On 10/01/2014 4:15 PM, trader_4 wrote:
....

I can show you plenty of rechargeable, cheap, consumer products that
sell for what a smoke detector sells for, or less that have battery
"Backup" or rechargeable batteries, that don't draw the battery down
along with using AC. Your argument about a 10 cent diode is silly.

That the cost/feature analysis comes out at a different place on other
products doesn't negate the general rule. And, in fact, the "feature
set" on your device pretty much confirms it for your particular device.

As said, it isn't/wasn't that the particular one selected component got
taken back out; the feature of which it might have been a key component
wasn't included to begin with. The decision as to whether it was/was
not to be included almost certainly included a consideration of the cost
for the design/manufacture in comparison to the expected margin and
potential increase/decrease in sales and was found lacking...

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