A few months ago, Holux released a new firmware for its M-241 GPS logger. This latest version v1.12 allows to turn off Bluetooth whereas before it was always on – whether used or not. Turning off BT is expected to lower the overall current consumption of the device. But does it really?
To find out more, Oliver and I set out to measure the power consumption. In theory, this is quite simple: Get your hands on a fairly accurate current meter (in our case a Fluke 87), put it in series to the power supply circuit and measure the current in various states.
I tested my Holux with rechargeable batteries from Ansmann and can report that they work fine (even on a winter day in the mountains). I’ve used the following type: Ansmann maxE 2100 mAh (it’s a NiMH HR6 with 1.2 V and 2100 mAh)
One problem I noticed though was that the battery diameter is too big meaning that you can get it in but not out again (at least not easily). Removing the wrapper helps. I don’t know whether the battery compartment is too narrow or the battery itself too wide. According to the AA specs, the diameter is supposed to be 14.0 +/- 0.5 mm.