Battery Protection Systems

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What Are the Benefits of Battery Protection Systems?2019-10-18T16:24:46+00:00

Battery Protection SystemsYou walk into work one morning and find out that a battery system isn’t working. What happens? How much time will you lose trying to fix it? Getting it back online will probably cost money, but how much?  

When it comes to battery malfunctions, that’s not even the worst-case scenario. What if damage to the battery system causes equipment damage further downstream or even creates a fire?

You consider eventualities like this whenever you integrate a new piece of machinery or develop a new work process, but have you gone through this process when integrating your battery system?  

In this article, we’ll take a look at circuit protection and why it’s so important for industrial batteries. We’ll analyze a few of the different options you have for battery protection systems and how each system can help you to avoid battery damage and dangerous accidents.  

Let’s start with the basics:

What Are Battery Protection Systems?

A battery protection system is any device that safeguards against battery malfunctions. Some are only effective against basic issues like overcharge or short circuit, while others provide complex monitoring and balancing for an entire battery system. 

What Do They Protect Against?

To really understand why battery protection systems are so important, you need to know what can happen if they’re not in place: 

Short Circuits

These occur when a current takes a shortcut. Electricity always wants to go back to the ground as soon as possible, but a correctly functioning circuit keeps it on the proper track. If the wiring in the circuit malfunctions, the current can escape and go back to the ground another way. That way might involve going through your equipment or one of your workers.

Overcharge

When you put too much charge into a rechargeable battery, that extra energy becomes heat. The temperature of the battery can rise beyond safe limits and reduce the battery’s lifespan.

Over Discharge

Draining too much of the charge from a battery can damage it in several ways, including decreasing the capacity of the battery, causing it to require charging more often, and causing a short circuit within the battery. If a lithium-ion battery lacks a protection system, it is highly prone to these and other malfunctions related to over-discharge.

Overcurrent

Too much current within the circuit can result from a number of malfunctions, including short circuits. If there is enough excess current, it can ignite components of the machinery and cause a fire.

How Do Battery Protection Systems Help?

Battery protection systems serve to keep the temperature and voltage balanced in your battery. Steady temperatures are critical for optimal battery life, which increases the safety of your operations and reduces your material costs. 

An effective battery protection system will measure the current and temperature in your battery and adjust the circuit to provide protection if levels become unsafe. The process typically involves a thermistor, a ceramic-type semiconductor that decreases in resistance when the temperature of the battery rises. When this happens, it indicates the need for control and simultaneously acts as a battery “first aid.” 

Thermistors work in conjunction with other safety mechanisms. Together, these systems provide the current and temperature control that a battery needs to stay operational. Let’s take a look at some of the most effective options:

Polymeric Positive Temperature Coefficients

The polymeric positive temperature coefficient, or PPTC, helps to balance the circuit against excess energy. Just like a standard fuse, it opens to create high resistance when there is too much current in the system. When the current decreases back to normal levels, it resets.  

Unlike some types of fuses, the PPTC resets itself so that you can still use the battery after the overcurrent is corrected. It simply serves to keep the battery functional until electricity resets back to normal levels.  

PPTCs are most commonly used for nickel batteries. They’re affordable, easy to install, and are compatible with most systems. 

Protection Circuit Modules

Protection circuit modules, or PCMs, protect against overcharge, over-discharge, and excessively fast discharge, all of which can cause an excess of current. In lithium batteries, the PCM usually protects against these situations using a metal-oxide-semiconductor field-effect transistor, or MOSFET.

The MOSFET alters the circuit’s conduction by switching cells on if the voltage falls too quickly or off if the voltage rises to unsafe levels. It keeps the battery running while helping to avoid damage, preserving battery life in the short and long-term.  

Battery Management Systems

A battery management system, or BMS, is necessary when you need more precise control over multiple batteries. They provide all of the standard protection involved with simpler systems while monitoring individual cells and the system as a whole.

A BMS can do any of the following:

  • Preserve the life of the battery and keep it safe to use 
  • Report the state of the battery’s charge and capacity
  • Indicate when the battery is in need of replacement
  • Warn the user when the battery needs repair or when the voltage flow is too high 

The most important difference between a BMS and a simpler battery protection system is the ability of the BMS to monitor each cell as well as the full system.    

Individual cell monitoring is critical for battery health because systemwide malfunctions often show themselves at the individual cell level first. By monitoring the voltage in each cell and alerting the user to voltage overages or drops, a BMS can prompt repair of issues such as corrosion or dry-out before they do extensive damage.

In addition to monitoring, a BMS provides safety protection during key processes, including charging and discharging and disconnects the battery in case of failure or safety hazard. It integrates completely with the machine’s software system, allowing the user to get battery alerts as readily as texts or emails.

The Takeaway

Battery protection systems ensure the correct flow of voltage through your batteries, protecting your machinery as well as the health and safety of your personnel.

At Vertical Partners West, we understand that battery protection is an essential safety function. We offer a variety of products to meet the needs of our industrial clients, and we take pride in our ability to help you select the right product for your business.

If you’re in need of a custom battery or battery charger, contact us today to get started.

Battery Protection Systems2021-02-22T21:26:24+00:00

Protection Systems for Industrial Applications

VPW provides PTC (Positive Temperature Coefficient) thermistors, PCM (Protection Circuit Modules) and BMS (Battery Management Systems) for a wide variety of batteries and chemistries. Using these control systems greatly improves safety, performance and longevity of any battery system.

