Using a 5 V Charger to Charge a 3.7 V Phone Battery: Safe?

Here’s whether you can use a 5-volt charger to charge a 3.7-volt cell phone battery.

It’s not safe to charge a 3.7 V cell phone battery with a 5 V charger for both the equipment and personal safety. 

The load the wrong charger will send into the phone battery is far higher than what it is designed to take.

The phone battery can heat up and explode in a worst-case scenario. 

If you want to know all the details about charging a 3.7 V phone battery with a 5 V charger, then this article is for you.

Keep reading!

Table of Contents

Can You Use a 5 Volt Charger to Charge a 3.7 Volt Cell Phone Battery?

When folks buy a device or electronic tool that requires recharging, it almost always comes with a matching charger. 

The same goes for cell phones and their batteries. 

However, for various reasons, chargers get lost, break, get stolen, or someone’s sibling thinks they make a great lasso for a toy cowboy. 

That can lead to the temptation to just plug in a compatible charger that seems to work, namely a 5-volt charger in a 3.7-volt cell phone battery. 

It’s not a good idea. Here’s why.

Batteries Have a Built-in Limit for How They Work

Just say no to wrong chargers.

Batteries are constructed with metal inserts within a chemical electrolyte. 

Together, the two components help process the chemical reaction that, in turn, provides the energy or electricity to a mobile tool. 

When the battery is being charged, one chemical reaction occurs as designed. 

When the battery is being drawn down, a different chemical reaction occurs. 

Both of these processes have a specific resistance they need to achieve to work. 

The resistance associated with charging needs to be higher than the resistance needed for the battery to discharge and provide electricity. 

However, if it is too high, the battery can get extremely hot and could explode in an extreme case.

Design-wise, the most a 3.7v battery in a phone can take the load from a 4.2v charger, at best. 

Going higher gets into the danger zone, and heat production can outpace the ability of the battery to dissipate that temperature rise. 

When it reaches a critical temperature, the high Ampere current then starts damaging the battery’s structure, and it begins to fail altogether.

Is It Just a Rumor That You Can Charge Your 3.7 V Cell Phone Battery With a 5 V Charger?

Unfortunately, many myths and rumors are floating around that make the question come up again and again. 

Somewhere, somehow, somebody figured out a way to make a 5 V charger work, and with the Internet, that rumor gets legs and runs. 

Technically, the setup will produce charge. 

And, assuming one took the battery off before it got too hot, it would, in theory, have a charge created that then produces power. 

Again, this is all possible, but the real question is for how long. 

Playing a risky game with timing the critical heat point of a battery before it explodes is a bad idea for a variety of reasons, not to mention splashing battery acid everywhere.

Go With a Matching Phone Charger Instead, But Don’t Go Too Cheap

When it comes to replacing a charger, it’s simply a smarter idea to find an alternative unit in the same voltage range and with a compatible connector. 

Phone batteries, in particular, tend to be extremely sensitive to charging, especially when they are loaded incorrectly. 

Not only does using the wrong charger create a heat risk, but it can also damage the phone as well. 

More than one cell phone as been basically turned into a dead hunk of plastic and metal with overcharging and a poorly designed aftermarket charger. 

These are the types folks typically find in a gas station for $5 or some similar cheap price. 

Made by the hundreds with poor materials and little attention to safety, these devices can do horrible damage to cell phones in a short amount of time simply because their charging is off-sync with the phone’s battery and assembly. 

And given the fact that one typically pays anywhere from $200 to $800 for a cell phone, getting damaged and destroyed by a cheap $5 charger is particularly insulting.

What Should You Consider When Traveling With Your Phone Charger?

The other thing to keep in mind with a charger choice is the plug, especially when traveling. 

A user could easily have the right charger but an incorrect plug end for the local country’s wall socket. 

Don’t try to jury-rig the situation. 

Instead, the user should be using the right adapter to translate the local socket to the plug type. 

Again, a bit of safety can go a long way to avoiding an expensive mistake. 

Most plug adapters can be found in airports if one forgets to pick them up beforehand, but understand the price may be a bit inflated for a captured market.

Should You Only Use Original Equipment Manufacturer (OEM) Phone Chargers?

Ideally, the cell phone battery should be matched to the manufacturer’s charger when possible. 

It’s already been tested and matched exactly to never over-charge the given phone assembly. 

However, most folks find that the OEM charge tends to be the most expensive option available, and the manufacturer or brand seller does this on purpose to maximize revenue. 

Along comes the substitutes. If someone can build a better mousetrap, which sometimes involves being cheaper, people flock to it. 

Aftermarket substitutes often make considerable income and enjoy demand simply because they sell at a lower price than the OEM charger. 

And small savings can be extremely attractive to consumers. However, as mentioned above, going too cheap comes with a huge cost.

How to Research a Phone Charger Aftermarket Alternative?

Picking a good aftermarket charger takes a bit of research. 

One of the best ways to go about it is to use the Internet and look for comments or reviews on various aftermarket models. 

If a brand has been around long enough, it’s going to have a track record of performance. 

If the quality and build are good, folks will note that and comment that the charger works. It’s reliable and a good bargain. 

On the other hand, if the charger is of poor quality, folks are pretty good at commenting on that aspect as well, usually with colorful language. 

A basic search engine query is usually good enough to find the relevant comments. 

However, another option is to look at the reviews for various chargers on Amazon.com or a similar consumer goods website. 

Just type in the name of the charger or do a mass search for matching chargers, and the results will usually provide more than enough info to make a decent decision on what will work.