Noob needs charging advice

[SafetyBob]

I finally got a real power supply for my Triton2 and made some cables to go from it to the Voltcraft 4 place battery holder I got too.

So I am charging Eneloops right now. I know it says 2000mA on the battery, so does that mean I could charge at two amps. I am right now charging at 1 amp. So I guess my question is, what is 1C for an eneloop AA battery?

Lets talk discharge now. If I want to "condition" these batteries (I have a boat load of older NiCD and NiMH batteries I really need to condition) what should I really do? Discharge at 1Amp and charge again at 1Amp? Any advice here would really be appreciated. Do you condition if you haven't used the battery for awhile and it is discharged pretty well?

For older batteries, how many cycles should I condition the batteries to?

Anyone having any tips for the Triton2 please feel free and vent. I can use all the help I can get!!

Bob E.

 

[65535]

I would charge your eneloops at 1.5Amps thats .75C (3/4C). As for conditioning charge them at .1C (1/10C) for 14-16 hours, and discharge them at .5C (1/2C), 5 cycles should get them back into the game.

 

[phenwick]

I
So I am charging Eneloops right now. I know it says 2000mA on the battery, so does that mean I could charge at two amps. I am right now charging at 1 amp. So I guess my question is, what is 1C for an eneloop AA battery?

Lets talk discharge now. If I want to "condition" these batteries (I have a boat load of older NiCD and NiMH batteries I really need to condition) what should I really do? Discharge at 1Amp and charge again at 1Amp? Any advice here would really be appreciated. Do you condition if you haven't used the battery for awhile and it is discharged pretty well?

For older batteries, how many cycles should I condition the batteries to?

Bob E.

C= the capacity of the battery. a safe charging rate is .5 to 1C.
The recommended discharge rate is generally .2C, 400ma in your case.
Number of cycles depends on the condition of the batteries. Anywhere from 2 to 5 cycles. If your not seeing improvement or something in the range of 80% of labeled capacity after this, consider moving on to new batteries.

 

[SafetyBob]

I will write those recommended setting down. Thanks.

What about some 3-4 year old Radio Shack NiMH 2000ah batteries. Would I condition those the same way too?

Lastly. I want to ask if I did something wrong or don't understand something. When I set the Triton2 up for the Discharge/Charge cycle and told it 4 times, set the battery pack voltage to 4.8 volts for the 4 eneloops, 1 amp charge, 1 amp discharge. As it was charging the voltage on the display was 6.03. I assume that tells me that it needs a higher voltage than the actual pack voltage to force electricity into the batteries, correct?

I think it went throught 3 cycles and I started getting worried that I may have done something wrong. Discharge voltage started out in the 5.9 or 5.8 volt range. I though these were 1.2 volt cells. That's what is says on the package and on the battery. When I took the batteries off just as it finished the third charge cycle, they all read with a fluke 87 meter 1.5 volts. Isn't this to high? Aren't I destroying these cells? Can anyone tell me what I need to go back and check for when I do another 4 cells tomorrow?

This is my first charger other than those stupid wall chargers, so I am having a learning curve here. Thanks for your help.

Bob E.

 

[phenwick]

I don't have knowledge of this charger, so others will have to jump in and help you with that. but charging and conditioning strategies of NiCads and NiMH are similar.

 

[SafetyBob]

Thanks for the words. As I recall, during charging, it read 1985mA. I am learning so much about this stuff...who would have thought that you could actually be able to really tell what and how your batteries are doing.
So I guess my capacity is ok, I just shorted the life of these four batteries by somehow overcharging them to 1.5 volts?

Will get my feet wet again tomorrow. Looks like ice all day (so I think I will stay home and play with the charger again), don't tell anyone....

And I promise I will reread the manual again. I think I know what to look for now.

Bob E.

 

[Mr Happy]

Fully charged Eneloops fresh off the charger will read about 1.5 V per cell, but it drops rapidly to about 1.45 V after you stop charging them. As soon as you start using them, or if you let them sit for a few days, the voltage will drift down towards 1.2 V or so, and after a while longer 1.15 V. The quoted 1.2 V per cell is just the nominal or average voltage assumed in normal use.

