LiPo Lithium Polymer Batteries

In the following post I am going to share with your what damages lithium polymer batteries used in smartphones, smartwatches, RC toys, electric vehicles of all kinds, tablets, laptops & other portable electronic devices of COTS, consumer of the shelf electronics.

LiPO stands for Lithium Polymer : Some Warnings

They are wrapped in a special kind of aluminized plastic foil, not a hard steel case like NiCD or NiMH or Alkaline batteries, or even the cylindrical type used in some EV's like the 4680 cells in the Tesla Model Y.

Don't Physically Damage LiPo Cells

If the wrapper or mylar or foil wrapping of the LiPo battery damaged in any way, torn, ripped, bend substantially, warped, bubble, punctured, sliced, crushed or otherwise mechanically damaged, an opening in the wrapper can allow oxygen & water vapor in, which will violently react with the lithium cobalt cathode materials & the flammable electrolyte, resulting in smoking with flame emissions, and the smoke will contain oxides of lithium, carbon, & cobalt, which are poisonous or toxic to breathe or inhale. 

Thermal Runaway Cells into a Sand Filled Bucket Immediately

Always place a malfunctioning or overheating or puffing LiPO into a bucket filled with sand & then take the bucket outside immediately. Cover the bucket with a lid to prevent water from getting in, as watch reacts with the cathode materials in a LiPo with an energetic reaction. 

Deep Cycling Shortens LiPo Useful Life

Fully charging a LiPO to 4.35vdc will shorten its useful calendar & cycle life. No battery engineer with knowledge of LiPO chemistries of the common type used in most portable electronics would ever charge beyond 4.11vdc or around 79% full, like a military com battery pack that never allows charging beyond this point, since the batteries cost $600 or more, for a small brick battery the size of a typical human hand formed into a fist. 

Charging a LiPo Battery

The C rate of charging relates to its capacity, so a 250mah LiPO shared at 1C charge rate would be charged at 250ma. CC/CV charging the correct method, where a constant 1 or 2 C charge rate maintained, so in this example 250ma or 500ma, until the target voltage, often 4.26vdc or in HV cells 4.35vdc, though I highly recommend never exceeding 4.11vdc, then the charger optimized for LiPO charging will slowly reducing charging to 1/50C until a full saturation charge achieved.

High C discharge rates, often 10C or 20C or 30C or 40C in RC LiPO packs, also abusive to the cells & degrade the cell charge holding capacity or battery life faster. 

Fast high current charging beyond 2C rates will shorten the useful life of LiPO especially cells that are not actively cooled. The cell temperatures should never exceed 60 degrees centigrade or about 140 degrees Fahrenheit (60 Centigrade / 140 Fahrenheit) / LiPO last significantly longer around 25 centigrade or 77 Fahrenheit, think STP or standard temperatures & pressure, just like most humans enjoy! 

Storing LiPo Batteries for more than 1 month 

A 1S or single liPo cell should be stored at 3.3vdc or around 40-50% charged, if stored for prolonged periods. If LiPO are stored deeply discharged or fully charged, doing so will greatly shorten the useful life or charge holding capacity will be lost by deeply discharging & storing at low states of charge, especially below 3.0vdc & the cell are very badly damaged by going lower than 2.7vdc. 

30-80% Long Life Charging Trick

I tell people in first person, charge your battery electric stuff for 10-40 minutes, never all night long. Never leave batteries parked in the charging system, as that can cause an electrical fire by causing overcharging of the cells & a thermal runaway event, like the battery on the Boeing Dreamliner, they also used LiPO for weight savings, even though that's not a very robust battery type for commercial aircraft, especially not in the temperature & charge rate regimes encountered by aircraft energy storage batteries, of typically passenger aircraft like the Boeing 747 or 767 or Airbus A380 as examples. Aerospace satellite grade lithium ion batteries are very different than the soft LiPo cells this posting talking about. 

