So at the beginning of summer I repurposed an old Android phone into a dedicated emulator. The phone's old enough it has an honest to god user replaceable battery so I decided to get another one and keep it in my backpack to double my gaming time.
A few weeks later I got caught in a thunderstorm and got absolutely drenched head to toe. I got home and found the phone and bluetooth controller were just a bit damp but okay, but I completely forgot the spare battery until the next day when I discovered it still in my backpack and absolutely soaked. I dried it and left it to dry on a shelf, and noticed some bluish corrosion forming at the contacts the next day that I promptly scrubbed off. I noticed more corrosion a few more times in the following days, but it's now sat on that shelf since June and looks normal.
How bad of an idea would it be to put it in the phone and see if it still works or holds a charge?
It's probably fine. The batteries don't care about moisture, as long as the pins don't get shorted or corroded.
If they were wet enough to short, the symptoms are usually a completely dead battery or it seeming puffy, a.k.a. spicy pillow.
You can measure the voltage with a voltmeter if you want to check. It should read around 3.5 to 4V, depending on charge.
Source: I handle a lot of LiPo batteries at work.
I don't have a voltmeter on hand, but the battery is not puffed out at all. The positive and negative terminals did have some blue gunk form on them for the first few days I had it drying out though, like I said.
You can test it in the phone and see if it has any juice in it, then. If I were in your shoes I'd feel safe in testing it that way.
Well, I have the battery in the phone right now and I'm attempting to charge it since it didn't seem to have any juice left and it's acting a bit weird.
First, the phone's charging LED blinks, then the screen shows the battery charging screen for a split second, then the first frame of the boot sequence pops up briefly, then it goes back to black and the charging LED flashes briefly again, rinse and repeat.
I assume it's not looking good for the battery. I'll give it a moment and see if it holds a charge