Hitachi G200 Hardware Reference Manual page 104

If the storage system is not charged for more than six months, the battery
can become overcharged and sustain unrecoverable damage. To avoid this
situation, charge the battery more than 3 hours every six months.
Insulation performance
Insulation withstand voltage
Insulation resistance
104
Item
VSP G200 storage system mechanical specifications
Hitachi Virtual Storage Platform G200 Hardware Reference Guide
Specifications
AC 1,500 V (100 mA, 1 min)
DC 500 V, 10 M Ω or more