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Calibration of timers required after replacing batteries?


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Hi everyone,

    We have several timers in our lab for which the calibrations aren't due until October 2021, per the calibration certificates that came with them from the manufacturer.  However, the batteries have all died prematurely.  My lab director is under the impression that we would have to recalibrate the timers if we replace the batteries, but we did not do this where I worked previously.  It seems like such a waste to buy all new timers every time the batteries die, when the calibrations are still good for over a year.  I'm just curious what is being done at other facilities, and if anyone knows of a regulation that states the timers must be recalibrated when the batteries are replaced.  I would appreciate any feedback you all have to offer.  Thanks.

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10 hours ago, Malcolm Needs said:

It sounds to me that your lab director is the kind of person who would want to measure the amount of oxygen and carbon dioxide in the air each time someone breathes, AND perform a Change Control at the same time.

She used to work in document control, so I think she sometimes goes overboard.  She said her previous employer recalibrated after changing the batteries, but I know for a fact that my previous employer did not.

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Perhaps the real question is: Do you (or the supplier/certifier) actually CALIBRATE them ? That is, can the reading be adjusted in any way ? If the timer differs greatly from the "Standard", can it be tweaked into range ? Most simple electronic (battery-powered) timers are not adjustable. I'm not even sure that the official certifiers (the ones providing the certificates) are able to adjust the cheap and cheerful electronic timers. The electronics are so reliable (and cheap) these days that it's rare to find an inaccurate timer. The ones with unacceptable performance are probably just discarded.

So, back the the main issue. If the time IS calibrated and the removal of the batteries nullifies that calibration, i.e., the timer loses its mind, then YES, the timer will need recalibration upon battery replacement. But, see above, I suspect not.

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We change all batteries annually while we are doing the QA on them so it's not likely that a battery will fail during the year.  However, things do happen and I agree with exlimely, if you do have to change or replace (say it fell out for some reason) a battery, then a 'calibration' would be prudent.

Also, we are not talking high precision here, i.e. wider acceptability range than a pipette would be, i.e. testing is done in ranges of time, not exact seconds.  This 'calibration' is just a simple check up to make sure the timer isn't totally out of range.  Most of the time, the error is the readout gets 'broken', not the accuracy of the timer.

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If your timers are digital I believe they are exempt from calibration due to the nature of digital timing.  They work until the batteries run out of charge.  The CAP requirement for timers does not apply to digital ones.  TRM.31900.  How could you calibrate a digital timer (compare it to the Naval clock?)

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2 hours ago, Joanne P. Scannell said:

However, things do happen and I agree with exlimely, if you do have to change or replace (say it fell out for some reason) a battery, then a 'calibration' would be prudent.

Also, we are not talking high precision here, i.e. wider acceptability range than a pipette would be, i.e. testing is done in ranges of time, not exact seconds.  This 'calibration' is just a simple check up to make sure the timer isn't totally out of range.  Most of the time, the error is the readout gets 'broken', not the accuracy of the timer.

Actually, I'm not suggesting that replacement of the batteries is cause to re-qualify a timer. Accuracy of most timers is not affected by battery replacement because there is no actual CALIBRATION, i.e., no adjustment process. Typically, today's timers are CERTIFIED - their accuracy is verified against a standard. That accuracy is independent of the batteries.

But, I do agree that a broken/unreadable timer is the ultimate expression of "inaccurate".:D

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On 9/30/2020 at 7:45 AM, Malcolm Needs said:

It sounds to me that your lab director is the kind of person who would want to measure the amount of oxygen and carbon dioxide in the air each time someone breathes, AND perform a Change Control at the same time.

Ouch !

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Just curious but has anyone thought to ask the timer manufacturer their thoughts replacing batteries?  Personally I don't think I would be overly concerned with the need to calibrate a digital time simply because I changed the battery.

Also, "However, the batteries have all died prematurely."  What makes you think that the batteries died prematurely?  Did the manufacturer indicate that the batteries would last the calibrations period?  If they didn't want you to replace the batteries they would probably make them inaccessible.  

Just a couple of thoughts.

:coffeecup:

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  • 2 weeks later...

Manufacturers calibrate the electronics and provide the certificate on the assumption of power to the electronics (which are simple and robust). As you did not change the electronics when changing batteries (the power input) you do not need to conduct a performance check (calibration). Or to put it another way: You do not recalibrate equipment after a power cut or if you remove and replace a mains plug. 

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