Cell Replacement procedure for APC Smart-UPS X 3000 Battery Packs

NOTE: This article specifically the APC Smart-UPS X 3000 UPS Units (Model SMX3000RMLV2UNC) and the APC RBC117 Battery cartridge. Other covered models include, but are not limited to: SMX3000RMLV2U, SMX2000RMLV2U, SMX3000RMVL3U, SMX2000RMLV2UNC, FJX3000RMHV2UNC, SMX3000RMHV2UNC, SMX2200RMHV2U, SMX2200RMLV2U, and SMX3000RMHV2U.

Wiring Diagram and Notes:

The RBC117 Battery Cartridge uses Ten (10) 12-Volt Sealed Lead-Acid (SLA) batteries, wired in series. The aftermarket replacement cell for this pack is an 12V 5.5 Amp-hour battery with F2 terminals and dimensions of approximately 3.54L x 2.76W x 3.98H.

IMPORTANT: Cells of different ages (used, new, etc) should not be used together, nor should cells with different AH or voltage ratings. ALL batteries in a cell should match, period. This also applies to refurbishing multiple battery packs within a single UPS or expansion unit.


This is a diagram (not to scale) of the wiring for this battery pack. All batteries are wired in series; it is VERY important that the connections between batteries are from red to black and vice-versa. NEVER connect a battery terminal to the other terminal of the same color; at best, this will damage the cells, and at worst, could cause the cells to violently erupt.

The interconnections between the cells are generally short black cables. The exception is the longer yellow cables in the top row. The longest cables run back to the plug that connects to the UPS or expansion unit, and those are colored to match the terminal they connect to: the long red cable runs from the last red terminal in the battery chain to the plug, and the long black cable runs from the first black terminal in the battery chain to the plug.

Note: When re-wiring the new cells, the long cables from the plug to the circuit endpoints down the middle between the two rows of batteries, contrary to what the wiring diagram indicates.


Disassembly Instructions:

There are five (5) screws securing the lid to the pack. Remove the three (3) that are indicated here and set them aside.
Remove the two (2) remaining screws indicated here and put them with the other lid screws. The lid, which has locking tabs, can now be slid off in one direction and set aside.
Remove the off-white plastic spacers and set them aside.
Remove the thin plastic shielding on the left and set it aside.
Starting from the middle of the top row, disconnect all the battery cells, carefully remove them, and set them aside for recycling. Retain the interconnecting cables, which will be re-used.


Reassembly Instructions:

Install the new cells exactly how the old ones were installed, working in reverse from the disassembly instructions. Follow the wiring diagram at the beginning of this document, and take extreme care that no battery terminals are wired to a terminal of the same color.

Once the unit is reassembled, you can verify the voltage with a multimeter. It should read approximately 120 volts DC or a few volts above (10 Cells in series x 12 volts = 120v).

Finally, before installing the battery packs, label each with the replacement date. Take care that the label is placed so that it will not be damaged when inserted into the UPS chassis, and will be obvious when the cells are replaced or inspected (Image is from a APC SMT 3000 unit.)

See Also: