The Golden Power Battery Caper

[joeqsmith]

A friend bought a new DMM that came with a typical Golden Power battery.   When they went to turn on the meter, it appeared dead.   The measured the battery voltage, it appeared fine.   Swapped the battery and the meter worked fine.  I later checked the battery myself and it measured something like 9.4 volts.  I installed it into a meter and the same thing, the meter was dead....

I thought a bad rivet as every battery I have seen normally will read a lower voltage.  Something about this one seems unique.

I pulled out my box of batteries from all the meters I had killed and sorted out the Golden Power ones.  These were then numbered.

Battery, Date Code, Weight (g), Open Voltage
1, 2015-04, 34.5572, 9.709*
2, 2016-05, 34.9859, 9.595
3, 2016-06, 35.8182, 9.402
4, 2015-04, 35.8207, 9.442
5, 2016-08, 35.4947, 8.758
6, 2015-10, 35.0441, 8.986

Battery 5 and 6 have been in use.  Battery 1 is the battery in question.  Note that Battery 4 & 1 have the same date code.

[joeqsmith]

These meters will turn on with a very lower battery voltage and the current draw is a few mA.   I pulled out a 3.9K resistor and measured the voltage across each battery with this load.

1,  3.30
2,  9.30
3,  9.09
4,  9.11
5,  7.78
6,  8.26

As suspected, battery #1 appears to have a very high resistance.  But why such a high open circuit voltage.  Strange.  Time to have a look. 

I measured with the 3.9K directly contacting the two outside plates and read 3.2 volts..  So it's not a bad contact like I had thought.

[joeqsmith]

I cut the wrapper and pulled out each cell making sure I kept them in order.   

Starting at the positive terminal, I measured each cells open circuit voltage:

1, 1.598
2, 1.608
3, 1.606
4, 1.607
5, 1.581
6, 1.449

[joeqsmith]

I would have expected them to me a little closer.  I then measured each cell using the 3.9K resistor as a load.

1, 1.601
2, 1.495
3, 1.595
4, 1.603
5, 1.557
6, 0.65

The bottom cell is the problem. 

[IanB]

I'd guess one of the cells is "dry" inside with insufficient electrolyte? Manufacturing defect?

[Edit: I saw where this was going and guessed the punch line...]

[joeqsmith]

Cell 6.  Why just one cell and why was the voltage so high.. 

[joeqsmith]

A little tape and a wire tie to hold the it together.   

[joeqsmith]

Final video.  Forgot to turn off the auto power down...

[IanB]

In my experience a brand new zinc chloride battery will read very close to 10 V open circuit (about 9.95 V in a few I just tested). I think the low voltages on your tested batteries suggests they are of poor quality or are past their sell by date.

[joeqsmith]

That's interesting.  I don't pay much attention.  There are some with mid 2016 data codes that have not been used.  The newest Golden Power one I listed from August of 2016 is used.   

I hunted through the box-o-batteries that have came out of the dead meters.  There is one, still sealed in plastic with a 06-2Q17 date code.  This is a Goldmen Super Heavy Duty 6F22.  It measure 9.872 which was by far the highest of them.  The second was a Toshiba 08-2016 date code that measured 9.751.    Take that back, there is a King Battery K B with a 2013-01 date code.  I suspect the oldest of the bunch.  It measures 9.770!
Several others were in the 9.7.  Most are mid 9's.  None of the others drop like this one did with that little bit of load. 

I can believe that most of these are a poor quality.  The meters I damaged where theses come from did not end up in the recycle bin because they where of great value.