess its value and buy it back at an appropriate price. If you are considering upgrading to a new smartphone, we encourage you to use PRODIG's buyback service to smartly monetize your old smartphone.

For your unwanted smartphone, choose PRODIG for a smart upgrade!
https://prodig-kaitori.com/

Summary: PRODIG comprehensively solves your used smartphone battery concerns!

Everyone has concerns about batteries when purchasing a used smartphone. However, as explained in this article, those concerns can be significantly alleviated by checking the "maximum battery capacity" and choosing a trustworthy retailer that offers a "generous warranty."

PRODIG ensures customers can use used smartphones with peace of mind through a thorough inspection system by specialized staff and a 1-year long-term warranty, which is rare in the industry. Furthermore, by implementing tips to extend battery life after purchase, you can continue to use your smartphone comfortably for even longer.

If you're considering buying a used smartphone, be sure to check out the PRODIG online store. With our extensive selection and reliable warranty, you're sure to find the perfect device for you.

View the entire PRODIG online store! 
https://prodig-shop.com/

Frequently Asked Questions (FAQ)

Q1. Should I absolutely avoid buying a smartphone with a maximum battery capacity below 80%?

A. It's not an absolute rule, but many used smartphone retailers and experts recommend aiming for 80% or higher. Devices below 80% are likely to have significantly worse battery life and may require a battery replacement soon after purchase. This is particularly true for those who frequently use their smartphone throughout the day or prioritize battery life, in which case it's best to avoid such devices. However, if your use is limited, such as a secondary device at home, and you always have access to charging, then considering a lower price might be an option.

Q2. Is it okay to replace the battery of my purchased used smartphone myself?

A. While it's possible with specialized knowledge and tools, it's not recommended. Smartphones are precision devices, and disassembling or repairing them yourself carries the risk of damaging other components or losing water resistance. Moreover, if you perform a self-repair, you will likely lose eligibility for manufacturer warranties or retailer warranties. We recommend having your battery replaced by a reputable professional. PRODIG can also introduce you to affiliated repair shops, so please feel free to consult us.

For affordable smartphone and tablet repairs, visit Smartphone Partner!
https://smart-partner.jp/

Q3. Can I actually see the device and check the battery status at a PRODIG store?

A. Yes, you can. At the PRODIG Akihabara store, you can actually pick up and examine the devices on sale. You can directly ask our staff about the maximum battery capacity, as well as the exterior condition and functionality. If you want to see the actual device for yourself and consult with our staff directly, please visit the PRODIG Akihabara store. We also post the latest information and stock updates on our official X (formerly Twitter) account, so checking it before your visit would be convenient.

Check the latest information on PRODIG Akihabara's official X! 
https://x.com/prodig_inc