Laptop battery unsafe?

[jasonck08]

Most laptop 18650 cells have a max discharge rate of 3-5 Amps. I have cells from an Asus and Dell laptop. They are Panasonic and Samsung cells. I looked up the max discharge current and it is 4.8A.

If you plan on using these in a flashlight, I suggest keeping a millimeter handy. You don't want to discharge them to under 3v or you could permanently destroy the cell.

One thing that you should also do is test the capacity of the battery see what kind of mah is left. I used a 3W 3v bulb and timed how long it took to discharge the battery to 3v. I was surprised that the Panasonic cells after being over a year old still had about 80%+ of their rated capacity!

 

[Fallingwater]

I suggest keeping a millimeter handy

Pretty sure you meant "multimeter" there :nana:

 

[Mjolnir]

So with a regulated light like the eagletac, the brightness won't decline before the battery voltage is low enough to overdischarge it?

 

[LuxLuthor]

Here's a site with video they made of a Li-Ion laptop fire, for all those who say "it's no problem using these." Take the time to learn about the pro's and con's of using them.

On that page there are some very useful follow up information links, such as this interview.

 

[mdocod]

So with a regulated light like the eagletac, the brightness won't decline before the battery voltage is low enough to overdischarge it?

Depends on the exact regulator, but generally speaking, most BOOST style regulators that are used in this type of flashlight, are capable of maintaining surprisingly good output down to ~1V input. While there may be some dimming as the voltage input drops below 3V, you likely wouldn't see it until it was much lower than that.

I'm not 100% sure about the eagletac, but until proven otherwise, any flashlight with regulation should be considered capable of over-discharging unprotected li-ion cells.

 

[Fallingwater]

Here's a site with video they made of a Li-Ion laptop fire, for all those who say "it's no problem using these." Take the time to learn about the pro's and con's of using them.

It'd be very interesting to know what exactly they did to make the battery blow.
Also: are you 100% positive those are 18650s and not, say, LiPo cells in a "slim" battery? I've tried to find data about the various laptop fire videos you can see on the net, but nobody says exactly what cells are inside.

 

[mdocod]

It'd be very interesting to know what exactly they did to make the battery blow.
Also: are you 100% positive those are 18650s and not, say, LiPo cells in a "slim" battery? I've tried to find data about the various laptop fire videos you can see on the net, but nobody says exactly what cells are inside.

As I understand, most of the "simulated" li-ion explosions of laptop batteries are achieved via bypassing the global protection and inducing a a sate of overcharge.

Most of the laptops that use LiPo and Prismatic shaped cells are more modern "compact" designs, and are often more expensive offerings from what I understand. I I were personally going to be demonstrating a li-ion explosion in a laptop, I would not be choosing a laptop with a lot of value left in it, and as such, it would be very likely that the cells contained within would be standard cylindrical style cells.

Eric

 

[LuxLuthor]

I do know that the millions of recalled laptop batteries were Li-Ion cells, just like those you see in the initial posts in this very thread. The recalls included the highest quality/reputation brands of cells, including LG, Sanyo, Sony, Panasonic. There are links to the various major PC vendor recalls with specific battery pack models involved which you can look up in more detail. This is the link to their forum discussion of the topic which also has numerous inaccurate comments from their own peanut gallery. That website is mostly not about laptop batteries, but rather PC performance enhancements.

The Pitstop guy's description in his writeup and video clearly says they are Li-Ion...not Li-Po. The description in this additional link on their site is describing Li-Ion cell construction.

I have no reason to think that there was any large scale use of LiPo in Laptops. While it is generally valid that LiPo and primary Lithium cells are more well known at CPF to cause fires and explosions, that does not mean that Lithium Cobalt Ion cylindrical cells are free of problems.

You can also read the authoritative Buchman report on the subject.

I don't see the point in endlessly trying to assert that Lithium Cobalt Ion cylindrical cells are "essentially free" from risks, or to give people a false sense of security...especially when you continue to see new member misunderstandings repeated in thread after thread.

