Hello all!
I opened an old broken laptops' battery and found 18650 batteries in the battery pack. I could use these 18650s for my flashlight and radio.

The flashlight & radio also take 18650s.

Do you guys see any safety issue at all in recharging these batteries and using them for non laptop uses? Is there a possibility of the battery exploding because the load the battery will be under is different than a laptop? Are all 18650 batteries the same when charging them?


A pic of the battery pack is below.

https://www.amazon.com/gp/product/B073VJVH1N/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

A pic of the charger is below.

https://www.amazon.com/gp/product/B0721JP6FK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Thanks for the replies!

 

I do the same. Since the 18650 cells will not have a protection circuit against excess charge or discharge (nor short circuits), keep in mind to not short the battery and use a reputable/decent charger.

 

I never buy dangerous Lithium batteries or a charger (that are not made by a good Name-Brand company) from an online joint that sells cheap clothes and shoes (Amazon). Because I do not want my home to burn down by using their cheap junk.
I am re-using Panasonic brand 18650 laptop cells in a portable little vacuum cleaner and they work fine.

Recently there were videos of Chinese electric motorcycles exploding and catching on fire.

 

Do you guys see any safety issue at all in recharging these batteries and using them for non laptop uses?

Individual cells won't have any protection that the assembled pack offered.

Is there a possibility of the battery exploding because the load the battery will be under is different than a laptop?

It can fail in catastrophic manners.

Are all 18650 batteries the same when charging them?

Capacity can vary. Not sure if charging protocol would be different, but I have a lithium-ion charger that has two voltage settings.

 

How do you intend to use them? You should have over voltage, under voltage, and over current protection on each cell or if you fix them together in a pack, on the pack. You can get cheap protection boards.

If you want to use them on individual cells and have them work in something like a flashlight or battery holder in a device, you will need to use a board designed to be attached to the end of the cell. Technically you should spot weld these but with care and practice, you can solder to the cell.

Any time you are doing something like building a pack or soldering it is best to discharge the cells first. Lithium cells are most dangerous when fully charged and not very dangerous at all discharged. With a protection board in place they are not very dangerous even charged.

I use a lot of 18650s and LiPo cells and I always add a protection board it there isn't one in place already.

 

How do you intend to use them? You should have over voltage, under voltage, and over current protection on each cell or if you fix them together in a pack, on the pack. You can get cheap protection boards.

If you want to use them on individual cells and have them work in something like a flashlight or battery holder in a device, you will need to use a board designed to be attached to the end of the cell. Technically you should spot weld these but with care and practice, you can solder to the cell.

Any time you are doing something like building a pack or soldering it is best to discharge the cells first. Lithium cells are most dangerous when fully charged and not very dangerous at all discharged. With a protection board in place they are not very dangerous even charged.

I use a lot of 18650s and LiPo cells and I always add a protection board it there isn't one in place already.

Ty for the reply.
I am intending on using one cell in a flashlight and another cell in my NOAA radio. I dont intend to put 2 cells together. I do intend to charge them with the charger mentioned in my original post.
Purim Sameach!

 

The chemistry of the lithium cells is important because modern 18650 cells have lower voltage LiFePO4 chemistry and need a charger designed for them.
"18650" is simply the physical size, not the chemistry.

Today I found a swollen Li-PO battery in my garden. I remember putting it there 5 months ago in case it exploded into a fire.

 

Gam lecha.

The problem with not including protection is not limited to charging, discharging can also be a problem if something goes wrong. The danger of lithium batteries is a combination of their very high energy density and the flammable electrolyte they use.

An internal short in a cell can initiate a thermal runaway. A condition where the cell heats up and the heating up itself causes more heating until the cell reaches a very high temperature, boiling the electrolyte causing an overpressure condition. In the 18650 there are vents. You can see them holes to accommodate them around the positive terminal on a cell that has no terminal, like your salvaged ones.

The flammable, boiling electrolyte comes out there and if the temperature is high enough it comes out in flames. By the way, 18650s can vent because of less lethal overheating and each time they do they lose come capacity, so keep them cool for a long life.

The other way a thermal overload can start is with an over discharge, either directly or indirectly. The indirect way is to bring the cell down below 2V or so and promote internal shorts in the form of dendrites. The direct way is to simply overheat the battery so far it goes into thermal runaway in the way it does with internal shorts.

Because most 18650 include internal protection against external shorts, direct cases are not likely but over discharge can do it, and if you do manage to run it too low, your battery charger will refuse to charge it for safety reasons.

The downside of adding protection to the cell is added length. Sometimes protected cells won't fit into battery holders because the board adds too much to the length. There are different boards and some are more low profile than others.

In summary: If you are going to use an unprotected cell in a device, be very careful not to over discharge it. If your charger refuses to charge the cell, write it off as too dangerous to charge. Or, add protection, it's what I do.

 

All Laptop batteries I have taken apart use unprotected cells with a separate protection circuit inside the battery case.

 

Gam lecha.

The problem with not including protection is not limited to charging, discharging can also be a problem if something goes wrong. The danger of lithium batteries is a combination of their very high energy density and the flammable electrolyte they use.

