Battery pack
{{Short description|Set of batteries or battery cells}}
{{More citations needed|date=January 2024}}Image:Acp_tzero_dsc00309.jpg consisting of 28 Optima Yellow Tops]]
File:Lucid battery pack 01.jpg for Lucid Motors]]
A battery pack is a set of any number of (preferably) identical batteries or individual battery cells.{{Cite book |last1=Hassini |first1=Marwan |last2=Von Hohendorff Seger |first2=Pedro |last3=Redondo-Iglesias |first3=Eduardo |last4=Pelissier |first4=Serge |last5=Venet |first5=Pascal |chapter=Capacity Dispersion and Impact of Outliers in a Second Life Battery |date=27 October 2023 |title=2023 IEEE Vehicle Power and Propulsion Conference (VPPC) |chapter-url=https://hal.science/hal-04177094 |pages=1–4 |location=Milan, Italy|doi=10.1109/VPPC60535.2023.10403384 |isbn=979-8-3503-4445-5 |s2cid=267337334 }}{{Cite journal |last1=Li |first1=Wei |last2=Garg |first2=Akhil |last3=Xiao |first3=Mi |last4=Peng |first4=Xiongbin |last5=Le Phung |first5=My Loan |last6=Tran |first6=Van Man |last7=Gao |first7=Liang |date=2020-10-10 |title=Intelligent optimization methodology of battery pack for electric vehicles: A multidisciplinary perspective |journal=International Journal of Energy Research |language=en |volume=44 |issue=12 |pages=9686–9706 |doi=10.1002/er.5600 |bibcode=2020IJER...44.9686L |issn=0363-907X|doi-access=free }} They may be configured in a series, parallel or a mixture of both to deliver the desired voltage and current. The term battery pack is often used in reference to cordless tools, radio-controlled hobby toys, and battery electric vehicles.
Components of battery packs include the individual batteries or cells, and the interconnects which provide electrical conductivity between them.{{Cite journal |last1=Harper |first1=Gavin |last2=Sommerville |first2=Roberto |last3=Kendrick |first3=Emma |last4=Driscoll |first4=Laura |last5=Slater |first5=Peter |last6=Stolkin |first6=Rustam |last7=Walton |first7=Allan |last8=Christensen |first8=Paul |last9=Heidrich |first9=Oliver |last10=Lambert |first10=Simon |last11=Abbott |first11=Andrew |last12=Ryder |first12=Karl |last13=Gaines |first13=Linda |last14=Anderson |first14=Paul |date=6 November 2019 |title=Recycling lithium-ion batteries from electric vehicles |url=https://www.nature.com/articles/s41586-019-1682-5 |journal=Nature |language=en |volume=575 |issue=7781 |pages=75–86 |doi=10.1038/s41586-019-1682-5 |pmid=31695206 |bibcode=2019Natur.575...75H |issn=1476-4687}} Rechargeable battery packs often contain voltage and temperature sensors, which the battery charger uses to detect the end of charging.{{Cite journal |last=Simpson |first=Chester |date=1995 |title=Battery charging |url=https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/858/snva557.pdf |journal=National Semiconductors}} Interconnects are also found in batteries as they are the part which connects each cell, though batteries are most often only arranged in series strings.
When a pack contains groups of cells in parallel there are differing wiring configurations which take into consideration the electrical balance of the circuit. Battery Management System are sometimes used for balancing cells in order to keep their voltages below a maximum value during charging so as to allow the weaker batteries to become fully charged, bringing the whole pack back into balance.{{Cite book |chapter=Battery balancing methods: A comprehensive review |chapter-url=https://ieeexplore.ieee.org/document/4677669 |access-date=2024-01-19 |doi=10.1109/VPPC.2008.4677669 |s2cid=42399871 |title=2008 IEEE Vehicle Power and Propulsion Conference |date=2008 |last1=Cao |first1=Jian |last2=Schofield |first2=Nigel |last3=Emadi |first3=Ali |pages=1–6 |isbn=978-1-4244-1848-0 }} Active balancing can also be performed by battery balancer devices which can shuttle energy from strong cells to weaker ones in real time for better balance. A well-balanced pack lasts longer and delivers better performance.{{Cite journal |last1=Duraisamy |first1=Thiruvonasundari |last2=Kaliyaperumal |first2=Deepa |date=2020-06-01 |title=Active cell balancing for electric vehicle battery management system |url=http://ijpeds.iaescore.com/index.php/IJPEDS/article/view/20414 |journal=International Journal of Power Electronics and Drive Systems |volume=11 |issue=2 |pages=571 |doi=10.11591/ijpeds.v11.i2.pp571-579 |issn=2722-256X}}
For an inline package, cells are selected and stacked with solder in between them. The cells are pressed together and a current pulse generates heat to solder them together and to weld all connections internal to the cell.
