APC Back-UPS 1500 Battery Replacement by Exact Model

Do not order by “APC Back-UPS 1500” alone. Find the complete model number on the UPS label, then match that model to its specified replacement battery cartridge. APC has sold multiple 1500 VA units that do not all use the same cartridge.

Two verified 1500-model matches

The BR1500MS2 manual names APCRBC163, while the BX1500M manual names APCRBC124 for both BX1500M variants (BR1500MS2 manual; BX1500M manual). Schneider Electric describes APCRBC124 as a 24 VDC, 9 Ah replaceable cartridge for compatible Back-UPS and Smart-UPS units—but that electrical description is not a substitute for model compatibility (APCRBC124 product page).

If your label says BR1500G, BN1500M2, BR1500MS, BX1500M, or another similar designation, treat every letter and suffix as significant. The table only establishes the exact models shown. Use the replacement-battery section of your model’s manual or APC’s support tools for anything else; do not select a cartridge merely because another UPS also says “1500.”

Replace the battery before outage protection becomes uncertain

For the BR1500MS2, APC instructs owners to replace the battery at least every five years or at the end of service life, whichever comes first, and immediately when the UPS signals that replacement is necessary. Its manual also requires the same number and type of batteries originally installed (BR1500MS2 manual).

The BX1500M manual gives a typical battery life of three to five years, shortened by frequent outages or elevated temperatures. It says an illuminated replace-battery indicator means to replace the battery as early as possible (BX1500M manual). Age is therefore a planning range, not proof that a particular battery remains dependable.

If there is electrolyte leakage or a battery over-temperature warning, do not treat this as an ordinary cartridge swap. The BR1500MS2 safety instructions say to power off the UPS, unplug it from AC, disconnect the batteries and not operate it until the batteries are replaced (BR1500MS2 manual).

Replacement and outage-readiness checklist

1. Read the model label, not just the front-panel “1500” marking. Record the complete model and suffix.
2. Confirm the cartridge in that exact model’s manual. Buy the complete specified cartridge rather than improvising from battery dimensions or voltage.
3. Protect the connected load first. Save work and shut down equipment that cannot tolerate interruption. Follow the illustrated battery procedure in the exact UPS manual.
4. Inspect rather than force. Stop if the battery is swollen, leaking, unusually hot or will not move normally; use APC support or an appropriate battery service instead.
5. Allow a full recharge before depending on it. Both cited 1500-model manuals specify a 16-hour typical recharge time (BR1500MS2 manual; BX1500M manual).
6. Run the UPS’s built-in self-test and check its status. Both manuals document a manual self-test using the front-panel controls.
7. Check outlet placement. Equipment that must stay on during an outage belongs in a battery-backup outlet, not a surge-only outlet. The manuals state that surge-only outlets continue surge protection but do not provide battery power during an outage.

Finally, test with only the devices you actually need during a blackout. UPS runtime is load-dependent, and the BR1500MS2 display reports estimated remaining runtime rather than a guarantee. Remove nonessential loads and plan around usable energy, device demand and battery condition; battery charge and runtime explains why the result can differ from a simple nameplate estimate.