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Discussion Starter #1 (Edited)
Successfully guess their capacity and win! We'll call it The Capacity is Right - InsightCentral Edition.

Contest Details
The person to guess closest to the average capacity of the two "D" size GE PermaCell NiCd batteries shown will win a free box of 20 untested Honda sticks with PTCs or a $50 prepaid VISA gift card, winners choice.

Anyone may participate, but the box of sticks is available to residents of the 48 contiguous states only. One whole number entry per username. In the case of duplicate entries, the earlier entry wins. Entries accepted until 3/9/2020 @ 11:59PM Pacific, at which point all of the data will be posted and the winner picked.

Cells were rated at 1.2Ah when originally manufactured.

Cells will be cycled at 100mA charge to 4mV -dV, 200mA discharge to 0.9V with a 20 minute wait. Capacity will be recorded on the 5th cycle.

Average Capacity means (Cell 1 cycle 5 discharge mAh + Cell 2 cycle 5 discharge mAh) / 2

Vital Stats as of 2/6/2020:

Voltage​
IR​
Cell 1​
0.59776V​
13.576mΩ​
Cell 2​
0.53060V​
9.779mΩ​

Once again, these cells were rated at 1.2Ah when new.

Commentary & Pictures
Probably not the "NOS cells" some of you were thinking of. ;) I found these beauties on eBay, and thought it would be fun to do something interactive with them. Yeah, they're NiCd, but the chemistry is remarkably similar to NiMH. As far as I have been able to tell, these GE PermaCell NiCd batteries debuted in 1968 and were manufactured throughout the 1970s, so they are between 40 and 50 years old. Will they live up to their namesake?

GEPermaCell1.jpg

Unpackaged, labeled:
GePermaCellLabeled.jpg

Here's an old ad I found via Google in the July 1970 issue of Field and Stream magazine.
July1970Field&StreamAd.jpg

I was going to use one of those "Cell Testers" that you can readily get from China:
CellTester.jpg

But unfortunately, I found them to be garbage. Contact resistance was all over the place. So I made my own:
GEPermaCellRig.jpg

Testing has officially begun.
GEPermaCellTesting1.jpg

I’ll start first as an example, but obviously I'm not in the contest. I'm going to be optimistic and say they were stored in a cool basement drawer for the last 40+ years. My guess is:

1200mAh

What do you all think? Let's see some numbers and discussion! And of course post any questions, glaring omissions, etc.
 

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cool test!!!!!!
I'll guess 1080 mAH.

Why:
I recall these not being real D cells, but AAs in a D package. (Cheaters!) So I'm going to guess that the marketeers went with the absolute maximum capacity they could get. Which may be at a lower charge rate than you're using.

Also, because one of the cells' IR is 50% more than the other (though both very low?) that may drop the average.

Then again, the electrolyte may be all dried out, and these have a lot lower capacity.
 

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Dibs on 900mAH, for no particular reason except the cells are old. Even then, they’re so old that ???

- Park
 

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Contact resistance was all over the place. So I made my own:
GEPermaCellRig.jpg
This. Is. Awesome.

It also deflates my ideas for a cell-level stick conditioner that merely perforates the stick shrink wrap with needles, even though the current would be low.

How much current were you pushing through the other holder?

(I suspected that contact issues might be a problem with the needle approach and this kind of confirms they will.)
 

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I'm gonna be a huge pessimist here and say 120mAh. I just don't trust batteries to sit on the shelves that long.
 

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Traditionally, NiCad liked to be stored discharged. I'm going for an optimistic 1100mAh, based on them holding full original capacity but originally coming up slightly short of their claimed capacity.

I'm not in the US though, so if I win I just win. And that's just as important :D
 

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Hmmm, I'm really not sure, but I'm going to be pessimistic and guess 155mah with the assumption of losing 5% capacity every year for the last 40 years.
 

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Discussion Starter #13
This. Is. Awesome.

It also deflates my ideas for a cell-level stick conditioner that merely perforates the stick shrink wrap with needles, even though the current would be low.

How much current were you pushing through the other holder?

(I suspected that contact issues might be a problem with the needle approach and this kind of confirms they will.)
I was just measuring resistance. Not good when moving the battery slightly changes readings. Since I'm only testing these cells at 100-200mA it probably isn't a big deal, but it helps eliminate things like false -dV triggers and such.

We will mail the gift card anywhere, so anyone may participate. It's just the sticks that are limited to the US.

Good guesses so far! Keep them coming. :)
 

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985mah, please.
 

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Discussion Starter #19
AC 1000Hz method
 
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