Data logging via Bluetooth connections - in a word, 'avoid'

Just as data loggers got that bit more reliable, in comes the wireless connection known as Bluetooth.
While recent devices use a USB lead to connect a data logger to the PC, several manufacturers offer the extra feature of a Bluetooth wireless connection.

USB is mostly good. USB not only transfers data, it can power the data logger and this is how logging is becoming more reliable. (See for example Easy sense 'Link' (Data Harvest) for a most reliable and inexpensive way to link three sensors to a PC.)

Enter Bluetooth and the logger transfers data over a wireless link. Like a mobile phone, the logger will need power so we're back to scratch on the power issue again. What's more, Bluetooth is flakey-flakey-poor. For example, the PC and logger have to be married and this marriage have a habit of falling asunder. So we jump from real gains with USB to real risks with Bluetooth. And reliability plummets.

Bluetooth is great for connecting the whole bunch of obscure devices like phones, headsets, speakers, PDA's, GPS navigators and personal gizmos you might buy. Instead of carrying a caseful of cables, you use Bluetooth to connect them up. So you can print, access the network / Internet and send data (phone numbers, pictures, music) between them.

Bluetooth is largely about getting different manufacturer's devices to interoperate with a bit of wireless convenience thrown in.

If Bluetooth data loggers enabled a small chunk of that ability we'd be gaining something. If Bluetooth could send data back from a hot water tank, different rooms, a pond or weather station we'd be gaining something but still not exactly massively. If they took photos and fed them back that would be a gain. If different maker's equipment worked with the PC we'd gain massively. But Bluetooth data loggers aren't doing that at all. At the most they exchange data with the PC, something which a simple USB cable does best.

I'd avoid. Given the track record of data loggers, and until someone shows reliability or 'learning' gains from using Bluetooth, I'd suggest staying away.