Best Charging practices

[tslrc]

I've done a lot of reading on these forums, and have read the many excellent threads, but am somewhat overwhelmed and still unclear about general charging best practices and reviving old batteries and have some questions.

My Chargers:

LaCrosse BC900

Sanyo Eneloop NC-MQN05U 4-slot, Individual channel(charges at AA-300mA, AAA-150mA)

Energizer CHCARCP-4 this one, charges 2 or 4 (charges at AA-700mA, AAA-350mA) if I put in charged batteries, it seems to detect this well and turns light green and goes to tricle charge. It seems to charge well and has a car cord.

Rayovac Hybrid, charges 2 or 4 (charges at AA-350mA, AAA-150mA)

I am considering getting an Energizer 15 minute charger with car cord, and possibly another charger for added capacity and charging flexibility.

My batteries:

I have many new AA & AAA Eneloops & Hybrids, with a lot of older Energizer AA & AAA's and some LaCrosse. Even a Sony Walkman NiCad.

1) Does anyone see a charger I could get to add flexibility and help my overall charging abilities based on charge and/or discharge rates for new, older, and regular use batteries? My LaCrosse gets backlogged at times with only 4 slots.

2) I have heard the Hybrid chargers are strictly timed chargers, and not 'smart' so should I throw them away? I'd rather not risk 'cooking' some batteries.

3) I seem to have had fairly good success reviving AA & AAA's that have sat for a couple years, relatively unused, by using the LaCrosse refresh with charge / discharge rates of 1000mA / 500mA for AA's, and 700mA / 350mA for AAA's, are these rates optimal or can I use others and improve. I believe I should be discharging at low rates and charging at higher rates than the LaCrosse provides in a regular 'refresh' cycle, if so, how do I accomplish this? Should I do a discharge at 100mA, then charge at 1000mA?

4) What general charge rates are best for normal charging of AA & AAA's? Should I vary this with Eneloops & Hybrid batteries vs. the older Energizers. Is the LaCrosse default of 200mA, Eneloops of 300mA best?

5) I plan to minimize the use of the 15 minute charger, but realize I sometimes may need it plus it gives me the car charging ability. For reviving older batteries, would discharging them on the LaCrosse at the lowest 100mA rate, then charging them in the 15 minute charger be best to reduce large crystal formation and improve their capacity.

Sorry for all the questions, but answers will really fill in the gaps in my understanding and be greatly appreciated !! I have learned a lot from many of you.

Thanks,
Steve

 

[SilverFox]

Hello Steve,

You may want to check out the various threads and reviews on the Maha C-9000. It is similar to the BC-900, but has more features and flexibility.

Your Hybrid chargers may have a specific use, so it may be better to retire them from everyday use and save them for special situations. Sometimes the voltage gets very low and "smart" chargers won't recognize the cells. Occasionally a timed charger is able to increase the voltage enough to allow it to be recognized by "smart" chargers.

Reviving old cells is interesting, but keep in mind that I consider a cell "crap" and ready to be recycled when its capacity drops below 80% of its initial capacity. Crap cells will still hold a charge, but their performance is way below stellar…

Your rates look reasonable for cycling cells, but reviving often is a bit more complex. When reviving, you often have to do multiple discharges, sometimes to lower voltages, to break up the large crystal formation. Keep in mind that over discharged cells often have electrodes that are damaged by oxidation, and age and use tend to break down the separator. No amount of cycling or forming will repair this damage.

The battery manufacturers recommend charging in the 0.5 – 1.0C range. This means that a 2000 mAh cell should be charged with a current in the 1000 – 2000 mA range. The other option is to charge at 0.1C for 14 – 16 hours on a timed charger. When your cells are new, you can get by with slower charging, depending on what the charger utilizes for an end of charge termination signal, but as cells age the 0.5 – 1.0C range will give a more reliable end of charge signal.

The 15 minute chargers are very picky about the batteries they charge. Older cells tend to have increased internal resistance. The increase in internal resistance will cause the cell to heat up more under fast charging. The 15 minute chargers will reject these cells to avoid excessive cell heating. Charging at a rate in the 0.5 – 1.0C range is enough to minimize large crystal growth.

I should also point out that the C-9000 also runs off of 12 volts, so you can reserve your 15 minute charging for those times when you are in a hurry.

Tom

 

[tslrc]

Hi Tom,
First of all, thanks for the reply and the wealth of information you share with us through your many knowledgeable posts on CPF!

I have looked at the Maha C-9000 and it does look interesting, and Thomas Distributing has it on sale. I will read up on it more closely, and try and figure how I could utilize it in my battery maintenance strategy.

So do you recycle(get rid of) the cells at 80% because in addition to only having 80% capacity, they also discharge much quicker even when idle?

It sounds like when reviving older batteries, it's a fine line, discharging below .9V but oh by the way, don't discharge too much. So really when a cell is degrading, a drop in capacity and life is noticed, probably due to the electrode and separator that have been damaged and this raises the internal resistance?

One other question, when matching cells is the ZTS mini good enough for this? Do I try to match batteries by this for everyday use, then when doing quarterly or semi-annual capacity tests, use that info as well? Would a multimeter be better for this task?

Thanks again for taking the time to help explain, things are finally starting to make sense..... I think!


Thanks,
Steve

 

[SilverFox]

Hello Steve,

I want my cells to work very well. I have a number of higher drain applications as well as some lower drain ones. When a cell is down 20%, it looses its "vibrancy," and is no longer able to maintain voltage under load. In addition, I have many applications that utilize multiple cells. When cells crap out, it is hard to keep them in balance. An out of balance battery pack does not perform well at all.

The main reason I don't collect or use "crap" cells is because their performance SUCKS!!! - BIG TIME!!!

