DIY professional High Current AA batteries holder - Charge / Discharge test bed

[Kiriakos GR]

My topic title this saying it all !! 

Naturally my solution as AA Charge / Discharge test bed, this is robust and almost professionally made due the quality of the materials.
I am industrial electrician and those Bakelite sheets they are not easy to find, but I do have same in stock which I did remove from an old electrical installation which this got modified by other parts.

Either way I was in need for a AA (type) battery holder that this will not melt if the batteries come close to 45C ~ 55 Celsius,  or if the current in use this is higher than 1-2A.

I am very happy by my design as AA type test bed, and I am ready to make and a second one, so to me to be able to connect and test from a single AA up to twelve AA cells in series.

Enjoy the pictures and copy this unique Greek design of my if you can. 

[Kiriakos GR]

My new battle zone   

[Kiriakos GR]

Our production line worked fast !!  While we do have another five multimeter as backup, most of our full size them are now busy.   

[Kiriakos GR]

After completing my batteries test bed project, and by having run all my tests at those GP batteries, now I am able to announce some conclusions.

Basically I did received as gift those eight GP Industrial  130AAHC NiMH.
These actually are 1300mAh made somewhere in 2010, and they were installed in to an Agilent handheld calibrator.
This voltage / current calibrator remained for years as unsold, and those supplied NiMH lost all their capacity by simply staying unused.

While these  GP Industrial  130AAHC NiMH they are just 1300mAh, their specifications them talking about 4000mA as Max instant discharge.
This detail makes them capable to serve also in digital cameras or even to dedicated camera flash units.

At my first tests all batteries looked as dead and a few were having less than 50mAh capacity.
Repeatable discharge / charge cycles by a smart charger this helped just a little.
Capacity were restored from nothing to 250mAH Max.

Then me started experimenting by exploring my own theory, this is about constant discharge at Max rated current according to their specifications.
By this repeated high drain discharge and regular charge at 800mA, those batteries chemistry it did started to wake up.

While all cells at my recovery process, them have identical handling, some battery cells them reacted with positive behavior and some not.

Today I have statistics from all eight cells:
1)  Three cells managed to restore capacity at 1000mAh & retaining their charge.
2)  One cell managed to restore capacity at  800mAh & retaining it charge.
3)  Four cells while them restored to 600mAh, them shown unable to handle constant current, and even as fresh charged, their voltage drops down fast, within 24 hours their charge becomes 50% and they cannot be trusted at powering anything, as they rapidly self discharge.
       
This week I am testing this team of four, that they did successfully recover at 80% or more of their capacity with my digital camera.

Today I feel very happy that my theory this it did worked !
Additional tests of my, with other NiMH cells which them was activated and them were used even occasionally and now lost some of their capacity, them did not shown able to restore any of their capacity.

In conclusion even today I am not sure if it worth all this spent time and effort at bringing back from the dead such new and unused NIMH.
I had to run almost ten cycles of  high drain discharge at 4A,  and around 20 times at cycling them with a smart charger, so its one cell to partially recover, and only the 50% of them shown as reliable about returning back in action.

Today I have the satisfaction that my own theory this worked, and this is enough for me.