Dell 40 Whr 4-cell Primary Lithium-ion Battery 33 (6) Write a Review Ask a Question
Battery research is focusing on lithium chemistries so much that one could imagine that the battery future lies solely in lithium. At that place are skilful reasons to be optimistic as lithium-ion is, in many ways, superior to other chemistries. Applications are growing and are encroaching into markets that previously were solidly held past lead acrid, such as standby and load leveling. Many satellites are besides powered past Li-ion.
Lithium-ion has not even so fully matured and is still improving. Notable advancements have been fabricated in longevity and rubber while the capacity is increasing incrementally. Today, Li-ion meets the expectations of most consumer devices only applications for the EV need further development before this power source will get the accepted norm.
As battery care-giver, y'all have choices in how to prolong bombardment life. Each bombardment system has unique needs in terms of charging speed, depth of belch, loading and exposure to adverse temperature. Cheque what causes capacity loss, how does ascension internal resistance affect performance, what does elevated cocky-belch do and how low can a bombardment be discharged? Yous may also be interested in the fundamentals of bombardment testing.
- BU-415: How to Charge and When to Charge?
- BU-706: Summary of Exercise'due south and Don'ts
What Causes Lithium-ion to Age?
The lithium-ion battery works on ion movement between the positive and negative electrodes. In theory such a machinery should work forever, but cycling, elevated temperature and aging decrease the performance over fourth dimension. Manufacturers accept a bourgeois approach and specify the life of Li-ion in most consumer products as beingness betwixt 300 and 500 belch/accuse cycles.
Evaluating bombardment life on counting cycles is not conclusive because a belch may vary in depth and there are no clearly defined standards of what constitutes a bike(See BU-501: Basics Virtually Discharging). In lieu of cycle count, some device manufacturers suggest bombardment replacement on a appointment postage stamp, but this method does not take usage into account. A bombardment may fail inside the allotted time due to heavy utilize or unfavorable temperature conditions; nevertheless, most packs last considerably longer than what the stamp indicates.
The performance of a battery is measured in capacity, a leading health indicator. Internal resistance and self-belch also play roles, simply these are less significant in predicting the end of battery life with mod Li-ion.
F igure 1 illustrates the capacity drop of 11 Li-polymer batteries that have been cycled at a Cadex laboratory. The i,500mAh pouch cells for mobile phones were first charged at a current of 1,500mA (1C) to 4.20V/jail cell and so allowed to saturate to 0.05C (75mA) every bit function of the total charge saturation. The batteries were then discharged at 1,500mA to 3.0V/cell, and the cycle was repeated. The expected capacity loss of Li-ion batteries was uniform over the delivered 250 cycles and the batteries performed as expected.
Eleven new Li-ion were tested on a Cadex C7400 battery analyzer. All packs started at a capacity of 88–94% and decreased to 73–84% after 250 full discharge cycles. The 1500mAh pouch packs are used in mobile phones.
Although a battery should evangelize 100 percent chapters during the first year of service, it is mutual to see lower than specified capacities, and shelf life may contribute to this loss. In addition, manufacturers tend to overrate their batteries, knowing that very few users will do spot-checks and mutter if depression. Not having to lucifer single cells in mobile phones and tablets, equally is required in multi-cell packs, opens the floodgates for a much broader functioning acceptance. Cells with lower capacities may skid through cracks without the consumer knowing.
Similar to a mechanical device that wears out faster with heavy use, the depth of belch (DoD) determines the cycle count of the bombardment. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avert full discharges and charge the battery more ofttimes betwixt uses. Partial discharge on Li-ion is fine. There is no retentivity and the battery does not need periodic full discharge cycles to prolong life. The exception may exist a periodic calibration of the fuel gauge on a smart battery or intelligent device(Run across BU-603: How to Calibrate a "Smart" Battery)
The following tables indicate stress related capacity losses on cobalt-based lithium-ion. The voltages of lithium iron phosphate and lithium titanate are lower and do not apply to the voltage references given.
| Note: | Tables ii, 3 and four indicate general crumbling trends of common cobalt-based Li-ion batteries on depth-of-belch, temperature and charge levels, Table 6 further looks at capacity loss when operating within given and discharge bandwidths. The tables do not address ultra-fast charging and high load discharges that will shorten battery life. No all batteries behave the same. |
Tabular array ii estimates the number of discharge/accuse cycles Li-ion tin can evangelize at various DoD levels before the battery capacity drops to 70 percent. DoD constitutes a full charge followed by a discharge to the indicated state-of-charge (SoC) level in the table.
| Depth of Discharge | Discharge cycles | |
|---|---|---|
| NMC | LiPOiv | |
| 100% DoD | ~300 | ~600 |
| 80% DoD | ~400 | ~900 |
| 60% DoD | ~600 | ~1,500 |
| twoscore% DoD | ~ane,000 | ~3,000 |
| 20% DoD | ~two,000 | ~9,000 |
| 10% DoD | ~half dozen,000 | ~15,000 |
A partial belch reduces stress and prolongs battery life, and then does a fractional charge. Elevated temperature and high currents also affect cycle life.
* 100% DoD is a full cycle; 10% is very brief. Cycling in mid-state-of-charge would have best longevity.
Lithium-ion suffers from stress when exposed to estrus, so does keeping a cell at a high accuse voltage. A battery dwelling above xxx°C (86°F) is considered elevated temperature and for most Li-ion a voltage above 4.10V/cell is deemed every bit high voltage. Exposing the bombardment to high temperature and dwelling in a full country-of-charge for an extended time can be more stressful than cycling. Table three demonstrates capacity loss as a function of temperature and SoC.
| Temperature | 40% Charge | 100% Charge |
|---|---|---|
| 0°C | 98% (after ane twelvemonth) | 94% (afterward one year) |
| 25°C | 96% (after ane year) | 80% (afterwards one yr) |
| 40°C | 85% (after 1 yr) | 65% (after i year) |
| 60°C | 75% (after 1 twelvemonth) | lx% (after 3 months) |
Elevated temperature hastens permanent capacity loss. Not all Li-ion systems behave the same.
Most Li-ions charge to 4.20V/cell, and every reduction in top charge voltage of 0.10V/cell is said to double the bicycle life. For instance, a lithium-ion cell charged to 4.20V/cell typically delivers 300–500 cycles. If charged to only iv.10V/prison cell, the life can be prolonged to 600–1,000 cycles; 4.0V/jail cell should evangelize 1,200–2,000 and iii.90V/jail cell should provide two,400–4,000 cycles.
On the negative side, a lower peak charge voltage reduces the capacity the battery stores. As a simple guideline, every 70mV reduction in charge voltage lowers the overall capacity by x per centum. Applying the peak charge voltage on a subsequent charge will restore the full capacity.
In terms of longevity, the optimal charge voltage is 3.92V/prison cell. Battery experts believe that this threshold eliminates all voltage-related stresses; going lower may not gain farther benefits but induce other symptoms(See BU-808b: What causes Li-ion to die?) Tabular array 4 summarizes the capacity as a function of accuse levels. (All values are estimated; Free energy Cells with higher voltage thresholds may deviate.)
| Charge Level* (Five/cell) | Discharge Cycles | Available Stored Energy ** |
|---|---|---|
| [4.xxx] | [150–250] | [110–115%] |
| 4.25 | 200–350 | 105–110% |
| 4.20 | 300–500 | 100% |
| four.xv | 400–700 | xc–95% |
| 4.ten | 600–i,000 | 85–90% |
| iv.05 | 850–i,500 | 80–85% |
| 4.00 | 1,200–2,000 | 70–75% |
| 3.90 | two,400–4,000 | threescore–65% |
| three.80 | See annotation | 35–40% |
| 3.lxx | Meet note | xxx% and less |
Every 0.10V drop beneath iv.20V/jail cell doubles the cycle but holds less capacity. Raising the voltage in a higher place iv.20V/cell would shorten the life. The readings reverberate regular Li-ion charging to 4.20V/cell.