I am Well Qualified to Give This Advice about LiPO batteries

I am professional battery engineer, Level 2 WISE certified device repair technician, and highly educated polymath scientist & give this advice because people unwittingly damage their smartphone & smartwatch batteries by repeatedly overcharging them & leaving them plugged into charging systems too long, all night longer or overnight charging. I never recommend charging beyond 90% state of charge or bellow 10% state of charge. That top 10% between 90% and 100% where LiPo batteries are damages, as does charging below 10% & 0% state of charge. 

I also study batteries on Battery University online & Isidor Buchanan the founder of CADEX, a premier battery electronics company in Canada, also one of my living heroes. Isidor is a battery genius & was hugely influential at encouraging my interests in batteries, battery charging, battery chemistries. I know a lot about NiCD, NiMH, and many variation of Lithium Ion batteries, the most popular is the LiPo with the lithium cobalt cathode & graphite anode, separated by a ion permeable membrane, inside an aluminized polypropylene wrapper, with an internal BMS on a tiny circuit board near the anode & cathode connections at the top of the cell. Newer NCA cell chemistries like the ones used by Tesla in the Model & in the 4680 batteries, are using an 8:1:1 ration of Nickel, Cobalt & Aluminum in the cathode, so as to reduce cobalt use, since cobalt the most toxic & most expensive & most damaging to other humans & the environment to mine & manufacture. Not to suggest that Nickel mining is eco-friendly, but Nickel, unlike cobalt, is also highly recyclable, exceedingly corrosion resistant, in fact nickel metal added to steel alloys, with chromium & vanadium, to make stainless steel that's also more corrosion resistant. 

Inside aircraft engines, the turbine blade in the hottest section are made using low creep at high temperatures super alloys made mostly with nickel metal. Aluminum is really cool, way less expensive, very widely produced, low cost, very strong for its weight, used in aircraft parts of all kinds, newer aluminum intensive vehicles are much lighter than their steel contemporaries. I smelt aluminum cans that I save to make aluminum magnesium alloy ingot bars with a small percentage of magnesium from the can lids. I sometimes add a small chuck of silicon to the crucible to improve the flow properties by reducing the viscosity of the molten aluminum. Lithium aluminum alloys were used to make the body shell of the Falcon 9 rockets from SpaceX. SpaceX switched to stainless steel in the BFR & Super Heavy to dramatically lower costs, that special aluminum lithium alloy very expensive by comparison to stainless steel. Newer stainless alloys can bet up to 980 megapascal's of strength too, know as grade 9 stainless, automakers use these super strong steel's in strength value parts in the suspension & drivetrain of cars & automobiles. 

Think Warm or Cool & Never Fully Charged or Discharged

So cool & partially charged makes the batteries last 5-10X longer, both longer in years of service & the number of useful charge discharge cycles you can get while using your portable electronics, from drones to self balancing electric scooters, to toy quadcopter like my NewBeeDrone Acrobee Lite Brushless RTF kit & its little single cell 250mah OEM flight batteries & 300mah aftermarket improved GNB or GAONENG batteries. 

Energy Density

With very low molecular weight plastic backed aluminum foil casing, the LiPo version of lithium ion batteries can approach 600 watt hours per kilogram in the most expensive & highest quality versions. A typical smartwatch has a tiny LiPo battery that holds a couple or few hundred milliamp hours of energy, enough to give 18 hours of runtime in the latest Apple Watch Series 8 like the one I wear on my right wrist daily now, after the accident that fatally destroyed by Apple Watch SE from a little over a year ago. At over $400 the Apple Watch is a high value added profit generating smartwatch that Apple capitalizes on to generate huge piles of cash so large that some foreign governments are smaller in fiscal scale of operations. This gives apple design prowess & the ability to work with TSMC & ASML to make the most amazingly dense SOC system on a chip, chipsets, like the S8 processor in the Apple Watch Series 8! 

In electric race vehicles like Formula-E, they use aerospace grade ultra high energy density LiPo packs with thermal management achieved using passive heat extraction in the oxygen free copper power buss connectors & aluminum housing, over which air passing by the vehicle moving at high speed takes away the waste heat from the finned aluminum housing heat sink housing the electric motors, batteries & digital to analog DAC & Analog to Digital charger motor controller regeneration management & energy storage controller devices respectively, all which produce waste heat.