Calculating state of charge
SOC, or state of charge, is the equivalent of a fuel quantity remaining. SOC cannot be determined by a simple voltage measurement, because the terminal voltage of a battery may stay substantially constant until it is completely discharged. In some types of battery, electrolyte specific gravity may be related to state of charge but this is not measurable on typical battery pack cells, and is not related to state of charge on most battery types. Most SOC methods take into account voltage and current as well as temperature and other aspects of the discharge and charge process to in essence count up or down within a pre-defined capacity of a pack.{{Cite book |chapter=Battery state-of-charge estimation |chapter-url=https://ieeexplore.ieee.org/document/945964 |access-date=2024-01-19 |doi=10.1109/ACC.2001.945964 |s2cid=57885701 |title=Proceedings of the 2001 American Control Conference. (Cat. No.01CH37148) |date=2001 |last1=Shuo Pang |last2=Farrell |first2=J. |last3=Jie Du |last4=Barth |first4=M. |pages=1644-1649 vol.2 |isbn=0-7803-6495-3 }}{{Cite journal |last1=Hassini |first1=Marwan |last2=Redondo-Iglesias |first2=Eduardo |last3=Venet |first3=Pascal |date=19 July 2023 |title=Lithium–Ion Battery Data: From Production to Prediction |journal=Batteries |language=en |volume=9 |issue=7 |pages=385 |doi=10.3390/batteries9070385 |doi-access=free |issn=2313-0105}} More complex state of charge estimation systems take into account the Peukert effect which relates the capacity of the battery to the discharge rate.{{Cite book |doi=10.1109/rICT-ICeVT.2013.6741545 |s2cid=5621134 |chapter=State of charge (SoC) estimation on LiFePO4 battery module using Coulomb counting methods with modified Peukert |title=2013 Joint International Conference on Rural Information & Communication Technology and Electric-Vehicle Technology (RICT & ICeV-T) |date=2013 |last1=Leksono |first1=Edi |last2=Haq |first2=Irsyad Nashirul |last3=Iqbal |first3=Muhammad |last4=Soelami |first4=F X Nugroho |last5=Merthayasa |first5=I G N. |pages=1–4 |isbn=978-1-4799-3365-5 }}
Advantages
An advantage of a battery pack is the ease with which it can be swapped into or out of a device. This allows multiple packs to deliver extended runtimes, freeing up the device for continued use while charging the removed pack separately.
Another advantage is the flexibility of their design and implementation, allowing the use of cheaper high-production cells or batteries to be combined into a pack for nearly any application.
At the end of product life, batteries can be removed and recycled separately, reducing the total volume of hazardous waste.
Disadvantages
Packs are often simpler for end users to repair or tamper with than a sealed non-serviceable battery or cell. Though some might consider this an advantage it is important to take safety precautions when servicing a battery pack as they pose a danger as potential chemical, electrical, and fire risks.
