Calculating State of Charge (SOC) for AGM Lead Acid Battery Using Inverter Data

Hello,
I am trying to come up with an equation to measure state of charge from an AGM battery. Because it is led acid, there is voltage sag with medium to high loads. This makes the voltage method completely unreliable. I am using a smart inverter that can tell me the following: Output AC voltage, Output AC Load, AND Battery Voltage (Taken every second). If I know the output AC load I can calculate the DC load. But how can I convert this to ah so i can subtract it from the known usable ah of the battery? Alternatively, is there an equation that accounts for dc load and voltage to give me a more accurate State of Charge? Thank You in Advance!

Hi Cody,

Here are some articles about how to measure the state of charge.:
# State of Charge (SOC) Determination
# How to Measure State-of-charge
# DEEP CYCLE BATTERY VOLTAGE & STATE OF CHARGE
# Battery Basics: A Layman's Guide to Batteries
# Lead-acid batteries

I hope this helps,
Kevin