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There’s no such thing as a “perfect battery.” The best way to find an ideal battery for a given application is to find one that offers the right combination of duration, cost, and performance. There are several important questions to ask when trying to find the right battery for your needs.
Amount of electric energy that can be withdrawn from a battery or cell under specified conditions. This energy is measured in milli-Watt-hours (mWh). Product of the discharge voltage, discharge rate, and discharge.
Ratio of a cell’s energy to its total volume. Usually expressed in Watt-hours per liter (Wh/l). Also called “power density”
A charger that limits the maximum voltage to a battery but allows the current to drop while maintaining the voltage limit. A voltage limiting charge normally also includes current limiting. (Typically used on Li-ion chargers).
A voltage value a battery is not permitted to rise above on charge and/or fall below on discharge.
During open circuit storage, some battery systems develop a passivation film on the surface of the active material. On the initial discharge, these batteries may momentarily demonstrate a lower than normal voltage until this film is removed by the discharge.
Electronics board which disconnect the load from a battery pack.
Movement of ions within a cell. Cations carry net-positive charges; anions carry net-negative charges.
Charge step designed to fully charge a battery or cell when a rapid or fast charge termination that does not reach 100% SOC is used. Most commonly used after a dT/dt termination.
A charging method, terminated after a predetermined amount of time, designed to charge a battery or cell within 6 to 16 hours.
Temperature sensing device, used to measure the temperature of a battery pack or cell. Typically a Negative Temperature Coefficient (NTC) device. Exhibits a predictable and precise decrease in resistance with an increase in temperature.
Circuit protection device used to prevent over-current and over-temperature. A thermostat will go from a low-resistance state to an open circuit at a predetermined temperature.
A critical condition arising during constant voltage charging in which the current and the temperature of the battery produce a cumulative mutually-reinforcing effect which further increases them and can lead to the destruction of the battery.
A one-time, non-resettable fuse used to protect against over-current Thermal runaway — A critical condition arising during constant voltage charging in which the current and the temperature of the battery produce a cumulative mutually-reinforcing effect which further increases them and can lead to the destruction of the battery.
Secondary charge termination at a specified temperature; used in timed, rapid, and fast charge systems.
The mechanical lug used to connect cells together to form a battery or to connect it to equipment.
Growth of lead sulfate crystals in SLA batteries which inhibits current flow. Sulfation is caused by storage at low state of charge.
The length of time a cell or battery can be stored on open circuit without permanent deterioration of its performance. Nickel-cadmium cells or batteries can be stored at any state of charge including a fully discharged state.
see “shelf life”
Ratio of electricity, usually expressed in capacity, remaining in a battery or cell on discharge compared to its rated capacity.
The available capacity of a cell or battery at any given time. Expressed as a percentage of C or its rated capacity.
C/10 charge at 25°C for 16 hours. Sometimes called an overnight charge.
Typically an over-night charge lasting about 14 hours at a charge current of 0.1C. Battery does not require instant removal when fully charged.
Under specified conditions, the duration for which a battery or cell can be stored and still retain its performance.
Loss of energy or capacity in a battery or cell due to internal chemical reactions.
A battery or cell in which passing electrical current through it in the opposite direction of its discharge can reverse the electrochemical process, recharging the battery or cell. Commonly called rechargeable batteries.
Charge method that intersperses discharge pulses between charge pulses to promote the recombination of gases generated during fast charge. Reverse Load charge also helps to reduce memory.
The capacity remaining in a battery after field use, prior to charge.
Vent built into cylindrical and prismatic cells which prevents the build up of high internal pressures.
Maximum charge/discharge rate of a battery or cell. Expressed in a multiple of the C rate.
Amount of mill-amperes (mA) a battery or cell can deliver under specified conditions. Rated capacity is measured at C/5 discharge rate to 1 volt @ 25°C after being charged at C/10 for 16 hours
Rate of charging a battery or cell to full charge capacity in 2 1/2 to 6 hours.
The amount of electric energy supplied to a battery. Its unit is Ah, (ampere-hour.)
A high-rate discharge, usually of 1 second or less.
Time rate of energy transfer, measured in Watts (W). Product the voltage (V) across a battery or cell and the current (A) through the battery or cell. W = V x A
Safety device used in battery packs. At a predetermined temperature threshold, internal resistance goes from a low-resistance state to a high-resistance one to provide over-current and over-temperature protection.
Obstacles to current flow within NiMH cells.
The charging current which can be continuously maintained, regardless of the state of charge of the cell.
Automatic charge termination based on the battery or cell being charged reaching peak voltage. Designed to terminate charge just as over-charge begins.
The difference between the actual potential of electro-chemical reaction and the theoretical value at which the reaction becomes balanced.
Discharging a battery or cell after all of its stored energy has been released.
Forcing of current into a battery or cell after all of its active material has been converted into stored energy.
Voltage between the two terminals of the battery without any load.
Potential difference between the electrodes of a battery or cell, measured at the terminals in a no-load condition.
Nominal Voltage: average working voltage of a battery or cell. Calculated by multiplying the power (Wh) by the capacity (mAh). (Cell voltages of 1.20 and 1.25 volts are used for NiCd and NiMH batteries.
The standard capacity designated by a battery manufacturer to indentify a particular cell model.
Mechanical connector used to electrically connect cells in a battery pack.
Electrode in a battery or cell acting as the anode during discharge. Composed of hydrogen-storing alloys. Also called the minus electrode.
Charge termination based on detecting a decrease in voltage which indicates a cell or battery is charged. Designed to terminate charge as over-charge starts.
Reversible capacity loss found on NiCd and to a lesser extend on NiMH batteries. The modern definition of memory commonly refers to a change in crystalline formation from the desirable small size to a large size.
Voltage-sensing device to automatically disconnect a battery or cell from a load at predetermined voltage. Low-voltage disconnects prevent cell reversal during discharge.
A special sensor which ends discharge at a specified voltage level.
Feel free to contact us by telephone, email, or online form for any questions or to discuss your next battery project. Our solution development team is standing by to help.
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