Power bank
A power bank is a portable device consisting of a battery, a charger to interface battery with charging power source and an output interface to provide desired output voltage.{{Cite book |last=Andrea |first=Davide |url=https://books.google.com/books?id=b6wCEAAAQBAJ&pg=PA31 |title=Lithium-Ion Batteries and Applications: A Practical and Comprehensive Guide to Lithium-Ion Batteries and Arrays, from Toys to Towns, Volume 2, Applications |date=2020-06-30 |publisher=Artech House |isbn=978-1-63081-770-1 |language=en}} Power banks are made in various sizes and typically based on lithium-ion batteries. A power bank contains battery cells and a voltage converter circuitry. The internal DC-DC converter manages battery charging and converts the battery stack's voltage to the desired output voltage. The advertised capacity on the product in many instances is based on the capacity of the internal cells, however the theoretical mAh available to output depends on the output voltage. The conversion circuit has some energy losses, so the actual output is less than theoretical.{{Cite journal |last1=Yang |last2=Gu |last3=Guo |last4=Chen |date=2019-09-20 |title=Comparative Life Cycle Assessment of Mobile Power Banks with Lithium-Ion Battery and Lithium-Ion Polymer Battery |journal=Sustainability |volume=11 |issue=19 |pages=5148 |doi=10.3390/su11195148 |issn=2071-1050|doi-access=free }}{{Cite journal |last1=Diao |first1=Weiping |last2=Saxena |first2=Saurabh |last3=Pecht |first3=Michael G. |date=2020 |title=Analysis of Specified Capacity in Power Banks |journal=IEEE Access |volume=8 |pages=21326–21332 |doi=10.1109/ACCESS.2020.2969410 |s2cid=211055705 |issn=2169-3536|doi-access=free |bibcode=2020IEEEA...821326D }} The theoretical mAh of a 3.7 V battery power bank with 5 V output is 74% of the battery mAh rating. The RavPower RP-PB41 with advertised capacity of 26,800 mAh that was evaluated in the journal has a theoretical capacity of 19,832 mAh, although the delivered capacity was 15,682 mAh, 78% of theoretical value. Authors attributed the difference to internal resistance in battery and converter losses. The circuit board can contain additional features such as over discharge protection, automatic shut off and charge level indication LEDs.{{Cite web |last1=Raja |first1=Ganesh |last2=Madaan |first2=Pushek |date=Oct 30, 2013 |title=Power Bank – Power On-The-Go (Part 1) |url=https://www.electronicdesign.com/technologies/portable-power-management/article/21196452/power-bank-power-onthego-part-1 |access-date=2023-06-21 |website=Electronic Design}}{{Cite web |last1=Raja |first1=Ganesh |last2=Madaan |first2=Pushek |date=Oct 30, 2013 |title=Power Bank – Power On-The-Go (Part 2) |url=https://www.electronicdesign.com/technologies/power/power-supply/pmics/article/21196473/power-bank-power-onthego-part-2 |access-date=2023-06-21 |website=Electronic Design}} Power banks may be able to detect a connection and power on automatically. If the current load is under a model-specific threshold for a specific duration, a power bank may power down automatically.{{cite web|url=https://www.ti.com/lit/pdf/slva770 |title=Port detection for power banks |publisher=Texas Instruments |date=April 2016 |access-date=2021-09-13 }}
The average power bank in 2023 transferred around 2/3, or 67% of the power bank's battery energy into the battery of the device being charged.{{Cite web |date=2020-05-09 |title=Here's How Much Charge Your Power Bank and Charging Case Really Has |url=https://www.digitaltrends.com/mobile/battery-capacities-explained-charge-power-bank-charging-case/ |access-date=2024-11-25 |website=Digital Trends |language=en}}
Some power banks are able to deliver power wirelessly, some are equipped with an LED flashlight for casual near-distance illumination when necessary, and some have a pass-through charging feature which allows providing power through their USB ports while being charged themselves simultaneously.{{Cite web|date=2018-06-01|title=How Pass Through Tech Lets You Use Power Banks In Creative Ways|url=https://blog.ravpower.com/2018/06/pass-through-creative-ways-power-banks-charge/|access-date=2020-09-06|website=RAVPower|language=en-US}} Some larger power banks have DC connectors (or barrel connectors) for higher power demands such as laptop computers.
= Battery cases =
Battery cases are small power banks attached to the rear side of a mobile phone like a case. Power may be delivered through the USB charging ports,{{cite web |last1=Stein |first1=Scott |title=Apple Smart Battery Case for iPhone 6S review: Addressing the iPhone's biggest weakness |url=https://www.cnet.com/reviews/apple-smart-battery-case-for-iphone-6s-review/ |website=CNET |language=en}} or wirelessly.{{cite web |title=Galaxy Note 7 S View Standing Cover and Battery Pack hands on |url=https://www.androidauthority.com/galaxy-note-7-cases-charger-packs-707458/ |website=Android Authority |date=2 August 2016}} Battery cases also exist in the form of a camera grip accessory, as was for the Nokia Lumia 1020.{{cite web |title=IRL: Testing the Nokia Lumia 1020's optional camera grip / battery case |url=https://www.engadget.com/2013-09-16-irl-lumia-1020-camera-grip.html |website=Engadget |language=en |date=2013-09-16}} For mobile phones with removable rear cover, extended batteries exist. These are larger internal batteries attached with a dedicated, more spacious rear cover replacing the default one. A disadvantage is incompatibility with other phone cases while attached.{{cite web |last1=Klug |first1=Brian |title=Samsung Galaxy S 4 ZeroLemon 7500 mAh Extended Battery Review |url=https://www.anandtech.com/show/7163/zerolemon-7500-mah-samsung-galaxy-s-4-extended-battery-review |website=Anandtech.com |date=2013-07-23}}
Prong cases included fold-out prongs integrated into the case itself.{{cite web|url=http://www.cnet.com/news/no-more-charging-cables-prong-iphone-case-has-wall-prongs/|title=No more charging cables: Prong iPhone case has wall prongs|publisher=CBS Interactive|work=CNET|accessdate=13 September 2024}}
= Rental/exchange =
File:At New York City 2024 082.jpg
In some parts of the world, there are kiosk based power bank rental or subscription services. Customers pay for the use of power bank for a specified period of time and return the depleted power bank to the kiosk.{{Cite web |date=2022-07-25 |title=Would you rent a power bank on the go? |url=https://lifestyle.livemint.com//smart-living/innovation/would-you-rent-a-power-bank-on-the-go-111658646528975.html |access-date=2023-06-21 |website=Mintlounge |language=en}} In one case with a brand called FuelRod, it was sold at an elevated price at various amusement parks with the understanding that they get a perk of free exchange at participating locations.{{Cite web |date=2019-11-05 |title=Class-action lawsuit seeks $5 million over portable chargers sold at Disney, Universal and SeaWorld parks |url=https://www.ocregister.com/2019/11/05/class-action-lawsuit-seeks-5-million-over-portable-chargers-sold-at-disney-universal-and-seaworld-parks/ |access-date=2023-06-21 |website=The Mercury News |language=en-US}} FuelRod moved to discontinue the free exchange in 2019 and resulted in a class-action lawsuit reaching a settlement that early adopters would be grandfathered to free exchange privileges.{{Cite web |last=Tuttle |first=Brittani |date=2020-07-10 |title=FuelRod lawsuit ends; 'Founders' can still receive free swaps |url=https://attractionsmagazine.com/fuelrod-lawsuit-ends-founders-still-receive-free-swaps/ |access-date=2023-06-21 |website=Attractions Magazine |language=en-US}}
= Air travel restrictions =
Per US Federal Aviation Administration regulations, power banks in the United States are not allowed in checked-in luggage. Power banks up to 100 Wh are allowed as carry-on and those 101 Wh to 160 Wh are allowed with airline approval.{{Cite web |last=McInnis |first=Kaitlyn |date=2022-05-18 |title=What's allowed in — and prohibited from — your carry-on bag, according to the TSA's rules |url=https://www.cnn.com/cnn-underscored/travel/what-is-allowed-in-carry-on-bag |access-date=2023-06-21 |website=CNN Underscored |language=en}}
After Air Busan Flight 391 in Korea, concerns about power banks on flights arose, and new regulations of power banks were issued. The Korean government issued a ban on using power banks on Korean flights.{{cite web | title=Power banks, e-cigarettes banned from overhead bins on Korean-owned airlines | website=Korea JoongAng Daily | date=2025-02-14 | url=https://koreajoongangdaily.joins.com/news/2025-02-14/business/industry/Power-banks-ecigarettes-banned-from-overhead-bins-on-Koreanowned-airlines/2242470 | access-date=2025-02-26}} In March 2025, Civil Aviation Authority of Malaysia issued a directive to advise passengers storing power banks on their person, and avoid in overhead bins.{{cite news |last1=Parkaran |first1=K. |title=New airline rule: keep power banks on you, not in your luggage |url=https://www.freemalaysiatoday.com/category/nation/2025/03/07/new-airline-rule-keep-power-banks-on-you-not-in-your-luggage/ |access-date=16 March 2025 |work=Free Malaysia Today |date=7 March 2025 |language=en}} In February 2025, Eva Air announced their ban on using power banks on flights. AirAsia, China Airlines, Starlux Airlines, Singapore Airlines, and Thai Airways issued similar bans later.{{cite web | last=Lee | first=Grace | title=EVA Air Announces Battery Bank Ban Onboard | website=Travel Radar | date=2025-02-25 | url=https://travelradar.aero/eva-air-announces-battery-bank-ban-onboard/ | access-date=2025-02-26}}{{cite news |last1=Cheng |first1=Ian |title=SIA, Scoot to ban use and charging of power banks on flights from April |url=https://www.straitstimes.com/singapore/sia-to-disallow-charging-of-power-banks-onboard-flights-from-april-1 |access-date=16 March 2025 |work=The Straits Times |date=12 March 2025 |language=en}}{{cite news |title=台6航空公司 禁机上使用充电宝 |url=https://www.sinchew.com.my/news/20250226/international/6334120 |access-date=16 March 2025 |work=Sin Chew Daily |date=26 February 2025 |language=zh-CN }}