APC RBC44 Battery Assembly Guide


When your APC RBC44 battery cartridge is on the fritz, there are two ways in which you could go about replacing it. The first way is to go directly through American Power Conversion company whom is the original manufacturer of the RBC44 and purchase a replacement through them. The second choice is purchasing the individual batteries that power your RBC44 cartridge and replace them yourself. When it comes time to replace your RBC44 battery cartridge, the only components that have gone bad and need to be replaced are the small sealed lead acid batteries within.

This article is for those of you who have chosen to replace the batteries yourself. I will assume that you have already purchased a APC RBC44 battery replacement kit and are  ready to put them in and get your Back-UPS up and running again.

Tools You Will Need For the RBC44 Installation


  • Philips Head Screw Driver
  • Flat Head Screw Driver
  • Pliers (not necessary but will make your life easier!)
  • 16 - 12V 5AH SLA Batteries (each RBC44 pack has two banks of 8 batteries)


Removing the Spent 12V 5AH Batteries


It is time to remove the APC RBC44 cartridge from your rack mount UPS system by disconnecting the plug that leads from the battery cartridge to the unit. Once the plug is disconnected, you can then slide the cartridge all the way out of the unit by pulling on the metal handle located on the front of the battery cartridge (underneath the plug). Once the unit is out of the UPS, its time to remove the cover to reach the sla batteries.

In order to get to the actual battery compartment of the RBC44 cartridge, we must first remove the top cover. To do this, you will have to remove the two Philips head screws located at the far end of the unit. The sole purpose of the two small steel screws is to secure the lid to the frame, so once you have removed them you will then be able to pull back on the lid and remove it from the cartridge entirely. Once you have gotten the lid off, you should now have a clear view of the 8 - 12V 5AH batteries.

Now this is one of the most important parts of the entire process - the wiring of the 12V 5AH batteries - which will become visible when you remove the two plastic terminal covers running down both sides of the cartridge. I have personally done so many of these units that I have memorized the wiring diagram, but I do recommend that a person with less experience in APC battery installations proceeds without either taking a picture (via camera phone) or drawing a quick wiring diagram for themselves. In your diagram or picture, make sure to make a note on how the batteries are placed inside the cartridge!
Once you have made a diagram of your choice, its time to remove the wiring from the batteries. The easiest way to do this is by using a pair of pliers to fist apply pressure to the plastic clips and then tug them off. These clips are unique from your run of the mill spade connectors in that they actually use a small metal fitting that secures them to the terminal of the 12V 5AH batteries. This metal fitting is “released” when pressure is applied to the plastic housing.

Once the wiring is removed from all the batteries, it is time to remove the spent batteries themselves. The easiest way is to use your pliers to get a grip on a single terminal of the battery and pull upwards until you can remove the battery by hand. This should prevent any fingers getting jammed or cut!

Installing the New 12V 5AH SLA Batteries


Alright, now that you have an empty RBC44 battery cartridge its time to install your fresh set of 12V 5AH batteries. I begin by placing all of the batteries inside of the cartridge before I begin attaching any wires. I have found this to be the most efficient way to not get confused when re-wiring the batteries! When setting the batteries in the cartridge, make sure that the terminals are facing the same way as when you removed them.

After the batteries have been replaced inside the RBC44 cartridge, its time to grad your diagram and re-wire the batteries. Once you are finished with the re-wiring, you can double check that it is correct by checking the voltage of the pack through the plug on the front of the battery pack - you should be seeing something around 100-104 volts. Assuming that you have wired up your batteries correctly, its time to place the lid back on the unit. This lid is a simple slide and lock design, so make sure the hooks on the lid line up with the holes on the side of the case and push forward until it is flush with the frame of the unit. Once the lid is on, re-insert your two Philips head screws and your all set!