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Repair - APC Back-UPS RS800


On one beautiful day the server died. And could not run. Everything was dead like a rock. The culprit was the UPS; the batteries failed and the UPS refused to run anymore.

The brand-name replacement batteries were available, but for significant cost and from an inconveniently located store. A different solution was therefore attempted.

UPS, front panel

UPS case label

Battery compartment


The failed battery pack was disassembled. It turned out that the brand-name labels hide underneath a pair of fairly standard sealed lead acid batteries, 12V/7Ah.

Battery pack

Battery pack detail

Old battery detail

Battery pack connector

Battery pack, disassembled

Battery pack, disassembled

The local vendors were queried and a replacement battery was chosen; a Shimastu-brand battery, 12V/12Ah, for significantly lower cost and with stated higher lifetime. Double-bonus, if that's true.

The batteries were bigger than the original; it was decided to not worry about it and just stand them next to the UPS. Who cares anyway. At least they will be better cooled if needed.

The new batteries however had slightly narrower fastons than the old ones had. A minor annoyance. Adapters were fashioned from larger fastons, the smaller ones on the batteries got 3mm holes drilled in, and the fastons were attached with M3 screws, using spring washers to maintain firm contact over time.

The cable from the original pack was just long enough to faciliate connections to the batteries without need for further modifications.

New battery detail

Battery terminal adapters

Battery terminal adapters

Battery terminal adapters

Battery connection

Battery connection detail

To facilitate easier transportation of the batteries and their placement in position, carriers were fashioned from a few loops of sellotape. The carrier part got the sticky side covered with a length of opposite-sided tape. The result is a handle that allows comfortable holding, carrying, and lowering of the battery to the place where it should be.

As the terminals were exposed, and as a contact of a conductive thing fallen across them could release a high enough amount of energy to cause a fiery problem, the terminals were capped with insulation caps made from PET bottle caps and affixed to place with a dab of silicone.

Battery carrier

Battery carrier

Terminal caps

Terminal caps, in situ

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