38 replies to this topic

[CA Curtis 17]

As more of us switch from lead acid to Lithium (Li ion) batteries lots of posts are appearing on this and other forums with questions such as:  Can I use this charger to charge my Li battery?; What size Ah battery do I need?;  How low can I discharge my battery?;  Why won't my battery take a charge? etc.  Unfortunately, I have seen many responses to these and other questions which just are not correct.  I have tried to provide accurate responses where I have seen misinformation.  I finally decided to do a complete write up which I call " Popular Misconceptions & Important Facts to Know About Lithium Power Sources" in the Blog section of my web site.  In it I explain the technology behind Li ion batteries, the key differences with lead acid batteries,  the two key Li ion chemistries of interest to us, LiFePO4 and LiNiMnCoO2, and an overview of what one needs to know about charging, discharging, handling and storing these batteries and power stations safely.  Hopefully this can help answer most of the questions that get raised from time to time.

 

You can find the Blog here https://www.californiaskys.com/blog

 

Best Regards,

Curtis  

[norvegicus]

Nice writeup, but I think I found a typo. 

 

 

LiNiMnCoO2 has an energy density as much as ~2X that of LiFePO4 cells. This is why LiFePO4 is commonly found in applications where weight is critical including ebikes, power tools, electric cars and portable power stations.

[CA Curtis 17]

Thank you.  I have corrected the mistake - I don't want to be the cause of more confusion.

[StargazerLuigi]

Great article. Took me a minute or two to associate DOD with 'depth of discharge'.

 

I've seen at least one question 'can I charge my LiFePO4 with my lead-acid charger' in these fora. Would it be okay to cite your article when answering those questions?

 

My Bluetti EB55 came with a charger; do others not?

Edited by ismosi, 01 April 2023 - 09:14 AM.

[SandyHouTex]

Well, we do research on Lithium Ion batteries where I work, and here's what we have found:

 

1. If damaged they smolder and then catch fire, which is virtually impossible to put out.  Kind of like a magnesium fire.  There is a video of a guy who crushed an 18650 (the size of the battery, a bit bigger than a AA battery)  Li-Ion battery in a hydraulic press on Youtube if you want to watch it.  https://www.youtube....h?v=EABkFbRUIOE
2. If left to discharge, after about 20 years, they'll self-ignite and catch fire.
3. Every time you charge them to 100%, you damage a portion of the insulator.  Eventually, they will catch fire.  Your phone should only be charged to 90%, and if being stored, they should only be charged to 80%.

This may sound extreme, but I put every Lithium-Ion battery I can, right in front of my fireplace on the tile.  The theory being that if they do catch fire, I may not lose my house.

[CA Curtis 17]

Great article. Took me a minute or two to associate DOD with 'depth of discharge'.

 

I've seen at least one question 'can I charge my LiFePO4 with my lead-acid charger' in these fora. Would it be okay to cite your article when answering those questions?

 

My Bluetti EB55 came with a charger; do others not?

I appreciate the positive feedback.  You absolutely can cite my Blog article wherever you think appropriate.

 

As far as I have seen, portable power stations do come with their own chargers.  But stand alone 12V LiFePO4 batteries usually do not.  So folks wanting to avoid the extra cost try to use whatever charger they already have.  

 

Regards,

Curtis

[bobzeq25]

Excellent material, well presented.

 

I believe this should be a sticky, these questions come up over and over again here.

[CA Curtis 17]

Well, we do research on Lithium Ion batteries where I work, and here's what we have found:

 

1. If damaged they smolder and then catch fire, which is virtually impossible to put out.  Kind of like a magnesium fire.  There is a video of a guy who crushed an 18650 (the size of the battery, a bit bigger than a AA battery)  Li-Ion battery in a hydraulic press on Youtube if you want to watch it.  https://www.youtube....h?v=EABkFbRUIOE
2. If left to discharge, after about 20 years, they'll self-ignite and catch fire.
3. Every time you charge them to 100%, you damage a portion of the insulator.  Eventually, they will catch fire.  Your phone should only be charged to 90%, and if being stored, they should only be charged to 80%.

