If you are tasked with maintaining the AEDs for a school district, a corporate campus, or a gym, you might have a mix of different Philips HeartStart models on your walls. The two most common are the Philips HeartStart OnSite (also known as the HS1) and the rugged Philips HeartStart FRx.

When it comes time to order replacement batteries, facility managers often hit a point of confusion: Both of these machines look completely different, so do they really use the exact same replacement battery?

The short answer is yes. Here is everything you need to know about Philips HeartStart battery compatibility so you can order with confidence.

One Battery for Three Models

The official Philips M5070A Lithium-Ion Battery is the universal power source for three distinct Philips HeartStart defibrillators:

1. The Philips HeartStart OnSite (HS1): The standard, light-blue unit designed for offices, schools, and home use.

2. The Philips HeartStart FRx: The darker, ruggedized unit built for first responders, law enforcement, and harsh environments.

3. The Philips HeartStart Home: The over-the-counter version of the OnSite unit.

If you own any of the three models listed above, the M5070A is the exact battery you need. It snaps seamlessly into the back of each device, providing a guaranteed 4-year installed standby life, or enough power to deliver 200 shocks.

Why Do They Use the Same Battery?

Philips designed these AEDs with cross-compatibility in mind to make maintenance easier for large organizations. Because the internal computer processors that run the daily self-tests and deliver the life-saving shock are very similar across the OnSite and the FRx, they both run optimally on the same 9-Volt, 4.2 Ampere-hour lithium manganese dioxide power plant.

This means if you manage a fleet of AEDs (e.g., OnSite models indoors and FRx models in your security vehicles), you don’t need to keep track of multiple battery part numbers. You can keep a single stock of M5070A batteries to service your entire fleet.

Warning: The Pads Are NOT Compatible

While the M5070A battery fits both machines, the defibrillator pads do not. This is a critical distinction that often catches buyers off guard.

• For the OnSite (HS1): You must use the blue plastic SMART Pads cartridge (Adult Part #M5071A).

• For the FRx: You must use the foil-packaged SMART Pads II (Part #989803139261). The FRx does not accept the plastic cartridge style.

Always double-check your machine model before ordering replacement pads to ensure you remain Rescue Ready.

Where to Buy the M5070A Replacement

Because this battery powers the most popular AEDs in the world, the market is flooded with cheap, unbranded knockoffs that risk liability and often fail early. It is critical to buy an OEM or FDA-cleared equivalent from an authorized distributor.

To guarantee your AED will function in an emergency, order the Philips HeartStart M5070A Replacement Battery here.

Simply pop the old battery out, slide the new one in, and wait for the machine to say “Ready” and flash a green light.