I use Lithium Cobalt Ion cells, but I understand how they can explode and burn at +1,000 F as a metal fire that essentially cannot be put out, and has toxic fumes. I have a safe setup for storing, charging, and using the cells.

Given what could go wrong immediately, or later due to heat damage of plastic PTC &/or separator components, I would NEVER recommend to anyone that they solder the ends of Lithium Cobalt Ion cells.

The point is to make people aware of proper handling, risks, charging, and give consistent, practical guidelines so new users will start out being safe. You see bad advice and lack of adequate understanding demonstrated in this very thread, and many other threads along the same lines at CPF. Fortunately, members like mdocod try and step in to give appropriate wake up calls and warnings.

Edit: This other page at Buchman's site has a lot of additional articles worth reading when you have the time.

 

[Fallingwater]

As I understand, most of the "simulated" li-ion explosions of laptop batteries are achieved via bypassing the global protection and inducing a a sate of overcharge.

How do you bypass the passive protection (assuming there is any)?

I don't see the point in endlessly trying to assert that Lithium Cobalt Ion cylindrical cells are "essentially free" from risks, or to give people a false sense of security...especially when you continue to see new member misunderstandings repeated in thread after thread.

I never said they are essentially free from risk. My position is just that they are less risky than many people think. I'm very aware that they can blow (which is why I always have safety precautions nearby when I experiment with them and charge them), but I think given proper precautions doing things such as soldering to them is not necessarily a dangerous procedure if you know what you're doing.

The purpose of my guide about soldering to them is to tell people how to do it in the least dangerous way possible. Those who don't know the proper way usually just heat and reheat the ends for minutes at an end, and that can very definitely do serious damage.

I have a few old tired LiIon cells that I intend to damage on purpose to determine just where the point of no return is as far as soldering and general heating are concerned. I want to see just how long one has to keep a soldering iron on a LiIon before it spontaneously combusts (if it ever does), and I want to do experiments with overcharging to see if the heat from soldering damages PTC protection enough to stop it doing its job.
I will report on my findings as soon as I carry out the experiments.

As for the laptop packs, I'm not trying to claim it's impossible that 18650 batteries can catch fire - I never, ever said this. I'm just curious about the cells used; I went searching for the type, but nowhere I could find mention on them. So I wondered if they didn't use a LiPo battery, on account on it being easier to set on fire.

On a related note: I understand the PTC protection is under the positive terminal. Is this correct?

 

[LuxLuthor]

My position is just that they are less risky than many people think.

I understand your premise. What I am more concerned about are those who have little or no idea of their having ANY risk. You see posts here indicative of this all the time.

I'm very aware that they can blow (which is why I always have safety precautions nearby when I experiment with them and charge them), but I think given proper precautions doing things such as soldering to them is not necessarily a dangerous procedure if you know what you're doing.

You and I will always have a disagreement on this. I do not believe Lithium Cobalt Ion cells should EVER be soldered, and have never found a respected source that advocated it can be done safely with this chemistry. You assume your techniques are safe, but you have not taken a cell apart that you soldered to see what impact your heat had on the plastic separator layer, PTC, or other parts. Just because it didn't blow up when you were soldering it, does not mean it is safe over time.

http://www.mpoweruk.com/instructions.htm
http://www.mpoweruk.com/safety.htm

On a related note: I understand the PTC protection is under the positive terminal. Is this correct?

That is my understanding, generally. But I am not certain that it must be in that location.

 

[mdocod]

I have to /agree with luxluthor on the soldering issue. Most manufactures clearly state in product specifications/warnings not to solder directly to these cells.

 

[Fallingwater]

I understand your premise. What I am more concerned about are those who have little or no idea of their having ANY risk. You see posts here indicative of this all the time.

You have a point. I'll make sure to stress the "not for newbies, don't attempt if not capable of handling a lithium fire" part of the whole deal in the future.

you have not taken a cell apart that you soldered to see what impact your heat had on the plastic separator layer, PTC, or other parts

I would like to, but I imagine you can only do this in an atmosphere saturated with inert gas so the cell doesn't instantly catch fire when it's opened. I don't have the means to generate such an atmosphere, so I'll do the experiments with the old cells instead.