Many rechargeable batteries have very high energy density and very specific charging and discharging requirements. Not properly caring for these batteries can lead to irreversible battery damage and in severe cases battery rupture and even fire. To help assure safe battery operation, peak performance and maximum longevity, battery protection circuits are often included within the battery pack, wired in line with the device being powered or integrated into the device itself.

PTC (Positive Temperature Coefficient)

Some times referred to as a resettable fuse or polymeric positive temperature coefficient device (PPTC), the PTC is typically utilized with Nickel battery chemistries to provide basic resettable protection for over current and short circuit. These simple devices come in a variety of sizes and mounting options to fit virtually any application and can be implemented quickly and cost effectively.

PCM (Protection Circuit Module)

Typically designed to provide basic protections such as overcharge, over discharge and short circuit protection, these are fairly simple circuits offering a limited degree of control and safety. Because they do not require software integration they can be implemented quickly and cost-effectively making them an excellent first-line approach to improving battery safety and cycle life.

BMS (Battery Management System)

When a higher degree of control is required a BMS system can be utilized to perform a much broader range of controls including short circuit protection, cell balancing, individual cell monitoring for internal resistance, temperature and more.

BMS modules are available as stand-alone circuits or as Smart BMS for communicating with your computer, charging system and flight controller. Many communication methods are available including I2C, SMB, USB, RS232, among others. Because software integration is required integration of battery management systems requires additional lead-time and development cost.

No Battery Protection

Protection circuits may not be utilized in instances where power requirements are very high, cost requirements are low and the development schedule is limited. Risk assessment is a large part of the decision to exclude protection circuitry for customers that may be willing to accept the potential risks or where the device the battery is utilized with contains the means for proper battery protection. VPW strongly urges customers to consider the use of some means for proper battery protection both for safety and longevity of the battery system. Some form of protection will be required for lithium battery chemistries to ensure compliance with UN38.3 transportation requirements for a lithium battery.

Since battery protection requirements can vary widely, Vertical Partners West works closely with our customers to make sure the selected protection device is properly specified and implemented to the specific customers project requirements.

Venom Industrial Battery Protection Systems

For most industrial applications, battery life and system safety are critical and a PTC device is a first line approach to improving battery safety and cycle life for Nickel based battery chemistries.

PTCs or positive temperature coefficient thermistors have been a long time standard solution for over current and short circuit protection and are offered in a variety of current ratings and mounting styles to fit most applications.

As current passes through the PTC its temperature increases and when the current exceeds the rated trip current it heats suddenly breaking connection between the conductive particles in the device. As current is removed from the PTC the device cools and returns to a low resistance state allowing current flow to resume.

For proper operation, when selecting a PTC, consideration should be given to the various factors that may affect its operating temperature.

Typically PCM devices are utilized for Lithium chemistries and offer many safety features, which are a requirement for transportation safety of lithium batteries per UN38.3 specifications. PCM circuits also help to extend battery life while improving battery safety.

Safety functions commonly offered in a PCM are:

  • Cell balancing (lithium chemistries)
  • Over charge and over discharge protection
  • Over temperature protection (NTC thermistor)
  • Over current and short circuit protection

Overcharge:

Overcharging can cause excessive heat, and shorten battery life and in extremes it can cause a fire. To safe guard against this, PCM devices are equipped with a FET switch that disconnects the battery from the voltage supply at a predetermined level.

Over-discharge:

If a battery voltage drops below the specified voltage, the PCM disconnects the battery to protect it. One of the dangers of over-discharging is that the weakest cell’s voltage may reverse. This can cause improper recognition of the battery by the charger and individual cells in the pack can become grossly overcharged and lead to the battery overheating and potentially rupturing.

Over Temperature:

The PCM monitors the battery temperature usually by monitoring the temperature of the hottest cell, that one which testing shows becomes the warmest in operation and in charging. If an over temperature condition occurs, the PCM disconnects the battery from the circuit until the battery cools to within specification then it automatically reconnects the circuit.

Over-current:

The PCM monitors current flow and disconnects the battery should over current condition exist. Over-current operation can cause the battery to overheat, shortening the battery life expectancy and in extreme cases cause the battery to vent or catch fire. Over-current protection usually keeps the battery circuit open until the over current situation is resolved.

Short Circuit:

If a hard short circuit occurs the PCM’s FET switch is designed to fail. This destroys the PCM and usually makes the battery useless but prevents fires, cell rupture with electrolyte leakage or other issues.

In addition to handling the same safety management as a PCM, a BMS incorporates a microprocessor that monitors, controls and reports on a variety of parameters. It is designed to manage and monitor the battery and communicate with the outside, which is usually a microprocessor or master computer.

Through software, a user can control the battery operation, keep track of statistics such as how many times the battery has been used, how many times it has been charged, the temperature, depth of discharge, current capacity and the degradation of capacity over time. The BMS can also communicate the state of charge (SOC) so that the robot or drone can be sure to have enough energy left to return to its starting point (ET Call Home).

FCC Testing Required:

BMS circuits contain a low power microprocessor to perform its functions and control. This means that these batteries must be tested and approved to FCC Part 15 emissions and susceptibility regulations. Look for the FCC logo on these batteries.

Communicating with the BMS

BMS communications are available through a variety of protocols. The most common are the I2C/SMB and CAN bus protocols. Also available are Ethernet, WiFi, RS485 and others depending upon requirements. VPW provides a full technical description of the protocol and works closely with customers to meet specific communication requirements.

For more information please call:
800-705-0620
or email: sales@vpwllc.com

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