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Battery Glossary
Primary Cell: An electrochemical device that is discharged only once and then discarded. Alkaline batteries are an example.Secondary Cell: Anelectrochemical device that may be discharged and recharged a number of times. Li-Ion batteries are an example.Battery Capacity: The ampere-hoursavailable from battery.Battery Float Voltage: A constant voltage applied to a battery to maintain the battery capacity.Amp Hour or Ampere-Hour : A unit of measurement of a battery’s electrical storage capacity. Current multiplied by time in hours equals ampere-hours. One amp hour is equal to a current of oneampere flowing for one hour. Also, 1 amp hour is equal to 1,000 mAh
C : Used to signify a charge or discharge rate equal to the capacity of a battery divided by 1 hour. Thus C for a 1600 mAh battery would be 1.6 A, C/5 for the same battery would be 320 mA and C/10 would be 160 mA. Because C is dependent on the capacity of a battery the C rate for batteries of differentcapacities must also be different.
Cycle Life : For rechargeable batteries, the total number of charge/discharge cycles the cell can sustain before it capacity is significantly reduced. End of life is usually considered to be reached when the cell or battery delivers only 80% of rated ampere- hour capacity. The life of a rechargeable battery operating under normal conditions is generally between 500 to 800 charge-discharge cycles. The cycle of a battery is greatly influenced by the type depth of the cycle (deep or shallow) and the method of recharging. Improper charge cycle cutoff can greatly reduce the cycle life of a battery.
Energy Density :Ratio of cell energy to weight or volume (watt-hours per pound, or watt-hours per cubic inch).
Memory Effect : A phenomenon in which a cell, operated in successive cycles to less than full, depth of discharge, temporarily loses the remainder of its capacity at normal voltage levels (usually applies to Ni-Cd cells). Note, memory effect can be induced in NiCd cells even if the level of discharge is not the same during each cycle. Memory effect is reversible.
Self-discharge: A phenomenon that an active material is transformed into the discharge condition even in the state of open external current circuit is called ’ self-discharge’.
Battery FAQ In General
1. How are batteries rated? (What Are Volts and Amps?)  
There are two ratings on every battery: volts and amp-hours (AH). The AH rating may also be given as milliamp-hours (mAH), which are one-thousandth ofan amp-hour (for example, 1AH is 1000mAH). The voltage of the new battery should always match the voltage of your original unless the batteries are different chemistries (NiMH and Li-Ion batteries have different voltage ratings, even if they’re for the same laptop). Some Hi-Capacity batteries will have higher amp-hour ratings than the original battery found in the device. This is indicative of a longer run-time (higher capacity) and will not cause any incompatibilities.
2. How can batteries be connected?
Batteries may be connected in series. The positive terminal of the first battery is connected to the negative terminal of the second battery; the positiveterminal of the second is connected to the negative of the third, and so on. The voltage of the assembled battery is the sum of the individualbatteries.The batteries are connected: + to - to + to - to + to -, etc. The capacity of the battery is unchanged.
Batteries may also be connected in parallel. The positive terminal of the first battery is connected to the positive terminal of the second battery, the positiveterminal of the second is connected to the positive of the third; the negative terminal of the first battery is connected to the negative terminal of thesecond battery, the negative terminal of the second is connected to the negative of the third and so on. The batteries are connected: + to + to + and - to - to-. In this configuration, the capacity is the sum of the individual batteries and voltage is unchanged.
For example, (5) 6V 10AH batteries connected in series produces a battery array that is 30 Volts and 10AH. Connecting the batteries in parallel produces abattery array that is 6 Volts and 50AH. Ordinary auto batteries are designed in the same fashion. Six 2-volt cells are arranged in series to produce a 12vbattery. Many NiCad batteries are arranged in the same way Note: When interconnecting batteries (cells), they must be identical in voltage and amprating!
3. Do batteries self-discharge when not in use?
All batteries, regardless of their chemistry, self-discharge. The rate of self-discharge depends both on the type of battery and the storage temperature thebatteries are exposed to. There is very little self-discharge in the solid electrolyte system, but it is very notable in the liquid electrolyte system. It is alsoinfluenced by the surrounding temperature. Summer can have more influence over it than winter .In the case of primary battery, the rate of selfdischarged are followed below:
Manganese battery : 10%/year
Alkaline battery : 5%/year
Lithium battery : 1%/year
The self-discharge rates of second battery are higher than those of primary battery. Particularly, the performances of second batteries are differentdepending on battery makers. It is because they form artificial, chemical structure in order to make it possible to use the battery many times. Withthis reason, there are differences of performance depending upon the battery makers although the variations are not big. Here are some examplesbased on second batteries.
Ni-MH cell : 5 ~ 10%/month
Ni-Cd cell : 25 ~ 30%/month
Li-ion battery : 2%/month
Lead-acid Battery :
Pb-Sb alloy group : 25 ~ 30%/month
Pb-Ca alloy group : 2%/month
4. What are the different types of rechargeable battery chemistries & technologies?
Batteries in portable consumer devices (laptops and notebooks, camcorders, cellular phones, etc.) are principally made using either Nickel Cadmium(NiCad), Nickel Metal Hydride (NiMH) or LithiumIon (Li-Ion) technologies. Each type of rechargeable battery technology has its own unique characteristics.
FAQ For Li-ion Battery
1. What is the difference between Lithium batteries and Lithium Ion batteries?
There are several important differences. The practical difference between Lithium batteries and Lithium-ion(Li-ion) batteries is that most Lithium batteriesare not rechargeable but Li-ion batteries are rechargeable. From a chemical standpoint Lithium batteries use lithium in its pure metallic form. Liion batteries use lithium  compounds which are much more stable than the elemental lithium used in lithium batteries. A lithium battery  should never berecharged while lithium-ion batteries are designed to be recharged hundreds of times.
2. What are the advantages of Lithium Ion batteries compared to other rechargeable batteries?
Lithium-ion batteries have several advantages:
They have a higher energy density than most other types of rechargeable. This means that for their size or weight they can store more energy than otherrechargeable batteries. They also operate at higher voltages than other rechargeable, typically about 3.7 volts for lithium-ion vs. 1.2 volts for NiMH orNiCd. This means a single cell can often be used rather than multiple NiMH or NiCd cells. Lithium-ion batteries also have a lower self discharge rate than other types of rechargeable batteries. This means that once they are charged they will retain their charge for a longer time than other types of rechargeablebatteries. NiMH and NiCd batteries can lose anywhere from 1-5% of their charge per day, (depending on the storage temperature) even if theyare not installed in a device. Lithium-ion batteries will retain most of their charge even after months of storage. So in summary; lithium-ion batteries can be smaller or lighter, have a higher voltage and hold a charge much longer than other types of batteries.





