Electronics > Projects, Designs, and Technical Stuff
CR2032 battery voltage with BLE
<< < (7/7)
jmaja:
I'm reading now battery voltage just after the peak. I could not read at the peak. I guess BLESS system has control at the TX, which is the peak, and I can't run application code to start the ADC at that point. The ADC takes 300 us and the middle point is about 200 us after the peak. The readings I get are now very close to the peak I see with the oscilloscope.

At the moment it is 2.60 V. I have had the sensor on for 12 days and done 2e6 transmissions now with this battery, which has seen some abuse due to soldering and bug I had. I will get new batteries with solder taps during next week. These seem to be quite hard to get. Not available at local electronics stores. Digi-Key, Mouser etc. won't sell them due to air transport problems. I bought them from TME, which has a ground transport option.
GeorgeOfTheJungle:

--- Quote from: jmaja on March 24, 2019, 03:11:51 pm ---It has a completely different curve for CR2450 with the same test setup! Now the pulse curve drops below 2 V already before 300 mAh while in the earlier one that happened at 550 mAh. Almost no additional capacity compared to CR2430 despite of more than double nominal capacity.

--- End quote ---

One .pdf says Typical Li Content: <0.3g (energizer.com) , and the other Typical Li Content: 0.47 grams (dixonelectric.ca) , that would be 50% more ions => more angry pixies, but the curves say the contrary.

jmaja:
Now I measured the standby current consumption without bigger caps, with just one and with two. Cyble module + sensors were powered in stop/shutdown mode. I got 40 nA with no bigger caps and just a 0805 10 uF ceramic cap. Then I added 1206 47 uF ceramic cap. First few seconds the consumption was 200 nA but in a few minutes it was 80 nA and still dropping. Nothing to worry about I think, since even 0.5 uA would be less than I expected, since the sensors should take almost that much, but seem to take less.

Then I notices something strange. The current consumption went to 2 uA when I put my small 40 W work light on with a traditional bulb. By shadowing different components with a finger or a business card I found out it was the BLE module that was sensitive to light. It was much less sensitive to a much brighter LED flashlight (>4000 lx vs. 600 lx according to the sensor on PCB). The sensitive area seemed to be the one with metal shield. How can it be affected through the shield? There are openings to the side.

I got the new batteries. Brand new Varta CR2430 seems to have less than 10 ohm internal resistance. Also it seems IR of lithium coins depends on how it is measured. I have a DE-5000 LCR meter. I measured resistance through a capacitor and the higher frequency I used the lower resistance I got. E.g. for a used CR2032 I get 130 ohm at 100 Hz, 122 at 120 Hz, 43 ohm at 1 kHz, 23 at 10 kHz and 17 ohm at 100 kHz. Using a 470 ohm resistor and multimeter I got about 180 ohm and calculating from rise time after a pulse I got about 300 ohm.

I first thought that DE-5000 + the cap I used fails to measure, but measuring a NiMh AA-cell gave about the same at every frequency (0.4-0.5 ohm).

This battery had been in my Polar heart rate monitor and was dead there. It still shows 2.93 V. It could not power up my device as is, but adding a 330 uF cap made it work OK.
Navigation
Message Index
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod