How Green Are Batteries?

When you peer into the world of batteries your first thought is “wow – there sure are a lot of batteries”. While this is certainly true as self directed environmentalist I wonder just how many batteries can actually be recycled. To answer the question let’s look at batteries from the manufacturing floor on up to the end user.

The battery business just as in any business requires that materials are bought, assembled into products, and eventually sold to an end user. Batteries however have an interesting collection of materials, which are designed to collect energy, store energy, and redistribute energy on demand. These processes on the surface seem very environmentally friendly but let’s see just how friendly!

As alluded to above building a battery requires basic components including: the casing, the chemistry, the electrolyte, and the battery’s specialized hardware

The Battery Casing

The purpose of a battery casing is for enclosing and hermetically sealing an internal battery body. Battery casings are manufactured in layers. The casing layers are developed from various raw materials and can include one or two polyethylene terephthalate layers (a thermoplastic polymer resin of the polyester family), a polymer layer, and a polypropylene layer (another thermoplastic polymer). The entire casing can be recycled.

The Battery Chemistry

As noted above a battery is a device that converts chemical energy into electrical energy. To convert chemical energy into electrical energy the battery must contain the chemical base to allow conversion to occur. Types of common chemicals used in batteries on the market today are:

• Lithium Ion (Li-ion)
• Lithium Polymer (Li-po)
• Lithium-thionyl chloride (Li-SOCl2)
• Lithium-sulfur dioxide (Li-SO2)
• Lithium-manganese dioxide (Li-MnO2)
• Nickel-cadmium (NICD)
• Nickel-metal-hydride (NIMH)
• Lead-acid batteries
• Reusable Alkaline

Each of these chemistries can be recycled.

The Battery’s Electrolyte

The actual conversion of chemical energy into electrochemical energy can only be done if an electron flow passes between two electrodes, an anode (the negative end) and a cathode (the positive end). The battery’s electrical current (electron flow) runs from one electrode to another through a conductive chemical called an electrolyte solution.

A basic electrolyte solution is a chemical compound (salt, acid, or base) that when dissolved in a solvent forms a solution that becomes an ionic conductor of electricity. In the battery cell the electrolyte solution is the conducting medium in which the flow of electric current between the electrodes takes place by the migrating electrons.

At the end of the battery’s electrolyte solution’s life, the spent battery acid can be neutralized using an industrial grade baking soda compound. After neutralization the acid turns into water, treated, cleaned to meet clean water standards, and then released into the public sewer system. Another option would be to convert spent battery acid into sodium sulfate, which is used in laundry detergent, glass and textile manufacturing.

The Battery’s Specialized Hardware

A battery consists of more than the casing, electrolyte, and the chemical. It requires some very specialized hardware, especially when we speak directly about a smart battery. Your typical smart battery may have a multitude of hardware components that when working in tandem not merely create electrical power and transfer it to a particular device but additionally sends data packets of information to the device so that the device can actually gauge the battery (at least in theory). Some of the common hardware features in a smart battery include: the connector, the fuse, the charge and discharge FETs, the cell pack, the sense resistor (RSENSE), the primary and secondary protection ICs, the fuel-gauge IC, the thermistor, the pc board, and the EEPROM or firmware for the fuel-gauge IC. The materials that comprise these individual components can be broken down and recycled.

So How Green Are Batteries?

Batteries are very environmentally safe, especially batteries that are rechargeable.

Until next time – Dan Hagopian,
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Lithium Ion Batteries Are Sensitive to Heat

Over 15 million students are enrolled in fall college classes across the United States according to a US Census Bureau study in 2004. Using that number as a base it can be projected that the fall of 2008 should see a slight up-tick in college enrollees. Interestingly the number of college students that are going to college with laptop computers have increased by 28% compared to 42% of college students in 2004. This means that nearly 70% of enrolled students are using laptop computers. In real numbers that represents 10,500,000 laptop computers.

Now listen up college students – your laptop battery is more than likely a Li-ion battery and if it is then there is a natural tendency to keep your laptop plugged into a wall outlet when you are close to one. You may also find that you are actually “plugged” in to a wall outlet more than you are not and there in lies a problem. When your laptop is plugged into a wall outlet your battery heats up big time and heat and lithium do not mix well together.

Hold on! You have to charge battery. Yes that is true, but you do not have to keep your laptop plugged into a wall outlet for the entire school year! But won’t that reduce my battery life if I’m constantly powered from the battery?

Your battery will diminish in capacity – the ability to charge and power your laptop. That is a fact and a natural consequence of batteries today. This diminishing power performance is called battery degradation and power loss. I have written on this topic before and you can read about it on my blog but on a high level a battery over time degrades and eventually stops working, this is no surprise, and it occurs due to the following technical processes: declining capacity, increasing internal resistance, elevated self-discharge, premature voltage cut-off on discharge.

