Battery Technology – Battery Education

What is the Best Temperature to Store Batteries?

To store batteries for long term or short term periods without losing quality please use the following information based on your specific chemistry type.

Li-ion Battery

Stored in cool and dry place, temperature ：14°F to 95°F
Max humitity: 80%
Max Shelf Life: 3 years
After charging one time it is recommended to charge battery one time per month

NIMH Battery

Stored in cool and dry place, temperature: -4°F to 95°F
Max humitity: 80%
Max Shelf Life: 3-5 years
After charging one time it is recommended to charge battery one time per month

NiCD Battery

Stored in cool and dry place, temperature: 0°F to 113°F
Max humitity: 85%
Max Shelf Life: 3-5 years
After charging one time it is recommended to charge battery one time per month

Special Note for all chemistry types: After a battery has been charged batteries will be frozen in very low temperatures and will not be able to fully discharge their power and therefore will cause reduced runtime and long term damage to the cells. It is best to keep batteries stored above freezing and below 85°F.

Battery Charging

The following is a response from a reader regarding battery charging….

Thank you so much for your question. It is a really good question. Your question just to restate is:

“If I charge my phone when it is at 50% capacity to full 100% capacity, would it be the same "1" charge as if I charged it from 20% to 100% capacity?”

To answer your question completely and to avoid confusion I will start with the basics and work my way to an answer for you!

To begin with battery capacity is a reference to the total amount of energy stored within a battery. It is a mathematical calculation to determine how long a battery will run (power a device) before the battery “dies”. Battery capacity is rated in Ampere-hours (Ah), which is the product of: Ah= Current X Hours to Total Discharge.

As with all metric measurements, Amps can be divided into smaller (or larger) units by adding a prefix. For example a milliAmp hour (mAh) is most commonly used capacity notation on small batteries. A small battery that is rated 1000 mAh can be rewritten to read as 1 Ah.

Secondly, Amp hours do not dictate the flow of electrons at any given moment but instead measures remaining electron flow per charge. Amperes (Amps ) is a measurement of quantity of the number of electrons passing through a given wire per second. For every second your battery is on Per second there are 62,000,000,000,000,000,000 electrons passing through your battery. This electron flow, once started will never stop even if you disconnect your battery from your device and is the primary reason why batteries in time “die”.

You see when you charge a battery what you are technically doing is introducing electrons into the batteries chemical housed inside the battery cell. This electron introduction is called intercalation. Intercalation is the joining of a molecule (or molecule group) between two other molecules (or groups). When it comes to charging your battery you are in effect pushing ions in and out of solid lithium compounds (or other chemical types). These compounds have minuscule spaces between their crystallized planes for small ions, such as lithium, to insert themselves from a force of current (i.e. wall or car charger). In effect ionizing the lithium loads the crystal planes to the point where they are forced into a current flow. The current flow is then channeled back and forth from anode to cathode and thereby creating an electrical flow to power on your device. This flow can never stop once started.

Intercalation is the process that creates the electrochemical reaction inside the battery and allows the battery to replenish electrons as the battery is used. It is in essence the catalyst to move chemical compounds. This normal and how batteries were designed. To move a chemical (lithium-ion, lithium polymer, lithium iron phosphate, etc) you have to have a minimum voltage applied. Most small battery cells are charged to 4.2 volts with relative safe workings at about 3.8 volts. Anything less than 3.3 volts will not be enough to charge or move the chemistry.

Now when we ask how long will my battery “last” we have to know that battery life varies depending on device configuration, model, applications loaded on the product, power management settings of the product, and the product features used. In addition to usage patterns battery life decreases every time you replenish electrons (i.e. charge your battery). This is called battery degradation and power loss and this is simply the normal use of any battery. Battery degradation and power loss varies with each battery and when it occurs it simply means that your battery has reached a point where it can no longer accept a charge and recharge the chemical inside your battery.

There are five overarching factors that govern battery capacity and they include:

Physical Size – the amount of capacity that can be stored in the casing of any battery depends on the volume and plate area of the actual battery. The more volume and plate area the more capacity you can actually store in a battery.
Temperature – capacity, energy store decreases as a battery gets colder. High temperatures
also have an effect on all other aspects of your battery.
Cut off Voltage – To prevent damage to the battery and the device batteries have an internal
mechanism that stops voltage called the cut-off voltage, which is tpically limited to 1.67V or 10V for a 12 Volt battery. Letting a battery self-discharge to zero destroys the battery.
Discharge rate – The rate of discharge, the rate at which a battery goes from a full charge to the cut off voltage measured in amperes. As the rate goes up, the capacity goes down.
Battery History – Deep discharging, excessive cycling, age, over charging, under charging, all
reduce capacity. Note charging your battery 1 time will reduce capacity as much as 15%-20% depending on your battery's chemistry.