This may sound extreme, but I put every Lithium-Ion battery I can, right in front of my fireplace on the tile.  The theory being that if they do catch fire, I may not lose my house.

Sandy,

 

1.  I think you overstate the danger as there are literally tens of millions of Li ion batteries in service these days.  As I quote OSHA, Li ion batteries are safe is used and handled properly.  If you abuse a Li ion battery it may well catch on fire, something called "vent with flame."  

 

2.  Every Li ion battery and power station I am familiar with lists a life of 11 years or less (most say 10 years), so I don't expect to have one lying around for 20 years.  

 

3.  I have seen nothing that agrees with this statement.  As I mention in the Blog, while most manufacturer's recommend charging a Li ion battery to ~50% if you plan to store it long term, Battleborn, a highly respected US based manufacturer, actually recommends charging it to 100% if you plan to store it long term.  While it is true, as I say in the Blog, that being in a state of 100% charge is more stressful to the battery, all manufacturer's of LiFePO4 batteries spec them at 2K or more full discharge cycles.  The recommendation to not fully charge your phone battery is to extend the useable lifetime capacity which I also mention in the Blog.  

 

Best Regards,

Curtis

[PEterW]

For EV charging often, not beyond 80% and not charging too fast are the best ways to keep the batteries for a long time. Another recent video of what not to do with a lithium battery - https://youtu.be/qJ8BzvbeRXQ (batteries contain a lot of energy… just like gasoline)

Peter

Edited by PEterW, 01 April 2023 - 02:06 PM.

[CA Curtis 17]

For EV charging often, not beyond 80% and not charging too fast are the best ways to keep the batteries for a long time. Another recent video of what not to do with a lithium battery - https://youtu.be/qJ8BzvbeRXQ (batteries contain a lot of energy… just like gasoline)

Peter

As I mention in the video you can certainly increase the life by not charging to 100%, but then do you need a bigger battery to offset the lost capacity.  2K full discharge cycles for LiFePO4 and even 500 full discharge cycles for LiNIMnCoO2 will supply power for a lot of nights.  Especially when you realize that you will still have 75 - 80% of the original capacity left after that.  So do what you think works best for you.

 

As for the video - yeah, don't do that!   To be precise, lithium batteries actually contain less energy per gram than gasoline, but as the video shows, there is quite enough to cause a flame if abused.

 

Regards,

Curtis

[Speedy1985]

Great info, thank you.

 

It seems like, while most Li-Ion packs seem pretty straightforward as far as how they are assembled, some are really lacking in QC. I've been looking at a lot of video reviews by the source you used as well as one other(Ice Hole Power), and some of the BMS's fail the simple short test. Certain capacity batteries from the same manufacturer fail tests while others are good. It also seems that it's somewhat of a gamble as far as what cells are used, and how old they are. It's perplexing when trying to decide which might be the best pick for my application. 

 

We use a 16v lithium battery in our race car. The car has no alternator. It weighs 8 lbs versus 40+ for lead acid, cranks over a 16:1 compression engine like nobody's business, runs the ignition, fuel and water pumps, onboard data logger, and 8 air/fuel ratio sensors with heaters. It gets charged after each run, which takes about 10 minutes, and in the offseason it will get put on the charger on occasion. It's been cycled about 500 times this way over the last 7-8 years. This is also in a car with no suspension and has been through some serious vibration. A lot of us use them and I don't know but of a few people that have ever had an issue with one and I don't know of any fires. The technology with these continues to amaze me.   

[SandyHouTex]

Sandy,

 

1.  I think you overstate the danger as there are literally tens of millions of Li ion batteries in service these days.  As I quote OSHA, Li ion batteries are safe is used and handled properly.  If you abuse a Li ion battery it may well catch on fire, something called "vent with flame."  