In space satellites, special LiPo batteries with active thermal management are about to operate from -250 deg F to +300 F, for 20,000 cycles & up to 20 years of continual use. The extreme cold from the coolness of space without solar energy input, the hot from direct impingement of the Sun's extreme energy output onto the Satellite when its facing the Sun. Nearly all satellites orbiting Earth utilize CIGS solar photovoltaic panels mounted to Kapton polymer that's been chemically vapor deposited with gold to act as a thermal reflectors or a special pink high emissivity coating to passively eject waste heat from the back of the panels. These CIGS panels are typically folded up like origami during launching of the Satellite & then an automated sequence of mechanical attenuations extend & thus unfold the PV array into the final flat facing side toward the sun for solar energy capture configuration to make DC electricity to run the satellite electrons & to accomplish recharging the LiPo battery energy storage module, which are made in clean rooms to the highest possible quality standard & cost more than a Tesla Model Y. A typical satellite battery can cost in excess of $50,000 USD2022! 

In RC or remote control toys, helicopters, drones, aircraft, cars, motorcycles, boats, submarines, in a wide variety of different RF & smartphone controlled remote toys, LiPo battery packs in 1S for tiny vehicles, 2S or two batteries in series, or 3S or 4S series, each time the number increases another battery put into series, such that a 2S battery has 2X the voltage as a 1S battery, so 4.2vdc fully charged becomes 8.4vdc respectively. Similarly the 3S battery would be 12.6vdc fully charged. A typical LiPO has a nominal voltage of 3.6vdc & HV LiPO have a nominal voltage of 3.85vdc. Nearly all LiPO batteries are either equipped with or connected to a BMS or battery management system, a small controller electronic that prevent shorting, self discharge, deep discharging, overcharging, cell balancing, pack balancing, charge controlling, discharge limiting, fusing to prevent critical shorting, cell pouch puffing disconnect so that if the cell starts swelling it mechanically disconnects the tabs connecting the cell to the circuit. A 4 pin connector on an LiPO means there is digital communication between the BMS & the device, since batteries only have a + positive & - negative tab or two electrical connectors to the BMS, the other pins in 3 & 4 pin connectors of a 1S cell are so that the BMS can report the battery voltage, state of charge, temperature, interval resistance, number of charge discharge cycles, manufacturing date & other data attributes or data about the batteries function or state, to further enhance safety of common consumer electronics energized by rechargeable LiPo batteries. 

Checkout LiPo Manufacturing Videos Online

If you want to watch an interesting documentary video, check out the video about "How LiPo batteries are made in China" / not withstanding the supply chain problems with lithium brine lake evaporation mining or cobalt mining or the negative environmental problems associated with a lack of mature lithium battery recycling capacity installed worldwide. Only a few small companies actually discharge & then shred lithium ion batteries for processing similar to the raw material mining used to make the ingredients that went into the new battery, in the first place. 

Lithium Recycling Emergent & Trending Commercialization Now :) 

Thankfully, due to the popularity of LiPo & similar lithium ion batteries in so many different mobile energy systems, electric vehicles of all kinds, electronics & many other devices & applications, commercialization of Lithium Battery recycling ongoing. Consider PbA or Lead Acid 12vdc car batteries or SLI batteries made with Lead, Lead Oxide & Dilute Sulfuric Acid in plastic box, made with 6 quantity 2vdc lead acid battery cells bonded together into a 12v high peak current discharge starting battery than can send many hundreds of thousands of amps to an automobile engine starter motor to accomplish cranking the engine electrically when the key is turned or button pressed by the driver, to start the car, truck, SUV or other similar vehicle. 

Electric Vehicle Starting

In the early days of vehicles, engines were hand cranked to start. Cadillac was the first automaker to offer an electric engine starter as a feature, consider a luxury back then! Actually automobiles are a luxury, even today in 2022 only 1 in 7 people worldwide owns a car. That might seem outlandish if you grew up in car crazed America like me, but its true! There are over 8 billion people, a typical car dead for scrap after 20 years of operation, and even the largest automaker in the world can only crank out 80 million vehicles per year, a far cry from making one for every person on Earth! Thankfully too, can you imagine the oil consumption that would happen if everyone alive used a gasoline or diesel fueled vehicle daily, the air pollution resulting would be horrible for public & environmental health & would make climate change even faster, storms even more powerful, droughts & floods longer lasting & more intense, and worse! 

