[imhoguy]

I see lots of poor Lassies in airports, conferencies and generally in crowded places. Not even mentioning flood or replay attacks.

Lassie's help needs to have some limits otherwise it may quickly drain batteries or mobile plans especially in roaming.

[stouset]

BLE is insanely battery-efficient. And in most scenarios with a lost device, it's either stationary or will be stationary for a sufficient period of time to be discovered, so a ping only once every hour is probably more than enough to locate it. Or a ping with exponential backoff as battery depletes.

Sending the locations from these pings likewise also uses negligible battery, as Apple already coalesces timers and network traffic like push notifications.

I don't understand the mentality where people think Apple would have announced this without doing any testing on its battery life impact.

[photojosh]

Yep. I have a BLE speed sensor on my bike which runs off a CR2032 coin cell. It's been two years of daily commuting and I've yet to change the battery.

[randyrand]

"Apple's recommended setting of 100 ms advertising interval with a coin cell battery provides for 1–3 months of life, which increases to 2–3 years as advertising interval is increased to 900 ms."

iPhone's have about at 10X larger batter than that. So iPhones can do this for ~20-30 years if configured correctly.

[ryanmarsh]

If I'm not mistaken the normal self-discharge rate for a phone's lithium ion battery will exceed the maintenance of BLE advertisement.

[imhoguy]

It is not about BLE beacons. Right, they are energy efficient. But receiving party needs to listen constantly and proces these messages. With 1000 beacons around at 1s interval it means the intermediary node needs to send 1000 notifications per second to Apple. That can be buffered and optimized, but still it is some non-trivial number and possible bottleneck to be exploited.

[saagarjha]

It's Bluetooth Low Energy, though. Should last for quite a while?

[diminoten]

I'm quite sure they've solved for this particular problem, or they wouldn't have launched the product...