Valve regulated lead-acid（VRLA） battery is widely used as DC backup power of substation.Since it is always at floating state for a long term

it still has the re-sue value.In this paper

the test platform including battery tester and electrochemical workstation is set up for experimental test of the 25 pieces of retired VRLA batteries provided by SHENSHAN substation of Guangzhou Electric Power Supply Co.

Ltd..Such experimental data as basic charging and discharging curves

battery capacity and internal Ohm resistance is obtained and

based on this experimental data

the performance of the retired battery is analyzed.It is shown by the experimental result that that the floating work state doesn’ t change charging and discharging curves and internal ohm resistance of battery has a definite relationship with capacity.SOH data provided by grid Co.has large deviation from the real value

which indicates SOH estimation method applied by grid Co.is not ideal.The study in this paper lays foundation for application of retired battery in energy storage.