That is my understanding, generally. But I am not certain that it must be in that location.

In the 18650s I have under whose positive terminal I can see, the terminal itself is attached to the body of the cell with a few metal tabs, with the underside exposed to air. Since it's phisically separate from the body of the cell, a quick solder joint on it shouldn't spread dangerous levels of heat to the rest of the cell, and shouldn't therefore damage the PTC, if it actually is on the positive side (makes sense that it'd be). The terminal plate and tabs should take most of the heat and dissipate it.
I can't confirm it's the same thing on the other cells, since I can't see under their positive terminal, but I can always see the tabs linking the terminal plate to the body, so it'd make sense if that was the case.

I wish I had an infrared thermal imager... sure would be handy for things like this.

 

[LuxLuthor]

I know you understand my point, but to emphasize my concerns, just go back and read the first 10 posts in this thread. This is the typical level of awareness that many (newer) CPF users have.

My biggest worry about soldering Lithium Cobalt is that you have plastic parts, and limited heat tolerances. Since individual soldering (vs. mechanized/robotic) is variable every time, there is no way to know (even with optimal soldering technique) how much heat was transferred inside the battery--pushing beyond its manufactured tolerances, leading to an explosive, toxic fire.

It's one thing to have a hand held light using a custom soldered NiMH battery pack that fails...but an altogether different risk with LiCo. I honestly hope that you never have any problems from doing this, but I don't see any way for you to have certainty that you are doing it safely.

 

[kuksul08]

Great info in this thread.

Does anyone know where I can get a connector to plug onto the 5 pin socket on the battery pack, so that I can take advantage of the global protection circuit? Also, why are there 5 pins if it's only +/-?

 

[mdocod]

Great info in this thread.

Does anyone know where I can get a connector to plug onto the 5 pin socket on the battery pack, so that I can take advantage of the global protection circuit? Also, why are there 5 pins if it's only +/-?

In no particular order, my guess would be:

positive, negative, balance tap, balance tap, temp sensor

 

[LuxLuthor]

Great info in this thread.

Does anyone know where I can get a connector to plug onto the 5 pin socket on the battery pack, so that I can take advantage of the global protection circuit? Also, why are there 5 pins if it's only +/-?

See now that question is exactly what I am trying to convey to Fallingwater.

I don't agree with MDOCOD's guess, or the fact that he even ventured a guess! We don't really know from his initial post what the voltage of this pack was, what serial/parallel setup it has (I know he described it as "Three are wired in parallel with 6 more in series for 11.1V total" but there is no confirmation), the charging voltage/amp method, what protection features, etc.

To answer your question properly, we would need to know what the 5 pin connector plugged into, how the batteries are connected to each other and other circuit/contact points. The charging interface, specifications, and circuit board details are also important.

With respect, it may literally blow up if you don't know how everything is designed. Nor did you say what you want to connect the 5 pin to in order to "take advantage of the global protection circuit." If the 5 pin connector was connected to the circuit, then that is where it should remain.

These kind of threads scare me.

 

[kuksul08]

See now that question is exactly what I am trying to convey to Fallingwater.

I don't agree with MDOCOD's guess, or the fact that he even ventured a guess! We don't really know from his initial post what the voltage of this pack was, what serial/parallel setup it has (I know he described it as "Three are wired in parallel with 6 more in series for 11.1V total" but there is no confirmation), the charging voltage/amp method, what protection features, etc.

To answer your question properly, we would need to know what the 5 pin connector plugged into, how the batteries are connected to each other and other circuit/contact points. The charging interface, specifications, and circuit board details are also important.

With respect, it may literally blow up if you don't know how everything is designed. Nor did you say what you want to connect the 5 pin to in order to "take advantage of the global protection circuit." If the 5 pin connector was connected to the circuit, then that is where it should remain.

These kind of threads scare me.

:confused: Yeah, I change my mind a lot. Initially I wanted to simply add some wire leads to the cells, but I then learned they are not individually protected, hence wanting to somehow use the circuit already in place.

