Amps per hour? Horsepower per hour?

[BatteryPro]

Originally Posted by ;2430852

... use 1/2 an amp per hour.

Some other brands, I have seen, use up to 4 amps per hour...

Originally Posted by 2430508

….As an example the phantom draw in our coach is around 4 amps each hour.

[moderator edit] I show [moderator edit], for example, a 10 amp PV solar module. They then ask me, is that 10 amps per hour?

Let’s look at this often used phrase, “amps per hour”. You see it used quite often in forums discussing power. Would you believe that this phrase is meaningless? It is! If I told you my car can produce 400 horsepower per hour you would wonder what I am saying. Am I saying it’s 400HP only if I run it for 1 hour? Or, does it take 1 hour to make 400HP? What if I only ran it for 1 minute? Then would I say it is 400HP per minute? Again confusing.

Amperes or amps is the term that defines current flowing in a circuit. If I turn on a load that is drawing 10 amps, it does not matter if the time is 1 second, 1 hour or 1 week. It is just a measure of current flowing and time has nothing to do with it.

The confusion comes from another term that does relate to time, “amp-hours” or AH. It is a reference to a quantity of something, much like a gallon is a quantity of a liquid. Amp-hours are a quantity of current flowing multiplied by time. A 10 amp load running for 1 hour is 1AH. But what if the load is only for 30 minutes or 0.5 hours? Multiply time (in hours) by the load: 0.5 X 10 = 5AH. If the load was for just 1 minute it would be 0.16 AH used.

The same applies to the term Watts and Watt-Hours. Watts is a measure of power, Watt-hours is power over an amount of time.

So, there is no such thing as "amps per hour" like there is no such thing as HP per hour.

Amps = current
AH = current over time
Watts = power
Watt-hour = power over time


Larry

[tncruiser]

if it were I ,Iwould draw an analogy of mpg @ idle vs parasitic draw under a no switch load draw. When I was a young lad I sold floor care at sears an engineer wannabe metal clipped scale in front pocket and all told me there was no way a vacuum clnr could be 3.5 hp and if I proved it he would buy my best model (can you say $55.00 commission in 1965) so I explained ohms law and locked rotor amp draw (which is the industry standard) and "learned him how it r done" then asked will that be cash or charge ,HE CHARGED IT
brianj

[BatteryPro]

This is the problem with evil minded marketing people. They use deception and guile to steal from lesser intelligent people. The deception in this case is advertising a 3.5HP motor which obviously (to you and me) is not turning under LRA so no vacuuming is happening. The instant the motor starts turning, current is greatly reduced until the 1/4HP motor is sucking up the dirt.

I remember seeing 2000 Watt car stereo amplifiers for $49.95 weighing all of 8 ounces. Same lie.

[wa8yxm]

I have never seen (Before your post) the phrase "Amps per hour"

What I have seen is "Amp Hours" which does have meaning and is totally different.. And I have seen so much confusion that I believe it is our 52 state (we have 53 if you count Washington DC as 51, and Denial as 53)

Amp hours is usually expressed as a quality of batteries and is at the C/20 rate. So a battery rated 100 amp hours, can deliver 5 amps for 20 hours (C=100/20hours)

SO a 10 amp panel, in full sunlight, in theory can deliver about 10 amp hours NOT amps per hour, but Amp hours.

In reality, most of 'em max out about 5

[BendOR]

Originally Posted by BatteryPro

...

A 10 amp load running for 1 hour is 10AH.

...

Larry

Fixed your post.

[BatteryPro]

Originally Posted by BendOR

Fixed your post.

Oops! Fixed Indeed. Thanks for that.

Larry