Guideline: Every 70mV drop in charge voltage lowers the usable capacity past about 10%.
Notation: Fractional charging negates the do good of Li-ion in terms of high specific energy.
* Similar life cycles apply for batteries with different voltage levels on total charge.
** Based on a new bombardment with 100% capacity when charged to the full voltage.
Experiment: Chalmers University of Technology, Sweden, reports that using a reduced charge level of 50% SOC increases the lifetime expectancy of the vehicle Li-ion bombardment by 44–130%.
Most chargers for mobile phones, laptops, tablets and digital cameras charge Li-ion to 4.20V/cell. This allows maximum capacity, because the consumer wants nothing less than optimal runtime. Industry, on the other hand, is more concerned about longevity and may choose lower voltage thresholds. Satellites and electric vehicles are such examples.
For safety reasons, many lithium-ions cannot exceed 4.20V/cell. (Some NMC are the exception.) While a college voltage boosts capacity, exceeding the voltage shortens service life and compromises safety. Figure five demonstrates cycle count equally a function of charge voltage. At four.35V, the cycle count of a regular Li-ion is cut in half.
Higher charge voltages boost capacity just lowers cycle life and compromises rubber.
As well selecting the best-suited voltage thresholds for a given awarding, a regular Li-ion should not remain at the loftier-voltage ceiling of 4.20V/cell for an extended time. The Li-ion charger turns off the charge electric current and the battery voltage reverts to a more natural level. This is like relaxing the muscles after a strenuous exercise(See BU-409: Charging Lithium-ion)
Effigy 6 illustrates dynamic stress tests (DST) reflecting capacity loss when cycling Li-ion at various charge and discharge bandwidths. The largest capacity loss occurs when discharging a fully charged Li-ion to 25 percent SoC (blackness); the loss would exist higher if fully discharged. Cycling between 85 and 25 percent (green) provides a longer service life than charging to 100 percentage and discharging to l percent (nighttime blue). The smallest capacity loss is attained by charging Li-ion to 75 per centum and discharging to 65 percent. This, however, does not fully utilize the bombardment. High voltages and exposure to elevated temperature is said to degrade the bombardment quicker than cycling under normal condition. (Nissan Leaf case)
Charging and discharging Li-ion only partially prolongs bombardment life just reduces utilization.
- Instance 1: 75–65% SoC offers longest cycle life but delivers only 90,000 energy units (Eu). Utilizes 10% of bombardment.
- Case two: 75–25% SoC has 3,000 cycles (to 90% capacity) and delivers 150,000 EU. Utilizes l% of bombardment. (EV battery, new.)
- Instance 3: 85–25% SoC has 2,000 cycles. Delivers 120,000 EU. Uses lx% of battery.
- Instance iv: 100–25% SoC; long runtime with 75% use of battery. Has short life. (Mobile phone, drone, etc.)
* Discrepancies exist between Table two and Figure 6 on cycle count. No clear explanations are bachelor other than assuming differences in battery quality and test methods. Variances between low-cost consumer and durable industrial grades may as well play a role. Capacity retention volition reject more rapidly at elevated temperatures than at 20ºC.
Simply a full cycle provides the specified energy of a bombardment. With a mod Energy Jail cell, this is about 250Wh/kg, but the cycle life will exist compromised. All being linear, the life-prolonging mid-range of 85-25 percent reduces the free energy to lx percent and this equates to moderating the specific energy density from 250Wh/kg to 150Wh/kg. Mobile phones are consumer appurtenances that utilize the full free energy of a battery. Industrial devices, such equally the EV, typically limit the accuse to 85% and discharge to 25%, or 60 percent energy usability, to prolong battery life(See Why Mobile Phone Batteries do not terminal as long as an EV Bombardment)
Increasing the cycle depth also raises the internal resistance of the Li-ion cell. Figure 7 illustrates a precipitous rise at a bike depth of 61 pct measured with the DC resistance method(Run across also BU-802a: How does Ascension Internal Resistance affect Operation?) The resistance increase is permanent.
