Checking battery status

Hi,
For a project I need to check the condition of UPS installed at remote places. For this I plan to check the battery also electronically and the send the data through mobile network. To check the battery condition, is it enough to check the battery voltage alone. I want to know whether the battery is down or normal. If the battery is above certain voltage I am going to consider it as normal and if it is below certain voltage ,I will consider it as low. Is this method correct?

Have a look at https://www.electro-tech-online.com/custompdfs/2011/05/lead_acid_battery_charging_graphs.pdf - it states that voltage, current and temperature (and probably other things) affect the state of charge.

Some battery status devices use coulomb counting to determine the state of charge (SOC); i.e. measure the charge going into the battery as well as the charge going out of the battery (must take into account the battery loss) to determine the SOC.

Thanks for the information.