This battery arrived in a box ten times too large, very loosely packaged and sliding around in the box. There were some loose pieces of borken plastic in the box that I have to assume broke off of the battery somewhere, but I could not find the damage. Although the battery installed and operated as it should, I remain nervous about the reliability of the battery and I am considering returning it for a proper replacement.

Purchased the APCRBC124 replacement battery through Amazon on 11-26-2017 (just as I had done back in 2014 when the unit indicated it required replacement, and the replacement worked without issue). This time this replacement failed self test from the start. I will give it a few hours to 'charge' before testing again just in case that may be the issue. Unit does indicate full charge but I hope it just needs a little top off time. If not I may look at another brand before deciding whether to replace the unit entirely or go through the hassle of trying to get a working replacement battery. I will update after a retest.

********Update- 12-6-2017
Installed 12-4-2017 and failed the self test at install as stated above. I gave it a couple days of charge time and ran another self test on 12-6-2017. This time it passed. I really hope it lives up to the 3 years they claim it should last. The first battery that was in the unit when I purchased it only lasted 2 years. The first replacement battery I had purchased in 2014 and it passed the self test right away. That one did end up lasting the 3 years as expected. This third and most recent replacement 2017 has me a little worried that it will not live up to the 3 years as claimed- we will see. I will add a couple of stars for now due to the fact it passed the self test on this second attempt after some charge time.

The battery in my BX 1550 G was overdue for replacement and suddenly failed in the middle of the night. I hot swapped this new replacement battery in less than one minute. It came pre-charged so it was ready for use. The unit came with installation instructions. There are also battery replacement instruction videos on the APC website. The unit did not come with recycling instructions. However, you can download a UPS shipping label for free recycling shipping from the APC website at "who-we-are/sustainability/recycling-options." Resealed the same shipping box.APC UPS Replacement Battery Cartridge for APC UPS Models BR1500G, BR1300G, SMC1000-2U and select others (APCRBC124) Dropped it off at UPS. Done and done!

Good batteries, but NOT for older "Back-UPS XS 1500".

The APC website says this is the correct set of batteries for a "Back-UPS XS 1500". But it does not fit.
This battery pack has two batteries with the leads facing each other in a "module". My "Back-UPS XS 1500" has two separate batteries set beside one another with both battery leads facing up. And my "Back-UPS XS 1500" uses two cables to connect to the batteries, not the plug that is on the side of this module.

Battery works great - took out old one, put in new one, did a self test, and it is perfect! Reason I deducted 1 star - these *real* APC batteries are supposed to come with free return shipping - this one didn't. But it did come with Australian warranty paperwork! So, now I have to drag the old battery someplace that will recycle it.

Update: I went to APC's website and found out that my local Ace Hardware would take the battery pack. I called there first - they said yes, no problem, they would take it. I dropped it off and I'm done! I would call first if you get a place from APC's website - I noticed they show many Radio Shack stores in my area, which are all closed.