 

2.  Every Li ion battery and power station I am familiar with lists a life of 11 years or less (most say 10 years), so I don't expect to have one lying around for 20 years.  

 

3.  I have seen nothing that agrees with this statement.  As I mention in the Blog, while most manufacturer's recommend charging a Li ion battery to ~50% if you plan to store it long term, Battleborn, a highly respected US based manufacturer, actually recommends charging it to 100% if you plan to store it long term.  While it is true, as I say in the Blog, that being in a state of 100% charge is more stressful to the battery, all manufacturer's of LiFePO4 batteries spec them at 2K or more full discharge cycles.  The recommendation to not fully charge your phone battery is to extend the useable lifetime capacity which I also mention in the Blog.  

 

Best Regards,

Curtis

Google is your friend.

[hpservertech]

Well, we do research on Lithium Ion batteries where I work, and here's what we have found:

 

1. If damaged they smolder and then catch fire, which is virtually impossible to put out.  Kind of like a magnesium fire.  There is a video of a guy who crushed an 18650 (the size of the battery, a bit bigger than a AA battery)  Li-Ion battery in a hydraulic press on Youtube if you want to watch it.  https://www.youtube....h?v=EABkFbRUIOE
2. If left to discharge, after about 20 years, they'll self-ignite and catch fire.
3. Every time you charge them to 100%, you damage a portion of the insulator.  Eventually, they will catch fire.  Your phone should only be charged to 90%, and if being stored, they should only be charged to 80%.

This may sound extreme, but I put every Lithium-Ion battery I can, right in front of my fireplace on the tile.  The theory being that if they do catch fire, I may not lose my house.

I'll jump on this bandwagon

 

2. Is this theory or provided by mfg of the cell mfg?  I can't imagine a company like Eve, Catl, Panasonic, etc stating this.   If so we are going to start having a bunch of fires in the near future.

3. So  Company A mfg a battery, has specifications that state it's capacity at 100ah but they puts in their specification to not charge it to 100% or it will eventually catch fire?    I understand what you are saying but I think this is more of a general statement and isn't an absolute truth for every single brand.

 

Dont these apply to the original Lithuim Ion batteries and not so much(or even at all) to LifePo batteries?  From my experience this is something that many people get confused about when both chemistries are intertwined with each other in discussions.  Charge controller companies are horrible about this as well.

 

Of course I have been wrong before...and will be wrong in the future.  But can you imagine hearing the add for a car with the disclaimer...."  Dont charge it to 100% before you go on vacation or leave it on the charger or it will catch your house on fire"  Think of all the snowbirds that leave a car in FL over the summer.

[davidgmd]

Thanks for the heads up. I was just about to put my TalentCell in a hydraulic press to see if I could squeeze a little more juice out of it.

[Kitfox]

I fly racing model sailplanes, and we run amp rates that discharge individual 3.7v nominal cells to just below 2v in less than 20 seconds. These are bare cells, with no protection circuitry.  At these discharge rates, sometimes they burn.
 

“Occasionally” I crash.  They don’t respond well to damage, and we keep fire extinguishers at the field.  Not to put the battery fire out, but to keep the fire from spreading. When they burn, they burn. 

 

I can’t emphasize enough how important using the correct charger is. Most consumer grade packs have extensive internal circuitry to avoid charge issues, but still…

 

And I’m with Sandy;  I store my lithium cells where they won’t take my family and home with them if they go. And loose cells stay in a fire-resistant, vented bag as at least a minimal protection.

 

The previous point about energy density vs gasoline is correct, but gas needs oxygen or some other oxidizer and can be smothered. Li ion cells don’t need an external oxidizer. Again, when they start burning, they burn until there’s nothing left. 

