Lithium-ion batteries are the most common battery in consumer electronics. They are used in everything from cellphones 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 of your batteries — or more. 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 batteries age from the following factors:
These articles explain each facet in detail and are worth reviewing if you’re interested in understanding the logic behind the following recommendations.
Try to buy batteries when you need them, because lithium ion ages from the moment it leaves the assembly line. However, by following the recommendations below you can get a longer lifetime from the batteries you own. If possible, look for the date stamp on any battery powered item you intend to buy and try get the newest one. Often you will find it on there, either on the outside of the package or on the item itself.
One cycle is fully charging the battery and then fully draining it. Lithium-ion batteries are often rated to last from 300-15,000 full cycles. However, often you don’t know which brand/model of battery is in the item you buy.
Partial cycles will give you many more cycles before the battery wears out, so when possible do partial discharges and then recharge. Don’t intentionally drain a battery before recharging for lithium-ion batteries.
For some equipment this is not realistic, in electric lawnmowers and other outdoor tools for example, but the manufacturer will hopefully have selected a battery chemistry designed for this use case.
Try to keep your batteries cool whenever possible. Don’t store a cellphone or other portable lithium battery in a car on a hot day, and keep them cool when not in use (bring your portable tool batteries inside instead of leaving them in an unconditioned shed/garage). Park an electric vehicle in the shade or a reasonable temperature garage when possible. Many EVs have active cooling of batteries so that will take care of this for you, although you still save battery power by parking in the shade or a conditioned garage.
Also, your pocket is about 30ºC, so store your cellphone on a desk and out of direct sunlight if you’re in the office or at home when practical.
Charge your battery at a slow rate when possible. For a cellphone, use a charger that is rated for about 1/4 of the battery capacity if you can. Avoid quick charging except for rare instances when you absolutely need the most juice as quickly as possible. Charging at 1/2 its capacity per hour is acceptable but chargers that can charge a phone in under 1.5 hours from empty can be very hard on the battery.
For power tools, try to get a slow charger instead of the quick chargers many of them come with. This is not always possible, but often is.
Don’t leave any device connected to the charger once charging is complete. In fact, you should aim to charge to a maximum of 80% (more on that below).
Try not to abuse your battery by pulling as much power as quickly from it as possible. For an EV, flooring the acceleration pedal on a regular basis is not good for the battery. Similarly, power hungry games can drain cellphone batteries quite quickly as well. If your phone gets hot from high power use (and not the sun or high room temperature), it is an indication that you are punishing the battery.
Sometimes taking it easy on batteries is not always possible because some products, such as lithium-ion powered tools, are hard on the battery by design (drills, lawnmower, snowblowers, etc.). In these cases, manufacturers will typically use batteries designed for high drain rates (but have lower capacity), but anything you can do to be gentle on even these batteries will pay dividends in longer life. For power banks, try to use the power at a moderate rate. USB models can be tricky to limit your current draw rate as a phone or tablet will draw what it wants up to the bank limit, but for non-USB items you can often try to limit how quickly it’s drawing power.
Also you can “hack” this issue by buying and using a larger capacity battery if your device can handle it. For the same power draw, a larger capacity battery will have a lower percent drain per hour. This also reduces cycle count.
For items you don’t use daily, check on your batteries from time to time in case they are draining themselves when not in use. For EVs and cellphones, this is not a noticeable problem, but for power tools and power banks it is a good idea to check on the battery every few months (or weeks if it drains itself quickly) and top it up to 50%-ish for storage.
Depth Of Charge
Unlike most other battery types (especially lead acid), lithium-ion batteries do not like being stored at high charge levels. Charging and then storing them above 80% hastens capacity loss. So charge the battery to 80% or a bit less if that will get you through the day/week. Most EVs have the ability to select a percentage to charge up to in the software.
