Backyard Aquaponics
A place to discuss aquaponics

Hi B
I have one of these and have been using it for a while. The Amp-hours and watt-hours is simply the total energy and amp consumption from when you start the unit. You can calculate how much energy you have drawn from your batterybank (and the use this to do a theoretical calc of the energy left in your battery bank). Note that the max watt-hour that the unit display is 7000 watt-hour, it will then start from 0 again.

Thanks everyone.

I did a test on my battery today and after half an hour from fully charged, it looks like it is in fact telling my how much I used rather than what's left.

I still cant figure out how to tell how much battery I have left though.

If 11.8v is empty when at rest without load, what voltage is empty when I'm drawing 19 or 35 amps?

seems to be the only thing left

How much is left is a tricky thing. Batteries capacity changes over time and usage.....or abuse.
Volts is a method but very rough
Some high end devices measure usage then predict whats left using equation, usually you have to say how big the battery bank is then set how far you want to draw down - 40-50% is as far as many prepared to go.
There is a device which uses capacitance?? to estimate batteries capacity, not sure how accurate but gives a snap shot of batteries max capacity at that point in time.

Other way is to look at battery Ahr, say 50% usable, watch watt meter usage stop when it gets to that point.

The problem is I have no idea what the real capacity of my battery is because of it's age.

I can run it to empty and check, but I'll have to do it over a few days (running then resting it then checking it), but I was trying to avoid leaving it close to flat for that long.