 

[SilverFox]

Hello Bob,

I believe I read somewhere that the Triton2 has been modified to allow you to do a 0.1C 16 hour charge. If your charger will allow you to do that, it is the best way to try to recover cells that have been in storage, or to condition brand new cells.

This forming charge takes a long time, so after you do 1 cycle of it you can speed things along by charging and discharging at higher rates. With 2000 mAh cells, I would charge at 1500 mA and discharge at 500 mA for a few cycles, keeping track of the discharge capacity. When the capacity levels out you have done as much as you can. If the capacity is below 80% of the initial capacity, recycle the cell and move on.

1.5 volts at the end of the charge is not unusual. The key to cell damage is heat. At the end of the charge you should be able to hold the cell comfortably in your hand. If you can't, you most likely have done some damage.

Tom

 

[SafetyBob]

Thank you everyone. MrHappy I checked this morning and the eneloops read 1.41 volts and it has been 10 hours since they came off the charger. And when they did come off the charger they were slightly warmer than room temperature. And I mean slightly warmer, you could hardly tell at all.

Silverfox, as I am reading the manual and playing with the charger it looks like .1C (200mA for a 2000mA battery) is possible. I think if I am moving the knob correctly, 100mA is the lowest I can set it for charging.

I think I will play around with these older Radio Shack NiMH just to see what they will do. They have been in a drawer for a long time and only see duty in flash strobes during prom season. This should be fun to see how long they last in a Fenix L2D that I have laying around.

Heres a stupid question: Should I ever let a NiMH discharge all the way? I know it's a no-no with Li-ion rechargeables, but haven't read much about NiMH.

Bob E.

 

[Anders]

Hello SafetyBob.

Our "Master" here, Silverfox earlier wrote:
"[FONT=&quot]Be very careful when discharging NiMh cells below 0.9 volts. If you are using a heavy load (1C or higher), it should not be a problem, however under very light loads, it is possible to damage the cell and cause it to vent through deep discharging.

There are actually two phases that occur during the deep discharge. The first involves the depletion of the active material of the positive electrode. At the end of this phase, hydrogen gas begins to form. The negative electrode is larger and begins to absorb the hydrogen gas. The second phase involves the complete depletion of the negative electrode. Once both electrodes are completely depleted, the negative electrode tends to absorb oxygen and the capacity of the cell is reduced. The generation of hydrogen and oxygen gas builds up the pressure within the cell, and it is possible for the cell to vent. Venting electrolyte leads to a further loss of capacity.

The exact voltages where these transitions accrue is very close to 0.4 volts, but varies depending on the condition of the cell.

Time is another variable. A short excursion to a lower voltage is not as damaging as shorting a NiMh cell out and leaving it a 0 volts for an extended period of time.

We have found that lower capacity NiMh cells are more tolerant of discharge abuse than the higher capacity cells. You can completely ruin a high capacity cell by allowing it to sit overnight with a resting voltage below 0.9 volts. It seems that the pressures cause separator damage and the cell develops soft shorts that lead to high self discharge rates.

When you are trying to break up large crystal formations by slow discharging to 0.4 volts, make sure that the cell doesn't spend any time at this discharge level. As soon as you hit 0.4 volts, immediately start a 0.1C charge to bring the cell back up to 1.0 volts. From there you can charge at your normal rate.

Most manufacturers consider a cell fully discharged at 1.0 volts. We run test data to 0.9 volts to get the extra little bit out of the cell."

No questions are stupid, we are here to learn from each other.

Some additional words, don't disharge your cell below 0,9V if they are connected, in flashlights or other stuff.




Anders

[/FONT]

 

[SafetyBob]

Thanks Anders, I need to read this stuff again. Right now I am discharging my stored Radio Shack NiMH to 1.0 volt. I was surprised to see these batteries still had 1.3 or 1.26 volts to them after sitting in a drawer for I don't know how long. I cannot remember when I recharged them last. It might have been April or May....and you thought Eneloops had low discharge rates.....

I am very surprised at these old batteries. I do not think the old Energizer ni-cads I have had for at least 8 years will do as well as the NiMH Radio Shacks.

I am excited because now I can build some 6xAA and 9xAA lights!!

Bob E.

 

[SilverFox]

Hello Bob,

I agree with what Anders said I said...

Tom