Detection of low charge in battery

RE: Detection of low charge in battery

Abrie — Wed, 10 Jun 2020 12:29:32 GMT

Thanks! Got it to work from the SAADC example just now but cannot find an example of how to set the gain? Just need the command to put in the saadc_init() function

RE: Detection of low charge in battery

Kenneth — Wed, 10 Jun 2020 12:20:01 GMT

There is internal path to VDD that can be used yes. No need for external connection.

Best regards,
Kenneth

RE: Detection of low charge in battery

Abrie — Wed, 10 Jun 2020 10:24:45 GMT

I am using the Ublox ANNA b112 which uses the NRF52832

RE: Detection of low charge in battery

Abrie — Wed, 10 Jun 2020 10:14:39 GMT

Hi Kenneth

Yes I think this will work. I am finalising hardware design. Do you need to make a physical connection (track) from VDD to one of the analog inputs or can the connection be made with software?

I allready made a board with no physical connection that is why I am looking for a way that does not require any connections from VDD to the analog pins

Thanks for the help

RE: Detection of low charge in battery

Kenneth — Wed, 10 Jun 2020 10:06:36 GMT

Is this question for nRF51-series or nRF52-series?

For new development I recommend to check out nRF52-series, in such case you can find that you can connect VDD internal as input for the SAADC:
https://infocenter.nordicsemi.com/topic/ps_nrf52840/saadc.html#register.CH-0-7.PSELP

In addition you can set gain to 1/6 and use 0.6V internal reference:
https://infocenter.nordicsemi.com/topic/ps_nrf52840/saadc.html#register.CH-0-7.CONFIG

Then when you sample VDD you should get a value between for instance for a fresh battery 3V : 3V * 1/6 = 0.5V, which is less than the internal reference than 0.6V so this should work without any external components.

RE: Detection of low charge in battery

Abrie — Wed, 10 Jun 2020 08:44:42 GMT

I will be using a CR2477 coin cell. Fully charged at 3.0V , depleted at around 2.0V

RE: Detection of low charge in battery

Kenneth — Wed, 10 Jun 2020 08:33:44 GMT

The answer depend on what battery you are using (e.g. max and min voltage).

RE: Detection of low charge in battery

Abrie — Tue, 09 Jun 2020 19:52:33 GMT

Hi. Do you have an answer on this? I need a solution to get a low battery warning without adding any external circuitry.

RE: Detection of low charge in battery

DMS — Thu, 05 Jul 2018 06:01:48 GMT

Will I be able to use those methods if i cant connect anything to the Analog input?

Because it looks like those methods need some ADC input from the battery.

RE: Detection of low charge in battery

Kenneth — Wed, 04 Jul 2018 13:47:02 GMT

Hi, check out:
https://devzone.nordicsemi.com/f/nordic-q-a/17395/reading-battery-voltage-using-nrf51822