Watt load question...

[Supervstech]

On the coffee grinder thread it came up about a 150 watt load for 20 seconds...

I calculated it as 30 watt minutes...

Another calculated it as .85 watt minutes...

I would think 150 watts for 20 seconds would be calculated as 1/3 of a minute at 150 watts, or 30 watt minutes...

The .85 number came from 150 watt hours divided by 60 to get .85 watt minutes...

I think I'm right.

But only because it logically makes sense...

.85 of a watt hour also makes sense...

Training needed? I wanna learn.

 

[Steve_S]

I had to laugh as I pondered that myself a bit yesterday. I'm also using a Kill-A-Watt meter on stuff and some of it does not run for a long time but is heavy when it does run. Luckily, I can also watch my MIdnite Classic through the software and see the AMPS demanded change thanks to the WizbangJr monitoring. It's kind of cool to see when you flick on an LED light an see it jump by 0.3a but then flick on the coffee maker & see an extra 60 amps for 6 minutes (no warming plate, thermos type carafe). Those darn < 1.0 amp things are a PITA to figure out into a usage chart.

 

[upnorthandpersonal]

Watts is power, kWh (or watts x time) is energy. If you draw 150 Watts for 20 seconds, than you used 3000 Watt Seconds of energy. 3600 seconds in an hour, means this is 0.83 Watt Hours of energy.

 

[Supervstech]

Watts is power, kWh (or watts x time) is energy. If you draw 150 Watts for 20 seconds, than you used 3000 Watt Seconds of energy. 3600 seconds in an hour, means this is 0.83 Watt Hours of energy.

This is the making sense to my brain explanation I needed...

Thanks very much.!

 

[upnorthandpersonal]

Another way of looking at it: if the load would be on for a full hour, you would have 150 Watt Hours of energy used. Now you only have 20 seconds instead of the hour, so divide by 3600 and multiply by 20 gives 0.83 Watt Hours.