Rebuilding a laptop battery pack

[Shrek]

Does it make sense to rebuild a laptop battery pack? both from the perspective of cost and the chip recording the age of the old batteries.

 

[Shihab]

Is it a good idea to mess with chemicals that tend to catch fire and explode when their state deteriorates?

 

[Frick]

Sure, but it requires technical know-how and tools. The cells might just be 16850's, which can be bought in bulk used in good condition, but the actual connectors are often welded (afaik).

 

[Shrek]

The spot welding is an issue; I'll not try.

 

[Bill_Bright]

How would you? Laptop batteries, along with the laptops they go in, are almost always proprietary.

How would you safely open the battery case, replace the cells (if you could even find the proper replacements, then properly close the battery case and still have it properly fit the laptop?

It is not like replacing industry standard SLA batteries in an UPS.

Does it make sense to rebuild a laptop battery pack?

No.

 

[Frick]

How would you? Laptop batteries, along with the laptops they go in, are almost always proprietary.

How would you safely open the battery case, replace the cells (if you could even find the proper replacements, then properly close the battery case and still have it properly fit the laptop?

It is not like replacing industry standard SLA batteries in an UPS.


No.

A lot of them use 16850 li-ion battery cells. Getting the pack apart is a bit tricky, hence the required knowledge and tools. It's not worth it unless you have those skills and tools, but if you do (say if you work with battery packs for e-bikes and other electrical light transports, which has become an industry in itself) it might be worth it because you probably have access to good batteries.

This is just according to my limited experience and knowledge though. I have taken apart a couple of old, really dead packs and they did use those batteries.

 

[Bill_Bright]

A lot of them use 16850 li-ion battery cells.

Did you mean 18650?

Regardless cells used, one has to be careful to note how they are strapped. The 18650, for example, is a 3.7V cell. Laptop battery voltages typically are rated considerably higher - with 19VDC being common. So they use many cells in series to boost the voltage while at the same time, strapping many in parallel to increase the current capability. One has to ensure the exact same series-parallel configuration is duplicated precisely, or a potentially serious, and dangerous (deadly!) situation may occur. And for sure, the battery compartment for a laptop battery will NOT be configured (or even labeled) in a way that would only allow each cell to be inserted only one (the correct) way.

 

[P4-630]

Also:

Unprotected 18650 Batteries AKA Flattops

Unprotected batteries do not have this electronic circuit in the cell packaging.
Because of this, they can have more capacity and current capability than a protected cell.
However, there is always a danger of over heating, short circuiting, or over discharging.

 

[caroline!]

Only if you can't find a replacement prebuilt battery anymore, so for a discontinued model, a rare laptop, etc.


And no, the battery will not "explode and catch fire" when you crack open the pack, that will ONLY happen if you purposedly puncture the cells. Most laptop batteries I've opened didn't involve spot welding (????) but soldered wires, glue or springs.

 

[LabRat 891]

The 18650-containing packs aren't especially difficult but,
without a self-built or purchased batt. tab spot welder and nickeled strips, you're gonna have a bad time.
(18650s *can* be soldered to but, it's *not* safe, whatsoever.)

It's far easier and safer to 'salvage' cells from them, than they are to repair.

If one is 'into' this kinda DIY stuff, procuring or producing a spot welder wouldn't be a bad investment.

PS. If you're in the US, Harbor Freight Tools' Bauer battery packs use very decent Samsung 18650 cells. (The 'low line' use lower-ampacity Samsung 18650 cells, too)

 

[Frick]

Did you mean 18650?

Regardless cells used, one has to be careful to note how they are strapped. The 18650, for example, is a 3.7V cell. Laptop battery voltages typically are rated considerably higher - with 19VDC being common. So they use many cells in series to boost the voltage while at the same time, strapping many in parallel to increase the current capability. One has to ensure the exact same series-parallel configuration is duplicated precisely, or a potentially serious, and dangerous (deadly!) situation may occur. And for sure, the battery compartment for a laptop battery will NOT be configured (or even labeled) in a way that would only allow each cell to be inserted only one (the correct) way.

Yes, i did.

And yeah, it requires tools and knowhow.

 

[ir_cow]

And no, the battery will not "explode and catch fire" when you crack open the pack, that will ONLY happen if you purposedly puncture the cells.

