How to Charge a 3.7v Battery Without a Charger – Charger and Charging Hour

A 3.7V lithium-ion battery typically lasts about 500 charge or discharge cycles and usually takes about 2 to 3 hours to fully charge. Sometimes you may not have your charger but you are in urgent need of a battery recharge. You can easily recharge your 3.7V battery without a charger using simple methods. Remember, despite how handy some of these methods are, it is not a guaranteed safe way to charge your battery.

In our article below, we delve deeper into explaining lithium-ion batteries. We discuss how to charge your lithium-ion battery without a charger and how to make your battery last longer. Here we go.

How to Charge a 18650 battery Without a Charger

A battery charger is one of the most important gadgets just like your phone. The same can be said when it comes to a 18650 battery. Purchasing this rechargeable battery and a compatible charger saves a lot of money and comes in handy. The charger will help you protect your battery as it comes with features that include: overcurrent protection, reverse battery polarity protection, and overvoltage protection. But, what if you do not have a charger for your 18650 battery and you need to recharge it?

You can charge your 18650 battery without a charger. For instance, you can use a trickle charger to recharge your battery. The problem with this charger is that it will take a lot of time to recharge as it provides a very weak electric current that the cells of your battery can absorb. Despite this disadvantage, it is the safer option as it will not damage your battery. When using this method, it is also good to have a regulator that will help apply a minimal charge to your battery. A regulator will control the amount of current that flows to your battery hence avoiding damaging it.

3.2V 20A Low Temp LiFePO4 Battery Cell -40℃ 3C discharge capacity≥70% Charging temperature：-20~45℃ Discharging temperature: -40~+55℃ pass acupuncture test -40℃ maximum discharge rate：3C

READ MORE

You can also use a USB cable and port to charge your battery. You can use a phone charger with a capacity of 500mA or more to charge your battery. With this method, ensure you also use a multimeter to keep on checking the output voltage of your battery. For safe operation, remove the battery at 4.1V.  Apart from this method, you can also directly charge your 18650 battery using another fully charged 18650 battery.

When charging your 18650 battery at home without a charger, make sure you observe safety precautions to avoid irreversibly damaging your battery. Make sure you do not leave your battery unattended for a period to avoid the risk of fire or damage.

How can I charge a 3.7V battery at home?

You can charge your 3.7V battery at home easily once you know the voltage you will need based on the number of cells. A 3.7V battery typically needs 4.20V per cell, and the battery will be fully charged once the current drops top 3 percent of the current it is rated to hold. When charging the battery, you will need to have a protection circuit board that helps ensure you do not overcharge or over-discharge your battery. In cases where you do not have a protection circuit board, you will need to charge your battery with a voltage of about 4.2V. So, when charging your battery at home, it is important to monitor the condition of the battery while charging it the entire time.

When you have a protection circuit board, you can use a USB 5V charger for a computer or a 5V charger for a mobile phone to charge your battery. But if you have a battery-specific charger, you do not have to use a USB cable. These batteries can easily be damaged by overcharging and over-discharging. Therefore, you can use the following four charging methods when at home.

Low Temperature High Energy Density Rugged Laptop Polymer Battery Battery specification: 11.1V 7800mAh -40℃ 0.2C discharge capacity ≥80% Dustproof, resistance to dropping, anti - corrosion, anti - electromagnetic interference

READ MORE

Activation charging – this is where you charge your battery when the voltage is too low. The low current is meant to activate and charge your 3.7V lithium battery.

Constant current charging – this is the charging you use after your battery is partially recharged. After activating your battery’s charge, you can change to a constant current fast charging.

Constant voltage charging – once your battery's voltage rises to 4.2V, you will need to change your charging to a 4.2V constant voltage charging. It ensures the charging current gradually decreases while at the same time avoiding overcharging.

Trickle charging – here you use a trickle charger to maintain the full charge of your battery once it is fully charged.

How do you make your battery last longer?

There are several ways and tips you can follow to ensure your battery lasts longer. Here, we discuss some of the most important tips to follow for optimum battery performance and long-lasting use.

Temperature

The most influential effect on battery life is temperature. Batteries need proper temperature for optimum performance and to last longer. High temperatures and very cold temperatures will damage your battery and reduce its lifespan. The hotter your battery gets, and the more time it is exposed to higher temperatures will destroy the chemistry of the battery. You should also avoid using your battery when it is very cold. Suddenly heating a very cold battery can cause localized internal heating which may destroy the battery.

Before recharging your battery, allow it to cool down first as it will help increase the life of the battery. 

Discharging

To ensure your battery lasts longer, avoid emptying it fully every time. Do not completely deplete your batteries charge constantly before recharging them. This ensures your battery stays longer as partial discharging and recharging multiple times is better. In case you happen to discharge your battery below 2.0V, recharge it at the slowest rate your charger supports and once your battery reaches over 3.0V, switch to the normal charging rate.

Charging

Avoid overcharging the battery frequently as an overcharged battery will not last long. After charging it, ensure your battery cools down first to room temperature before using it again. To avoid overcharging your battery, ensure the charger you use automatically turns off once your battery is fully charged.

If you have Li-Ion batteries, it is recommended to avoid trickle chargers as they continuously hold the battery at the trickle charge voltage which ends up causing damage.