SensorPal Battery impedance measurement

martak7

on May 12, 2023

Category: Software

Product Number: CN0510

Software Version: Sensor pal

I am using this circuit to measure battery imepdance: https://wiki.analog.com/resources/eval/user-guides/circuits-from-the-lab/cn0510 and I have connected it to the battery as shown in general setup picture, but when it comes to Nyquist plot in Sensor pal, the measurement doesn't look correct. Also, for the same input values in 2 measurements, the plot looks different which you can see on screenshots (there are few different screenshots of different or same input values because each measurement gives different Nyquist diagram). The resistor value was always the same and the battery that I've been using is NCR18650A (datasheet is inserted as picture). Can you tell me which input values should give me better measurement or if there is problem with hardware? I have connected the EVAL-AD5941BATZ to the EVAL-ADICUP3029 via the Arduino headers and have used BNC cables to connect the battery to the boards.

Tags: software AD5941BATZ cn0510 SensorPal adicup3029 eis CN0510 / AD5941BATZ Sensor Pal Show More

0 FormerMember

on May 15, 2023 9:29 AM

Hi martak7,

I'm going to loop in Akila who's more familiar with this product and software.

0 Akila

on May 18, 2023 5:08 AM

Hi,

One reason could be that in Sensorpal plot, the measurement points are joined to show line plot.

You may export the excel sheet containing measured data and check (This is done by clicking the excel sheet symbol next to measure button).

For example:

ACVoltPP = 300.0f; /* Pk-pk amplitude is 300mV */

DCVolt = 1200.0f;

Start freq = 1Hz,

End Freq = 50KHz

Points = 50

Same plot in excel:

Allowed range of values for Sensorpal parameters are mentioned here: https://ez.analog.com/reference-designs/f/q-a/563846/software-operation-of-battery-impedance-spectrum-measurement/489023

0 martak7

on May 24, 2023 11:13 AM in reply to Akila

Hi Akila,

thank you for your reply, the problem really was with SensorPal plot and it looks much more accurate in Excel.

Also, I know that this circuit is compatible with lithium-ion batteries, but could I do impedance measurement of Nickel-Metal Hydride battery or no? If not, why?

0 Akila

on May 24, 2023 10:05 PM in reply to martak7

Hi,

CN0510 measure impedance of any battery that is within below limits:

Max allowed current through battery is 3A.

Minimum current measurable by AD5940 (Analog front end used in CN0510) is 50pA.

0 LIUSIXIAN

on Jul 18, 2023 12:03 AM

Hi, how do you connect this battery of yours with a BNC cable? Alligator clips cannot hold the positive and negative terminals of this battery.

0 mso

on Jul 18, 2023 12:09 AM in reply to LIUSIXIAN

Hi Liusixian,

You may use BNC to alligator clips to connect the battery. You may also refer to the CN0510 user guide for the setup, CN0510 User Guide [Analog Devices Wiki].
May I see your current setup on how you connect the battery?

Regards,
Michelle

0 LIUSIXIAN

on Jul 18, 2023 12:47 AM in reply to mso

I use the alligator clip on the BNC cable to clamp the positive and negative poles of the battery, but the cylindrical battery positive and negative pins cannot be clamped.

In the picture below, the battery on the left cannot be clamped, but the battery on the right can.

0 mso

on Jul 18, 2023 1:47 AM in reply to LIUSIXIAN

It would be really difficult to clamp a battery like that (AA battery). I would suggest, you may use a single battery holder for AA battery and connect the alligator clips to the positive and negative terminal.

Regards,
Michelle

0 LIUSIXIAN

on Jul 18, 2023 2:46 AM in reply to mso

OK,thank you very much

0 LIUSIXIAN

on Jul 19, 2023 4:21 AM in reply to Akila

May I ask whether the minimum current of 2.66A here should be mA, 2.66A is a very large current. The user guide says 50mA through the battery.