Battery Protector Circuit – Introduction, MOSFET, and Module

Batteries have been around for many years. We use them for powering many of the electronic devices out there.

However, there is also one issue that many battery users don’t take very seriously- protection. Some batteries, like lithium-ion batteries, are known to explode, causing fires other issues.

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Proper protection is required for these batteries. Whether you use batteries in mobile devices or power more demanding machines, you need to understand how battery protection works.

In this guide, we will be introducing you to the battery protector circuit and how it works. Come along.

Battery Protector Circuit Schematic

Every battery manufacturer offers recommended ways of using and taking care of their products. That means different technologies may have different demands in terms of protection.

Let’s talk about lithium batteries. These are the most common batteries and perhaps the most vulnerable to issues like explosions.

Lithium batteries can charge to 4.1v or 4.2v and cannot go any higher. Overcharging any batteries can lead to more harm instead of more power as most users think. And when it goes beyond the charging point, you are looking at serious damages.

Moreover, lithium batteries are said to be empty when they have been discharged to 2.5v. Anything below this could be too stressful for the cell, and it can reduce their lifespan.

Most batteries behave in this manner. They are designed to charge to a specific point and discharge to a specific level. Some batteries come with ‘battery memory.’ You can never unplug them from power until they are fully charged or connect when they still have some power.

Luckily, batteries come with a protection circuit. It offers protection if a battery is overcharging.

Another factor to put in mind when using lithium batteries is that they should never be discharged too fast. They have very high discharge current ratings.

A good protection circuit removes the batteries from circuits whenever there is too much overload. Many of the battery protection circuits out there use MOSFETs to protect the battery.

One cannot easily connect in parallel lithium cells of the exact same age as the part number. That means they can also use one distinct protection circuit.

Do batteries need protection?

The simplest answer is yes. If you want to use any battery comfortably without worrying about fires, then protection is necessary. The protection comes in the form of a circuit board joined to the batteries. It comes wrapped with the distributor’s label.

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Battery protection circuits make sure the battery never gets overcharged or over-discharged. They are computerized to make sure only the desired level of charging or discharging is achieved.

Lithium batteries, for instance, offer about 3.7 volts. When charging, manufacturers advise that you never let it go beyond 4.2Vs.

And when it’s discharging, it should never drop below 2.8 V.

This would mean you get a way of measuring everything your battery is charging or discharging. But we don’t have that time.

Therefore, batteries need a protection circuit to keep the batteries out of danger. The circuit shuts down when the battery is going above the charging point or when it is going below.

Some chargers come with smart features. They will stop charging a lithium battery, for example, when it’s closest to 4.2v. Doing this makes sure there is no overcharging or over-discharging.

Battery Protector Circuit MOSFET

We have mentioned MOSFET as the common system used in battery protection circuits. One of the most common ways of mitigating the risk of serious damage is by placing MOSFETS in the charge and discharger way. This system breaks the electrical connection between the battery and the rest of the circuit whenever the battery voltage seems to go outside the proper range. It will also disconnect when the IC shows an overcurrent surge during charging and discharging,

This is not a fast-switching application. And hence, you need to understand the worse scenario and take appropriate precautions. Also, this will help you choose the right MOSFET system. The selection process is similar to choosing a load switch.

But there are some unique considerations to keep in mind when choosing a MOSFET. Understand first that a battery-protection MOSFET is both enhanced and has a continuous current discharge. Besides, it will completely shut off to disconnect the circuit of the battery from the rest of the electronics. You can therefore neglect to switch the parameters when choosing a specific system. Instead, you can follow the same method of choosing a load switch. In this case, you can choose the FETs based on their ability to handle power, resistance, and package type. These are the most important factors to keep in mind.

Put your devices in different tiers as recommended when choosing MOSFETs. In the first category, you have low-power personal electronics that use two battery cells. A good example is your cellphone, tablet, smartwatch, or personal health tracker. These devices don’t consume a lot of power when charging. Besides, most manufacturers are trying to reduce the sizes of these batteries more and make them as small as possible. With that in mind, you need to choose a MOSFET system that is as small as possible.

One must also understand that MOSFETs are placed back-to-back in these applications. That is how they block the charge and discharge paths. Sometimes they integrate both devices into a single package in a common drain configuration.

?In a nutshell, the MOSFET system is the most common battery circuit protection app on the market. It’s crucial to choose carefully something that will serve you well.

Battery Protector Circuit Module

Any battery, especially a lithium battery pack, requires safety protection. We all know the UL has specific regulations on the safety of these batteries. Still, it’s crucial to use an extra layer of protection just to make sure the device operates efficiently.

There are different battery protector modules for these functions:

Primary safety circuits – these are safety circuits that manage all basic safety operations like overcharge, undercharge, and over-current.

Protection circuits – these are contained in the Protection Circuit Module. The PCM is part of the battery management system, which makes these protector circuits more advanced.

Fail-safe environments - Many protection modules can be reset. However, in fail-safe environments, one can design so they cannot be reset. The ICs are manufactured by Texas Instruments and Seiko.

Now that you understand how to choose a battery protection circuit, you should feel safer. These circuits will help you use batteries without worrying.