This happens a lot, really easy to do when the packs don't come apart.

 

[LabRat 891]

This happens a lot, really easy to do when the packs don't come apart.

Li-Po / Lithium 'Prismatic' Packs, yes. (Main reason why it's standard practice to only replace polymer cells/packs when discharged.)

'hermetically sealed can' cells (like 18650s), not so much.


It's relatively hard to get a canned cells to go nuclear. (Some sub-chemistries more/less than others.)

 

[natr0n]

Leave it on the plug.Older laptop battery dont last long on charges anyways.

 

[LabRat 891]

Leave it on the plug.Older laptop battery dont last long on charges anyways.

Not always an option but, brings up another option.

Laptops are DC-powered; one could build (or purchase) an external battery pack.
AFAIK, most laptops rated 18-21VDC will take 20VDC (which, is a USB-PD spec. DIY boards are common)

 

[Bill_Bright]

And no, the battery will not "explode and catch fire" when you crack open the pack, that will ONLY happen if you purposedly puncture the cells.

"ONLY"? Not even! Exploding Li-ion batteries has been a genuine problem for years!!!! By percentage, the odds of this happening are very low. But by the numbers, because there are 100s and 100s of millions (billions?) of these batteries out there, it happens a lot. Note this article from 2015.

This is not just laptops, but cell phones, e-cigs and more.

This happens a lot, really easy to do when the packs don't come apart.

Right. And for sure, heat is a common cause - and an inherent problem with laptops. But heat is not the only cause.

'hermetically sealed can' cells (like 18650s), not so much.

Actually being hermetically sealed is part of the problem with "exploding" batteries. Being sealed tight is a good thing - up to a point. Being sealed helps prevent leaking gases and chemicals - that's a good thing.

But, if the battery gets too hot, or if there is a poor design or defect such as commonly seen in cheap knock-off batteries, being sealed allows the pressures inside to build.

The sealed battery's casing will contain the swelling pressures, until it can't.

 

[thesmokingman]

Why not just buy the replacement battery?

 

[caroline!]

The way I see it, poor design and poor practices kill, deadly combo. Remember a news story about a guy who had purchased a cheap noname scooter and let it charge overnight (DON'T DO THIS!!!!!!). The thing bursted into flames first and then exploded, launching parts of the batteries, on fire, over couches, beds, rags, clothes, furniture... everything was in flames in a matter of seconds. All 5 inhabitants of the apartment died either by fire or by smoke, and the flames engulfed the hallway and other 2 apartments as well -one was empty and the other evacuated when they heard the explosion- so yeah they tend to create a mess.

I deal with bare cells for several gadgets and always monitor charging and temperature, since my chargers are dumb there's no cutoff when the cell reaches 100% so if I'm not there to take it out it'll probably overheat and go boom.

"ONLY"? Not even! Exploding Li-ion batteries has been a genuine problem for years!!!! By percentage, the odds of this happening are very low. But by the numbers, because there are 100s and 100s of millions (billions?) of these batteries out there, it happens a lot. Note this article from 2015.

Where I live there's little to no knowledge on how dangerous electricity and electric appliances can be if mixed with negligence and/or ignorance, if you ask me I'll always tell you to never leave anything with batteries plugged overnight when you're not aware, always have a proper fire extinguisher at home (somehow this isn't a requirement for landlords yet here), and the usual... don't buy garbage noname products. #1 reason for house fires is still faulty electrical products, from dangerous cheap extension cords that aren't rated for anything over 1 amp to heaters, microwave ovens, phone chargers, fake laptop power supplies (have a few of em), even faulty switches due to the use of low quality wiring and conduits.

 

[Bill_Bright]

and the usual... don't buy garbage noname products.

Totally agree. However, the problem here is there have been big name brand products from Apple, Samsung and others where batteries caught fire and/or exploded.

I think it was UPS plane that crashed but there have been other cargo shipments on other planes, trucks and maybe ships. I know large cargo shipments on aircraft have been banned by some carriers.

Remember a news story about a guy who had purchased a cheap noname scooter

Hoverboards suddenly bursting into deadly fires were a big news item a few years ago too.

