Bill Wright wrote:
Bill Wright wrote:
harryagain wrote:

The other good news is that they use electricity all the time.
Whereas a battery operated doorbell only uses power when a finger is on the button.

So how much does 1kWh cost if you get it from AA cells?
Bill

No-one seems inclined or able to answer this,

Mostly because other factors come into play rather than just price of
electricity.


, so I will
A decent quality alkaline AA battery will produce 2.75 watts for one hour.

1kWh of mains power costs about 10p. So 1 watt/hour of mains costs 0.01p.
So 2.75 watt/hours of mains power costs 0.0275p.

If an AA battery of reasonable quality can be had for 10p, that makes the
power from it 363 times the price of mains power.

So so it doesn't matter how you obfuscate it, anyone using batteries
without very good reason is daft.

Well, not completely. It would cost me a *lot* of time, trouble and money
to get mains supply to my front door bell. As has been mentioned, a
transformer is using power all the time and if you can do without an
illuminated bell push, that's power that you don't need to waste.

Lastly, as I mentioned before, our doorbell was powered by a couple of HP2
batteries that I reckon must have been at least 20 years old. That seems
like a reasonable battery life to me.

Tim