So should you constantly keep your battery charged at 100% capacity? No you should not. Why? To answer that question let’s look at what is occurring when you charge a battery. When charging your battery you are forcing electrical current into a battery cell from a charger. The force of electrical current causes temperature increases.

Now it is true that contained within your laptop battery are integrated power management circuits that are designed to protect against over-voltage and under-voltage conditions that increase heat in the battery but one factor of how well a battery is being protected during a charge depends on the ratio of the heating rate versus the dissipation rate. If the heating rate is higher then the dissipation rate then thermal runaway will occur (leaking, smoking, gas venting, flames).

Now don’t go into panic mode since the integrated circuits are really good at keeping the heating rate lower than the dissipation rate and you are in extremely minimal danger of thermal runaway occurring.  But the practice of keeping your battery charged continuously can negatively affect your battery’s longevity. So charge your battery and then run your laptop on battery power until you have to charge it again.

Until next time Dan Hagopian
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Batteries – One Size Does Not Fit All

I have a Palm Zire 72 and a Palm m505 PDA. If I buy a Palm Zire 72 Battery that is 3.7 volts can I plug it into a Palm m505 and have that battery power both devices as needed?

In a nut shell the question above seeks to ascertain if all 3.7 volt batteries are the same?

The quick answer is no – all 3.7 volt batteries are “not” the same – and a battery specifically designed for a Palm Zire 72 will not be compatible with a Palm m505 PDA.

Let me explain.

It is true that all batteries share similar components and share common electrical measurements. But just because all batteries have some common components and measurements does not mean at all that you can interchange batteries with various devices even if the technical ratings are the same. Note that a component is something tangible and a measurement is intangible – a result of an action contained within the battery system.

Quick Review: What is a Battery and how does it work?

A battery in its most basic definition is a device that converts chemical energy into electrical energy. Batteries have two electrodes, an anode (the negative end) and a cathode (the positive end). Collectively the anode and the cathode are called the electrodes. What is positve and what is the negative terminal? It would be great to simply say that the anode is negative and the cathode is positive, however, that is not always the case. Somtimes the opposite is true depending on battery technology.

In between the battery’s two electrodes runs an electrical current caused primarily from a voltage differential between the anode and cathode. The voltage runs through a chemical called an electrolyte (which can be either liquid or solid). This battery consisting of two electrodes is called a voltaic cell.

Electrical measurements that can be gleaned from battery operations inclued the measurements of:

Volts – or V – is the electrical measure of battery’s energy potential. For example you can think of energy potential as the pressure being exerted by all the electrons of a PDA Battery’s negative terminal as they try to move to the positive terminal.

Amps – or A – which is a measure of the volume of electrons passing through a wire in a one second. One Amp equals 6.25 x 1018 electrons per second.

Watts: Volts x Amps = Watts. Watts are important because a watt represents the electrical energy spent by a battery (power generator) and used by an electrical device. Watts in effect is the measure of the amount of work done by certain amperage (amount) of electric current at a certain pressure or voltage.

Now beyond that basic review of the common components and measurements of batteries begins the radical differences between batteries. If you have a PDA, MP3, MP4, Laptop, Cell Phone, Smartphone, DVD players, or other electronic devices then more likely then not the battery within your device is a high capacity smart battery pack.

What is a high capacity smart battery pack? A high capacity smart battery pack is a complex battery system designed to power high tech electronic devices.

To construct a smart battery the battery manufacturer must carefully plan the internal battery design environment by considering the:

• design parameters
• current requirements
• capacity and runtime requirements
• temperature requirements
• safety requirements
• ambient operational/non-operational temperatures

As a design for a smart battery pack is considered manufacturers must evaluate the differences in components in relation to their design environment. Proper component evaluation and specification selection based on the intended application will determine the ultimate performance of the entire battery.

To give you an example of why smart batteries are carefully designed consider a PDA that when turned on explodes (don’t think it can’t happen) thankfully it occurs very rarely. To be a more reassuring the US Consumer Product Safety Commission has noted that 339 battery-related overheating incidents have occurred since 2003. Since conservative estimates puts the sale and use of devices containing smart batteries in excess of 100 million battery related devices during the same period makes the 339 incidents reported by the Saftey Commission at .000003% (a very small percent) of all battery related devices on the market. What is preventing more battery related fires -reliable and safe design under worst-case conditions is especially critical when designing with lithium based batteries. Specifically over-voltage and under-voltage of the cells and over-current of the battery pack.

Now with all this said I can tell you again, almost emphatically, that not all batteries are the same. From battery to battery the internal design will be different depending on the device the battery was specifically built to work within.

Until next time, Dan Hagopian –
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