An internal short in a cell can initiate a thermal runaway. A condition where the cell heats up and the heating up itself causes more heating until the cell reaches a very high temperature, boiling the electrolyte causing an overpressure condition. In the 18650 there are vents. You can see them holes to accommodate them around the positive terminal on a cell that has no terminal, like your salvaged ones.

The flammable, boiling electrolyte comes out there and if the temperature is high enough it comes out in flames. By the way, 18650s can vent because of less lethal overheating and each time they do they lose come capacity, so keep them cool for a long life.

The other way a thermal overload can start is with an over discharge, either directly or indirectly. The indirect way is to bring the cell down below 2V or so and promote internal shorts in the form of dendrites. The direct way is to simply overheat the battery so far it goes into thermal runaway in the way it does with internal shorts.

Because most 18650 include internal protection against external shorts, direct cases are not likely but over discharge can do it, and if you do manage to run it too low, your battery charger will refuse to charge it for safety reasons.

The downside of adding protection to the cell is added length. Sometimes protected cells won't fit into battery holders because the board adds too much to the length. There are different boards and some are more low profile than others.

In summary: If you are going to use an unprotected cell in a device, be very careful not to over discharge it. If your charger refuses to charge the cell, write it off as too dangerous to charge. Or, add protection, it's what I do.

Ty.
Going a little further with what you said........I have a similar flashlight to the one below and it comes with a 18650 Rechargeable battery. I dont see any protection on the battery. Does it mean it is not safe to use then? How is this battery any different from the ones that I got out of the laptop?

 

I have a similar flashlight to the one below and it comes with a 18650 Rechargeable battery. I dont see any protection on the battery. Does it mean it is not safe to use then?

You can use them, but they're not protected from shorts.

I use 18500's in LED flashlights that take 3 AAA batteries. Ideally, you'd use a spacer to keep the battery centered in the flashlight. To use 18650's, I need to use an aluminum extension (if it fits the flashlight). The extender keeps the batteries centered in the battery compartment.

 

Ty.
Going a little further with what you said........I have a similar flashlight to the one below and it comes with a 18650 Rechargeable battery. I dont see any protection on the battery. Does it mean it is not safe to use then? How is this battery any different from the ones that I got out of the laptop?



View attachment 262939

The protection would coaxial with the cell on the top or bottom, you wouldn't see it. It looks like this, and the heat shrink and positive or negative terminal would hide it. You'd have to disassemble the cell to see it.

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That said, cheap cells will frequently count on the PTC in the cell which is only protection against overhearing and over current, it resets but it gets higher resistance with use. It also does nothing at all for over-discharge.

Does the cell that came in your flashlight seem to weigh a lot less than the one that you got from the laptop?

 

Does the cell that came in your flashlight seem to weigh a lot less than the one that you got from the laptop?

Videos of 18650 Lithium cells taken apart show that the ones with a low capacity measurement weigh about the same as good ones but are mostly full of rice flour.

 

Videos of 18650 Lithium cells taken apart show that the ones with a low capacity measurement weigh about the same as good ones but are mostly full of rice flour.

Yes, though I have several examples here that weigh considerably less. For instance a cell that came with a laser pointer weighs only 23.9g while an LG manufactured cell from a laptop battery weighs 42.64g.

 

The scare stories about exploding flashlights often turn out to be extreme examples. Like the guy with a ridiculously powerful flashlight powered by a slew of cells which he'd been too impatient to charge or balance correctly.
I've been running a single-18650 flashlight from various salvaged 18650 cells for ten years now with hardly any fires or explosions. The end buttons keep getting dented in from dropping it, though. YMMV.

 

The scare stories about exploding flashlights often turn out to be extreme examples. Like the guy with a ridiculously powerful flashlight powered by a slew of cells which he'd been too impatient to charge or balance correctly.
I've been running a single-18650 flashlight from various salvaged 18650 cells for ten years now with hardly any fires or explosions. The end buttons keep getting dented in from dropping it, though. YMMV.

Explosions and fires are rare but they do happened and they can be vert damaging and injurious. I have never had an adverse event but I have seen them. I actually witnessed something I’d never even heard of, a fire from a primary lithiums cell.

My son had a good quality flashlight (Inova 5) that used two CR123A cells. He picked it up off the shelf and a jet of flame shot out the back. He dropped it and it burned for several seconds, really scared him. He wouldn’t handle lithium powered devices for a whlie.

I still have no idea what triggered it. I mean, clearly moving it started the thermal runaway, but why?

 

I haven't had any mishaps with 18650 batteries, but I've had several unwelcomed incidences with Li-ion batteries with my smartphone and 2 DSLRs.

The phone batteries expanded enough to dislocate the screen; happened with 2 batteries so far. Most would notice before the condition got to that point, but I'm not a slave to my phone and it I can go weeks without touching it (and yes, it often has a dead battery when I want to use it). One camera battery swelled up and was a PITA to remove. The other camera battery became bloated; it was charged once and had never been used. If they had kept deforming, the next step would have likely been an internal short, then a fire.

 

Swollen batteries may be too weak to make fire. We did an experiment in the back yard with a couple of cells like that and an air rifle, with a GoPro behind a protective barrier to record the results. Nothing happened. I'm guessing that the best results come from healthy cells that are full of energy, but I haven't been willing to sacrifice a good battery to test that hypothesis.