How to charge NiMH batteries
I was wondering if someone can describe to me the care and maintenance from opening of package to initial charge and subsequent charges and how to store these batteries. I've been charging at 1.6 amp rate from opening the package til it dies. This has to be wrong. I've never been told how to charge batteries and when I ask I get a multitude of answers that doesn't seem to coincide with other answers Hoping someone out there can help me.
Thanks
A NiMH battery will not reach its maximum potential until 4 cycles. The 1600 NiMH is a 1.6 amp per hour battery. In other words, if you discharged it at 1.6 amps it would be completely dead in 1 hour. It's best to charge this battery at 160 milliamps at 7.5 volts for 10 hours. The battery will become warm to touch at the end of the charge. You can charge a NiMH at 1.6 amps (fast charge) on occasion, but not everytime. Heat is the killer of these batteries. The heat breaks down the insulator between the plates and a short is formed. A good NiMH battery will actually store 140 % of it listed capacity.
You can store your charged NiMH in the refrigerator, but not the freezer.
Frank
There is a lot of "not so good advice" often quoted here in the forums.
Slow charging is a .1C charge rate timed for 14-16 hours. The battery is overcharged every time. You should not use a peak charger at a .1C charge rate since the charger may miss the peak.
This happens quite often with my Accucell 6 charger when charging Nicads or NiMh batteries.
The enphasis perhaps should have been on "for the appropriate length of time." If charged at .1C for the APPROPRIATE length of time the Nicd , by definition, will not be over charged?....
The timed charging was used for NiCads and 14 to 16 hours at .1C was long enough to fully charge the battery, but it was longer than necessary to ensure a full charge. There is no good way to calculate the exact time required for a full charge. NiCads could handle the overcharging, but NiMh degrade under this condition. For that reason sanyo recommends 3 quick charging methods (see sanyo pdf in previous post)
If you really want some good reliable info on how to charge and care for your batteries check out www.hangtimes.com/redsbatteryclinic.html
There is a lot of "not so good advice" often quoted here in the forums.
Another good source for NiMH information is Radical RC. Check their articles on care and feeding of NiMH batteries. That's whatI followed whenI was running these batteries several years ago, and was steered or ledto the right path....
They also have information on care and feeding of L-ions and Lipos. BTW- their batteries and prices are pretty good too
Here it is again.
I'm more interested in what I should do from out of the package and subsequent charges. Also should I discharge after use? and if so to what? I'm using 1600 mah receiver packs. What I've been doing is was setting the charger to 1.6C throughout the life of the battery. For all this time I believed this was right until I notice that the final read out after the charge was decreasing. I wanna do it right to get the most life of the battery.
Byron
I don't know just exactly what is different between the lengthy SANYO data sheet and red's clinic. The Sanyo sheet gives you directions on establishing a .1C charge rate at one point. Spog if you could specifically cite the differences you think are significant that would make digesting your opinions easier.
I think that if you follow Red's advice you will be happy with your batteries. You state you are charging your NiMh at 1.6C- that would be 2.56 amps. Since you had 1600mah batteries, I wondered if you were charging them at 1.6 amps or 1C. I think 1C is the max you want to charge them at and you need to be on your toes as you get near the end as Red cautions.
I charge new NiMh batteries at .1c a couple times and though my Dynamite charger has never missed a peak even at .1 I watch their heat as Red had suggested. After they have been in service for a few rotations I then charge them at .5 c and have never had the charger miss the peak. I check them before I go to the field with a loaded volt meter. I check them if I fly a lot while at the field. With 60 to 90 sized sport and scale planes (no 3d) with 5 to 8 standard servos the 2000 mah 6v packs have been good for many flights and plenty of reserve.
Since NiMh don't develop a memory you don't need to routinely discharge them.. But to make sure they still have adequate capacity, before the beginning of the season I use a 10ohm 10watt resister to discharge the packs to 1 volt per cell and then recharge them to see how much the charger had to put back in to get them to full charge. It should be somewhere near the stated capacity of the battery.
Good luck
Mike
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