Amp hours vs Watt hours

[electricthot]

I am off grid, and get all my power from the sun. I am wanting to compare my daily use with my daily charge rate. My solar charger has a meter that gives me daily output in amphours. But the meter I bought to measure my disharge rate only gives it in watthours. Is one better than the other, or do I simply need to learn to convert watthours to amphours (or amphours to watthours)?

[J.P.M.]

Daily or other time period use of energy is described by watt-hours. Amp-hr. has more meaning/usefulness for charging and storage systems.

Short but incomplete answer to your question is yes.

Learn the basics of electricity and understand the relation between current, voltage and electrical resistance (and/or impedance), and the difference between power and energy.

[Sunking]

Amp Hours is meaningless without a Voltage.

Watt Hours = Nominal Battery Voltage x Amp Hours.

But make no mistake if you look at how many Amp Hours you put into a battery and apply the above formula will not work like you think because a battery is not 100 efficient charging, and Amp Hours go in at a higher voltage than they come out of a battery.

Example lets say you put 100 Amp Hours in at 14 volts and comes out at 12 volts which is realistice

14 volts x 100 AH = 1400 watt hours.
12 volts x 100 AH - 1200 watt hours.

[electricthot]

I understand you have to put about 25% in a battery more than you took out to get it fully charged.
But the meter I'm using to measure how much I'm using uses real time voltage to calculate wattage, rather than nominal voltage. Since the voltage in my system can vary by nearly two volts through a 24 hour period, can I just use a value somewhere in the middle to convert watt hours to amp hours?

[Sunking]

Since the voltage in my system can vary by nearly two volts through a 24 hour period, can I just use a value somewhere in the middle to convert watt hours to amp hours?

No. When it comes to electrical energy and engineering we use a Micrometer to measure things, use Chalk to mark the line, and a dull Ax to makes the cut. You can get close enough to make it work. Just too many variables that come into play. Example you are not taking into account wire losses, Peukert effect, and temperature.