The only thing I know about it is that it connects to my laptop... I figured there must be some kind of standard when it comes to the plugs, pin arrangements, etc.

The pack has three 3.7V cells wired in parallel, in series with three more in parallel, and 3 more in parallel. Total voltage is 3.7*3=11.1V and capacity is 7800mAh (2600mAh per cell).

For all I know there could be more going on inside the laptop when it comes to cell balancing/protection, monitoring. Maybe the best course of action would be to separate the cells and make a custom pack, using a completely different circuit, which I at least know the parameters of (http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1249)

 

[LuxLuthor]

:confused: Yeah, I change my mind a lot. Initially I wanted to simply add some wire leads to the cells, but I then learned they are not individually protected, hence wanting to somehow use the circuit already in place.

The only thing I know about it is that it connects to my laptop... I figured there must be some kind of standard when it comes to the plugs, pin arrangements, etc.

The pack has three 3.7V cells wired in parallel, in series with three more in parallel, and 3 more in parallel. Total voltage is 3.7*3=11.1V and capacity is 7800mAh (2600mAh per cell).

For all I know there could be more going on inside the laptop when it comes to cell balancing/protection, monitoring. Maybe the best course of action would be to separate the cells and make a custom pack, using a completely different circuit, which I at least know the parameters of (http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1249)

Again, with respect...I think you should learn about Lithium Cobalt cells in more depth before considering this project. I strongly recommend that you not proceed for your own protection. I'm saying this as respectfully and firmly as I can, so please don't think I'm trying to be rude.

Batteryspace.com has various protection boards, and you thinking of using an individual cell board like you linked is continuing to demonstrate your inexperience with this project. For one thing, you would need to get a 3s board if you are using these cells in a 3s3p configuration. You need to make sure these cells can safely output the voltage and current you are intended to use them for. You need to have a safe charging solution. You need to find a way to safely make connections between the cells without soldering. You need to make sure you don't have any shorts anywhere in your setup.

The computer is making terminal connections with the contact points in the battery pack. It is supplying a certain level of voltage and current that applies to this pack and its circuit. You need to know all of the basics before embarking on this project.

 

[kuksul08]

Again, with respect...I think you should learn about Lithium Cobalt cells in more depth before considering this project. I strongly recommend that you not proceed for your own protection. I'm saying this as respectfully and firmly as I can, so please don't think I'm trying to be rude.

Batteryspace.com has various protection boards, and you thinking of using an individual cell board like you linked is continuing to demonstrate your inexperience with this project. For one thing, you would need to get a 3s board if you are using these cells in a 3s3p configuration. You need to make sure these cells can safely output the voltage and current you are intended to use them for. You need to have a safe charging solution. You need to find a way to safely make connections between the cells without soldering. You need to make sure you don't have any shorts anywhere in your setup.

The computer is making terminal connections with the contact points in the battery pack. It is supplying a certain level of voltage and current that applies to this pack and its circuit. You need to know all of the basics before embarking on this project.

I appreciate the warnings with regard to safety. I don't plan on doing anything until I know exactly what is safe. In fact I can't do anything for a couple months because I don't even have the battery with me :o

Maybe part of this is the lack of information I provided. Without going into depth, I would only use a 3p configuration if I were to disassemble the pack, hence the board rated for 3.7V (Basically, if the pack was staying intact at 11.1V, I would modify my project to accept that. If I disassembled the pack into individual cells, I would modify it to accept a 3.7V input voltage - for current regulator reasons). I was unclear; however, whether that board would support as many cells in parallel as I want, or if it's specifically for one cell, and whether or not all the cells would discharge equally.

Although there is a lot to know about these batteries and its variants, I think I have a general understanding. Maybe not enough yet to go making battery packs, but that's why I'm here, to research and get advice :)

:wave:

 

[LuxLuthor]

OK a 1s3p 3.7V setup would use the PTC you mentioned. The other issues in my last post are still important though. Keep reading, asking, and Good Luck!