Philips HeartStart OnSite Pads & Battery (M5071A / M5070A): Complete Guide

The Philips HeartStart OnSite is the best-selling AED in the world, and the one we field the most part-number questions about — largely because it goes by three different names and because its pads look almost identical to those of a different Philips model they will not fit.

OnSite, HS1 and Home are the same platform

If your device is labelled HeartStart OnSite, HeartStart HS1, or HeartStart Home, you are looking at the same consumables. They take the identical M5071A SMART Pads cartridge and the identical M5070A battery — which is why our own listings carry the "OnSite/Home" label.

The practical upshot: don't hunt for "HS1 pads" or "HeartStart Home pads" as separate products. Order M5071A and you have the right part.

The SMART Pads cartridge

Philips supplies the OnSite pads as a sealed cartridge that clicks into the base of the device, rather than loose electrodes in a pouch. Two things follow from that design:

• The cartridge is the serviceable part. You replace the whole cartridge, not the pads inside it.
• Seating matters. A cartridge that is not fully clicked home is a frequent cause of a chirping OnSite that otherwise looks healthy. If your unit starts beeping shortly after a pad change, re-seat the cartridge before assuming a fault.

Adult SMART Pads are generally replaced on a 2-year interval, or immediately after any use.

Pediatric coverage

The OnSite uses genuinely separate Infant/Child SMART Pads, part M5072A. Swap the cartridge and the device adjusts its energy delivery for a paediatric patient.

Note this is different from the FRx, which uses an Infant/Child Key and keeps the adult pads on the device. If you manage both models, they are not the same drill — worth covering in training.

The battery, and a cheaper alternative

The OnSite runs on the M5070A lithium battery with roughly a 4-year standby life. The device self-tests regularly and will signal when the battery is low, but the printed install-by date is what you should schedule against.

We also stock a re-celled battery, M5070A-ABE, at a meaningfully lower cost. It is an aftermarket cell replacement rather than a Philips OEM part. That is a legitimate option for budget-constrained programmes, but if your AED programme is governed by a medical director or an insurer who specifies OEM consumables, order the M5070A. We are happy to talk through which fits your situation.

For units that fly, the FAA-approved aviation battery 989803139301 is the compliant choice.

Training pads are not rescue pads

Philips sells training pads — M5093A adult and M5094A pediatric — for use with trainer units. They deliver no shock and must never be loaded into a live AED. They are inexpensive and easy to order by mistake, so check the part number against the list above.

Replacement intervals

Because pads run on a 2-year cycle and the battery on roughly 4, expect to replace pads twice per battery. Always follow the date printed on your own parts.

Bundle the reorder

Our HeartStart OnSite Maintenance Package pairs the battery with pads in four tiers:

• Basic — one battery + one pair adult pads
• Select — one battery + one pair adult pads + one pair pediatric pads
• Standard — one battery + two pairs adult pads
• Complete — one battery + two pairs adult pads + one pair pediatric pads

The Standard tier maps neatly onto the OnSite's cycle: two pad replacements per battery. And whatever you order, we contact you 90, 60 and 30 days before it expires.

Frequently asked questions

What pads does the Philips HeartStart OnSite use?

The OnSite uses the SMART Pads cartridge, part M5071A, for adults, and the Infant/Child SMART Pads cartridge, part M5072A, for paediatric patients. The same parts fit the HeartStart HS1 and HeartStart Home.

What battery does the HeartStart OnSite take?

It takes the M5070A lithium battery, which has roughly a 4-year standby life. The same battery also fits the Philips HeartStart FRx.

Are HeartStart OnSite and HS1 pads the same?

Yes. HeartStart OnSite, HS1 and Home are the same platform and use the identical M5071A adult pads cartridge and M5070A battery.

Can I use OnSite pads in a HeartStart FRx?

No. The FRx requires SMART Pads II, part 989803139261. Only the battery is shared between the two models.

Related

• AED pads & batteries by model — the full compatibility guide
• ZOLL AED Plus pads & batteries
• How often should you replace AED pads and batteries?

Last reviewed: 17 August 2026. Part numbers checked against our live catalogue.