NDS battery bulging

First things first, I hope this is the right place to post this.

About two days ago, I noticed that the battery cover of my DS didnt fit as well (slightly sticking out). Today I opened it and checked the battery and it felt slightly off, compared it to a replacement that I got around and its definitely bulging.
Now Im not sure where to sort this in: is the battery about to die with a literal blast (which Id love to avoid at all costs!) or is it coming from the rather heavy usage over the past 2 weeks (9 days with at least 3 to max 6 hours of almost nonstop playing)?

Hope its the latter, cause I dont really want to swap the battery (as this DS is, with the exception of the touchscreen overlay, the same as when I got it), but safety first D:

 

This is a standard failure mode for LiPo batteries. It's very unlikely to blow up, but that swelling does indicate permanent damage to the battery, and there will be at least some loss of capacity.

My experience has been that once batteries start to do this, they aren't going to last very long.

 

So the only thing I got to worry about is the time that it lasts between charges?

Also, theyre marked as Li-ion not poly ones, or are those the same (the wikipedia article says theyre used synonymously)?

 

Yeah, although at some point it might stop holding a charge at all. A "LiPo" is just a Li ion battery that's sealed in a plastic pouch; that's why they bulge when they generate gas. (At least this is the current use - the term originally meant Li batteries using a polymer electrolyte, but this is pretty much relegated to academic use now).

 

Alright, and since I havent actually "felt" a decrease in time per charge, as long as its safe, Ill just keep on playing till it dies completely, thanks

 

Better stop charging it. When it gets low or dead, take it out and take it to a recycling place that accepts batteries. You never know it can fail and complete die in the middle of an important gaming session or worse, bulge more and crack the cover.

 

Hrm, kay. I hope the replacement I have is good to go...

 

Worst case: it catches fire or burns your junk as well as ruining the case.
Best case: it stops charging one day and you're tied to the wall.

Replace that thing ASAP. Bulging batteries are not a gamble you want to take.

 

Decent replacements aren't hard to come by, and will last a lot longer than the bulging one. If you've already opened it, there's zero reason not to replace it.

 

Alright, played the bulgin battery dry and put in the replacement I had, now the lid fits again and Im happy.

Thanks guys