Re: worried about 18650's
Why are laptops not exploding all over the world. I mean alot of laptops......
But why, oh why, are laptops not exploding?
Hi loquutis and welcome to CPF!:thumbsup:
I see reference to this quite often. What most people don't realize is that the protection circuitry built in to laptops and other consumer devices that utilize various types of Li-Ion battery packs, are designed for that specific device and it's associated current demands.
The best we flashaholics can do to simulate this type of protection, is purchase cells with a protection PCB that has been added onto the bottom of the cell by a third party, or only buy lights that have their own built in protection circuitry. The later, which is really the prefered method, in all cases I'm aware of, is only effective with single cell lights, however.
As for protection circuits added to individual cells by third parties, these circuits by necessity, have to cover a wide range of potential operating conditions. Will the cell be used in a light that draws 20mA, or one that draws 5A? The protection circuit added to the cell can't really do both effectively, so a compromise has to be made.
Also, there is the quality of the components used and the construction of the protection circuits. Some are made with precision and from quality components, others, maybe not.
Li-Ion cell manufacturers do not supply Li-Ion cells at the consumer level, nor do they manufacture protection circuits. Protection circuitry is normally provided by the device, or battery pack maker, and proof of such is required before a Li-Ion cell manufacturer will provide them with cells. This is for liability reasons. So, protection circuits that have been added to individual cells is one point where a compromise has been made concerning the safety level of our lights.
In many cases (more than likely most), the individual, or "loose" as they are called, Li-Ion cells that we purchase for use in our lights are bought up as "factory seconds" that for one reason or another were deemed not useable for the manufacturing of battery packs by the manufacturer of the cells.
The last I was aware of, there is a worldwide shortage of, in particular, 18650 size Li-Ion cells, for use in the making of battery packs for laptops and other consumer products. If you search the net, you will find many trading companies, mostly in China, offering name brand Japanese and Korean 18650 cells in large quantities (eg. 1000+) from companies such as Sanyo, Samsung, Panasonic, LG, and others. With this worldwide shortage of 18650 cells, you have to ask yourself, where did these cells come from? And, who do you suppose buys them?
Many of the Chinese Li-Ion cell distributors (not manufacturers) actually relabel recycled cells, as well as those obtained from battery packs that were involved in a "recall" for whatever reason. Most of these companies go by some sort of "Fire" brand name, such as "CrapiFire", or BangiFire, or some such other nonsense name that plays upon the U.S. based SureFire company name. At any rate, here we have yet another drop in the potential safety level of the cells we obtain. Some might be just fine, but others.....?
The best we can do is buy cells from a reputable source. Due to the higher cost of quality cells, and better components used in the protection circuits (if added), cells from these distributors are going to carry a higher price. Top tier cells (whether "seconds", or not) no doubt cost more than lower quality cells, or those obtained from recalled or recycled battery packs, so the distributor/dealer has no choice but to pass this additional cost on to the buyer.
So anyway, you can't really compare the cells and associated protection circuitry used in our hobby, to those used in laptops, or any other consumer device. There are just too many potential variables for a comparison.
EDIT: I see that in the time it took me to write this up, Tom posted. Oh well, the more the merrier.
Dave
