Question Computer mouse mysteriously got wet over night

[dkop]

So I woke up this morning, and my mouse, a Logitech M705, was on my kitchen counter where I left it. I picked it up and placed it on the table where I would go to use it a few minutes later. When I sat down to use it, it was laying in a mouse-shaped puddle of water. There was no water on my counter, and no water had been on the table when I put the mouse down.

Before going to bed, I turned the mouse off using the switch underneath and rested it on the kitchen counter as I do every night. I don't leave it on the table because I have a cat, and I don't want to have to look for it on the floor in the morning (good boy stays off the counter).

The mouse powered on okay and clearly right-clicked without issue, but tracking was a problem as water had gotten inside. The batteries are 2 Energizer AA alkalines. They were undamaged and function normally, but there was a bit of water inside the compartment (underside of the mouse). The mouse has now dried out and works fine.

The question is how did water accumulate inside the mouse overnight? As I stated, it was not powered on, the switch was in the off position. Also, I'm in the Arizona desert where the humidity is currently only 18% with my humidifier on. Even overnight, it never gets above 50%. Any theories or explanations are welcomed.

 

[Lutfij]

Condensation could be one thing. The Kitchen I'd assume would have higher humidity ... and your room where the PC is, is air conditioned? This is an assumption since I don't know the layout of your house/apartment/crib.

 

[Ralston18]

How much water?

Anyone else in the house - besides the cat?

Does the cat get on the table?

If the counter was cool then the base of the mouse was likely cool.

Once the mouse was placed on the table any nearby moisture likely condensed under the mouse.

 

[dkop]

How much water?

Anyone else in the house - besides the cat?

Does the cat get on the table?

If the counter was cool then the base of the mouse was likely cool.

Once the mouse was placed on the table any nearby moisture likely condensed under the mouse.

It was probably a good 4 tablespoons or so I soaked up.
I live alone.
The cat gets on the table, but not the counter where the mouse was.
The counter and mouse were both cool.
The humidity was low to normal at most (maybe 25% when I went to bed), why would moisture condense under the mouse like that? Also, this has never happened before, and I put the mouse in the same place each night.

 

[Ralston18]

I do not know.

4 Tablespoons is a lot of water. Teaspoons maybe?

Curiosity got the better of me. 😺

A careful but informal experiment here resulted in in a roughly 3 diameter circle of water via a single tablespoon on my counter. Roughly the area of my mouse - Logictech M310.

A teaspoon full flowed out to just a bit less area 2" x 3" oval.

And, on a grosser note: you are sure that the liquid is indeed water and not cat pee? Very sure if that was the case you would know by the smell. And the mouse would likely have been wet on top. Still compelled to ask.

All I can suggest is to follow your routine and discover if it all happens again.

 

[dkop]

I do not know.

4 Tablespoons is a lot of water. Teaspoons maybe?

Curiosity got the better of me. 😺

A careful but informal experiment here resulted in in a roughly 3 diameter circle of water via a single tablespoon on my counter. Roughly the area of my mouse - Logictech M310.

A teaspoon full flowed out to just a bit less area 2" x 3" oval.

And, on a grosser note: you are sure that the liquid is indeed water and not cat pee? Very sure if that was the case you would know by the smell. And the mouse would likely have been wet on top. Still compelled to ask.

All I can suggest is to follow your routine and discover if it all happens again.

Didn't actually measure the water, but it was enough that it started rolling off the table once I lifted the mouse up (the table is not perfectly level). And there was more still inside. Mouse was dry on top and did not smell, definitely not cat pee, or a drip from above. I'm thinking from now on, I should put it in a Ziploc bag at night.

 

[Ralston18]

Add in some grains of rice.

Read up on Gremlins - not just the movies.

Will leave further speculation to others.

 

[Themonolith]

Wow I've never, ever seen this this bad before. To drive condensate in a manner to cause this you'd have to remove the mouse from a freezer and put it on the bench in a high humidity environment, or use it right after, heavily, and then shelf it. There's no water in an alkaline battery that could leak even when corroded, and even with the most extreme temperature and condensing humidity conditions I cannot imagine the mouse could require enough thermal energy to *not* match the environment temp within half an hour or so driving minimal condensation. I've got an M325 and an M280 - never had this issue...there is no source of moisture within a mouse.

However.....

Depending on the operating conditions prior to you placing the mouse on the bench, it's possible that evaporated sweat and and non-sweat moisture exuded from the skin has condensed inside the mouse during operation - in volume - and had run out on the bench overnight.

I have in the past had a mouse that got wet inside - not enough moisture to run out, but enough for a film of condensate to coat interior surfaces, the bottom of the mouse, and the desktop immediately around it. Had I not noted it and dismantled/cleaned out the mouse it might have come together and run out the bottom. This was caused by an extended period of operation during a system implementation done in a very cool airconditioned office but with a nervous and frantic implementer using my mouse (me). So the mouse was cool enough to condense out the moisture from my hand and accumulate it inside the mouse but not in volume on the desktop (the hint for me was a patch of misty condensate around where my hand was resting on the desk). If you are confident the cat didn't decide your mouse is a good litter tray, and with utter conviction you can conclude there is just no other physical way moisture got to the mouse such as dripping from above or being used in a condensation pool from a drinking glass (water will wick upwards through the case joins) - it will be condensate. Deductive reasoning can apply here with success. Therefore if on the same night you placed the mouse in a ziplock - you still would likely have woken to water in the bag. Smaller mice like Logitech wireless ones tend to drive the operator to use the mouse with fingertips rather than cupping the body of the mouse like with a full size mouse. Cupping the body would increase it's temp pretty quickly, but driving it "palm off" would mean the mouse body stayed pretty cool (close to the ambient temp) and would be the first nice place for airborne moisture from your hand to condense.

My conclusion without personally examining the scene and mouse - condensation!

EDIT: I just re-read your post and noted your location in AZ. Temperature swings even with low RH% and human hands will definitely cause condensation in places you might not expect. So I'm about 10% more confident in the condensation root cause, with the moisture source being your otherwise dry hand. As I type, there are two small patches of consolidated moisture droplets on the palm rest of my laptop. Indoor temp is currently 19 degrees celsius and RH is 38%, the laptop palm rest is probably 3-4 degrees above ambient - but still I have this condensate. It evaporates rapidly if I remove my hands but that would not be the case if the moisture was accumulating inside an enclosure.