UPS problem

i have a twister 1.2kv ups. i have connected a 12V 135 AH AGS battery (about 4 months old) with it. The battery capacity is low because i have a generator, so as soon as electricity goes out, ups takes over. and after 1 min, generator starts hence charging the ups. The problem i am facing is, when UPS is receiving input from WAPDA (implying electricity is present) it shows battery capacity at 100%. i checked the terminals of battery (with digital voltmeter) which show 12.8 V which isnt right, since fully charged 12V battery should show 13.5V. as soon as i turn the input to ups off (implying electricty as gone out) the ups starts showing 10% battery capacity, and the voltage of battery rapidly drops from 12.7 to 11.5 (within a matter of minutes).

^ if the ups was working fine before this problem with THIS battery..then Probably fault battery... requires checking specific gravity when battery shows 100% charge

Otherwise UPS charging kit may need adjustment,

i m pretty sure the battery is fine, because this is the 3rd or 4th battery with this ups, and ups showed similar behaviour with all of the batteries. if the ups charging is faulty, how shall i charge the battery to 100% to check its specific gravity at full capacity? also, what should be the voltage of a fully charged 12V battery?

during winter, the load was only energy savers. so the ups showed 100% charge on wapda, and constant 40-35% during load shedding. i suppose it stayed pretty much constant since not much current was being drawn from battery because the load was too low (merely 200Watts i guess)

I think better is fine. Just remove terminal lug from battery and clean it properly then install back. There seems to be a rust between the lug and the battery terminal that does not allow current to flow and charge battery properly. I have faced this problem many times specially after winter or rainy season when the moisture creates a bit of presence in that area,

[quote=", post:3, topic:20960"]

i m pretty sure the battery is fine, because this is the 3rd or 4th battery with this ups, and ups showed similar behaviour with all of the batteries. if the ups charging is faulty, how shall i charge the battery to 100% to check its specific gravity at full capacity? also, what should be the voltage of a fully charged 12V battery?

during winter, the load was only energy savers. so the ups showed 100% charge on wapda, and constant 40-35% during load shedding. i suppose it stayed pretty much constant since not much current was being drawn from battery because the load was too low (merely 200Watts i guess)

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if it is similar behaviour, then your ups is at fault.

get it charged from market for around 100rs or so..

full charged battery should be at 13.5-13.75 depending on age of battery..it should discharge to 12.5V on load within minutes, then stay on this for the backup till 11.5V.

low load doesnot matter..