Charging above 80% is not a big problem if you intend to draw it down quickly and need the full capacity. Of course, try not to do this regularly if you don’t have to. Avoid overnight charging of your phone unless it has a smart charging feature, such as some Apple phones. For Android phones, use Accubattery software or similar, which will beep at 80% charge as a reminder to unplug the cord. Charge to full in the morning if needed to get through the day.
Similarly, for your EV if you have a long driving day planned, setting the software to charge to full by morning (not storing the vehicle overnight at full) and driving until you are below 80% rather quickly will not cause much extra wear to your batteries.
In general, it’s the storage time above 75-80% that causes most of the extra high charge wear.
For storing batteries long term, charge them to about 50% and check on them every now and then.
Depth Of Discharge
According to many sources, lithium-ion doesn’t like being fully discharged. So try to avoid draining your batteries below about 25% when possible. If unavoidable, then charge it back up to above 25% as soon as possible so the time spent near empty is minimized.
Miscellaneous Battery Information
- Lithium-ion batteries have no memory effect. This was a facet of Nickel Cadmium batteries that went out of style decades ago, yet this is a surprisingly common question people ask about any rechargeable battery.
- Most name-brand devices use quality name-brand batteries, but some devices (such as cheap power banks or no-name products) use off-brand or grey market batteries that will not last for years no matter how much you baby them. Try to avoid buying products with these batteries because the money you save buying them translates into reduced product life.
- For some devices, the charge gauge can fall out of calibration and give you incorrect readings. This can typically be fixed by either fully charging or fully discharging then recharging the battery back to full. However this is hard on the battery, so it’s not something you want to do regularly, but in the rare instance that this is the cause of your issues, then a full charge or charge-discharge cycle will solve it. Quickly draw the battery back down to 80% before putting it back in service.
- Everything stated above is quite generalized, and with the various battery chemistries on the market, all of them have slightly different characteristics. Once facet may be stronger in one chemistry vs. another but in general the advice provided is applicable to all lithium battery chemistries.
End Of Life (EOL)
End of life for a lithium-ion battery typically occurs when the battery can no longer perform the function the user requires of it. Commercially, when a battery (pack) has reached 80% of its design capacity it is considered EOL, but for end users, it’s typically looked at as when the device (or battery pack) becomes unusable.
When your battery starts acting funny, it can mean it’s ready to be retired. Some Apple phones have the ability to calculate capacity remaining (it is buried in the settings) and Accubattery for Android can do the same thing if installed and used for at least a week.
These are some of the strange quirks you may run into that can occur with worn out lithium-ion batteries:
- Device shuts down stating low battery even though it should have plenty of runtime left, even if it stated a decent percent charge remaining just minutes before
- The battery percentage meter drops randomly
- Charging finishes prematurely even though the battery did not accept much power
- Sudden capacity drops without warning
- Self-discharge rate soars and is often uneven
- The battery (pack) gets very hot during charging (sometimes the charger shuts down due to this)
- Pouch batteries can start bulging (seen on some cell phones)
Be sure to recycle all batteries at the end of their life as they contain valuable materials that can be recycled into new batteries.
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.
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.
Avis has new T&Cs for renting its EVs, and they’re a little weird
Tesla Model 3 Source: Tesla
Car rental giant Avis just sent an email out today to its customers to let that it has new rental terms and conditions for its fleet EVs. Some of the company’s EV rules are a bit of a head scratcher.
Here’s what the email said:
As we introduce Electric Vehicles to our fleet, our rental terms have been amended. To accommodate our expanding vehicle inventory, this amends the agreement signed by you with respect to the rental of a vehicle powered by an electric motor (an “EV”). Our updated terms can be found here.
Note that these were sent out by Avis Canada, but the rental terms and conditions are for both the United States and Canada.
I’ve pasted the seven-plus points terms included in the EV section below, and my comments are after each point, in bolded italics:
39. ELECTRIC VEHICLE (EV) TERMS. This EV Amendment amends the rental agreement signed by you with respect to the rental of a vehicle powered by an electric motor (an “EV”) from Avis Rent A Car System, LLC, Aviscar, Inc., or any Avis Rent A Car System, LLC, affiliate, or the independent Avis Rent A Car System, LLC, licensee identified on the rental agreement (collectively referred to herein as “Avis”).
