protected or unprotected that is the question

[strik3]

is there a major difference in using protected or unprotected batteries in our builds?
i understand what the protection circuit does in the battery but are there any reasons to go with a particular battery?

 

[LaZeRz]

Probably just for the added safety, im sure lots of people (including me) would prefer a battery rather then a bomb....Also, the thing with li-ion batteries is that if you try to extinguish a fire made from them with water, you will just intensify it since it releases gas when it comes in contact with water. pretty much the only way to extinguish it is by chucking sand or salt on it

although sometimes we have to sacrifice a bit of safety in some of our builds just so a certain battery can fit, I usually babysit even my protected cells, not to mention unprotected ones. Trust me, when you've had 2 bad situations with batteries you start to act like that

once I forgot a battery pack on my bed and it was shorting out for about 10 minutes..... I came into my room to find the smell of smoke and a just about melting battery on my bed, theres still a big mark there to remind me of the dangers when using batteries, I instantly picked up the battery pack and chucked it on the floor to dislodge the batteries from it and the left it to cool

the other time wasnt so dramatic but, I left some Nimh cells on a charger for about 6 hours because I forgot them there and when I came back they were hot enough to burn my skin, luckily they didnt explode

 

[LarryDFW]

strik3;

I've used about 500 cells without protection circuit boards,
in RC trucks and Flashlights.

I have never had a cell even vent, much less catch on fire.

My experience has indicated ~10 times greater reliability . . .
with cells that have passed U.L. 1642 testing.

They are put thru a series of rigorous tests for safety, including shorts & punctures.

The only cells that have passed this testing are name brands like

Sanyo, LG, Panasonic, Samsung, and a few others.

IMO, the "chinese" protection circuit boards are of poor quality,
from the ones I have looked at.

LarryDFW

 

[BShanahan14rulz]

protection circuits are good for DIY builds because who knows what's been shorted out inadvertently. You could turn the thing on, nothing would happen, and then if you don't turn it off it will either just sit there because of an open circuit, or it will destroy the cell because of a short circuit.

Depending on the cell, this could result in explosion, vent with flames, etc. Or there might just be some internal damage and reduced capacity with better-made cells.

Alternatively, some cells are capable of higher outputs than others, and the protection circuit would just limit these to lower current max. This isn't necessarily bad, since we rarely pull that much current with a laser diode anyways, but with a flashlight or something else that needs the power, unprotected cells is a risk that actually has a noticeable benefit.

If you are making a quality build and have a driver that actually cuts out at ~2.7V input, I'd say get some good OEM cells like those sanyos that Larry has. They'll have great capacity, they can supply whatever you need to pull from them, and are built better than generic cells.