A 24v battery would need to have 2x the AH as a 12v battery...

[fblevins1]

I think you have pretty much zeroed in on my weakness. Real time measurements are somewhat easy for me but when you start talking about amp hours and wat hours my mind goes bonkers. I mean if you have a real time 100 watts the time thing is so hard for me to understand. If I am measuring 100 watts and 10 seconds later it is is still 100 watts I just don't get it. Then again, I have been hitting the port so probably best I defer this until tomorrow.

 

[MichaelK]

Yeah, I'm trying to figure out how that happened?

 

[fblevins1]

You've got all the numbers wrong. Go back and correct them. The Voc is ALWAYS greater than the Vmp, and the Isc is always greater then the Imp.
View attachment 60887

O _ O

 

[MichaelK]

Sorry fblevins, that was not directed at you!

 

[fblevins1]

Sorry fblevins, that was not directed at you!

Oh crap, you just made me realize I answered another post in the wrong thread. Whooopsie, thanks for chiming in, my O _ O was directed at you but I also realized I was posting on the wrong thread. I blame the port wine. Nothing to see here.

 

[John Frum]

I think you have pretty much zeroed in on my weakness. Real time measurements are somewhat easy for me but when you start talking about amp hours and wat hours my mind goes bonkers. I mean if you have a real time 100 watts the time thing is so hard for me to understand. If I am measuring 100 watts and 10 seconds later it is is still 100 watts I just don't get it. Then again, I have been hitting the port so probably best I defer this until tomorrow.

I bet you are no stranger to work and have collected a paycheck or 2 in your time.
Man hours is a measure of work.
The idea is that a man can do some amount of work in an hour.
Say that he works 40 hours a week.
Its expected that he will do 40 times the amount of work that he can do in an hour.

Watts are a measure of work.
Watt hours a measure of work over time, same as man hours.

 

[Lt.Dan]

I think you have pretty much zeroed in on my weakness. Real time measurements are somewhat easy for me but when you start talking about amp hours and wat hours my mind goes bonkers. I mean if you have a real time 100 watts the time thing is so hard for me to understand. If I am measuring 100 watts and 10 seconds later it is is still 100 watts I just don't get it. Then again, I have been hitting the port so probably best I defer this until tomorrow.

This has gotten me confused a few times as well, and smoothJoey has explained it pretty well.

Basically, if you have a 100 watt load, and you leave it for 10 minutes, it will have only consumed 16.6 watts. If you leave it for 30 minutes, it will have only consumed 50 watts, etc.

 

[rmaddy]

Basically, if you have a 100 watt load, and you leave it for 10 minutes, it will have only consumed 10 watts. If you leave it for 30 minutes, it will have only consumed 50 watts, etc.

Right idea but 10 minutes is 1/6 of an hour so it would have been 16.6W with a 100W load. And that assumes a constant 100W load.

Here's another way that may help.

Let's say you have an LED light that uses a constant 10W and say it is on a full 24 hours. In a day it would consume 10W x 24hours = 240Wh.

Or you have a 100Ah capacity 12V battery. 100Ah x 12V = 1200Wh of available energy. Now you want to know how long that battery can power the 10W LED light. 1200Wh / 10W = 120h. You can run the light 120 hours assuming you could use the full 100% capacity of the battery at 100% efficiency.

The math is all pretty simple. The really important part is keeping the units correct and that is also part of the math.

Earlier I said the LED uses 240Wh/day and the battery is 1200Wh. 1200Wh / 240Wh/day = 5 days. And 5 days is 120 hours. Same result.

 

[Lt.Dan]

Right idea but 10 minutes is 1/6 of an hour so it would have been 16.6W with a 100W load. And that assumes a constant 100W load.

You are 100% correct. It was too early when I was typing lol. I will correct my post.