NFC Card Emulation with a dead battery

How-to

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Did you know that your NFC-enabled BlackBerry® smartphone may be able to process NFC transactions, such as payments, even when it has a completely dead battery? Smartphones which support NFC will continue to be able to provide NFC card emulation functionality when in “low battery mode” or, in some circumstances, even when the battery is completely dead.

Let’s explore what the difference between “low battery” versus “dead battery” is before we move on.

Low battery mode starts when the smartphone OS turns off the user interface due to the battery being deemed “low”. The smartphone appears to be off to the user, but internally, the Power Management Integrated Circuit (PMIC) is still on. Dead battery mode, by way of contrast, starts when there is no longer enough power in the battery to keep even the PMIC powered on.

How long low battery mode will last before moving into the dead battery state varies from smartphone to smartphone, but is typically at least four or five hours.

In low battery mode, all BlackBerry smartphones will continue to be able to provide NFC card emulation functionality. But when it comes to dead battery mode, whether NFC card emulation will continue to work or not depends on the smartphone model; for instance, the BlackBerry® Curve™ 9380 smartphone and BlackBerry® Bold™ 9790 smartphone do support dead battery mode. This mode is not supported on the BlackBerry® Bold™ 9900 smartphone and BlackBerry® Curve™ 9360 smartphone.

The user has no way of knowing just from looking at their smartphone if they are in low battery mode or have a completely dead battery. Because of this, they have no way of knowing whether or not NFC transactions in card emulation mode will work or not in a given instance.

Developers have an API function called
SecureElementManager.setCardEmulationWhenPoweredOff(true|false) which they can call to control whether or not card emulation will work or not when the battery is dead or has been removed.

You may also have noticed that the Near Field Communication options screen has a setting in the section entitled “Allow NFC Card Transactions” labelled “When Powered Off”. This setting will also affect the behaviour of a device when in low battery or dead battery mode.

To learn more about NFC, check out our online developer documentation.

About mdwrim

My name’s Martin Woolley and I work in BlackBerry's Developer Relations team as a Senior Application Development Consultant. I’ve been with BlackBerry since 2009 but have worked in software development in various capacities for 30 years in a whole range of industry sectors and on numerous computing platforms small and large. These days I specialise in areas such as Bluetooth Low Energy, NFC, Internet of Things (Iot) and wearable technologies amongst other things.

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