Power, battery & charging

To power ON the unit, simply tap the ON button once. To turn OFF the unit, press and hold the power button for ~2 seconds.

The CurrentRanger requires a standard LithiumPolymer/LithiumIon battery that charges to 4.2V. This ensures optimal operation through the full range of the battery discharge cycle (4.2V fully charged down to ~3.4V discharged).

  • Lithium Polymer 3.7V battery (any capacity) with a standard JST 2mm pin pitch PH-series connector (the CurrentRanger part used is this one, and here is an example mating housing with corresponding inserts)
  • Maximum battery dimensions to fit the case: 48x60mm (up to 10mm thick)
  • Charges via MCP73831 charger (454mA charge current) from USB power
  • Can alternatively be powered from a 3xAAA pack, but this should be disconnected when uUSB is plugged in
  • VIN limits: [3.3, 6]V
  • To minimize noise pickup, keep battery leads as short as possible
Double check the polarity of your battery JST connector, proper polarity is marked on the silkscreen, here’s an example of a small 500mAh battery connection:

If you have a battery but don’t have the correct JST mating connector, you can pick one up from the store here.

Due to the low profile of the JST battery connector housing and its proximity to SMD components, exercise case when you plug/unplug the battery, to avoid damage to the components or even snapping them off the PCB.
The uUSB port is used for logging, programming and charging the internal LiPo battery. You should understand the safety and proper usage while you have USB plugged in. Also note that switching power supply noise and other harmonics can couple through the USB grounding from mains or even from a battery powered laptop which in can then make its way to the raw output, especially visible in the nA and uA ranges. Even just an open ended USB cable can act as an antenna that will induce GROUND noise into the sensitive CurrentRanger circuitry. For best accuracy and use with USB disconnected.

Typical power consumption*

  • OFF quiescent current: 0.6µA
  • ON: 17mA
  • 18mA with LPF activated
  • 20mA with Bias activated (Bidirectional)
  • 21.5mA with LPF & Bias activated
  • OLED adds ~5mA with 25% pixels ON
  • HC-06 BT module adds up to extra 20mA with 40mA spikes during TX/pairing

* Note: this may vary slightly due to various LEDs and other resistors being changed from batch to batch.