A TL-5186/P battery is suspected for short-term short circuit - an advice needed

Thread Starter

Anton202107

Joined Jul 18, 2021
3
Dear Sirs,

having a TL-5186/P battery (https://ru.mouser.com/datasheet/2/474/TL-5186-1214094.pdf) suspected to have been short-circuited for a tiny bit of a second (while measuring the voltage). The suspection is just because the cell have rolled right a bit, displacing the pins, while measured. The voltage is correct (3.6 V) afterwards, and no short-circuit effects (sparks, etc.) have been observed at all. But I’m still afraid of if it can malfunction someday. The cell is intended to be installed in a medical appliance. The question is – may the battery be accepted or better to be rejected and replaced? Can the case described really lead to the cell malfunction or it’s nothing to worry about? The abuse tests in brochure (https://tadiranbatteries.de/pdf/Technical-Brochure-LTC-Batteries.pdf) describe much more harsh terms concerning external short circuit, so I tend to think the small part of a second cannot be a reason to reject the cell that shows normal operation after all? Sorry for such a question, registered here especially to ask it. Thanks in advance for your advices, they are appreciated.
 

Irving

Joined Jan 30, 2016
2,322
Welcome to AAC!

Do you mean the pins have been bent at the junction with the case? If so the hermetic glass/metal seal may have been damaged which could lead to premature failure (but not to worry about spark/fire/etc, there's not enough energy stored to be significant). An inspection under a high-power microscope may help alleviate that concern.

My other concern would be how much capacity has been taken out of the cell - it only had 0.4Ah to start with. Fortunately cells like that have fairly high internal resistance so the short circuit current would be quite small, as suggested by figure 2.9 of the Technical Brochure (TB), probably only a few 10s of mA. However, as section 2.3 of the TB states, that significantly higher than standard discharge current will have caused changes to the structure of the electrode. Its impossible to say exactly how much impact this will have had on capacity, but if this is for a critical system where data retention is guaranteed for a specific time period, this may have been compromised.

If this is for medical equipment used in life-preservation situations where memory data includes calibration settings, or other operational data,etc. then only you can assess that risk.
 

Audioguru again

Joined Oct 21, 2019
3,872
The battery is not rechargeable so your 1 second short-circuit drained some of its lifetime. It will run down sooner than if it was never shorted.
Does the medical product warn that the battery is near the replacement voltage?
 

Irving

Joined Jan 30, 2016
2,322
Hi aga... its a soldered in part - probably assumed to be fit n forget and then buy a new unit when the battery fails ;):rolleyes:
 

Thread Starter

Anton202107

Joined Jul 18, 2021
3
Hi Irving!

Fortunately the pins haven’t been bent, the cell just rolled in place horizontally by approximately 120 degree angle, which could lead to that – the tester probes could touch one another instantly after the pins displaced. What is the most annoying – I cannot say for sure if any shorting happened at all. I would like to think it’s all just fine with the cell, but the purpose of medical equipment, which is indeed to be used in life-preservation situations, totally makes me prefer to purchase another battery rather than suspect any non-zero probability of failure then. So, I feel ought and must to reject the present cell and consider it compromised. And I’m going to do so, despite a number of respected evidences that nothing critical should have been happen to the cell. So I’ve finally decided to replace it with another brand new, handling it all ultimately careful in the future. In particular, it’s always a good idea to temporarily place a good piece of insulator between the pins, totally preventing anything to make a shorting accidentally while operation. And use insulating mat on workbench, with nothing unnecessary made from metal near at hand.
But, well, I can still use that poor cell to build a model load circuit somewhat electrically similar to the device part of original purpose, and emulate the discharging process, monitoring the dynamics of discharge current and voltage. At least, I’ll get some knowledge from the case. And even have got some already.



Hi Audioguru again!

It doesn’t seem to have such a function, but just resets CMOS and starts to think it’s 2001 now or smth. alike. And stops to operate. It would be great, without a doubt, if manufacturers provided such a function of indicating battery extinction with a luminodiode and sound, and even by means of remote monitoring.
 
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