Note: DC method delivers different internal resistance readings than with the Air-conditioning method (green frame). For all-time results, use the DC method to calculate loading.
Effigy 8 extrapolates the data from Figure six to expand the predicted cycle life of Li-ion by using an extrapolation programme that assumes linear decay of bombardment capacity with progressive cycling. If this were true, so a Li-ion battery cycled within 75%–25% SoC (blue) would fade to 74% chapters later xiv,000 cycles. If this battery were charged to 85% with aforementioned depth-of-belch (light-green), the capacity would drop to 64% at 14,000 cycles, and with a 100% accuse with same DoD (black), the capacity would drop to 48%. For unknown reasons, real-life expectancy tends to be lower than in false modeling(See BU-208: Cycling Functioning)
Li-ion batteries are charged to three dissimilar SoC levels and the cycle life modelled. Limiting the charge range prolongs battery life merely decreases energy delivered. This reflects in increased weight and higher initial cost.
Battery manufacturers frequently specify the wheel life of a battery with an fourscore DoD. This is practical considering batteries should retain some reserve earlier charge under normal use(See BU-501: Basics about Discharging, "What Constitutes a Belch Cycle") The cycle count on DST (dynamic stress examination) differs with battery type, charge time, loading protocol and operating temperature. Lab tests oftentimes get numbers that are not attainable in the field.
What Can the User Do?
Ecology conditions, not cycling solitary, govern the longevity of lithium-ion batteries. The worst situation is keeping a fully charged battery at elevated temperatures. Bombardment packs do not die suddenly, but the runtime gradually shortens as the capacity fades.
Lower accuse voltages prolong battery life and electric vehicles and satellites take advantage of this. Like provisions could as well be fabricated for consumer devices, but these are seldom offered; planned obsolescence takes care of this.
A laptop bombardment could be prolonged by lowering the charge voltage when connected to the Air conditioning grid. To brand this characteristic user-friendly, a device should feature a "Long Life" manner that keeps the battery at 4.05V/cell and offers a SoC of about lxxx percent. One hour earlier traveling, the user requests the "Total Capacity" manner to bring the accuse to iv.20V/cell.
The question is asked, "Should I disconnect my laptop from the power grid when not in use?" Under normal circumstances this should not exist necessary because charging stops when the Li-ion battery is full. A topping charge is merely applied when the battery voltage drops to a certain level. Most users do non remove the AC power, and this exercise is safe.
Modernistic laptops run libation than older models and reported fires are fewer. Always keep the airflow unobstructed when running electrical devices with air-cooling on a bed or pillow. A absurd laptop extends battery life and safeguards the internal components. Energy Cells, which most consumer products take, should be charged at 1C or less. Avert and then-chosen ultra-fast chargers that merits to fully accuse Li-ion in less than one hr.
References
[one] Courtesy of Cadex
[two] Source: Choi et al. (2002)
[3] B. Xu, A. Oudalov, A. Ulbig, Thousand. Andersson and D. Kirschen, "Modeling of Lithium-Ion Bombardment Deposition for Jail cell Life Assessment," June 2016. [Online]. Bachelor: https://www.researchgate.cyberspace/publication/303890624_Modeling_of_Lithium-Ion_Battery_Degradation_for_Cell_Life_Assessment.
[4] Source: Technische Universität München (Tum)
[v] With permission to use. Interpolation/extrapolation by OriginLab.
cranswicklizeatied.blogspot.com
Source: https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries