OK, the following teardown says the Dash lithium battery is spot welded in place, making it not possible to replace. They’re estimating close to 1000 uses of battery life. However, as was already mentioned in this thread, the device has a built-in repeater, so that it actually will make five attempts each time if it doesn’t connect to Amazon. I’m not sure whether the approach detailed in this project means you’ll only get 200 button presses of battery life or not. It’ll be somewhere in the range of 200 to 1000 anyway.
http://mpetroff.net/2015/05/amazon-dash-button-teardown/
So compare that to Flic’s spec’d 60,000 uses. Since the Flic at Amazon costs 7 times the Dash but lasts at least 60 times as long, the Flic has a much lower cost per use over time. And the flic’s battery is easily replaceable (,standard twist off compartment), preserving your investment in the device itself.
http://www.amazon.com/Flic-Wireless-Smart-Button-White/dp/B00ZAEOC5K
So as usual, it comes down to your use case. If you’re using it as a switch that you only operate maybe once or twice a week, it’s pretty similar to Amazon’s intended use pattern and you’ll probably get two years out of it. But then you have to replace the whole device.
If you’re using the Dash for a switch that you expect to use four times a day, battery life will likely only be a couple of months. And then again you’ll have to replace the whole device.
And if you give it to the baby to play with, it could be a few weeks.
Just sayin’…