Cycle Testing Observations…

[SilverFox]

Hello Mighty,

I think this has to do with heat. If you let the cells cool off, you can do as many cycles as you want to. As it works out, I am getting around 4 cycles a day.

Tom

 

[SilverFox]

Well, after 30 days self discharge on the cells, the effects of 15 minute charging are becoming clear.

Under a 1 amp load, the voltage of the cell dropped almost to 0.9 volts, then held for awhile. Gradually the voltage climbed to over 1.0 volt, but that was about as good as I could get.

Normally, Eneloop cells will test at around 80% on my ZTS tester after they have been sitting for a few weeks. These cells tested at 40%.

It looks like they lost around 15% of their capacity in 30 days after all these cycles. I could probably bring them back for daily use, but if they were sitting on the shelf for any length of time, the internal resistance will go up to the point where they would be unable to hold voltage under load.

Very interesting test.

I try and get the graphs up in the first post shortly.

Tom

 

[mighty82]

Exacty what I was worried about. The low self discharge ability will disappear over time, especially with quick charging.

 

[Black Rose]

What is the charge rate on the Energizer charger?

I would guess somewhere in the 7A to 8A range in order to get a 2000 mAh cell to charge in approx 15 minutes.

 

[SilverFox]

Hello Black Rose,

The Energizer 15 minute charger charges at 7.5 amps.

Tom

 

[TorchBoy]

How did I ever miss this? Awesome stuff, Tom.

 

[SilverFox]

Well... R. I. P. Eneloop test cells.

I have been trying different things with these cells, but it looks like after 150 cycles at 7.5 amp charging, they are done.

I charged them up and put them into my Cannon Powershot A540. I usually get hundreds of shots on a set of batteries, but these cells only gave me a total of 23 shots, with flash. The low battery indicator came on after 10 shots and I was able to coax another 13 shots out of them before the camera shut down and would not turn back on.

I tried to charge them in the 15 minute charger, but it rejects both cells.

If you plan on using 15 minute charging with Eneloop cells, don't expect to get more than 150 cycles from them.

Tom

 

[Mr Happy]

Hmmm. It seems like I will be putting away my Energizer 15 minute charger and not using it again.

To put this into context, what might be expected of other LSD cells, or perhaps the ordinary non-LSD cells that are more likely to find themselves in need of a rapid charge?

 

[BackBlast]

Hmmm. It seems like I will be putting away my Energizer 15 minute charger and not using it again.

To put this into context, what might be expected of other LSD cells, or perhaps the ordinary non-LSD cells that are more likely to find themselves in need of a rapid charge?

I'm slow charge cycling an eneloop and a rayovac hybrid. I just finished cycle 177. (c9000 1A discharge/1A charge)

The Eneloop is still holding up well, it might be showing the first real signs of wear. The Hybrid started to noticeably deteriorate around cycle 130, it still works at cycle 177 but it has around 85% capacity and falling. Eneloop is still looking at >95% capacity.

I'm gonna kill these cells eventually :twothumbs

 

[WildChild]

I'm slow charge cycling an eneloop and a rayovac hybrid. I just finished cycle 177. (c9000 1A discharge/1A charge)

The Eneloop is still holding up well, it might be showing the first real signs of wear. The Hybrid started to noticeably deteriorate around cycle 130, it still works at cycle 177 but it has around 85% capacity and falling. Eneloop is still looking at >95% capacity.

I'm gonna kill these cells eventually :twothumbs

After 200-250 cycles on the Eneloop you should do a self-discharge test.

 

[TorchBoy]

To put this into context, what might be expected of other LSD cells, or perhaps the ordinary non-LSD cells that are more likely to find themselves in need of a rapid charge?

The graphs in the first post address that, although there may be a large difference in opinion on "how bad is bad?" Are they useless when the voltage drops too much for the purpose or when the charger doesn't recognise them?

 

[Mr Happy]

The graphs in the first post address that

Thanks for the reminder -- I'd forgotten about those.

 

[Black Rose]

Well... R. I. P. Eneloop test cells.

You should report your findings to Sanyo, they might find your test results interesting.

The fact that those cells were able to take 150 brutal charge cycles before becoming unusable is very impressive.

 

[SilverFox]

Update:

The graph of the data from this round of testing on the Eneloop cells is now posted in the first post.

It looks like the Eneloop cells can handle about 100 charges on the Energizer 15 minute charger, then they start to fade. I think they did very well.

Tom

 

[TorchBoy]

Overall, I was impressed that they held up as well as they did, but for longer cycle life it would be better to keep the charge rate in the 0.5 – 1.0C range.

Now where's the graph for that?

Thanks, Tom - great data, as always.

 

[Anders]

Thankyou Tom for you time and effort, as usual...

Anders

 

[HarryN]

Thanks Tom - interesting work.

 

[BackBlast]

After 200-250 cycles on the Eneloop you should do a self-discharge test.

After 201 cycles, I did a 30 day self discharge test on the Eneloop and Hybrid cells I'm testing..

Eneloop clocked 91% capacity retention (~95% original capacity) after 30 days.
Rayovac Hybrid clocked 68% capacity retention (~87% original capacity) after 30 days.

They were in my basement, side by side, during the 30 days. I imagine a fairly consistent 65-70 degrees or so there.

 

[TorchBoy]

Rayovac Hybrid clocked 68% capacity retention (~87% original capacity) after 30 days.

Interesting results. Does that imply the Rayovacs lost their LSD quite quickly, or was it not there to begin with?

 

[BackBlast]

Interesting results. Does that imply the Rayovacs lost their LSD quite quickly, or was it not there to begin with?

It's losing it with the cycling, I believe it starts out with ~85-90% after 30 days on a new cell. The more wear on the cell increases self discharge.