Replacement Batteries for Emergency Lighting

Last updated: November 2026

Quick Answer: Most emergency lights and combination exit signs that run on sealed lead acid use a 6-volt SLA (Sealed Lead Acid) battery, typically rated between 4.5 to 12 amp-hours (Ah) with F1 terminals. Newer LED fixtures may use NiCd or Lithium (LiFePO4) packs instead. To ensure your building passes the mandatory 90-minute NFPA 101 Life Safety Code test, you must replace your failing battery with one that perfectly matches the original chemistry, voltage, and physical dimensions.

Failing an annual fire safety test can lead to code violations. Fortunately, replacing your battery is an easy, low-cost fix. This guide covers how to identify your battery, testing requirements, and step-by-step replacement instructions.

In a hurry to pass your inspection? Shop exact-fit emergency light replacement batteries at BatteryClerk today for fast shipping and volume discounts.

What Battery Does an Emergency Light Use?

Emergency lights and exit signs use one of three battery chemistries. The fixture charges the battery continuously from building power. When the power fails, it switches to the battery automatically and lights the exit route.

• Sealed Lead Acid (SLA/AGM): Found in two-head emergency lights, combo exit/emergency units, and larger remote-capable units. Identifiable by a rectangular black or gray case, 6V or 12V on the label, and spade terminals. Typical life is 3 to 5 years.
• Nickel-Cadmium (NiCd): Found in many LED exit signs and compact LED emergency lights. Identifiable by shrink-wrapped cylindrical cells joined into a pack with wire leads and a plug. Typical life is 5 to 7 years.
• Lithium (Li-ion or LiFePO4): Found in newer long-life and self-diagnostic LED fixtures. Identifiable by a wrapped pack with a plug, labeled Li-ion, LiFePO4, or LTP. Typical life is 7 to 10 years.

Life ranges come from fire protection contractor Koorsen and assume normal indoor temperatures. Always replace a battery with the exact same chemistry. NiCd, lithium, and lead acid batteries require different charging profiles, and the charger in your fixture is built specifically for one of them.

Common Emergency Light Battery Sizes & Replacements

The 6V 4.5Ah SLA battery with F1 terminals is the undisputed most common size in emergency lighting. At BatteryClerk, we highly recommend upgrading to our 5Ah version, which fits in the exact same footprint but provides a slightly longer runtime during a blackout.

Here are examples of popular fixture batteries we stock:

• Lithonia ELB06042 Replacement: 6V | 4.5Ah (5Ah Recommended) | F1 Terminal | 2.76 x 1.85 x 3.98 in
• Sure-Lites 026-117SP Replacement: 6V | 4.5Ah (5Ah Recommended) | F1 Terminal | 2.76 x 1.85 x 3.98 in
• Dual-Lite 12-255 (0120255) Replacement: 6V | 5Ah | F1 Terminal | 2.76 x 1.85 x 3.98 in
• Interstate Power Patrol SEC1055 Replacement: 12V | 5Ah | F1 Terminal | 3.54 x 2.76 x 3.98 in

Larger emergency units with more lamp heads or longer remote runs use higher capacities, such as 6V 7Ah, 6V 12Ah, 12V 7Ah, and 12V 9Ah.

Need to replace batteries across an entire facility? We carry top-tier AJC® replacements for Lithonia, Dual-Lite, Sure-Lites, Lightalarms, Prescolite, Chloride, Hubbell, and many other brands. Search our emergency light battery collection by the part number, or contact us regarding our wholesale battery program for volume pricing.

How Do You Match a Replacement Emergency Light Battery?

The label on the old battery and the fixture's model plate tell you what to buy. Check these five things before you order:

1. Voltage: Voltage must match exactly. Never put a 12V battery in a 6V fixture or a 6V battery in a 12V fixture. A mismatch can damage the charger board or leave the lamps too dim to light the exit route.
2. Capacity (Ah): Amp-hours measure how much energy the battery stores and sets how long the fixture can run its lamps. Match the original rating. A slightly higher rating in the same case size, such as 5Ah in place of 4.5Ah, is fine and adds runtime. A lower rating can cause the fixture to fail its annual test.
3. Terminal type: Most 6V emergency light batteries use F1 spade terminals (0.187 in wide). Some larger batteries use wider F2 terminals (0.250 in) or bolt-on terminals. The fixture's wire leads are sized for one type, so match the original. See our guide to SLA battery terminal types.
4. Physical size: The battery has to fit the bracket or strap inside the fixture. Measure the old battery or compare the dimensions on the product page. Upsizing capacity usually means a bigger case, so check the space first.
5. Chemistry: Replace SLA with SLA, NiCd with NiCd, and lithium with lithium. Don't put an SLA battery on a NiCd or lithium charger board, or the reverse. Learn more in SLA batteries vs. lithium.

How Long Do Emergency Light Batteries Last?

Sealed lead acid (SLA) emergency light batteries typically last 3 to 5 years, while NiCd packs last 5 to 7 years, and Lithium packs last 7 to 10 years. However, you should not wait for the battery to die of old age. If the battery can't power the fixture for a full 90 minutes during the annual test, it fails the NFPA 101 test and should be replaced.

Several factors will drastically shorten your battery’s lifespan:

• Heat: Fixtures in hot attics, warehouses, or outdoor housings wear out faster than those kept at the standard 72°F.
• Frequent outages or long tests: Every deep discharge eats away at the battery's total lifecycle.
• A faulty charger board: A board that overcharges or undercharges will kill a brand-new battery early. See SLA battery sulfation for how undercharging damages lead acid cells.
• Long periods without AC power: Leaving a battery connected in an unpowered fixture will drain it and can cause permanent damage (Lithonia warns damage may occur after just 24 hours).

For more ways to extend battery life, read our SLA battery care guide.

Pro Tip for Facility Managers: Don't wait for individual lights to fail. Smart facility managers replace all SLA batteries on a fixed 3-to-4-year cycle to help them stay compliant and pass annual fire inspections. Stock up on AJC® wholesale replacement batteries today.

How Do You Test Emergency Lights and Exit Signs?

Testing is how you find a failing battery before an outage does. In the US, most jurisdictions base their emergency lighting rules on NFPA 101, the Life Safety Code. Section 7.9.3 requires two functional tests for battery-powered emergency lighting:

• Monthly: A functional test at 30-day intervals lasting at least 30 seconds.
• Annually: A functional test lasting at least 1½ hours (90 minutes).

The owner must keep written records of the inspections and tests for the authority having jurisdiction (AHJ), usually the local fire marshal.

What a passing test looks like

NFPA 101 requires emergency lighting to provide illumination for at least 90 minutes when normal power fails. If the lamps go out or fade badly before the 90 minutes are up, the battery or the fixture has failed the test.

How to run the tests

1. Press and hold the fixture's TEST button, or switch off the circuit breaker feeding the fixtures, to simulate a power failure.
2. Confirm every lamp head and exit sign lights up right away and stays bright.
3. For the annual test, leave the power off for the full 90 minutes and check the lamps at the end.
4. Restore power and confirm the charge indicator comes back on.
5. Write down the date, the result, and any fixtures that failed.

Note: Self-testing/self-diagnostic fixtures run these routines on their own and show failures via an LED indicator. However, you must still visually inspect them every 30 days and keep written records.

What Are the Signs an Emergency Light Battery Needs Replacing?

• The lamps don't come on, flicker, or go dim during the 30-second monthly test.
• The fixture can't stay lit for the full 90-minute annual test.
• A self-diagnostic fixture shows a battery fault on its status LED.
• The charge indicator stays off or shows a fault after the fixture has had 24 hours of AC power.
• The battery is swollen, cracked, leaking, or corroded at the terminals.
• The battery is past its expected life (3 to 5 years for SLA) or past the date on its service sticker.

How to Replace an Emergency Light Battery

These steps cover a typical wall-mount emergency light or combo exit sign with a 6V or 12V SLA battery. If the fixture is hardwired at height, on a fire alarm-monitored circuit, or if you aren't comfortable working on electrical equipment, have a qualified electrician do it. Review our SLA battery safety tips before you start.

1. Turn off the power to the fixture. Switch off the branch circuit breaker that feeds the unit. The fixture will switch to its old battery, which is normal.
2. Open the housing. Remove the faceplate or cover screws, or release the clips, and locate the battery and its bracket.
3. Disconnect the old battery. Pull the black (negative) lead off first, then the red (positive) lead. Pull on the connector, not the wire.
4. Check the new battery. Confirm the new battery has the same voltage, terminal type, and size. A healthy new 6V SLA battery should read about 6.3V or higher on a multimeter.
5. Connect the new battery. Push the red (positive) lead onto the positive terminal first, then the black (negative) lead onto the negative terminal. Secure the battery in its bracket.
6. Close the fixture and restore power. Refit the cover and switch the breaker back on. The charge indicator should light.
7. Let it charge, then test. Allow 24 hours of charging before the first test. After that, press TEST to confirm the lamps come on, and record the replacement date in your test log.

Want a quick printable version? See our emergency light battery replacement guide.

Why Do So Many Emergency Lights Use Sealed Lead Acid Batteries?

SLA batteries have powered emergency lighting for decades, and they are still the standard for several reasons:

• Built for standby duty: SLA batteries are designed to sit on a continuous float charge for years and deliver full power when the lights go out. See other uses of SLA batteries.
• Low cost: At the time of writing, AJC® 6V 4.5Ah emergency light batteries cost under $10 on BatteryClerk.
• Maintenance-free: AGM construction is sealed and spill-proof, with no water to add. Read more about AGM battery pros and cons.
• High current: SLA batteries easily supply the higher current that multi-head units and remote lamp heads draw.

What Should You Do With an Old Emergency Light Battery?

Never put an emergency light battery in the trash. Lead acid batteries are one of the most recycled products in the United States, with a recycling rate of about 99%. Take used SLA batteries to a battery retailer, auto parts store, or local recycling center, or see our guide to recycling SLA batteries. For NiCd and lithium packs, tape the terminals and drop them off at a Call2Recycle location.

Frequently Asked Questions

How long do exit sign batteries last?

Most exit sign and emergency light batteries last 3 to 5 years for sealed lead acid, 5 to 7 years for NiCd, and 7 to 10 years for lithium at normal indoor temperatures. Replace the battery whenever the sign fails its monthly or annual test, regardless of its age.

How often should emergency light batteries be replaced?

Replace them when they fail a test or reach the end of their expected life. Many facilities replace SLA batteries on a strict 3-to-4-year schedule so fixtures don't fail between annual tests.

How long should an emergency light stay on during a power outage?

At least 90 minutes. NFPA 101 requires battery-powered emergency lighting to provide illumination for at least 1½ hours when normal power fails.

Can I use a higher Ah battery in my emergency light?

Yes. As long as the voltage, battery chemistry, and physical dimensions match, upgrading to a higher capacity is a great idea. For example, upgrading a 6V 4.5Ah battery to a 6V 5Ah battery fits the same space but provides extra runtime during an outage.

Can I replace a 6V emergency light battery with a 12V battery?

No. The voltage must match exactly. Installing a 12V battery in a 6V fixture can damage the fixture's charger board and lamps.

Why won't my emergency light work after I replaced the battery?

Emergency light batteries require time to charge. After installing a new battery, leave the fixture connected to AC power for a full 24 hours before pressing the test button. If it still fails, check that the terminal connections are secure and the correct polarity was used. For more help, see troubleshooting SLA batteries.

Do LED exit signs have batteries?

Most do. Exit signs with emergency backup have a built-in battery, usually a NiCd pack in LED-only signs, or an SLA battery in combo exit and emergency light units. Signs without a test button or charge indicator are likely AC-only or photoluminescent.

Find Your Replacement Emergency Light Battery

BatteryClerk stocks replacement batteries for thousands of emergency lights and exit signs from Lithonia, Dual-Lite, Sure-Lites, Lightalarms, Prescolite, Chloride, Hubbell, and more. AJC® batteries ship with a 12-month warranty and 30-day returns. Shop our exact-fit emergency light batteries today to help keep your building bright, safe, and up to code.