Lithium Motorcycle Batteries

Some people cook up LiPo engine starting batteries, this are popular for motorcycle battery upgrades that weight 5X less than an typical AGM battery used as the OEM solution by the motorcycle manufacturer. I put just such a 7A lithium iron phosphate starting battery in our 2013 Honda PCX Scooter, in 2015, and its still working in 2022 ^^ LiFePO4 is a low voltage, lower energy density version of lithium ion batteries, that has a much longer working life, can operate in a much broader range of temperatures, has tremendous peak current discharge, but not ideal for small mobile electronics that are handheld. In China, Tesla uses LiFePO4 or lithium iron phosphate cathode batteries, not NCA. NCA offers better energy density & higher specific performance, but more heat & fade sensitive. 

LiFePO4 or Lithium Iron Phosphate ( Like A123 Batteries from Boston, Now Defunct) 

They put abuse tolerant batteries in Chinese EV because the charging infrastructure & electrical grid or access to EV chargers much worse in most locals in China. LiFePO4 can be fully charged, deeply discharge & still operates for 3000+ cycles & for up to 10 years of more before losing a significant amount of energy storage capacity or range reduction in electric vehicles. I had an electric folding mountain bike called a Prodeco Phantom X, with a 48vdc 12.5AH LiFePO4 battery pack, but that bicycler was stollen out of the locked underground parking garage of the Excalibur Apartment in downtown Bellevue, Wa, 98004, back in 2014. 

My Stollen Prodeco Phantom X E-Bike 

Local police in King County tracked down my stollen electric bike, to Shenzen, China, where it along with many other bicycles stollen from America were seized by local Chinese police in a sting operation concentrating on a bicycle theft ring that was operating in and around Seattle, in Washington State, USA. The local man responsible went to prison with a 25 year sentence, for being convicted of organizing the theft ring which was responsible for millions of high end bicycle thefts, the thieves targeted high value bicycles like my then very new E-bike. I hope someone recycles "Ebert" battery pack when its EOL or end of life! Today my daily bicycle a Crossroads by Specialized, an analog traditional human powered bike.

Gasoline Fueled Yamaha Sport Touring Bike

I also ride our 2020 Yamaha MT-O3 motorcycles, a twin engine 40hp fuel economy champ that does 0-60 mph in less than 5 seconds while top speed over 100 mph, it can cruise at highway speeds in America, but at slightly lower speeds in 6th gear gives 80 mpg or ultra low fuel consumption & thus great range with its 3.5 gallon tank, perhaps 260 miles or more, though I never fully drain the fuel tank. I also use Stabil storage enhanced ethanol free gasoline from the Grange in Issaquah, to fuel that motorcycle! I add fuel stabilizer to the motorcycle gasoline storage can to improve the shelf life of the E0 or ethanol free gasoline. Normally gasoline starts to oxidize, become sour or rancid after 2-3 months of storage, but adding a quality fuel stabilizer to the storage can improves gasolines shelf life to up to 2 years! This MT-O3 came equipped with an AGM or absorbed glass mat lead acid battery. The glass mat in an AGM makes this configuration of lead acid more vibration & deep discharge tolerant. I use a battery tending solution to keep the AGM battery mostly fully charged in storage, as lead acid batteries last longer when kept fully charged, at 13.2vdc // by battery tender or similar automatic battery charger with an AGM charging mode as AGM batteries require a tad higher voltage for complete charging. I will likely replace this AGM battery with a Lithium Iron Phosphate or LiFePO4 power sports ultra long life low mass battery in the future, inside of which LiPO batteries with that chemistry, in high C discharge or high current pulse generation variations enables high current peak output to crank the 321cc offset parallel twin cylinder gasoline fuel injected engine with advanced emissions controls & digital engine management wizard electronics that can be easily energized with LiPO batteries :P