c9000 with old battery problem

timcook

Newly Enlightened
Joined
Dec 25, 2009
Messages
8
I recently got a new c9000 charger after lurking about the forums. It is from the 0H0FA batch. I got some eneloops as well which have performed as expected. When I've been using some of my old (ranging from 2 - 5 years) NiMH batteries I've noticed some weird behavior.

When I insert either a Lenmar 2000 mAh or Duracell 2650 mAh battery the charger flashes 'mode' and I am able to select any of the four functions. Regardless of what I choose, or if I let it sit and default to the 1000 mA charge rate it will begin for a few seconds and then return to flashing 'mode' as if I had just inserted the battery again.

I know that there have been reported problems with the c9000 restarting, but from what I can tell this is different. If I am charging in a different bay, those bays continue to function fine. The other 'restart' problem seems to be that the entire recharger was restarting over and over, not a specific bay. If I move one of my eneloops to the bay in question it works fine.

Other batteries purchased at the same time as the old ones (and used roughly the same amount) give the 'HIGH' impedence error, so I suspect the fault is the batteries and not the charger.

My question/concern is: why are these particular batteries not also simply giving the 'HIGH' error? I noticed that if one of the problem batteries sits in the charger it continually defaults to the charge mode, restarts, and repeats until the battery gets very hot. Another gives the 125 mA charging current with 0 V, a problem I have read about after searcing the forums and have attributed to battery failure, not a charger issue.

I am going to dispose of all the old batteries, but I wanted to make sure that my charger is working as intended. I don't want a new battery to suddenly induce an endless loop of restarting/default charging causing damage.

I'm quite new, so if I'm leaving out any needed info please let me know. Thanks!
 
I think you are right in your estimations.

The C9000 seems to have two levels of error indication. If it thinks the battery is a rechargeable cell but has an impedance too high for successful charging it shows 'HIGH'. If it thinks the battery is not rechargeable, but is instead an alkaline or carbon-zinc battery, it resets to the mode screen. You can test this by inserting a dead alkaline battery into a slot and seeing what happens if you try to charge it.

Apparently some of your old NiMH cells have such a high impedance the charger thinks they are alkaline.
 
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