Now with all of the above laid we can look at your original question with greater understanding. Your question was:

“If I charge my phone when it is at 50% capacity to full 100% capacity, would it be the same "1" charge as if I charged it from 20% to 100% capacity?”

We know that the life of a lithium based rechargeable battery operating under normal conditions is generally up to 500 charge-discharge cycles with the maximum capacity decreasing with each charge-discharge cycle. NICD or NIMH batteries can last up to 800 charge-discharge cycles

Charge-discharge cycling a battery means to completely discharge (or drain) a battery’s created electricity to where there is a charge of less than a 1% capacity remaining. At this point the power to the device will cease and your device will power off. Then after the power is off you recharge the battery to 100% capacity using a power adapter from a wall socket for example. Regardless of how you charge the battery that process of discharging and charging represents one complete charge cycle.

A battery in generally can have between 300-500
charge-discharge cycles (for lithium based chemistries – NIMH can have up to
800 charge-discharge cycles and NICD chemistries can have more). A
charge-discharge cycle means that a battery once at 100% draws power down to
0%. Then after recharge it will be back at 100%. This can be done 300-500 times
on the same battery. Also with each charge-discharge cycle the runtime (time
between charges) is reduced by the gradual depletion and usage of the battery's
chemistry inside. For example you may notice in the first 3-4 months you are
getting between 3-5 hours of runtime on your battery. Then in month 5-12 (after
your purchase) you notice that you are slowly getting less and less runtime in
between charges. This is the normal use of the chemistry inside your battery
and DOES NOT mean that the battery is bad or defective, but simply has been
used by you.

Now one complete charge-discharge cycle means that you draw your batteries capacity (the abiltity to run your battery) from 100% down to 0%. If you draw the battery from 100% to 50% capacity then recharge the battery back to 100% that would represent ½ a charge-discharge cycle. Now technically this is different than running your battery from 100% to 20% then recharging.

Now if you plug your device in 4 times a day to recharge it whether it starts at 20% or 90% then each recharge would be some percentage of one complete charge-discharge cycle. Again each complete charge-discharge cycle does degrade the lifespan of the battery by a small percentage.

Now one thing that should also help is that inside your battery are integrated power management circuits that protect your battery and device against over-voltage and under-voltage conditions. The power management circuits also maximize battery life between charges, minimize charging times, and improve overall battery life. So no need to worry about leaving your battery on your charger – when the battery is done charging it will simply stop accepting a charge!

Now keeping all the above in mind does it make sense to keep your device plugged in continuously if each charge-discharge cycle does degrade the lifespan of the battery by a small percentage? Each person has to make their own conclusion to that question. If your battery is near the end of its useful life then of course you will find that you must constantly recharge your battery but if your battery is new then it does not need to stay on the charger as frequently. I typically wait till my battery is almost dead before I recharge unless I know I will be away from any means of charging the battery. By the way a really cool device for recharging a battery is the Universal USB Battery Pack. It conveniently stores 5600 mAh of portable power to charge your mobile devices anywhere, anytime. It includes 8 connectors, USA and Europe adapters, plus universal USB charging cable. This is awesome!

I hope this helps answer your question! Thank you and Happy New Year!

Battery Self Discharge Rates

Battery Self discharge rates:

Bad news: all batteries have what is called a
self discharge rate.
Good news: if you have a rechargeable battery
all you need to do is recharge your battery!

Let me explain in greater detail the concept of battery self discharge.

All batteries will self discharge over a period of time naturally whether the battery is used or not. This means that the battery capacity will go from 100% down to 0% over a time period regardless if the battery is being used or not. Again recharging the battery corrects this naturally occurring reality.

Battery self discharge rate varies based on the chemistry type used and the temperature the battery is at: higher temperatures increase the self-discharge rate. This explains why batteries left inside cars on hot days must be recharged more frequently!

Battery self-discharge is a phenomenon in batteries in which internal chemical reactions reduce the stored charge of the battery. Battery self-discharges does decrease the overall shelf-life of batteries and causes them to initially have less than a full charge when actually put to use.

Here are average self discharge rates for the following chemistries:

	NiCd	NiMH	Lead Acid	Li-ion	Li-ion polymer	Reusable Alkaline
Self-discharge / Month (room temperature)	20%	30%	5%	10%	~10%	0.3%

NiCd

NiMH

Lead Acid

Li-ion

Li-ion polymer

Reusable Alkaline

Self-discharge / Month (room temperature)

20%

30%

10%

~10%

0.3%

The rate at which batteries self discharge depends on the type of battery, state of charge, charging current, ambient temperature and other factors. Lithium based batteries suffer the least amount of self-discharge (around 2–3% discharge per month), while nickel-based batteries are more seriously affected by the self-discharge rate.

To reduce the rate of battery self discharge during storage then store the battery at lower temperatures to reduce the rate of self-discharge and preserves the initial energy stored in the battery.

What Battery Chemistry Type is Better To Use With Power Tools?

There are three types of battery chemistries currently in use with power tools. They are NiCD, NiMH, and Li-Ion chemistries. The decision to choose one of the specific battery chemistry for your power tool depends on your application, the frequency of use, and the amount of power you need. Here is a brief breadown of the top benefits of each type:

Benefits	NiCd	NiMH	Li-ion
Life Span	Avg 5-10 years	Avg 3-5 years	Avg 1-3 years
Weight	Heavy	Medium	Light
Capacity – The higher the capacity rating, the longer your battery can last between charges (this is runtime).	Average runtime per charge	Highest -longest lasting runtime per charge	Good runtime per charge
Power per Charge	Average	Excellent	Good
Charge Time	Depends on Capacity	Depends on Capacity	Depends on Capacity
Environmentally Friendly	Ok	Good	Excellent
Economical	Lowest Cost	Average Cost	Highest Cost
Best Suited For	Home Owners	Contractors / Companies	Homeowners / Contractors / Companies

Here is a more detailed account of the 3 chemistry types…

The Nickel Cadmium (NiCd) battery is a popular choice for two-way radios, emergency medical equipment and power tools.

NiCd batteries have both their advantages and disadvantages:

Advantages of NiCD

Fast charge.
High number of charge/discharge cycles — if properly maintained, the NiCd provides about 1200 charge/discharge cycles.
Good load performance in low temperatures.
Long shelf life.
Simple storage and transportation — no special conditions exist for most airfreight
companies.
Forgiving if abused — the NiCd is is a rugged rechargeable battery.
Economically priced
Available in a wide range of sizes and performance options.

Disadvantages of NiCD

Low energy density — compared with NiMH.
Memory effect.
Environmentally unfriendly .
Has relatively high self-discharge.
Battery failure typical between 5-10 years based on usage.

The Nickel-Metal Hydride (NiMH) battery offers high energy density and the use of this chemistry is vastly more environmentally friendly than its counterpart NiCD batteries.

NiMH batteries have both their advantages and disadvantages:

Advantages of NiMH

30– 40 percent higher capacity over a standard NiCd.
Less prone to memory effect than NiCd. Periodic exercise cycles are required less often.
Simple storage and transportation — no transportation regulatory control.
Environmentally friendly — contains only mild toxins; profitable for recycling

Disadvantages of NiMH

Limited service life — if repeatedly deep cycled, especially at high load currents, the performance starts to deteriorate after 200 to 300 cycles.
Limited discharge current — although a NiMH battery is capable of delivering high discharge currents, repeated discharges with high load currents reduces the battery’s cycle life.
More complex charge algorithm needed
High self-discharge
Performance degrades if stored at elevated temperatures — the NiMH should be stored in a cool place and at a state-of-charge of about 40 percent.
About 20 percent more expensive than NiCd — NiMH batteries designed for high current draw are more expensive than NiCd.
Battery failure typical between 3-5 years based on usage.

The Lithium Ion battery is the lightest of all metals, has the greatest electrochemical potential and provides the largest energy density per weight.

Advantages of Li-ion

High energy density — potential for yet higher capacities.
Relatively low self-discharge — self-discharge is less than half that of NiCd and NiMH.
Low Maintenance — no periodic discharge is needed; no memory.
Lightweight compared to NiCd and NiMH.
Environmentally freindly.