 

[Frick]

The way I see it, poor design and poor practices kill, deadly combo. Remember a news story about a guy who had purchased a cheap noname scooter and let it charge overnight (DON'T DO THIS!!!!!!). The thing bursted into flames first and then exploded, launching parts of the batteries, on fire, over couches, beds, rags, clothes, furniture... everything was in flames in a matter of seconds. All 5 inhabitants of the apartment died either by fire or by smoke, and the flames engulfed the hallway and other 2 apartments as well -one was empty and the other evacuated when they heard the explosion- so yeah they tend to create a mess.

Regulations are written in blood, and all of that. That said, given the amount of batteries and chargers that are out there, the actual percentage of accidents are quite small.

don't buy garbage noname products.

Which is the point of regulations.

However, the problem here is there have been big name brand products from Apple, Samsung and others where batteries caught fire and/or exploded.

Sure, but I do believe that thing of "don't charge stuff overnight" is overblown, because it's generally the chargers that catch fire, and you have exactly the same danger (power supplies catching fire) in literally everything these days: fridges, computers, TV's (even in standby) network equipment, LED light bulbs...

 

[silentbogo]

Does it make sense to rebuild a laptop battery pack? both from the perspective of cost and the chip recording the age of the old batteries.

Depends on the battery. Most new-ish laptop batteries need reflashing and recalibration after a cell swap. I do fix laptops for a living, but even I cannot justify spending $400 on a mystery box that also comes with subscription bullshit, just to reset a few batteries every once in awhile. In most cases it doesn't even make financial sense to repackage it(especially for cheaper/older mainstream laptops).

There's other software that works with CP2112 adapter(usb-smbus), but it only supports much older BMS ICs.

 

[Good Guru]

I once was trying to get a battery out of a cell phone with a metal pick like tool and it exploded into flames. I dropped it on my carpet, ran for the sink poured water on it, now there's a burn mark on my carpet. Lesson learned don't put metal in a cell phone, I would'nt even use it for the sd or sim card pin hole.

 

[Shrek]

Lithium and water don't mix well.

 

[Bill_Bright]

Sure, but I do believe that thing of "don't charge stuff overnight" is overblown

It is definitely shyster... err... lawyer-speak. If you look at the documentation that comes with many, if not most electronic devices (plug-in or battery operated) it will say to unplug when away, or something similar.

I mean our PCs have CMOS batteries. We leave batteries in our TV remotes all the time. Same with garage door openers. Our UPS use rechargeable batteries. So do our cars. Emergency lighting, by definition, has batteries and are plugged in full time. Home wireless phones, cell phones and more. Many have batteries that cannot be removed - forcing consumers to buy whole new products when the batteries finally die.

because it's generally the chargers that catch fire

Not sure that is true. Yes, chargers do, but so do batteries.

 

[LabRat 891]

Lithium and water don't mix well.

IIRC, those Li-Po pouches have 'the most' Lithium metal in 'em too.

Basically, they did the household electronics equiv. to: (trying to) put out a grease fire with water. Glad everything worked out okay, though.


(Small) Lithium battery fires should get a bucket of sand (or salt), IIRC.
I believe baking soda will have its water ripped from it, fueling the fire

How Do You Put Out a Lithium-Ion Battery Fire?

Discover how to prevent and extinguish lithium-ion battery fires to keep your workplace safe and operational.

resources.impactfireservices.com

So, how do you choose the right fire extinguisher in this scenario? Lithium-ion batteries are considered a Class B fire, so a standard ABC or dry chemical fire extinguisher should be used. Class B is the classification given to flammable liquids. Lithium-ion batteries contain liquid electrolytes that provide a conductive pathway, so the batteries receive a Class B fire classification.

Apparently, the electrolyte is more of a concern than the metal.

I'd believe batteryU over the other sources

https://batteryuniversity.com/article/bu-304a-safety-concerns-with-li-ion

When encountering a fire with a lithium-metal battery, only use a Class D fire extinguisher. Lithium-metal contains plenty of lithium that reacts with water and makes the fire worse.

BattU does make a distinction between Li-Ion and Li-Metal variant cells) and (apparently) BattU does recc. water as a last resort (to prevent spread).

So, I guess they didn't really 'mess up'

Note: "Soda" is not 'Baking Soda'; it is "Washing Soda". Sodium Carbonate is slightly different than Sodium Bicarbonate.