My NiMH batteries charger rejects specific cells , what I should do?

[Kiriakos GR]

An NiMH charger this operating with internal micro controller, this could have a larger number of functions, than of what we can see externally.

internal micro controller this uses as User input, push buttons over the charger.
internal micro controller this has a factory loaded operating system (software).

micro controller factory loaded operating system, this it does include battery detection routines.
Battery detection routines:
These should define if a Battery this is Alkaline or NiMH?
Is this NiMH functional?

In both cases in which these Battery detection routines measure battery internal resistance this exceeding higher acceptable value, then the charger will stop, and it will try to inform the charger operator by a visual charge error indication.
Blinking LED or LCD screen text.

Is there a fix?
If your battery poles they are full of dirt, and charger bay this is full of dirt?

You can use isopropyl alcohol along of dish sponge at it Green side, so to clean both cells and charger contacts.
You need to wait 30 minutes prior powering up the charger.

If the charger fails again to determine the battery cell as good?
Then this battery its not good any more for normal operation.

But this cell it can have an second chance, if this get charged with a simpler in technology charger, and this cell to be used at low drain applications, wall clock or FM radio.

Such battery cells,  they should be marked by a paper sticker, and never be mixed again, with any healthy pack of cells.
Such a half dead NiMH, this will continue to serve for another four years before it become totally unusable.   
 
Prior of us using chargers with smart detection, and by assuming that you own a digital camera.
The weak battery pack, or a weak link within a battery pack of two or four cells, this it was detected if you are trying to use camera flash light.

Charging process of camera flash light, this is No1 real life test, if battery pack performance this is Good or Not.
Digital camera, this is a dynamic DC load.
Zoom of lens,  this is a dynamic DC load.
Flash light charge, this is a heavy weight dynamic DC load. 
 
Individual battery cell evaluation.
This is a process of us discovering and replacing the most weak link within a battery pack.
If this is made properly, we are saving money,  we replace with a new only the damaged cell.

Individual battery cell aging
From my experiences, when one AA 2000 mAh, this starting to measure 1800mAh (at refresh mode) , this cell is near to the limit as normal NiMH.
When this measure 1600 mAh this is not a normal operating NiMH.
When this measure 1400 mAh this is a half dead NiMH.

Half dead NiMH
The major unseen problem with Half dead NiMH, they do not respond at all at trickle charge.
Charger light stays Green, trickle charge this is active, but actual battery cell this is empty at zero % of charge.

If you got quality NiMH cells, you will see this happening after 12 years of time.
If you got low-quality NiMH,  this will happen much sooner.