luxlover
Banned
Warning: Do not remove a cell from this charger, until the green light indicating end of charge appears.
My good NYC friend Joe (jtr1962) came to the conclusion that I was using my Amondotech bought Titanium TG1000 four bay AA/AAA charger incorrectly. It seems that my impatience in waiting for a full charge to occur may have been instrumental in causing the destruction of ten NexCel 2,300mAH NiMH AA cells, and eight Energizer 2,500mAH NiMH AA cells.
How this occured is through my periodic removal of a cell from the charger to "check" it's voltage at that point in the charge. According to Joe, this charger will only work as designed and complete a charge without any damage to a cell, if it is left alone until the green light appears. By removing a cell before the green light appears, the voltage and temperature detection features are disrupted, and the charger will continue to charge the cell beyond what it should. In my case, I remember that every cell I charged became very hot to the touch well before the green light appeared. In effect, I fried all eighteen of my cells by removing them for premature voltage checks and returning them to the charger. Now that I have twelve AA Eneloops in my AA arsenal, I will charge them properly by letting the charger do it's work uninterrupted.
Thank you Joe for the enlightenment.
Jeff
My good NYC friend Joe (jtr1962) came to the conclusion that I was using my Amondotech bought Titanium TG1000 four bay AA/AAA charger incorrectly. It seems that my impatience in waiting for a full charge to occur may have been instrumental in causing the destruction of ten NexCel 2,300mAH NiMH AA cells, and eight Energizer 2,500mAH NiMH AA cells.
How this occured is through my periodic removal of a cell from the charger to "check" it's voltage at that point in the charge. According to Joe, this charger will only work as designed and complete a charge without any damage to a cell, if it is left alone until the green light appears. By removing a cell before the green light appears, the voltage and temperature detection features are disrupted, and the charger will continue to charge the cell beyond what it should. In my case, I remember that every cell I charged became very hot to the touch well before the green light appeared. In effect, I fried all eighteen of my cells by removing them for premature voltage checks and returning them to the charger. Now that I have twelve AA Eneloops in my AA arsenal, I will charge them properly by letting the charger do it's work uninterrupted.
Thank you Joe for the enlightenment.
Jeff
I have a detailed description of what happened. Most NiMh chargers which detect end of charge by negative delta V will store the highest detected voltage value since the cell was inserted and the difference between the present and last voltages. How often the voltage is sampled depends upon the design of the charger. Anyway, when the difference between the highest and last value is negative, the charger will interpret this as an end of charge signal, and terminate fast charge. When a partially charged cell is removed and reinserted, all the stored voltage information is lost. This is not necessarily a problem is the cell is not close to fully charged. The cell voltage will rise for a while and eventually drop slightly, and the charge will terminate properly. However, consider if the cell was nearly fully charged. The cell voltage may have already started to drop before the cell was removed, but not enough for the charger to detect and terminate fast charge. Now if you remove and reinsert the cell, the prior voltage information is lost. The charger will charge and look for a voltage drop. However, if such a drop had already partially occurred the cell voltage may not drop enough for the charger to terminate. Hence, the cell will continue to fast charge until the overtemp sensor (if one exists) shuts down the charger. This means the cell gets much hotter than it otherwise would.