Disadvantages of Li-ion

Requires protection circuit — protection circuit limits voltage and current. Battery is safe if not provoked.
Subject to aging, even if not in use — storing the battery in a cool place and at 40 percent state-of-charge reduces the aging effect.
Moderate discharge current.
Shipment of larger quantities of Li-ion batteries may be subject to regulatory control.
Expensive to manufacture — about 40 percent higher in cost than NiCd.
Capacity deterioration is noticeable after one year, whether the battery is in use or not.
Battery failure typical between 1-3 years based on usage.

Battery Chemistries by the numbers:

	NiCd	NiMH	Li-ion
Gravimetric Energy Density(Wh/kg)	45-80	60-120	110-160
Internal Resistance (includes peripheral circuits) in mΩ	100 to 200¹ 6V pack	200 to 300¹ 6V pack	150 to 250¹ 7.2V pack
Cycle Life (to 80% of initial capacity)	1500²	300 to 500^2,3	500 to 1000³
Fast Charge Time	1h typical	2-4h	2-4h
Overcharge Tolerance	moderate	low	very low
Self-discharge / Month (room temperature)	20%⁴	30%⁴	10%⁵
Cell Voltage(nominal)	1.25V⁶	1.25V⁶	3.6V
Load Current – peak – best result	20C 1C	5C 0.5C or lower	>2C 1C or lower
Operating Temperature(discharge only)	-40 to 60°C	-20 to 60°C	-20 to 60°C
Maintenance Requirement	30 to 60 days	60 to 90 days	not req.
Typical Battery Cost (US$, reference only)	$50 (7.2V)	$60 (7.2V)	$100 (7.2V)
Cost per Cycle(US$)¹¹	$0.04	$0.12	$0.14
Commercial use since	1950	1990	1991

1: Characteristics of commonly used rechargeable batteries

Internal resistance of a battery pack varies with cell rating, type of protection
circuit and number of cells. Protection circuit of Li‑ion and
Li-polymer adds about 100mΩ.
Cycle life is based on battery receiving regular maintenance. Failing to apply
periodic full discharge cycles may reduce the cycle life by a factor of three.
Cycle life is based on the depth of discharge. Shallow discharges provide more cycles
than deep discharges.
The discharge is highest immediately after charge, then tapers off. The NiCd
capacity decreases 10% in the first 24h, then declines to about 10% every 30
days thereafter. Self-discharge increases with higher temperature.
Internal protection circuits typically consume 3% of the stored energy per month.
1.25V is the open cell voltage. 1.2V is the commonly used value. There is no difference
between the cells; it is simply a method of rating.
Capable of high current pulses.
Applies to discharge only; charge temperature range is more confined.
Maintenance may be in the form of ‘equalizing’ or ‘topping’ charge.
Cost of battery for commercially available portable devices.
Derived from the battery price divided by cycle life. Does not include the cost of
electricity and chargers.

Lithium Cell Manufacturing Part 5

We are coming to the end of our article series on the manufacturing of lithium battery cells. In the first few articles we introduced the battery cell and looked at it a macro level, the lithium metal and saw how it was formed, we looked at the cathode and its material composition, and now we are going to look at the battery’s electrolyte.

Every battery has an anode, a cathode, and an electrolyte solution. There are mnay variations of an electrolyte solution. One common solution is sulfuric acid. Another common solution that is in use today is a Lithium hexaflourophosphate (LiPF₆) in a mixture of organic solvents including: [Ethylene Carbonate (EC) + DiEthyl Carbonate (DMC) + DiEthyl Carbonate (DEC) + Ethyl Acetate (EA). This electrolyte solution like others is used to facilitate the transport of ions between the anode and the cathode. In fact that is the purpose of the electrolyte in a battery is to conduct or transport ions from the negative and positive terminals.

One other newly developed electrolyte solution is a high-purity lithium hexafluorophosphate (LiPF₆), a conductive salt that was developed by Honeywell International. In fact this electrolyte research and development was paid for through the American Recovery and Reinvestment Act of 2009. The U.S. Department of Energy awarded Honeywell a $27.3 million grant that is designed to accelerate the market introduction and penetration of advanced electric drive vehicles, reducing fuel consumption and vehicle emissions of greenhouse gases. This electrolyte is one of the primary components that is intended to be used in these upcoming electric cars.

Until next time, Dan Hagopian www.batteryship.com

Lithium Cell Manufacturing Part 4

We are currently in the middle of a series on the manufacturing of lithium battery cells. We have looked at the battery cell on a macro level and then at the lithium ingot. Now we are looking at the cathode.

In every battery there must be present a cathode. The cathode is an electrode (electrical conductor) by which electrical current flows out of a polarized electrical device. A cathode can be either positively charged or negatively charged depending on the device type and operating mode.

There are various material compositions that cathodes can be made of including the common metallic oxide cathode. Metal oxides are crystalline solids that contain a metal cation (an ion with more protons than electrons) and an oxide anion (an ion with more electrons than protons). But other cathode compositions do exist and all have their positive benefits and negative side effects.

Some other cathode material compositions include: LiCoO₂ , LiMn₂O₄ ,LiNiO₂ , Li₂FePO₄F. There are others but all variations include oxygen.

In the next article we will look at the battery's electrolyte.

Until next time, Dan Hagiopian www.batteryship.com

Lithium Cell Manufacturing Part 3

We are currently in the middle of a series on the manufacturing of lithium battery cells. In the first 2 articles we introduced the battery cell and looked at it a macro level. We looked at what processes are used to make a cell, how a battery is hermetically sealed, and the four main components of a cell (lithium, the metallic oxide cathode, the electrolyte, the metallic current collector. Now we want to look at the processes of battery cell manufacturing more closely by breaking down how the four main components of a cell come together.

Lithium Ingots

Battery cell manufacturing processes begins with a lithium ingot. A lithium ingot is often times a cylindrical roll of lithium that weighs about 11 pounds on average. Special order ingots of course can be requested thereby changing the average weight.

Lithium ingots come from technical grade lithium carbonate which is a byproduct of lithium and a solution of lithium hydroxide. The conversion of lithium in the lithium hydroxide solution results in lithium carbonate as a fine white powder. This powder is placed into a billet container prior to being processed through the extrusion. The extruded billet may be solid or hollow in form, commonly cylindrical, used as the final length of material charged into the extrusion press cylinder. It is usually a cast product, but may be a wrought product or sintered from powder compact. This billet of lithium carbonate is the ingot.

As mentioned above the extrusion press – used to shape lithium by forcing it to flow through a shaped opening. The extruded lithium emerges as an elongated piece with the same profile as the opening. The shape is typically a thin piece of metal that stretches over 650 feet. Once the ingot is made the ingot is transformed by the extrusion press and accompanied roller system into a thin sheet of metal that is only 1/100th of an inch thick and 650 feet in length. A laminator furthers the process by stretching the 655 foot lithium roll to about 1.25 miles of lithium used to make 210 lithium batteries. The battery cell is then tested to measure 3.6V. Volts – or V – are an electrical measure of energy potential. You can think of it as the pressure being exerted by all the electrons of a battery’s negative terminal as they try to move to the positive terminal.

A punch machine is then used to cut the thin metal into the physical cell size requirements and a purification machine remove dirt and other unwanted particles.

In the next part of the series we will look at the metallic oxide cathode.

Lithium Cell Manufacturing Part 2

In this current series on lithium cell manufacturing we are going to be looking at the processes that are used to construct a lithium battery cell. These processes are highly technical and require complete precision in order to make an individual battery cell function according to the specific power demands of the device that the cell will ultimately be used within.

On a macro level when we look at a battery we see completed unit (which we call a battery) however the battery is actually an assembled collection of material and hardware. The outside plastic cover is called the casing. The casing encloses and hermetically seals the battery cell and specialized hardware. Battery casing is manufactured in layers. The casing layers are developed from various raw materials and can include one or two, for example, of polyethylene terephthalate layers, a polymer layer, and a polypropylene layer. Another example may be a casing with layers of carbonized plastic.

Within the casing is the hardware and the battery cell. When we look inside a lithium based battery cell, for example, there are four main components and they include:

The lithium (which acts as an anode)
The metallic oxide cathode
The electrolyte
The metallic current collector

Lithium

As noted above lithium within the battery cell is used as the battery’s anode. The anode is the part of the cell that acts an electrical conductor (electrode) through which electrical current flows into a polarized device. As current flows into the lithium, a chemical process called intercalation occurs. Intercalation is the joining of a molecule (or molecule group) between two other molecules (or groups). When it comes to charging your battery you are in effect pushing ions in and out of solid lithium compounds. These compounds have minuscule spaces between the crystallized planes for small ions, such as lithium, to insert themselves from a force of current. In effect ionizing the lithium loads the crystal planes to the point where they are forced into a current flow. The current flow is then channeled back and forth from anode to cathode and thereby creating an electrical flow to power on your device.

