Rid of Energizer AA's NIMH

I have found the above batteries to be, as others have already stated, not reliable if you don't use them pretty soon after charging.
That said, I loaded up 12 that I was about to throwaway and took them back to Walmart. I explained the problem, walked back and got a blister pack like they were packaged and gave it to the nice lady in returns, to help here with the product number.
She took back the batteries and in exchange I picked up the Duracell white top batteries made in Japan.
These although lower in capacity, seem to work when I need them and not self discharge so rapidly. ALso they seem to hold up better in my digital camera.
Now I only have the Rayovac Hybrids and the Duracells. Here is North Ga the Eneloops are difficult to come by.
Just thought this might be interesting and helpful to someone.
Greg

duracell white tops or *duraloops* are rebranded eneloops. Too many people have found the nimh cells above 2300mah to be FSD or fast self discharging.

I believe the energizer cells were hit or miss. I still have 2 batches of 2500s that were made in Japan and have performed very well over the past 3 years. They've been sitting in cold storage for over a year and I pulled out last night. I'm going to run them through a break-in cycle on the C9000, then a refresh analyze mode to see how they're holding up.

On the other hand, I have a set of Sony 2700s that I've had for a couple years. Ran them through a break-in mode on the C9000 a few days ago and achieved average results of 2550. That's all great, but I pulled them off the charger last night at 1.47V and they're already down to 1.33V on a DMM. These are going in the trash can as they've lost half of their capacity overnight.

coppertrail said:

On the other hand, I have a set of Sony 2700s that I've had for a couple years. Ran them through a break-in mode on the C9000 a few days ago and achieved average results of 2550. That's all great, but I pulled them off the charger last night at 1.47V and they're already down to 1.33V on a DMM. These are going in the trash can as they've lost half of their capacity overnight.

Click to expand...

Don't throw those batteries out just yet, you can't tell so easily what state they are in just from a single days drop in voltage. NiMH cell voltages are not linear with capacity, i.e. as you discharge a cell initially the voltage drops quickly but then levels off for quite a while falling sharply as the cell is fully discharged. You can expect a 10% loss in charge from a NiMH cell on the first day after charging (coupled with a large voltage drop), but the initial self discharge does not continue, it reduces to perhaps 1% per day after the first day. I'd see what their capacity is like after a fortnight of standing to see whether they're ready for the bin or not.

KowShak said:

Don't throw those batteries out just yet, you can't tell so easily what state they are in just from a single days drop in voltage. NiMH cell voltages are not linear with capacity, i.e. as you discharge a cell initially the voltage drops quickly but then levels off for quite a while falling sharply as the cell is fully discharged. You can expect a 10% loss in charge from a NiMH cell on the first day after charging (coupled with a large voltage drop), but the initial self discharge does not continue, it reduces to perhaps 1% per day after the first day. I'd see what their capacity is like after a fortnight of standing to see whether they're ready for the bin or not.

Click to expand...

Hi KowShak - I am going to hold on to them for at least another day, will test them in the morning. But, 40% loss of capacity in less than 24 hrs is not a good sign . I do realize that the largest drop in capacity and voltage is right after the cels come off the charger, but based on past experience, this drop is a bit extreme

coppertrail, if I were you, I'd run a "discharge" in your C-9000 first. You may be surprised. In my experience, judging capacity by voltage alone, is very inaccurate.

Good luck! :thumbsup:

Dave

Hi Dave -

I tested them with both a DMM and a ZTS tester, the voltages matched the ZTS results.

The forming charge should have made them a little better, capacities were decent, but the discharge is bad. They really do me no good if they discharge that quickly. This also matches what folks have said in the reviews of these cells on Amazon.

To give you a rough idea, have a quick look at the graphs on this page...

https://www.candlepowerforums.com/threads/79302

These are discharge curves for a battery with a load, so an unloaded battery would have a higher voltage. You should be able to see that a voltage drop from 1.47 to 1.33 is more like 10% capacity than 40%, its a curve not a straight line.

coppertrail said:

But, 40% loss of capacity in less than 24 hrs is not a good sign .

Click to expand...

You can't tell capacity by using a DMM to check the voltage on NiMh cells.

Unless you have something like a ZTS tester, the only other accurate way is to do a discharge like 45/70 said.

Black Rose said:

You can't tell capacity by using a DMM to check the voltage on NiMh cells.

Unless you have something like a ZTS tester, the only other accurate way is to do a discharge like 45/70 said.

Click to expand...

See my last post, I tested on a ZTS as well and it's showing 60% capacity.

ZTS testers have been known to be wrong with NiMH's, sometimes. I'd still do a discharge with your C-9000. You may very well be right, but you may as well check them out.

Dave

Let me add to the chorus, that neither voltage nor ZTS test readings are reliable indicators of the state of charge and capacity of an NiMH cell. A NiMH cell with a voltage of 1.33 V could be fully charged or it could be three quarters charged. You just cannot know unless you run a discharge test on it.

Concerning the voltage drop from 1.4x volts to 1.3x volts, this is normal for NiMH cells. That extra little bit of voltage is what is called a "surface charge". It bumps the voltage up very high temporarily but does not indicate a corresponding increase in charge, and that extra voltage bleeds off very quickly when you take the batteries off the charger.

Thanks Dave and Happy, good points. I'm going to wait until tomorrow evening (that will be 48 Hrs) and run through a discharge cycle on the C9000. I'll post the results when finished.

coppertrail said:

I believe the energizer cells were hit or miss. I still have 2 batches of 2500s that were made in Japan and have performed very well over the past 3 years. They've been sitting in cold storage for over a year and I pulled out last night. I'm going to run them through a break-in cycle on the C9000, then a refresh analyze mode to see how they're holding up.

On the other hand, I have a set of Sony 2700s that I've had for a couple years. Ran them through a break-in mode on the C9000 a few days ago and achieved average results of 2550. That's all great, but I pulled them off the charger last night at 1.47V and they're already down to 1.33V on a DMM. These are going in the trash can as they've lost half of their capacity overnight.

Click to expand...

If they are truly bad in about 2-3 days they should be down to about 1.2v or less but if they hold at 1.33v or thereabouts that is what most of my nimh non LSD cells tend to graviate to after they *cool down* a day or so after recharging. The LSD cells tend to cool down to higher voltages from what I have seen. My energizer 2500s will run my rayovac 1AA headlamp for about 2.5 hours fresh off the charger but 24 hours later they wont run it for but an hour and after 2 days sitting they won't run it for more than 20 minutes.