 

There is a reason airlines take these things so seriously. Smoke inside the plane of late is usually traced back to a Li battery, either brought onto the plane or part of the plane’s infrastructure. And heaven forbid a hoverboard end up on a plane  
 

Edited by Kitfox, 03 April 2023 - 06:21 PM.

[davidgmd]

Not to take a potentially serious issue too lightly…

 

Absent improper charging, extreme use without protection circuitry, crashes/hydraulic presses, or other misuse, what is the risk that consumer lithium batteries like those typically used by amateur astronomers will spontaneously combust under normal proper use or storage?
 
I’m not asking about anecdotal reports that anyone can find by Googling. Actual numbers of spontaneous combustion per battery-year. Can anyone offer an evidence-based comparison to things like the risk of your house or car catching fire, or being badly injured in a car accident, or being hit by lightening?

[Jon Isaacs]

 

2. Every Li ion battery and power station I am familiar with lists a life of 11 years or less (most say 10 years), so I don't expect to have one lying around for 20 years.  

 

I am quite sure I have Lithium Ion batteries that are at least 14 years old in old smart phones and devices. Does this mean that if they sit around another 6 years, there's a chance they'll catch fire?

 

If there is, then I expect that in the future, the number of fires resulting from Li batteries will become are real problem.

 

A local fire:

 

https://www.nbcsandi...rtment/3200651/

 

Jon

[davidgmd]

There’s always a chance. But how much of a chance?

  
 

[CA Curtis 17]

I fly racing model sailplanes, and we run amp rates that discharge individual 3.7v nominal cells to just below 2v in less than 20 seconds. These are bare cells, with no protection circuitry.  At these discharge rates, sometimes they burn.
 

“Occasionally” I crash.  They don’t respond well to damage, and we keep fire extinguishers at the field.  Not to put the battery fire out, but to keep the fire from spreading. When they burn, they burn. 

 

I can’t emphasize enough how important using the correct charger is. Most consumer grade packs have extensive internal circuitry to avoid charge issues, but still…

 

And I’m with Sandy;  I store my lithium cells where they won’t take my family and home with them if they go. And loose cells stay in a fire-resistant, vented bag as at least a minimal protection.

 

The previous point about energy density vs gasoline is correct, but gas needs oxygen or some other oxidizer and can be smothered. Li ion cells don’t need an external oxidizer. Again, when they start burning, they burn until there’s nothing left. 

 

There is a reason airlines take these things so seriously. Smoke inside the plane of late is usually traced back to a Li battery, either brought onto the plane or part of the plane’s infrastructure. And heaven forbid a hoverboard end up on a plane  
 

Li ion cells should not be discharged below 2.5V (2.75V for LiNiMnCoO2), otherwise you risk damage which, as you have found, can lead to them burning.   This is from Samsung's web site on Li ion battery safety "  Do not charge or use lithium-ion batteries or packs if the voltage is less than 2.5 V/cell." which you can find here https://www.samsungs...nformation.html  Samsung is one of the biggest Li ion battery manufacturers.  Operating your Li ion battery out of the manufacturer's safety specification and then noting it caught on fire should not be a surprise to anyone.  The internal BMS in a 12V battery or a power station will not let you discharge the cells inside below the lower voltage limit, but individual cells don't come with a BMS.

 

Also, the Li chemistry in your model planes is most likely LiCoO2 which is most commonly used in small electronic devices including cell phones, laptops, etc. because it has the highest energy density which counts in this applications.  Unfortunately LiCoO2 has the lowest thermal runaway temperature which is why these things are the ones that fail the most.  LiFePO4 and LiNiMnCoO2 have the highest thermal runaway temperatures which is one reason they are popular in the applications you find them.

 

I agree with storing Li ion batteries somewhere where they won't cause extensive damage in the unlikely event that they burn.  No matter how safe the chemistry, there is always a potential for a fire and, yes, a Li battery on fire is difficult to put out.  But don't forget you are likely walking around with a LiCoO2 cell in your pocket if you carry your cell phone there.  

