understanding battery specifications

BATTERΥ

ΕΙΔΗ – ΚΑΤΗΓΟΡΙΕΣ – ΤΕΧΝΙΚΑ ΧΑΡΑΚΤΗΡΙΣΤΙΚΑ

Understanding Battery Specifications

Applications

Capacity – Χωρητικοτητα

BATTERRY CHARACTERISTICS 2

• The coulometric capacity, the total Amp-hours available when the battery is discharged at a certain discharge Current (specified as a C-rate) from 100 percent state-of-charge to the cut-off voltage .

• Capacity is calculated by multiplying the discharge current (in Amps) by the discharge time (in hours) and decreases with increasing C-rate

The terminal EMF provided by a battery is known as it’s voltage.

The Voltage of a battery depends upon various other characteristics of the batteries like cell-chemistry , internal impedance etc.

The average Voltage of a lead acid cell is 2.0 V

Βut it depends on various other factors like , temperature, time between the measurement and last charge etc.

Voltage – Ονοματικη ταση

BATTERRY CHARACTERISTICS 1

Efficiency of a battery is the ratio of the energy provided by the battery/cell or output energy while in use over the energy used by the battery/cell to get charged or input energy expressed in percentage.

Efficiency - Αποδοση

BATTERY CHARACTERISTICS 3

• The minimum allowable voltage .It is this voltage that generally defines the “empty” state of the battery

Cut-off Voltage, Ελαχιστη ταση λειτουργειας


• The number of discharge- charge cycles the battery can experience before it fails to meet specific performance criteria.

• Cycle life is estimated for specific charge and discharge conditions. The actual operating life of the battery is affected by the rate and depth of cycles and by other conditions such as temperature and humidity.

Cycle Life (number for a specific DOD)


The energy density of a battery is generally expressed in two ways

The gravimetric energy density of a battery is a measure of how much energy a battery contains in comparison to its weight, and is typically expressed in Watt-hours/kilogram(W-hr/kg).

The volumetric energy density of a battery is a measure of how much energy a battery contains in comparison to its volume, and is typically expressed in Watt-hours/liter(W-hr/l).


Energy Density (By Weight and Volume) – Πυκνοτητα Ενεργειας

The maximum current at which the battery can be discharged Continuously.

This limit is usually Defined by the battery manufacturer in order to prevent excessive discharge rates that would damage the battery or reduce its capacit y.

Along with the maximum continuous power of the motor, this defines the top sustainable speed and accelerat ion of the vehicle

Maximum Continuous Discharge- Μεγιστο συνεχομενο επιτρεπτο ρευμα


The voltage that the battery is charged to when charged to full capacity. Charging schemes generally consist of a constant current charging until the battery voltage Reaching the charge voltage, then constant voltage charging, Allowing the charge current to taper until it is very small

Charge Voltage – Ταση φορτισης



The ideal current at which the battery is initially charged (to roughly 70 percent SOC) under constant Charging scheme before transitioning into constant Voltage charging.

(Recommended) Charge Current - Ρευμα φορτισης


• Batteries are acutely sensitive to operating temperature with respect to their charging characteristics and A-hr capacity.

• Most well-designed chargers have temperature sensors to assure that the battery temperature is within the allowable "window" for charging (if not, the charger will not turn on the current source)

Operating Temperature- Θερμοκρασια λειτουργιας

Temperature vs. Capacity - Flooded Lead Acid Batteries


• Self-discharge (which occurs in all batteries) determines the "shelf life" of a battery.

• It is important to note that self-discharge is highly dependent on temperature, increasing as the battery temperature is increased

Self Discharge < Χρονος αυτοεκφορτισης


Self Discharge < Χρονος αυτοεκφορτισης


• The amount of time that the typical consumer finds acceptable for battery recharging is highly variable, and depends on the item being powered..

Recharge Time > Χρονος φορτισης


• It should be no surprise that the Ni-Cd cell offers the best cost/performance value of any rechargeable battery: it is a mature technology that is being produced in large volumes by many different manufacturers.

Cost- Κοστος


• A 1C discharge rate would deliver the battery's rated capacity in 1 hour. A 2C discharge rate means it will discharge twice as fast (30 minutes). .

C rate

Battery Condition 1

Depth of Discharge (DOD) (%)

The percentage of battery capacity that has been discharged expressed as a percentage of maximum capacity. A discharge to at least 80 % DOD is referred to as a deep discharge

Battery Condition 1

Depth of Discharge (DOD) (%)

Depth of Discharge vs Cycle Life

The voltage between the battery terminals with load applied.

Terminal voltage varies with SOC and discharge/charge current.

Terminal Voltage (V)

Battery Condition 2

The voltage between the battery terminals with no load applied.

The open-circuit voltage depends on the battery state of charge, increasing with state of charge.

Open-circuit voltage (V)

Battery Condition 3

BATTERY TYPES

Household (rechargeable and non-rechargeable),

Industrial

Vehicle batteries.

BATTERY TYPES

These are the most common types of batteries powering devices you use everyday.

•Some are rechargeable, you can plug them in to charge and get multiple uses before the battery needs to be replaced.

•Some are non-rechargeable or single-use, once they are fully discharged, they should be recycled.

Household Batteries

BATTERY TYPES

Rechargeable Household Batteries

Lead Acid Gel

• Lithium-ion (Li-ion)

BATTERY TYPES


Lead Acid Gel• Description: Small to medium, dry-cell batteries, sealed, rechargeable

Formats: Rectangular, custom sizes in hard plastic case

• Common Uses: Wheel chairs, scooters, golf carts, ride-on electric toys, boats, military aircraft, portable tools and instruments

• Safety: Non-spillable , lead is a toxic heavy metal, can cause fire if short-circuited

BATTERY TYPES


Description: Small dry-cell batteries, sealed, rechargeable

Formats: Custom sizes in hard plastic case, small-cylinder, button cells

Common Uses: Cell phones, laptop computers, power tools, hybrid automobiles (see Hybrid Automobile section also), video cameras, handheld electronics

Safety: Non-spillable, non-toxic

Lithium-ion (Li-ion)

BATTERY TYPES


• Nickel-Cadmium (Ni Cd)

• Nickel Metal Hydride (Ni MH)

BATTERY TYPES


Lithium-ion (Li-ion) Advantages High energy density Does not need prolonged priming when new. One regular charge is all that's needed.

Relatively low self-discharge - self-discharge is less than half that of nickel-based batteries.

Low Maintenance - no periodic discharge is needed; there is no memory.

Specialty cells can provide very high current to applications such as power tools.

BATTERY TYPES


Lithium-ion (Li-ion) Limitations

Requires protection circuit to maintain voltage and current within safe limits. Subject to aging, even if not in use - storage in a cool place at 40% charge reduces the aging effect. Transportation restrictions - shipment of larger quantities may be subject to regulatory control. This restriction does not apply to personal carry-on batteries.

Expensive to manufacture - about 40 percent higher in cost than nickel-cadmium.

BATTERY TYPES Rechargeable Household Batteries

• Description: Small dry-cell batteries, sealed, rechargeable

• Formats: AAA, AA, C, D, small-cylinder, poly-wrapped cell packs, custom sizes in hard plastic case

•Common Uses: Cell phones, laptop computers, power tools, handheld electronics, toys, medical equipment

•Safety: Non-spillable, cadmium is a toxic heavy metal, never incinerate - produces toxic cadmium vapors

Nickel-Cadmium (NiCd)

BATTERY TYPES


Nickel-Cadmium (NiCd) Advantages / Disadvantages:NiCd batteries are often lower cost than NiMh batteries or lithium-based batteries. They can have a memory if not charged properly.

When to use:

If a low-cost rechargeable battery is needed.

If a long lifespace is needed. NiCds typically can be charged and discharged a large amount of times. If done properly, these batteries can be charged more times than other rechargeable chemistries.

When not to use:If the conditions of use are not known. NiCd require a specific charging procedure for best longevity. For applications where this procedure might not be kept, other batteries may be best suited.

BATTERY TYPES


• Description: Small dry-cell batteries, sealed, rechargeable

• Formats: AAA, AA, C, D, 9 volt, 12 volt, poly-wrapped cell packs, small-cylinder, custom sizes

• Common Uses: Cell phones, laptop computers, PDAs, power tools, hybrid automobiles (see Hybrid Automobile section also), cameras, handheld electronics

• Safety: Non-spillable, non-toxic

Nickel Metal Hydride (NiMH)

BATTERY TYPES

rechargeable Household Batteries

These batteries often contain more energy, more resilience, and offer a lower number of cycles than NiCd batteries.

When to use:If a high discharge current is needed, such as in cordless power tools.If the charging procedure is not known. For example, if the battery may be charged when it is at half capacity, this would be detrimental for NiCd batteries but would be fine for NiMh batteries.

When not to use:•If long life span is needed. The advertised life of NiMh batteries are typically fewer than 1000 cycles. •If a product is going to be recharged daily, the life of a battery may not last longer than a few years.

Nickel Metal Hydride (NiMH) Advantages / Disadvantages

BATTERY TYPES

While the everyday battery user may never run into these batteries, they exist to power the heavy duty applications like machinery, railroad and backup power for data centers, utilities, or telecommunications , solar panel.

These are the kind of batteries you would be afraid of running into in a dark alley. Kidding, they won’t hurt you if you don’t instigate them.

Industrial Batteries

BATTERY TYPES

Industrial Batteries

Absolyte

Nickel Iron

Steel Case

BATTERY TYPES

Vehicle Batteries

Hybrid Automotive

Lead Acid

BATTERY TYPES

Lead Acid charging

The constant-current charge applies the bulk of the charge and takes roughly half the required charge time

The topping charge uses a lower charge current and provides saturation. The float charge compensates for loss caused by self-discharge.

For optimal charging, lead-acid batteries should be charged in three stages.

BATTERY TYPES

Lead Acid AdvantagesLow cost.

Reliable. Over 140 years of development.

Robust. Tolerant to abuse.

Tolerant to overcharging.

Can deliver very high currents.

Indefinite shelf life if stored without electrolyte.

Can be left on trickle or float charge for prolonged periods.

Wide range of sizes and capacities available.

Many suppliers world wide.

The world's most recycled product.

BATTERY TYPES

Lead Acid / Disadvantages:

Very heavy and bulky.

Typical coulombic charge efficiency only 70% but can be as high as 85% to 90% for special designs.

Danger of overheating during charging

Not suitable for fast charging

Typical cycle life 300 to 500 cycles .

Must be stored in a charged state once the electrolyte has been introduced to avoid deterioration of the active chemicals.

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understanding battery specifications

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