Boilerplate text. All good. Next.
1) AMENDMENT TO RENTAL AGREEMENT: This EV Amendment simultaneously amends the terms of your rental from Avis with respect to the terms herein only. All other terms of your rental remain in full force and effect. In the event of any conflict between the terms of this EV Amendment and your other rental terms, the terms of this EV Amendment shall govern.
More boilerplate. Nothing to see here.
2) ONE WAY RENTALS ARE NOT PERMITTED: Due to unique infrastructure needs associated with EV’s, your EV must be returned to your rental location on the date/time specified in your rental terms. If your EV is not returned to the renting location, all costs incurred in transporting your EV back to the renting location will be assessed to you. In addition, you will be assessed a fee for Avis’ loss of use of the EV between the time that you should have returned the EV to the renting location and the time that it is returned to the renting location up to a maximum of thirty (30) days. The loss of use fee will be your daily rental rate.
“Unique infrastructure needs.” LOL.
At the end of January, a couple of us at Electrek received a PR announcement announcing that Avis was launching a “significant number of EV charging stations at the George Bush International Airport in Houston” with EverCharge. The EV charging stations will “only be used by the Avis and Budget fleets of EVs and PHEVs available for rent” at Houston airport.
I asked, “How many EVs does Avis have for rent across the US, and which makes and models?” And got the reply: “Avis is not commenting on the specifics of its fleet at this time.”
Bummer, because Hertz sure is commenting, and with Tom Brady to boot.
I asked the spokesperson how many EV charging stations Avis is installing at Houston airport, and they wouldn’t tell me – they only said that both DC and Level 2 are being put in.
I asked what the rollout plan is for other North American airports, and got the reply:
Following the launch at the Houston airport, Avis and EverCharge plan to extend the partnership to additional airport locations this year.
So, based on the above information, it would appear that the reason why a car rental customer has to return the EV to the original rental location – in this case, airports – is because Avis doesn’t have enough EV charging infrastructure yet.
I get that this is a growing pains issue, but simply, it isn’t very practical. Not everyone returns to the place where they rented a car.
Maybe Avis should have installed more EV charging infrastructure before it rolled out its unknown quantity of EVs.
One can currently rent a Tesla Model 3 from Avis in seven US states – all in the West. It’s kind of silly that one can’t drive between those locations without having to return to home base.
3) BATTERY CHARGING LEVELS AT VEHICLE CHECK OUT: Avis will rent the EV with at least a 70% charge on the battery. The range of your EV will vary based on a number of factors including vehicle load, driver’s actions such as speed and acceleration, climate and terrain factors such as inclines. Avis does not warrant or guarantee the range of an EV.
Why 70%? The ideal topped-up charge level is 80%. If Avis has EV chargers at its rental locations, then it should charge them to 80%.
And Avis ought to print up a helpful document, or give renters a QR code, so they can read about why and how vehicle load, speed, and acceleration affect charge. Let’s not say there are factors without explaining them.
4) BATTERY CHARGING LEVELS AT VEHICLE RETURN: Your EV must be returned to Avis with a battery charge level of at least 70%. If returned at less than 70% but more than 10% battery charge level, a charging fee of $35 will be assessed to you. If returned with less than a 10% battery charge level, you will be assessed an additional low charge fee of $35 (a total of $70 charging fees if returned with a battery charge of less than 10%). The charging fee is based on the kilowatt hours, overhead, loss of use of the EV and administrative costs Avis incurs in charging the vehicle. Note: fees assessed in the United States refer to U.S. dollars and fees assessed in Canada refer to Canadian dollars.
A $35 car charging fee is a bit steep. Let’s say a driver returns the car with 50% charge – the amount of money to bring it to 70% would be around US $5 at the most.
