I store my NiCds and NiMhs at one volt per cell in a plastic box at room temperature. I cycle the NiMhs every 12 weeks and Nicads every 8 weeks and the NiMh cells I use every couple dozen charges. Does all of this sound like what I should be doing? Is it necessary to cycle NiMhs that are used frequently and depleted way down each time before charging? Also, when cycling NiMh should they be fully discharged or only discharged down to 80%. Thanks for any replies.
Charging questions
- Thread starter 777qqq
- Start date
SilverFox
Flashaholic
Hello 777qqq,
If your open circuit NiMh voltage is 1.0 volts, it is too low. If you are discharging and end the discharge when the cell reads 1.0 volts under load, that is OK.
NiMh cells will remain vibrant if you do a charge/discharge cycle every 4 weeks. NiCd cells are much more robust and you can pretty much store them any way you want to. They may take a few charge/discharge/charge cycles to get back into shape, but they usually come back very well.
Frequently used NiMh cells only need to go through a complete discharge every 20 - 25 charge/discharge cycles.
Cycling usually involves a complete charge followed by a complete discharge.
Tom
If your open circuit NiMh voltage is 1.0 volts, it is too low. If you are discharging and end the discharge when the cell reads 1.0 volts under load, that is OK.
NiMh cells will remain vibrant if you do a charge/discharge cycle every 4 weeks. NiCd cells are much more robust and you can pretty much store them any way you want to. They may take a few charge/discharge/charge cycles to get back into shape, but they usually come back very well.
Frequently used NiMh cells only need to go through a complete discharge every 20 - 25 charge/discharge cycles.
Cycling usually involves a complete charge followed by a complete discharge.
Tom
SilverFox
Flashaholic
Hello 777qqq,
NiMh cells remain vibrant longer when they are stored discharged. When you get new cells, you should run a standard charge and discharge to make sure they are good. This involves charging at 0.1C for 16 hours, then discharging at 0.2C. The capacity should be close to the labeled capacity.
If you plan to store the cells, you should charge them back up, then discharge them at 500 mA or 1000 mA down to 1.0 or 0.9 volts. At the end of the discharge, the voltage should rebound back to around 1.2 volts.
To keep the cells vibrant, you should do a charge/discharge cycle every month.
Some people think this is too much work, so they live with a little less performance and at the end of the discharge cycle, they put a little charge back in. Then they extend the length of time between charge/discharge cycles to 2 or 3 months.
Cells in storage that drop below 1.0 volts open circuit usually suffer some damage. It is better if they remain above 1.2 volts. The same goes for recently purchased cells. If they are below 1.0 volts, they have been in storage for too long and will most likely not perform up to standards.
Cells that are only partially discharged before charging, as often happen in use, show an improvement by going through a complete discharge down to 0.9 volts every 20 - 25 charge/partial discharge cycles. If this is not done, voltage depression often occurs. This is reversed by the complete discharge.
Tom
NiMh cells remain vibrant longer when they are stored discharged. When you get new cells, you should run a standard charge and discharge to make sure they are good. This involves charging at 0.1C for 16 hours, then discharging at 0.2C. The capacity should be close to the labeled capacity.
If you plan to store the cells, you should charge them back up, then discharge them at 500 mA or 1000 mA down to 1.0 or 0.9 volts. At the end of the discharge, the voltage should rebound back to around 1.2 volts.
To keep the cells vibrant, you should do a charge/discharge cycle every month.
Some people think this is too much work, so they live with a little less performance and at the end of the discharge cycle, they put a little charge back in. Then they extend the length of time between charge/discharge cycles to 2 or 3 months.
Cells in storage that drop below 1.0 volts open circuit usually suffer some damage. It is better if they remain above 1.2 volts. The same goes for recently purchased cells. If they are below 1.0 volts, they have been in storage for too long and will most likely not perform up to standards.
Cells that are only partially discharged before charging, as often happen in use, show an improvement by going through a complete discharge down to 0.9 volts every 20 - 25 charge/partial discharge cycles. If this is not done, voltage depression often occurs. This is reversed by the complete discharge.
Tom
Bones
Enlightened
Well stated 777qqq...
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