Back-UPS CS-650 dead after troubled battery replacement

[Anonymous user]

I have an old APC Back-UPS CS 650 (RBC17 battery); after 4 years the original APC 12V 9Ah battery was then replaced by a 12V 7,2Ah battery, which lasted a few months less. Last time, I purchased a battery on Ebay advertised as

“Gel battery AGM Elsy Power 12V 7,5Ah ideal for UPS compatible with APC RBC2 RBC17. The battery capacity is determined considering the discharge at 1/20 ° of the nominal capacity in 20h with 10.5 V at the end of the discharge. We recommend using a suitable and appropriate charging device.

nominal voltage: 12V

nominal capacity: 7,2Ah

stand by use 13,5-13,8 V

cycle use 14,5-15 V

initial current: 2,1A”

After some weeks of regular use, with the refund period already expired, the overload/replace battery red leds started to flash continuously. The seller advised me to disassemble the battery, measure the residual voltage and have an external charge cycle carried out, to exclude that there may be a charging problem and  the APC had not charged the battery correctly.

I could not run the tests but with his help I discovered the battery had 4,8mm faston pins instead of usual 6,3mm; the seller suggested to purchase a correct  6.3 mm version, he said having also a larger charge load. I ordered a new battery, but the only available 6,3mm version was a little different, 12V 10Ah, advertised as:

“Gel battery AGM Elsy Power oversize version 12V 10Ah 9Ah for UPS, ideal for UPS compatible APC RBC2 RBC1. The battery capacity is determined considering the discharge at 1/20 ° of the nominal capacity in 20h with 10.5 V at the end of the discharge. We recommend using a suitable and appropriate charging device.

The dimensions are identical to those of the common 7Ah despite having the nominal amperage of 9 Ah.

It can therefore be installed in place of the common 7Ah by checking in advance the size of the connection fastons and the charging capacity of the device in which they are installed. It allows you to increase the autonomy of electronic devices quickly and without precautions. 10Ah model with same size of 7Ah 7.2Ah 8Ah 9Ah. With this model it is possible to obtain the maximum power for batteries of this size.

nominal voltage: 12V

nominal capacity: 10Ah

stand by use 13,5-13,8 V

cycle use 14,5-15 V

initial current: 2,7A

maximum discharge current: 120A (5s)”

In brief, the battery has a 10Ah capacity instead of the original 9 Ah APC battery. After one day of use, the APC is now almost dead, no output, no flashing leds nor alarm sounds, only some little buzzs and strange whispers and casual briefly lighted lamps. At this point, I think it is useless to install Powerchute to verify anything, so I ask if someone could suggest me a test for the device or the battery, and an opinion about my possible errors and about information/advice correctness provided by the seller. Thank you!