 

Li ion batteries do need oxygen to burn.  In a catastrophic "internal" failure due to improper charging, defects or damage which doesn't crack the casing, O2 can be released from the Li compound in the cathode to cause combustion.  One of the things that makes LiFePO4 the safest of all Li ion chemistries is that it will not release O2 from the cathode in a catastrophic internal failure.  Now, if you crack the case, O2 is obviously available from outside.

 

This is precisely why I took the trouble to write the Blog and post about it here.  Anecdotal stories are not science.  Let the science drive the discussion which is what I attempted to do in my Blog.  Also, let's not be surprised that abuse of a battery either by crushing it or operating it outside of the design specs can cause failures.  This is true for Li ion, lead acid and other battery chemistries, although I do agree a Li ion battery can cause a much more serious fire if abused.   Also there is a big difference between a stand alone Li ion cell and a battery or power station with a BMS designed to keep the cells from unsafe operation.

 

LiFePO4 batteries and LiFePO4 or LINiMnCoO2 power stations are safe when operated as specified by the manufacturer.  And these are the chemistries we astronomers use to power our equipment in the field.  

 

Regards,

Curtis

[NinePlanets]

So, I gather that any 18650's and such that I have laying around are time bombs waiting 20 years for a countdown to finish?

 

You guys are scaring me! I've got loose batteries like that all over the place, in addition to old cell phone batteries waiting for a project.

 

And yes, sometimes I charge them manually with a DMM and current / voltage- limited power supply.

 

Now I'm thinking I should just toss them out.    That's too bad. Some of my gizmos like lasers and flashlights ONLY run on 18650's.

Edited by NinePlanets, 04 April 2023 - 07:34 AM.

[Kitfox]

Curtis, I have kept a link to your blog and appreciate all the work that went into it.  Your points in your follow up post after mine are ALL accurate.  Just a few more points:

 

-Our planes have cutoffs that kill the motor at 2.0v under load. At these current draws, that equates to a resting voltage of over your minimum of 2.5v resting.  The cost of this is a very short life of these cells, exacerbated by the extremely high discharge rates in excess of 200 x C(apacity).

 

-We know we are operating outside any reasonable expectations, but the cell manufacturers do custom manufacture these cells specifically to meet these high discharge rate, and then we hook a higher amp motor up front to get even more out of them!

 

-You make an excellent point to follow up to what I said…All consumer oriented battery packs have layers of electronics to prevent everything I do…charge too fast (hot packs perform better), discharge too fast, discharge too far, subject them to mechanical forces and excess G’s, etc.

 

-Disposal is an issue. We pierce the foil casing and soak in a bucket of water for a month. Then dispose of them. I don’t know about other countries, but the USA has not dealt with the coming battery apocalypse of dead cells. Big problem. 

Edited by Kitfox, 04 April 2023 - 08:08 PM.

[NuovaApe]

Hi Curtis,

 

Yes a nice set of easily digestible knowledge based articles would be great.

Lead is dead. Lead makes you dead - time we stopped using it where possible.

 

You obviously have expert insight into this Li stuff. I think you've just set yourself up for a challenge!

 

Astro dudes and dudettes ultimately want a portable energy source that

 

a) wont explode for no good reason (you know the good reasons)

b) wont drop < 12v when it's cold (perhaps wrap a snug dew heater around it)

c) is reasonably rugged for outdoor use

d) can supply their xyz amps needs for a known amount of time

 

I must have spent 30 hours of my life this week googling all the above for my purchase.

 

To understand mAh I had to imagine a big box full of electrons.

Poke a small hole and it will take ages for the box to empty.

Punch a big hole and the box will be empty in seconds.

The size of the hole is the amps needed by the equipment.

So how long the battery will last depends on that.

 

You know this. We kinda do. I had to "think it out".

