I have a local made UPS 500W (not pure sine wave) for home use. I connected OSAKA lead acid battery 190A. Now just after 11 months of use, I have observed that during charging battery voltage don’t exceed from 12.4V while UPS cut-off voltage is 14V. Normally if such problem appears, battery generates heat but temperature of my battery is remained normal. During UPS working, battery voltage drops at almost 11.6V and after one hour almost 10.5V. Our load is just two (some time three) PAK ceiling fans and two energy savers. I also checked the gravity of battery acid which was low but after a long time charging at high current, it is now ok.
Does any body have experience in such case? Is this problem is related with battery or UPS?