An 80kwh Tesla battery x 20c/kwh (high estimate) = $16 assuming 0-100% charge.
But I guess this is like when you bring a gas car back empty without prior arrangements, and car rental companies charge you a really high fill-up fee. And if Avis has DC chargers, then they won’t have to wait long to charge up a car that has a battery charge level of less than 70%.
5) ROADSIDE ASSISTANCE: Roadside assistance is available for your EV but fuel cannot be delivered to EV’s. If you require roadside service because you depleted your EV’s batteries, your EV will be towed to your renting location and the towing expense will be assessed to you. If you require another vehicle due to a breakdown, you may be provided a gasoline powered vehicle in which case, all fuel provisions of your rental terms shall apply with respect to your replacement vehicle.
“Fuel cannot be delivered to EVs” – heehee. Love it. It would be cool if Avis invested in some mobile EV charging trucks to make up for the fact that they don’t actually have enough EV charging infrastructure yet to service their EV fleets.
Why can’t the EV be towed to the nearest Tesla Supercharger or Electrify America or similar? Why does it have to go all the way back to the renting location? What if the driver is on a road trip? This one definitely qualifies as weird. This may scare some people off who wanted to try an EV for the first time.
6) SPECIAL EV EQUIPMENT: All EV equipment including, but not limited to, charging equipment, keys, key cards, fobs and/or remote (“EV Equipment”) provided with your EV must be returned. The full replacement cost of any EV Equipment not returned with your EV will be charged to you. LDW, even if elected, does not cover EV Equipment.
Maybe this is a legal thing, but surely it would be common sense that keys, key cards, and fobs would have to be returned, much like any gas rental car? Perhaps Avis has experienced some customers throwing away key cards because they think they’re like hotel key cards? At any rate, I’d be pretty annoyed if I was an Avis employee and customers kept throwing away the key cards, so fair enough. Fobs is a bit of an overstretch. I guess they just had to mention them to cover backs.
7) UNIQUE TESLA TERMS: If you rented a Tesla EV, you will be able to access Tesla Superchargers, subject to availability, to recharge Tesla vehicles provided, however: 1) any fees, charges and/or costs to access and utilize the Tesla Superchargers shall be your responsibility; 2) any Tesla “idle fees”, as defined and charged by Tesla, shall be your responsibility (see Tesla’s website for details https://www.tesla.com/support/supercharger-idle-fee); and 3) the provisions of “Battery Charging Levels at Vehicle Return” shall continue to apply to you.
These are fair terms, because they’re essentially Tesla terms 101.
TESLA VEHICLES MAY NOT BE WASHED AT AN AUTOMATIC CAR WASH. ANY DAMAGE CAUSED BY AN AUTOMATIC CAR WASH SHALL BE ASSESSED TO YOU PURSUANT TO THE “DAMAGE/LOSS TO THE CAR” PROVISIONS OF YOUR RENTAL TERMS AND WILL NOT BE COVERED BY LDW.
I love the bold capital letters for the CAR WASH RULES. One can take Teslas through car washes, but only in touchless car washes. Teslas have Car Wash Mode.
Maybe Avis decided that putting its Teslas into Car Wash Mode is too complicated for its customers and too much like hard work for its reps to explain how to use the feature to every EV renter? It’s never occurred to me to take a rental car to a car wash, but I’m not fastidious with my cars. I’d love to hear your thoughts on this car wash thing in the comments below.
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Elon Musk found not guilty in the Tesla 420 take-private case
A jury has found Elon Musk not guilty in the case of his tweet about taking Tesla private at $420 a share.
5 years later, this single tweet is still haunting the Tesla CEO.
For those who don’t remember the situation, back in 2018, Musk briefly considered trying to bring Tesla private and disclosed that to investors through a simple tweet.
The Security and Exchange Commission (SEC) ruled that Musk exaggerated and misled shareholders when saying that the funding was “secured” in the tweet:
Musk went on a campaign against the SEC, calling them names and claiming that they were working for people shorting the electric automaker. But ultimately, Tesla and Musk ended up reaching a settlement with the SEC.
