Alt text: picture of a Costco mechanical fish (cat) toy taken apart.
I had one of these fail last night from the battery lead coming off as pictured. That is something I expected. Upon opening the mechanism, both sides of the lithium cell have very concerning damage in a piercing type of abrasion. The cell is relatively small.
Speculatively, I expect the stuffed toy is flammable, making this an ideal house fire starter if the cell gets bridged layers in the battery from a puncture and goes into a runaway state.
All it needs is a way to secure the battery with some double sided tape and extra insurance like some kind of soft filler fabric or material to stop it from rattling around. Maybe add a bit of hot glue to the battery leads at the circuit board to insure they do not fail from a lack of strain relief.
I haven’t retraced the circuit, but the battery looks fine otherwise. It appears to have a DW01 like protection board at the cell, and a 4054 batman according to the silkscreen.
This is a serious issue that should not be ignored.
My cats don’t like it so I’ve been thinking of returning it. This settles that.
how powerfull is this thing that regular batteries weren’t enough?
A normal AA battery is probably more powerful than this tiny thing. That cell is probably 3.7v 250 mah at best. My “shitty” ikea rechargeable AAs are like 900 mah, and the good ones are 2400 at 1.2V. 3.7 * 250 is 925 watt hours, 1.2* 900 is 1000, and 1.2 * 2400 is 2800.
The biggest benefit is these are easily and quickly rechargeable.
An alkaline AA may have more capacity, but the LiPo has lower internal resistance and it’s electrolyte is flammable. The worst the alkaline would do it shorted or punctured is get warm and poop out KOH.
By “regular” batteries I assume you mean alkaline ones like your standard AA and AAA. Lithium Ion batteries aren’t really more “powerful”, more likely the circuit was simply designed for constant 5V because that is cheap and easy nowadays. Small lithium batteries like the one used here and a simple charging circuit and port are dirt cheap when purchased in bulk.
Not to mention there’s a size difference both for the battery itself and mounting area for it. For something like a AA battery there needs to be a user accessible battery compartment to replace them. It’s cheaper and easier to just not do that.
Other versions of this use coin cell batteries, not AA or AAA.
Okay but why did you put this in /c/cat ?
It’s a fairly common type of cat toy…
I updated the post to reflect the “(cat)” toy nature in the alt text first line. Sorry I took this for granted as a clearly understood context as a common cat toy (in the USA) and failed to describe it as such.
I posted it here because I wanted to reach the most significant audience. Posting this in electrical engineering would have missed the majority of people this is intended to inform.
You’re getting down voted but I was wondering the same. I had no idea this was a cat toy.
maybe it’s a catfish
