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Lithium-Ion Battery Care Guide — Part Two

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Lithium-ion batteries are the most common battery in consumer electronics. They are used in everything from cell phones to power tools to electric cars and more. However, they have well defined characteristics that cause them to wear out, and understanding these characteristics can help you to double the life — or more — of your batteries. This is especially useful for products that do not have replaceable batteries.

Battery wear is loss of capacity and/or increased internal resistance. The latter is not a well known concept, but over time the battery is able to put out less amperage as the battery ages and eventually the battery is unable to generate power quickly enough to operate the appliance at all even though the battery is not empty.

The standard disclaimers apply, all advice is for informational purposes only, CleanTechnica is not responsible for any damages caused by inaccurate information or following any advice provided. Also, new technology may change the characteristics spoken about, making them less or more relevant in the future or even rendering them obsolete.


Lithium-Ion Batteries Age From The Following Factors:

  • Time – Part One
  • Cycles – Part One
  • Storage/operating temperature – In this article
  • Charging – In this article
  • Discharging – Part Three (upcoming)
  • Depth of charge – Part Four (upcoming)
  • Time spent at near full/empty – Part Four (upcoming)
  • Depth of discharge – Part Five (upcoming)
  • End Of Life – Part Five (upcoming)
  • Summary – Part Six (upcoming)

Storage & Operating Temperatures

Lithium-ion batteries achieve an optimal life at around 10-20ºC (50-70ºF). This can be impractical to guarantee for EVs, but if you have a climate controlled garage or underground parking you can help extend their life when the vehicle is not in use. Severe winter temperatures are considered hard on batteries, but hot temperatures are extremely severe on lithium batteries, as they vastly accelerate temperature-induced wear. Most batteries have liquid cooling, but when you are not using the vehicle, only some models actively cool the batteries while parked. An extreme example of heat killing batteries was the first generation Nissan Leaf in hot climates losing capacity alarmingly quickly because they were air cooled and operated in desert temperatures.

However, for items like cell phones and power tools and other small products you can more easily control their storage and operating temperatures. Storing them indoors in winter and in air conditioned buildings or basements in summer and out of direct sunlight (while operating them and especially when not in use) will help extend their lifespan.

If you find your batteries are overheating during use or when charging them then you should try to figure out why. You can tell if the battery is overheating if it feels very hot to the touch. Of course, if the battery is bulging disconnect it if possible, and if it’s smoking or ignites, call your local fire department immediately and evacuate the building as the fumes are toxic.

EVs in general have liquid cooling and are typically able to regulate battery temperature. While problems are likely to be very rare, if there is a battery issue contact the vehicle manufacturer.

Sometimes cellphones overheat the battery for unknown reasons. This can be caused by an errant app, too many apps being open, something taxing the processor, or other operating system issue. Try to determine the cause and solve it. Whether this involves discontinuing use of a particular app (and contacting the author of the app), performing a factory reset, or contacting the phone manufacturer.

Using a phone as a GPS with a windshield mount can heat batteries to very high temperatures. It is a trifecta — direct sunlight, charging, and high app draw. However, directing AC to the windshield area can sometimes help reduce the phone temperature. There are apps that will tell you the current battery temperature.

If items such as power tools or battery banks or other lithium-ion powered products overheat, contact the manufacturer. Some may claim this is normal, but if it is this badly designed, then the manufacturer has decided to foist poor design onto their customers who will end up with prematurely aged batteries. In this case see if you can get goodwill replacement upon premature failure and/or look for a competitor with a better product. As with any expensive product keep receipts and note the warranty length. Some credit cards offer complimentary extended warranties on purchases if the card is used to buy the item in question (for example warranty doubling up to an extra year). Consult your card provider(s) to see if you have any extra coverage.

Charging Lithium-Ion Batteries

Lithium-ion batteries prefer to be charged at about 1/4 of their capacity or less per hour. In battery terms, this is known as 0.25C (C is battery capacity). Faster charge rates are more stressful on the battery. Some chemistries handle faster charging better than others, though what chemistry your product has was chosen by the manufacturer when they designed it.

However, consumers prefer faster charging so manufacturers often design the charger to accommodate this. Charging above 1C is much harder on the battery. The best way to reduce this stress is to use a charger that charges more slowly. For a cellphone charged by USB this is pretty simple — most of us have old charger bricks laying around. Your phone’s capacity is easily Googled and a charger that provides 0.25C should not be hard to locate. That is assuming you have the time to wait for it to charge. Avoid overnight charging of your phone (talked about in the upcoming Part Four). For items like power tools or lawn equipment, the charger that came with the item may not have a user selectable charge rate and you might be stuck with fast charging. Or you might be able to buy a slower charger.

That said, many people get frustrated with slow charging even if they are getting more battery life in the future (and many trade their cellphones every two years anyway, argh!). If you want faster charging, then 0.5C (peak) is not terrible. But 1C or above is going to wear out your battery more quickly, so bear this in mind.

For EVs, try to avoid supercharging a Tesla unless you need the fastest charge rate (say on a road trip). Most EVs have the ability to charge at varying rates, either chosen by software or by charger. Feel free to explore your options. Also many EVs have the ability to delay charging after being plugged in at home. This is ideal if you can select the charging start or finish time so that charging concludes around the time you start your day. Thus the vehicle spends less time at a high charge level (the reason for this is explained in the depth of charge facet in Part Four of this article series).

Don’t leave batteries connected to the charger after they have finished charging. If left plugged in, they typically maintain the battery at 100%, shortening its life considerably.

Stay tuned for Part Three, Discharging Characteristics


A summary of the terminology used in the battery world:

Charging algorithm = Battery is charged at Constant Current, then near full charge (typically over 80%) the charger switches to Constant Voltage. The charging rate slows until the battery reaches 100% charge. Many EVs modify this algorithm.

C = Capacity of the battery

  • Battery ability to output power is measured in 1/C. 1C means the battery drained in one hour, 2C means 30 minutes (1/2 hour), 3C means empty in 20 minutes (1/3 of an hour) and so forth.
  • Charging can also be measured in C, 1C means charged in 1 hour, 0.5C charged in 2 hours, 2C charged in 30 minutes and so forth.
    Charge rates are not typically linear, the battery is typically charged more rapidly until it reaches the Constant Voltage stage.

Series = Multiple batteries linked in a chain to increase the total voltage of the pack.

Parallel = Multiple batteries linked side by side to increase amperage instead of voltage.

(x)S(x)P configuration = explains how multiple batteries are linked. 4S2P for example means 8 cells, four in Series and two Parallel rows

Volts (V) = Electric potential. Power outlets are measured in volts.

Amps (A)= Number of Coulombs of electrons carrying those volts.

Watts (W)= Volts x Amps. Energy/Power usage is often measured in watts. A kilowatt is 1000 watts. kWh is Kilowatts per hour.

Energy is measured in Joules and is convertible to Watts/second if you have a time component.

Power = Energy over time. Typically measured in Watts. One Joule per second is 1 watt. The same number of Joules or Watts in half the time is twice the power.

Nominal voltage = Voltage used to calculate Watts of a battery.

Battery capacity = How many Ah of power the battery can output (when new).

Load = Device that uses the power from the battery.

Internal resistance of a battery affects its Power output. Increased internal resistance is the reduction in rate of Power output the battery can deliver. Energy output is affected somewhat by increased internal resistance.

Featured image: Kristoferb, licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. 


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