wierd eneloop question

[Jeep olllllo]

I recently bought the costco eneloop pack. I mainly bought them to use in a radio near my shower. They will need to be recharged about every two weeks. I have a question about re-charging........The radio uses Three AA bats. When I charge them I have to do it in pairs (right?). If I charge this way I will be knowingly recharging a fully charged battery. Will this greatly diminish the life of said battery? I plan to rotate them on at every charge so I am not constantly overcharging the same cell.

I have thought of finding something I can put the 4th cell in to run it down a bit so it will need a charge when I charge the 3 from the radio.

Thoughts, suggestions,

Thanks in advance!

 

[SilentK]

if i were you, i would charge two of the cells and put the other to the side and wait untill you go throught the next set so you have an even number. this is what i tend to do with applications where i have an even amount of cells that need recharging. or you could always find a good charger that will charge them individualy.

 

[jzmtl]

Depends on what charger you have. If you have independent channel charger it'll charge any number of cells without problem. How many AA do you have? if you have 8 then rotate them like previously mentioned, so you always have even number of cells to charge.

 

[TakeTheActive]

I recently bought the costco eneloop pack. I mainly bought them to use in a radio near my shower. They will need to be recharged about every two weeks. I have a question about re-charging........The radio uses Three AA bats. When I charge them I have to do it in pairs (right?). If I charge this way I will be knowingly recharging a fully charged battery. Will this greatly diminish the life of said battery?

Yes.

Depends on what charger you have. If you have independent channel charger it'll charge any number of cells without problem. How many AA do you have? if you have 8 then rotate them like previously mentioned, so you always have even number of cells to charge.

As previously stated, your choices are simple:

1. Devote SIX cells to your radio and thus always charge in pairs.
   • Discharge A, B, C. Charge A, B.
   • Discharge D, E, F. Charge D, E, F, C.
   .
2. Buy an individual cell charger (the Maha MH-C9000 and/or La Crosse BC-900 come to mind ) and charge *ONLY* the discharged cells.

 

[clintb]

I'm not up on the current pack Costco offers; is it still being sold with a charger? If so, you may already be good to go with an independent channel charger.

 

[Turbo DV8]

Devote SIX cells to your radio and thus always charge in pairs.

1. • Discharge A, B, C. Charge A, B.
   • Discharge D, E, F. Charge D, E, F, C.

But, I don't like the idea of leaving cells completely discharged for two weeks. It's a crying shame Eneloop had to cheap down their newer combo packs with a pairs-charger and fewer cells.

 

[Mr Happy]

But, I don't like the idea of leaving cells completely discharged for two weeks.

There's nothing wrong with that. Why don't you like it?

 

[lolzertank]

There's nothing wrong with that. Why don't you like it?

The cells would be wasted for those 2 weeks?

 

[Turbo DV8]

There's nothing wrong with that. Why don't you like it?

Unless I got off at the wrong bus stop, leaving NiMH cells completely discharged accelerates cell degradation.

 

[SilverFox]

Hello Turbo DV8,

I think you have it backwards...

With the possible exception of the Low Self Discharge NiMh cells, keeping NiMh cells at full charge will increase degradation. I store my cells discharged, and advise others to do so too. They won't store as long in a discharged state, so you need to do a charge/discharge cycle every 30 days. This keeps NiMh cells vibrant and deters the onset of increasing internal resistance.

I think the Low Self Discharge cells are better off at around 75% charged for longer term storage, but there isn't enough data to fully support that opinion.

Tom

 

[Turbo DV8]

They won't store as long in a discharged state, so you need to do a charge/discharge cycle every 30 days.

I've read many times here that it is not good to completely discharge a NiMH cell and leave it in that state. Not sure how I got my signals crossed on that one. What do you mean by "they won't store as long in a discharged state?"

 

[Mr Happy]

I've read many times here that it is not good to completely discharge a NiMH cell and leave it in that state. Not sure how I got my signals crossed on that one. What do you mean by "they won't store as long in a discharged state?"

If you discharge a NiMH cell in a normal manner (for example, down to 0.9 V under load), and then stop the discharge, the voltage of a healthy cell will recover to about 1.2 V and stay there. That voltage is quite within the normal range for the cell and it will come to no harm sitting like that.

However, if the cell is suffering from high self-discharge, or if you leave a load on the cell once it is discharged, the voltage will drop right down towards 0 V. This is the point where the cell will start to suffer damage and the voltage must be increased by charging as soon as possible.

Since even a healthy cell will have some self-discharge, a cell sitting at 1.2 V should be cycled every few weeks to keep it in good shape. However, leaving a cell sitting empty at 1.2 V for a few weeks while it is waiting to be charged is not a problem.

 

[Turbo DV8]

Ah so, very good. So choice #1 for longevity is to leave them discharged, and then charge and discharge them every few weeks? I have about 70 LSD cells in one denomination or another. I have left them charged and run a test cycle on them every three or four months. I don't see myself leaving 70 cells discharged, and doing a charge-discharge cycle on them every two or three weeks. Besides, I don't have a convenient "discharge & hold" feature on my BC-900 analyzer, since you guys convinced me to return my C-9000's! Hehehe... just joshin'! So, what's worse for cell longevity? Leaving LSD cells fully charged, and doing a discharge-charge cycle every few months, or leaving them fully discharged for extended intervals (several months) after discharging to 0.9 volts?

 

[Mr Happy]

The LSD cells seem to be a little different from other NiMH cells and I leave my eneloops fully charged when not in use. As far as I can tell they can be stored for a year or two like this. If they have been in storage for a while I will cycle them to wake them up before use.

So with LSD cells, storing them charged or discharged is fine. Either way, they will probably benefit from cycling every few weeks or months to keep them vibrant.