BR2325 voltage range - fake battery? - Page 1
Forum section: electronics / general

author: matthuszagh
author_rank: Frequent Contributor
timestamp: June 03, 2022, 12:51:07 am
content: I recently received an instrument sold for parts displaying an error indicating loss of calibration data. The cal data is made persistent by a 3V BR2325 coin cell (https://www.mouser.com/datasheet/2/315/AAA4000C226-1889696.pdf). So, I ordered some replacements from amazon. They arrived today and I tested the voltage first through a 10 MOhm resistance (my multimeter presents 10MOhm at its highest range). I was surprised to see it read 3.38 V, which seems pretty high for a 3 V nominal level. I also checked the datasheet (see link) and the "Operating voltage vs. load resistance" chart shows a voltage a 3 V for this load at room temp. I didn't, however, see any sort of max/min specs. Is this a reasonable voltage level, or is there a good chance this is a fake battery.Another question: when I measured the existing battery voltage it read 2.93 V under load, which seems ok to me. At what level would I want to replace this?

author: bdunham7
author_rank: Super Contributor
timestamp: June 03, 2022, 01:03:19 am
content: Your battery is not fake, that is about what you should see from a new one, or even perhaps a bit more. 3V open circuit is dead for those, 2.93 is good and dead.

author: ebastler
author_rank: Super Contributor
timestamp: June 04, 2022, 04:28:31 pm
content: Quote from: matthuszagh on June 03, 2022, 12:51:07 amPlease note that the "Operating voltage vs. load resistance" chart in the datasheet refers to a half-discharged battery.Quote from: bdunham7 on June 03, 2022, 01:03:19 amYou mean "good andnotdead", I assume?

author: bdunham7
author_rank: Super Contributor
timestamp: June 04, 2022, 04:47:59 pm
content: Quote from: ebastler on June 04, 2022, 04:28:31 pmNo, <3V open circuit (or with a 10M DMM) for a coin cell is completely dead for most practical purposes. Some very low drain devices might live on for a while, but most will have stopped functioning at that point.

author: tooki
author_rank: Super Contributor
timestamp: June 04, 2022, 05:08:50 pm
content: Quote from: ebastler on June 04, 2022, 04:28:31 pmNo. In English, “good and ” means “very ”, so “good and dead” means “so richtig tot”.

author: ebastler
author_rank: Super Contributor
timestamp: June 04, 2022, 07:39:37 pm
content: Quote from: tooki on June 04, 2022, 05:08:50 pmThank you, learned something new! I don't think I have ever come across that idiom.Quote from: bdunham7 on June 04, 2022, 04:47:59 pmBut the 2.93V was measured under load according to the OP. And the datasheet suggests that for a few µA of load current, 2.9V output voltage is just fine, roughly consistent with a half-full battery. While it obviously can't hurt to replace the battery, I don't think it was responsible for the loss of calibration.

author: bdunham7
author_rank: Super Contributor
timestamp: June 04, 2022, 07:53:09 pm
content: Quote from: ebastler on June 04, 2022, 07:39:37 pmFirst, I'm basing my statement on my experience with devices with that have ceased to function due to dead coin cells. And I'm assuming from the OP's description that what he meant by 'load' was 10M. Obviously if the voltage was 2.93V installed in the relevant device and that device had a constant load (which is the real deal-breaker for most devices as the impedance of the batteries goes up with discharge) then you'd be right, it should still function.

author: tooki
author_rank: Super Contributor
timestamp: June 04, 2022, 11:28:25 pm
content: Quote from: ebastler on June 04, 2022, 07:39:37 pmThe same happens with me and German. I’m fluent (but it’s not my native language) and I occasionally encounter new idioms as well.Upon further reflection, I think an more precise explanation of “good and …” would be “totally …”, in that the idiom implies completeness, thoroughness, and finality. I think the most common phrase you encounter is “I’ll do it when I’m good and ready”, meaning they’ll do something once they’rethoroughlyprepared and not a moment sooner, also meaning that they won’t let themselves be rushed.Like in this comedic dialog at 3:40:https://youtu.be/0C-9DLDCmjAAnd apparently there was even an eponymous 90s pop song:https://youtu.be/XYx7zV-IcB4

author: matthuszagh
author_rank: Frequent Contributor
timestamp: June 10, 2022, 10:08:19 pm
content: I figured I should add some additional clarity since there's been further discussion.Just to clarify, the 2.93 V was measured under loadin-circuit. I apologize that I didn't make this very clear in my original post. When I removed the battery from the circuit (which I did after this post) it measured >3V into a the 10M of my DMM.However, it turns out that I wasn't actually measuring the battery at all, but instead the voltage across a tantalum capacitor in parallel with the battery. There had been some rust formation on the battery holder that was effectively removing it from the circuit, causing the tantalum to try (and eventually fail) to provide the supply. Cleaning the holder with deoxit resolved the issue, and the actual battery measurement was then a steady 3.18 V in-circuit.Details here:https://groups.io/g/HP-Agilent-Keysight-equipment/topic/91536275#126872