To create an electrical flow from lithium you have to move the lithium. To move the lithium chemistry (lithium-ion, lithium polymer, lithium iron phosphate, etc) you have to have a minimum voltage applied to the lithium. Most battery cells are charged up to 4.2 volts with relative safe workings at about 3.8 volts. Anything less than 3.3 volts will not be enough to charge or move the chemistry. One thing to note here is that volts are an algorithmic measurement of current. So in a sense to create current through your battery you have to introduce current into your battery’s lithium.

The Metallic Oxide Cathode

The cathode is an electrode (electrical conductor) by which electrical current flows out of a polarized electrical device. The metallic oxide component of the cathode is the composition of the cathode. Metal oxides are crystalline solids that contain a metal cation (an ion with more protons than electrons)and an oxide anion (an ion with more electrons than protons).

The Electrolyte

In the battery cell the electrolyte solution is the conducting medium in which the flow of electric current passes through between the electrodes. Electrolytes can be wet, solid, gel, or dry. Dry polymer design offers simplifications with respect to fabrication, ruggedness, safety and thin-profile geometry. Dry polymers do not conduct electricity but allows for ion exchange. The real benefit is the fact that the dry polymer design is only one millimeter (0.039 inches) thick. The drawback is that the dry polymer design suffers from poor conductivity. Today lithium hexafluorophosphate and tetrafluoroborate are the preferred electrolyte salts for lithium batteries.

The Metallic Current Collector

A current collector is an inert structure of high electrical conductivity used to conduct/transmit current from or to an electrode during discharge or charge. There a variety of metal based current collector from zinc to liquid metal that can provide a good conductive path between the electrodes.

Closing

From the above we can see that a battery cell, being just one component of a battery is a highly complex system. As we move into the next portion of the series we will break down each of these 4 key components of a battery cell and see how they are actually made.

Lithium Cell Manufacturing Part 1

Smart Battery packs have very specialized hardware that make possible a battery to provide just the right power at just the right moment. This hardware includes 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. One of the most critical component in this list is the cell pack. The battery cell pack can be thought of as the holding area of the battery’s chemical. The battery cell pack is critical to the overall capability of the smart battery. Cell packs have to be designed and integrated based upon the vitals of the battery including chemistry type (Li-ion, Li-po, NICD, NIMH, etc.) cycle life, storage-capacity loss, shelf life, impedance, capacity at different rates of discharge and temperature, and mechanical and environmental requirements. It is critical to say the least. But how do you make a battery cell pack? What are the manufacturing processes necessary to make lithium based cell?

Lithium cell manufacturing was first developed in Japan using heavy machinery and automated equipment to perform certain steps while using robots to transfer partially assembled materials from one step to another. Chinese companies developed a manual approach to take advantage of inexpensive labor. This is not to say that it is 100% manual on the contrary it more correct to say that it is a semi-automatic production process of Li-ion cells using automated equipment in the most critical areas such as mixing of powder, coating and winding.

In this series we are going to look at the critical processes involved in the manufacture of lithium-ion cells. What critical components are required for a lithium battery and how each component is made.

What is the Total Equivalent Lithium Content of My Battery?

If you ever were curious to know just how much of the chemical, lithium, was packed into your battery then there is a way you can calculate it.

Let's look at an example, say the HP Compaq 367759-001, we know that this battery has the following technical specifications: 10.8V, 8800 mAh, Li-ion.

So now let's determine the ELC for one of the cells in this battery. As stated above the rated capacity is 8800 mAh. The mAh is the milliamps and so if we convert that to Ah or amp hours in order to do our calculation you get 8.8 Ah (8800 mAh is the same as 8.8 Ah).

Secondly, we need to divide the voltage by of the battery by the known voltage of each cell used in the battery. Most batteries use either a 3.6V or a 3.7V cell. In the HP Compaq 367759-001 battery cells have a 3.6V.

Finally we can complete our effort in knowing the total ELC in the 367759-001 by performing the following…

1. Divide the stated volts (V) on battery pack by 3.6 (or 3.7) and round to the nearest whole number. 2. Multiply the resulting number by the stated capacity in ampere-hours (Ah).
3. Then multiply that result by 0.3

Example: A lithium ion battery with 10.8 (V) and 8.8 ampere hours (or 8800 mAh).

1. 10.8 ÷ 3.6 = 3
2. 3 x 8.8 = 26.4
3. 26.4 x 0.3 = 7.92 grams of equivalent lithium content

To determine the amount of ELC in your battery follow the steps above and just input the technical specifications of your battery.