Discharging NiMH, to what effect?
11-09-2006, 12:52 PM
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Discharging NiMH, to what effect?
I have my first plane and the manual says to discharge the NiMH battery, then charge it. I have heard others mention this but I have not found an explanation nor a FAQ on it. Is there a FAQ on different batteries and best practices? If not, can someone enlighten me as to why it is necessary to discharge a NiMH prior to charging?
11-09-2006, 03:12 PM
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RE: Discharging NiMH, to what effect?
I believe that the manual was written when NiCd batteries were in use. Some people say that the batteries perform better if you run them through some full cycles, while others say that there is no benefit to doing so. I've tried both ways and have not found any benefit to running down the NiMh. Just charge it and go.
11-09-2006, 07:19 PM
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RE: Discharging NiMH, to what effect?
I would have to disagree here, the purpose for discharging the battery is to allow it to build memory, agreed the nimh are not as prone to this as the nicd were but they still build memory
if you don't discharge a batt completely then you charge it and you do this over and over the batt will soon appear to be dead when it actualy has charge in it, it is the memory that makes this happen. now this won't happen overnight and if you forget from time to time it's no big deal
BUT if you make it a point to only run your batts to the cut off then full charge them they will not last long before your flight times will be reduced, then you create a new shorter memory and so on and so on untill the batt is no good at all. It is a good practice to run your nimh down as low as you can after each flight by running the motor at low rpm till it will barely turn. I take 3 good cycles of discharging the batt to see the improvement, this is the amount of time it takes to build the memory..... this is just my 2 cents worth
if you don't discharge a batt completely then you charge it and you do this over and over the batt will soon appear to be dead when it actualy has charge in it, it is the memory that makes this happen. now this won't happen overnight and if you forget from time to time it's no big deal
BUT if you make it a point to only run your batts to the cut off then full charge them they will not last long before your flight times will be reduced, then you create a new shorter memory and so on and so on untill the batt is no good at all. It is a good practice to run your nimh down as low as you can after each flight by running the motor at low rpm till it will barely turn. I take 3 good cycles of discharging the batt to see the improvement, this is the amount of time it takes to build the memory..... this is just my 2 cents worth
11-10-2006, 01:06 PM
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RE: Discharging NiMH, to what effect?
I agree, I always discharge my NiMh's all the way down. The cells do have memory, and leaving charge in them, then charging full capacity can shorten the life and possibly overcharge the battery. They will get use to having that little bit in them and possibly not accept a full charge decreasing the actual mah. Plus, running them down then giving them a full fresh charge allows them to hit their full potential and have completely new juice, instead of some old lingering juice, with some new piled on top 