As part of the settlement, Musk agreed to step down from the role of chairman of the board, and Tesla and Musk had to each pay $20 million in fines.
The CEO presumably didn’t want Tesla to have to pay for his issue with the SEC. While he couldn’t directly pay for Tesla’s part of the fine, he decided to buy $20 million worth of shares from Tesla. That way, he sort of indirectly ended up paying for Tesla’s fine – though he also ended up with ~71,000 additional Tesla shares in the process.
As we previously reported, Musk ended up actually making money from the settlement due to Tesla’s stock price surging.
Another part of the settlement was that Musk and Tesla had to agree for the former to have his tweets reviewed by the latter’s legal department if they are material to the company.
Musk has consistently denied any wrongdoings and claimed he settled with the SEC under pressure from Tesla investors.
Separately, Tesla investors have sued Musk personally over the tweet – claiming that they were defrauded of millions of dollars as Musk exaggerated the claim that funding was secured.
The case was ongoing for years, but it was finally heard by a jury in Northern California last week.
Today, the jury released its verdict – finding Musk not liable for the investor’s losses.
Musk commented on the verdict:
Thank goodness, the wisdom of the people has prevailed! I am deeply appreciative of the jury’s unanimous finding of innocence in the Tesla 420 take-private case.
That’s probably the end of this saga – though Musk is still fighting some of the aspects of his settlement with the SEC, primarily the need to review his tweets material to Tesla’s stock.
That’s probably the right thing.
As we previously reported, all the evidence pointed to Musk being a bit too excited and jumping the gun with the tweet.
For him to be found liable, they would have to prove that he was intentionally planning to defraud investors and that’s a tall task.
He certainly should be more cautious about tweeting things like that when no deal has been signed, but I don’t think it’s fraud.
However, you’d hope that he would become more cautious about his tweeting after this entire saga, but we haven’t seen much evidence of that either.
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Jury find Musk, Tesla not liable in securities fraud trial following ‘funding secured’ tweets
Tesla CEO Elon Musk and his security detail depart the company’s local office in Washington, January 27, 2023.
Jonathan Ernst | Reuters
Elon Musk and Tesla were found not liable by a jury in a San Francisco federal court on Friday in a class action securities fraud trial stemming from tweets Musk made in 2018.
The Tesla, SpaceX and Twitter CEO was sued by Tesla shareholders over a series of tweets he wrote in Aug. 2018 saying he had “funding secured” to take the automaker private for $420 per share, and that “investor support” for such a deal was “confirmed.” Trading in Tesla was halted after his tweets, and its share price remained volatile for weeks.
Jurors deliberated for less than two hours before reading their verdict. Plaintiffs’ attorneys told CNBC they were “disappointed with the verdict and considering next steps.”
“I am deeply appreciative of the jury’s unanimous finding,” Musk wrote on Twitter.
“He doesn’t think ahead of time in that rushed moment that this could be interpreted differently and what it means to him,” Musk’s attorney told the jury earlier on Friday. “In that moment he didn’t think, ‘how could my words be interpreted differently by you than it means to me.'”
“You have to assess this in context – he’s considering taking it private and the issue is will it actually take it forward,” Musk’s attorney said. “No fraud has ever been built on the back of a consideration.”
Musk’s lead counsel did not immediately respond to requests for comment.
The shareholders in the certified class action lawsuit included a mix of stock and options buyers who allege that Musk’s tweets were reckless and false, and that relying on his statements to make decisions about when to buy or sell cost them significant amounts of money.
Musk later claimed that he had a verbal commitment from Saudi Arabia’s sovereign wealth fund, and thought funding would come through at his proposed price based on a handshake. However, the deal never materialized.
During the course of this trial, Musk also said he would have sold shares of SpaceX to finance a going private deal for Tesla, as well as taking funds from the Saudi Public Investment Fund.
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