RE: problem in battery measurement with NRF51822

Håkon Alseth — Mon, 13 Aug 2018 11:46:36 GMT

Hi,

Judging by your configuration, you are sampling VDD_NRF*1/3, using the internal bandgap regulator (1.2V).

If you are drawing more current in pulses, like adding a LED, you will draw more current from the battery, which again will add a voltage drop in a small time period, before the capacitors are recharged. Have you tried scoping your VDD to see the ripple under normal operation?

If you're using a CR2032 battery for testing this, it is quite normal that they will perform worse (higher ripple) with lower voltage (~2.5V, you only have 10 to 20 % capacity left according to this discharge curve).

Best regards,

Håkon