Hacker News Reader

Comment by evan_ | Hacker News Reader

This is interesting, since from teardowns it looks like there's literally just a AAA battery in there:

https://mpetroff.net/2015/05/amazon-dash-button-teardown/

Yup, but they decided to weld the contacts of the board to the battery. I'm guessing that they calculated it was cheaper (or more business savvy) to get users to replace the button every X months/years than to make the button in such a way that the battery is user replaceable and also indicates charge level.

It also means they can reasonably assume there aren't 10 year old buttons using an ancient protocol out there to support.

Sometimes planned obsolescence is a good thing.

You'd have to order an awful lot of toilet paper to have it only last 10 years. Even at a rate of one-press-per-week, it'll last getting on for 20 years.

The sample use cases for these buttons is more frequent use than the Dash "order me something" ones.

But do they use a different protocol?

It's a thing with an ID that sends a single event. How much can the protocol evolve?

Maybe the next version will have a thumbprint scanner so it knows who initiated the event. Maybe multiple buttons will be in a mesh network and send data about the other devices they're in contact with. I highly doubt we've seen the final feature set for IoT buttons.

But why would you deprecate the ability of a button to send a single event since that's what buttons do. Coordinating them in a mesh should be done outside of the device so it still works as a simple signaler.

Because fuck the environment!

Is it even safe to weld an alkaline battery? I don't know.

Why not just solder the contact? If it's soldered, you should be able to swap the battery with a soldering iron. Sure, heating the iron and cleaning it will take much more time than swapping a battery in a spring-loaded housing, but I've spent just as long opening battery compartments held shut with tiny stripped screws.

Yes. The welding heat is VERY localized to the spots where the electrodes made contact. Very small spots and very localized heating for a secure connection. In this regard, less heat gets "into" the battery than would be the case from soldering, the operation is very fast (cycle times in the low number of seconds and welding times in the few milliseconds range), and more than strong enough for the application.

The better ones use a double pulse for a cleaner weld without the need for any flux.

Reply on news.ycombinator.com