Hobby Charger wont terminate with Accuevolution D cells?

[netprince]

So I recently picked up an entry level hobby charger (G.T. Power X-Charger B6), and I've been trying to cycle an accuevolution 10Ah LSD cell. I disabled the protection timer and protection milliamp limit temporarily, and set the nimh sensitivity to 5ma. (the lowest setting)

I selected the discharge->charge cycle mode, 1A discharge, and 2A charge, and have been keeping a close eye on things. I was watching the milliamp counter and voltage to see when the charge terminates, but when it reached 1.6v (1.5v resting) and 12500mA I chickened out and stopped the charge. The cell was warm to the touch, but not hot.

So here's my question, did the charger miss termination, or did I stop the charge too soon? Anyone have any suggestions? This is my first hobby charger...

Thanks!

 

[Mr Happy]

What is the resolution of the voltage display? In other words, is it 1.600 V or just 1.60 V? If you have 1 mV resolution (1.600 V), then just keep watching the voltage. You should see it flatten out at the end of charge, and then slowly start to go down. If it reaches a maximum and stays flat for more than about 20 minutes then you can pull the plug. Otherwise, I would keep watching it a little longer. Try to make sure the cell is not being excessively cooled during charging as this may prevent termination. Put the cell inside a box rather than in the open air, and definitely don't let the cell be in a draft or anywhere like a cold concrete floor that will cool it excessively.

 

[KiwiMark]

I would keep feeling the cell to see if it was getting uncomfortably hot and see if the charger would terminate before that point. It is pretty normal for NiCd & NiMH cells to warm up during charge, they also take in more capacity than they put out so you should expect 10Ah cells to take in more than 10Ah when they are charging.

 

[45/70]

......they also take in more capacity than they put out so you should expect 10Ah cells to take in more than 10Ah when they are charging.

I was going to mention this earlier today, but since I don't charge D cells much with a hobby charger, I didn't post. I would think though that somewhere around the 12.5Ah point, is about when the charge would terminate, at a 0.2C charge rate. I think maybe net stopped the charge probably at about the same time the charger would have.

Dave

 

[netprince]

Thanks for the suggestions everyone. The second cycle seems to have worked much better. I didn't write down the exact numbers, but discharge reported 9400 and charge reported 10800. I moved the cell away from a nearby basement fan so perhaps that was the difference. (thanks Mr Happy) Strangely my cradle chargers terminate fine in that location (with the nearby fan). I'm going to try this several more times to see if I can figure out the specifics...

 

[HarryN]

It might be that your charge rate: cell capacity is too low to sense the end of charge voltage shift. I have seen that on my Triton II in the past.

It seemed like charging at a low rate was the right thing to do, but in actual practice, it missed, while at higher charge rates, it worked fine.