Protected batteries?

[Joed]

We all know that it is best practice to use protected batteries in our mods. The question I have is are protected batteries used in the production models where the battery is sealed in a casing? My guess is that the batteries are not protected but that the protection circuit is built into the switch or is located somewhere in the sealed battery container.

Next question. If the manufacturers of production PV's starts making units where the battery is replaceable with generic batteries like the 14500 or the 18650, will the batteries need to have the protection circuit encased in the battery as a single unit or would it suffice to have the protection circuit in the switch assemble or elsewhere in the case?

 

[warbdan]

I have taken several batteries apart. There is no protection physically ON the e- cig battery. There is protection somewhere, because they prevent undercharging. It's probably on the switch pcb like you said. There is also protection in the charger.

 

[WillyB]

... If the manufacturers of production PV's starts making units where the battery is replaceable with generic batteries like the 14500 or the 18650, will the batteries need to have the protection circuit encased in the battery as a single unit or would it suffice to have the protection circuit in the switch assemble or elsewhere in the case?

Don't they do that already with the Janty Stick, DSE stick and DSE905? Which BTW ship with unprotected batteries.

 

[Ed W]

I have a DSE905 and it has the unprotected but even so I use the protected. Don't really know if it makes a difference.

 

[WillyB]

It must, an extra layer of circuitry has to have some impact.

 

[Joed]

Why would you want to have an extra layer of circuits? That sound silly.

 

[Java_Az]

Why would you want to have an extra layer of circuits? That sound silly.

Not as silly as you would look with a PV blowing up in your face. I know That some professional battery pack makers double protect their packs. Not with two circuits but with pollyswitch added to the protection which works kinda like a circuit breaker in a house.

 

[mdocod]

LiCo cells generally don't go fiery death during a discharge, it's normally during a charge. That said....

The quality of the cell is almost always more important than PCBs. A cheap random chinese cell with a protection circuit is no safer (and probably less safe) than an unprotected modern panasonic, lg, sanyo, sony etc... basically just pick a name brand that is held to manufacturing standards and has actually suffered the costs of huge recalls from a few bad cells in the previous decades, the latest generation cells these companies are making are very difficult to get an explosion out of even when heavily abused in an unprotected circuit well outside the recommended voltage and current ranges for the cell.

Eric

 

[Joed]

Thanks for all of the feedback on my question. Nobody wants a battery blowing up in their face or anywhere else. What I am trying to get to here is how much protection is enough before the added protection starts to effect the PVs performance. From what I have read there really hasn't been any issues with production PV going off in someone's face. I read some about melt down caused by constant pressure on the button in a pocket or purse. So, if production PVs use unprotected batteries and the protection is built into the hardware how many levels of protection are required? I would guess that the production PV's have enough built into them to provide attiquite protection. Am I wrong? If so please enlighten me. I'm asking to learn.

 

[mdocod]

Most li-ion powered consumer electronics have a single global protection circuit for the cell/s, and implement proper charge algorithms. Stacking protection will hurt performance as each protection circuit adds resistance to the circuit. When dealing with the relatively low resistance loads presented by typical atty's, it's important to keep the resistance in the rest of the circuit as low as possible. I suspect that in a typical small form factor ecig, it's probably not uncommon for 20-35% or more of the voltage drop in the circuit to be taking place as a result of the resistance of the cell.