PHILIPS ONSITE & FRX AED BATTERY M5070A. The M5070A is a replacement battery for the Philips HeartStart OnSite and FRx AEDs. This automated external defibrillator (AED) battery is a 9 Volt DC, 4.2 Ah disposable long-life lithium battery. Its capacity is a minimum of 200 shocks or 4 hours of operating time. Price per each.