 

People ask "how long will a 12345 mAh battery last?"

That needs demystifying more than anything. Yes it needs a tiny bit of math. A/B = answer. For me it was 42Ah / 3A = 14 hours.

 

Your blog is incredibly useful for those wanting a deep dive into the facts.

But I think we need a middle ground that tempts people away from lead and into Li Life.

 

People will just stick to lead because it worked last time. They need to know the benefits to make them budge from their standard procedures.

 

I used to have a 40Ah lead car battery. Weighed a ton! I had no idea what I needed so I just bought "too much".

Now I have a Lithium Polymer 42Ah battery with USB connectors and old school cigarette lighter socket.

It has powered my iOptron HAE29 + Quark solar for 10 hours and it's only half empty.

It weights 850g (1.8 pounds).

It's just astonishing.

 

So yeah Curtis get that "sticky post" done here that sells it to us and lead us away from lead 

 

Huge thanks to all you scientists out there.

Edited by NuovaApe, 05 April 2023 - 07:12 PM.

[CA Curtis 17]

Hi Curtis,

 

Yes a nice set of easily digestible knowledge based articles would be great.

Lead is dead. Lead makes you dead - time we stopped using it where possible.

 

You obviously have expert insight into this Li stuff. I think you've just set yourself up for a challenge!

 

Astro dudes and dudettes ultimately want a portable energy source that

 

a) wont explode for no good reason (you know the good reasons)

b) wont drop < 12v when it's cold (perhaps wrap a snug dew heater around it)

c) is reasonably rugged for outdoor use

d) can supply their xyz amps needs for a known amount of time

 

I must have spent 30 hours of my life this week googling all the above for my purchase.

 

To understand mAh I had to imagine a big box full of electrons.

Poke a small hole and it will take ages for the box to empty.

Punch a big hole and the box will be empty in seconds.

The size of the hole is the amps needed by the equipment.

So how long the battery will last depends on that.

 

You know this. We kinda do. I had to "think it out".

 

People ask "how long will a 12345 mAh battery last?"

That needs demystifying more than anything. Yes it needs a tiny bit of math. A/B = answer. For me it was 42Ah / 3A = 14 hours.

 

Your blog is incredibly useful for those wanting a deep dive into the facts.

But I think we need a middle ground that tempts people away from lead and into Li Life.

 

People will just stick to lead because it worked last time. They need to know the benefits to make them budge from their standard procedures.

 

I used to have a 40Ah lead car battery. Weighed a ton! I had no idea what I needed so I just bought "too much".

Now I have a Lithium Polymer 42Ah battery with USB connectors and old school cigarette lighter socket.

It has powered my iOptron HAE29 + Quark solar for 10 hours and it's only half empty.

It weights 600g (1.3 pounds).

It's just astonishing.

 

So yeah Curtis get that "sticky post" done here that sells it to us and lead us away from lead 

 

Huge thanks to all you scientists out there.

Ed, clever post!   I have given a talk on Li ion battery options which discusses the "why" one should consider Li ion instead of lead acid to a couple of astronomy clubs and at the Nightfall Star Party in 2021.  I also gave the talk on The Astro Imaging Channel (TAIC) almost 2 years ago.  I think this does much of what you are asking for.  The TAIC presentation is available on line here 

 

https://www.youtube....h?v=6cCSPgtmd7U

 

Best Regards,

Curtis

[CA Curtis 17]

I still see a lot of misunderstanding and misinformation when it comes to lithium power options.  So I need to update the link to my blog "Popular Misconceptions and Important Facts to Know About Lithium Power Sources" which includes LiFePO4 batteries, LiNiMnCoO2 Portable Power Stations, powerbanks, etc.  

 

Here is the updated link  https://www.californ...rchives/03-2023

[NinePlanets]

That's a lot to read.

Can you answer this please:

 

Are rechargeable lithium batteries safe to store in the house for 20 or 30 years, or not?