Working UPS battery voltage is low

Working industrial ups power supply battery voltage is low, but start charging more than 10 hours of battery charge voltage is still not up.
Failure Analysis: Phenomenon judged from the battery or charging circuit failure, according to the following steps to check:
- Check the charging circuit input and output voltage is normal;
- If the charging circuit input is normal, the output is not normal, disconnect the battery
Then measured, if not normal, compared with the charging circuit fault;
- After disconnecting the battery charging circuit if the input and output are normal, then the battery is not charged due to long-term, over-discharge or other reasons, to the life of the damage.