... )CE&UL approved 5) 8 years manufacturer Lead acid battery 6V 4Ah:Application: new energy, telecommunication, banking, medical industry, fire fighting ... do have a normal open circuit voltage without leakage, batteries swelling or cracking problem after one-hour vibration. 4. ... normal open circuit voltage and be without leakage or batteries swelling or cracking after droping three times from 20cm ...