good for 1500 recharge cycles; does each one count?

[Eneloops]

Does anybody know if it's each time I put my Sanyo eneloop on the charger, does that take off one of the 1500 cycles? Would I get more "mileage" out of them, if I used them all the way up before charging?

What I'm wondering, is if it's okay to charge a battery that has only been 30% discharged, or would that be deducting from the 1500 recharge cycles it has, so I'd get more "juice" if I used it until it was drained, then charge it?

Or, does that 1500 cycle number mean full charges? If I were to keep all my batteries topped up all the time, would I then get more than 1500 recharges?

 

[cckw]

It's sorta like the saying that each cigarette takes one hour off of your life. It's not that automatic. Charger quality make a big difference in a battery life. A Maha or Duracell CEF23 or a handfull of others will ge the most. Part #2: discharging completely is bad for an eneloop. Each discharge to zero chips away at its (LSD) ability to hold charge. An Eneloop (or any electronic item) will slowly go bad over time with or without use. so lets say they are good for 15 years if used only once a year. That is the same hypothetical life span as charging them every 3 days that whole time.

So in short, use a good charger and at any point beyond 15% usage top them off so you are always ready for anything. And don't discharge completely unless in a pinch, then do it and forget about it.

 

[SilverFox]

Hello Eneloops,

Usually a cycle life claim has some conditions associated with it. If your use follows the testing pattern that the claim was based upon, you can expect to get similar results.

There are a lot of variables involved with cycle life but in general a full charge and discharge cycle counts as 1 cycle. A half discharge and then recharge cycle counts as half a full discharge cycle. This works out to 2 half cycles to a full cycle. From there it goes non linear. For example if you discharge 25% and then charge, it may work out to 3 of those cycles to 1 full discharge and charge cycle. Unfortunately there are variations between brands and variations between cells of different capacities.

The least stressful approach to this is to plan and budget on replacing the cells after 500 cycles. If they last longer you can smile and be amazed at the wonderful quality of these cells.

The other end of this spectrum is to track your usage and the amount of charge put back into the cell each time. Using an analyzer you can figure out the ratio of how much is put into the cell versus how much you can get out at the charge rate you are using. After collecting this data you can fit a curve to the data and figure out if your typical use pattern fits the cells advertized cycle life pattern. Of course you will need at least 5 sets of data for confidence and you may want to compare a few different usage patterns.

If your cells only last 1000 cycles the way that you use them, and you check 2 different patterns of usage, and you collect a set of data from each use pattern a night, this project will take a little under 3 years to complete. If battery technology remains the same, you will end up with useful data. However if battery technology changes, your data will have limited usefulness. Still it would be an interesting test.

Tom

 

[Kestrel]

[...] Still it would be an interesting test.

So Tom, how's your test going? :nana:

 

[Eneloops]

Thank you. I understand now. I was trying to squeeze every milliamp hour from each cell, because I didn't want to use up my "1500 cycles", but now I'll just change them out more frequently, so I can keep them "topped up" and in better service. I appreciate the responses. Thanks.

 

[Norm]

Does a refresh (discharge to .9 Volt and recharge) effect cell life or performance?

Norm

 

[Wrend]

Does a refresh (discharge to .9 Volt and recharge) effect cell life or performance?

Norm

Both. It will likely reduce cell life somewhat and can potentially also increase performance.

Basically, everything you do and don't do to you rechargeable cells wears on them over time. Some things just aren't as bad for them, and can also sometimes help maintain or improve their performance (maintaining higher voltage under higher current drain rates, and having a higher usable capacity).

Generally what you want to achieve is getting the most productive life from your cells. An exception to this might be if the cells are for emergency use only, or some other specific application.

...

Thought I'd mention to the OP that with Eneloops in particular there isn't much need to top off the cells if they haven't been used much and are still mostly charged. The exception to this would be if you're not sure if the cells you're using together in series are at the same level of charged capacity. Then you might want to top them off to make sure they're more closely balanced. Of course if you're going to need their full capacity for whatever reason, then you might want to top them off for that too.

However, as the others have said, it's fine to recharge them before they're empty. Also, you should avoid using them until they're empty, especially if they're being used togehter in series, because of the risk of reverse charging.

 

[SilverFox]

Hello Norm,

I agree with Wrend in that using the cell effects cycle life and that a Refresh cycle can improve performance.

My long term testing and use is revealing that even with good care cells wear out. In 2005 I put a number of the Titanium 2400 mAh cells into service and set a few aside for test comparisons. They are finally wearing out... A few that I have kept track of lasted around 700 charge/discharge cycles.

Tom

 

[entercpf]

:Read: "Up to 1500 cycles"

That claim is meaningless, because there's no guarantee. Heck I remember my first Panasonic Ni-Cd claims "up to 1000x" :shakehead, we all know that ain't true.

 

[Norm]

Thanks for the answers guys.

Norm

 

[ShineOnYouCrazyDiamond]

I know that a few people will and have actually tracked the lifetime of rechargeable AAs, but I wonder if the masses even have any idea at all?

Personally, I don't think I actually use my AAs fast enough to actually reach any sort of lifecycle limits. Most things I put them in last weeks to months between changes so 50-100 cycles over a lifetime would be a lot. Even my flashlights that use AA or RCR-123 cells I would say don't charged more than every week or two.

 

[Norm]

Pretty much the same here SOYCD, my EDC (VR10 TI with 18500 battery tube) only requires a top up every few months and my eneloops are all 2006 and still have adequate performance for my needs.

Norm