Cycle life (cycles)




Energy efficiency (C discharge/C charge)




Weight comparison for the same capacity




Size comparison for the same capacity








3. What are the disadvantages of Lithium Ion batteries compared with other rechargeable batteries?
Lithium-ion batteries are more expensive than similar capacity NiMH or NiCd batteries. This is because they are much more complex to manufacture. Li-ionbatteries actually include special circuitry to protect the battery from damage due to overcharging or undercharging. They are also more expensivebecause they are manufactured in much smaller numbers than NiMH or NiCd batteries. Li-ion batteries are becoming less expensive and overtime we should see their price decrease significantly. Lithium ion batteries are not available in standard cells sizes (AA, C and D) like NiMH and NiCd batteries. Lithium-ion batteries also require sophisticated chargers that can carefully monitor the charge process. And because of their different shapes andsizes each type of Li-ion battery requires a charger designed to accommodate its particular size. This means lithium ion battery chargers are moreexpensive and more difficult to find than NiMH and NiCd battery chargers.
4. What is the best way to store Lithium Ion batteries?
Lithium-ion batteries can hold a charge for many months. It is best to store a lithium-ion battery with a partial or full charge. Occasionally, a lithium-ionbattery with a very low charge is stored for a long period of time (many months) and its voltage slowly drops to below the level at which its built in safety mechanismallows it to be charged again. If the battery is going to be stored for several months it’s a good idea to take it out and recharge it after a fewmonths. Better yet would be to actually use the battery every few months and then leave it partially or fully charged。
5. How should I dispose of Lithium Ion batteries?
Lithium ion batteries, like all rechargeable batteries are recyclable and should be recycled. They should never be incinerated since they might explode. Most places that sell rechargeable batteries will also accept them back for recycling.
FAQ For LiFePO4 Battery
1. What is a Lithium iron phosphate battery?
The lithium iron phosphate (LiFePO4) battery is a type of rechargeable battery, specifically a lithium ion battery, which uses LiFePO4 as a cathode material.
2. What are the characteristics of LiFePO4 battery compared with other Lithium base batteries?
There are three types of lithium ion cells based on different cathode materials. They are lithium cobalt oxide, lithium manganese oxide and lithium ironphosphate types. Although lithium cobalt oxide cell has the advantage of high energy density, it suffers from safety concerns. Lithium manganese oxidecell has been evaluated for the application on high rate due to the better safety characteristics. However, its high temperature performance is the majordrawback. While Lithium iron phosphate cell has the best safety characteristics, long cycle life (up to 2000 cycles) and good availability. It has higherdischarge current, but has lower voltage and energy density than normal Li-ion cells. It is the safest and most suitable for high output usage. It is alsothe best for storage battery usage. It is not necessary to use the equalizer and the protecting PC Board module. Comparison Data among Various Lithium Base Batteries:








Not Stable


Not Stable

Environmental concern

Most Enviro-friendly

Very Dangerous


Very Dangerous

Cycle life





Power/Weight Density





Long Term Cost

Most Economic/Excellent




Temperature Range

Excellent (-20C to 70C)

Decay beyond (-20C to 55C)

Decay extremely fast over 50 C

-20C to 55C

In summary, the characteristics of lithium iron phosphate (LiFePO4) are as follows:
A) . The safest and the most environmental friendly
The Lithium Iron Phosphate Battery has been proven as the most environmental friendly battery. The primary concern with Li-Ion batteries is safety.Overcharging and overheating can cause fire and explosions. The exception to this is the LiFePO4 battery.
B). Fast "forced" charging
Because an overvoltage can be applied to the LiFePO4 battery it can be charged by only one step of CC to reach 95%SOC or be charged by CC+CV to get100%SOC. This is similar to the way lead acid batteries are safely force charged.
C). Large overcharge tolerance and safer performance
A LiFePO4 battery can be safely overcharged up to 30V without protection circuit board. It is therefore suitable for large capacity and high power applications.From the viewpoint of large overcharge tolerance and safety performance, a LiFePO4 battery is similar to a lead-acid battery.
D). Higher energy density
the lithium iron phosphate (LiFePO4) cell is a non-aqueous system, having 3.2V as its nominal voltage during discharge. Its specific capacity is more than145Ah/kg. Therefore, the gravimetric energy density of LiFePO4 battery is 130Wh/kg,
E). Simplified battery management system and battery charger
Large overcharge tolerance and self-balance characteristic of LiFePO4 battery can simplify the battery protection and balance circuit boards, lowering theircost.
F). Longer cycle life
In comparison with LiCoO2 battery which has a cycle life of 400 cycles, LiFePO4 battery extends its cycle life up to 2000 cycles.
G). High temperature performance
It is detrimental to have a LiCoO2 battery working at elevated temperature, such as 60°C. However, a LiFePO4 battery runs better at elevated temperature,offering 10% more capacity, due to higher lithium ionic conductivity.
H). What are the main applications of the lithium iron phosphate (LiFePO4)?
Due to the characteristics of lithium iron phosphate (LiFePO4), it is very suitable for high discharge rate occasions such as EV (including e-bike, electricscooter, and electric car), power tools (for example, electric drill, electric motor saw, cropper), UPS and emergency lighting, solar energy system.According to different applications, the design of battery pack can be modified to provide the best solution to satisfy the customer’s needs

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