Call me a "battery snob" if you must, but I use my cells hard and expect them to perform. When their performance drops off, I get rid of them.

Increasing internal resistance is a normal cell aging process. Voltage depression can be brought about by slow charging and letting the cells self discharge in storage. Voltage depression due to large crystal growth can usually be reversed through cycling. Voltage depression due to electrode and separator damage can not be improved.

Matching cells for multi cell use with the ZTS tester is a good practice to get into. Sometimes with CR123 cells, the ZTS can be a little off, but matching after a few minutes of running the cells usually gives very good results. In high drain multi cell applications, it is better to match cells on mid point voltage first, then on capacity under load. Keep in mind that a battery pack used in a high drain application will need to be balanced every 5 - 10 charge/discharge cycles.

When you get everything figured out, let me know and we will compare notes. I have been at this for quite a few years now, and am still learning...

Tom

 

[tslrc]

Thanks Tom, I tried to reply yesterday but due to the problems on this site was unable to.

Sounds like you work your cells to the max, what do you use them in?

I will probably pick up the Maha C9000 soon.

Before I realized the Hybrid chargers were strictly 'timed' chargers, I may have slightly cooked some Eneloops (painful to say), I realized it was charging too long, then researched and noticed they were not very 'smart' chargers. I will keep just one for the situations you mention.

I think I'm sick, last week I had 4 chargers going at once, was actually kinda cool, I thought I was a battery expert or something. It is interesting when I look at the spreadsheet I started when I got the LaCrosse in Jan. and started to refresh some older batteries, I can see the improvements, and sometimes they would level off, then improve a few refresh cycles later. I know I probably spent more $$$$ in electricity then the batteries were worth, refreshing for over 10 full refresh cycles on the BC900, but it got me comfortable using that charger and seeing how the batteries responded.

If you are planning any upcoming tests, I'd be willing to contribute some new batteries, if so let me know what kind and how many.

Steve

 

[Zenster]

I just ordered the Maha C-9000 from Thomas Dist. yesterday to take care of my NimH cells. I like the fact that you can select the charge rate because different types of cells will last longer if you charge them at a slower rate (low-discharge such as the Hybrio's or Eneloops) while standard NimH's do very well on higher charge rates.

LithIon batteries are a different breed altogether and I like to use the dedicated chargers for those (such as the WF-139).

I'm with Tom on his general evaluation of battery use, and I also toss them if (when) they drop to 80% capacity. There's no point in keeping batteries that test below that because what you're really doing is keeping and using batteries that will go dead MUCH faster than you think. Giving up the time a battery would normally give you during that first 20% from a healthy full charge is giving up a LOT of time.
I'm also not that picky about "matching" batteries because if you simply get rid of your 80%< batteries, the ones that remain are reasonably matched for most applications anyway.
And I say that as a long time Radio Control hobbiest (more than 25 years in the hobby), so I am very well aware of the importance of matching batteries in some R/C applications. But most of what we're talking about here is about flashlights or other household items like radios or whatever.
Matching cells is a big waste of time and mental effort for this stuff.

Batteries are cheap (in the big scheme of things), and it's just not worth it to try to "revive" a failing battery because what you're fighting here is basic chemistry. A battery fails because the closed-system chemical concoction within it is no longer working at it's original efficiency.
In other words, if a battery tests to below 80% capacity, it's broke, so don't waste time trying to "fix" it.

What you're left with is that you want to have a "plan" of battery usage and maintenance. And the plan is simple:
1. Don't hoard any more rechargeable batteries than you need. Determine how many you need to power the things you have, and then buy no more than 10% more than that number (to have only the fewest "spares" as possible).
If you keep more than that, many will go unused for a long period of time which in turn can lead to neglect to where the un-needed extras go below it's safest low charge and is damaged, at which point the chemistry gets damaged and it becomes useless.
Batteries are the happiest when they are used, but not abused.

2. Test the capacity of your batteries about every 5th charge cycle, throw away the under 80% batteries and buy new, FRESH, batteries to replace them and put those new ones in the rotation. (I always write the date I buy a new battery right on it with a permanent marker just for reference).

3. Your "back up" plan should not include your rechargeables, but rather, fresh primary (non-rechargeable) Lithiums or Alkalines that have an expiration date as far out as possible (5 or 6 years or more).
The reason to use rechargeables is to save money, but in a real power-out emergency at your house or whatever, you may not be able to recharge those rechargeables. Plus, rechargeables self-discharge (yes, even the hybrids, only slower), so the spares you may have on hand that you thought were "fresh" may have much less capacity than you think. It's impossible to plan on exactly when you will lose power at your home so you can't anticipate exactly when you'll need to have freshly charged rechargeable batteries, but you can have a plan to keep fresh primary batteries on hand at all times as backups.
So while I don't hoard rechargeables at all, I do hoard fresh Lithiums and/or Alkalines.

I'll note here that I keep track of the expiration dates on the stashed primary batteries I have on hand, and if they enter into the actual year of their expiration date, I go ahead and use them up (so they don't go to waste) and then buy a fresh stash that are dated several more years out.
(One last thought... I just bought a package of Lithium primary batteries with an expiration date of 2021. That troubled me for a moment, and then it came to me... for the very first time, the batteries I bought may very well have an expiration date further out than my own "expiration date".
I gotta' tell 'ya, that's one "Holy Crap!" moment.)

So there's my plan, and I'm sticking to it.

 

[tslrc]

Thanks Zenster,
These sound like some good, sound practices. I have been using some of my near expiration batteries similiar to how you do, and rotate batteries in flashlights that get kinda low. I then use them in other things, like a desktop battery powered fan, or lights I use every day.

I probably have more rechargeables than you recommend, but if I test some current ones, they'll probably fall below your 80% recommendation, so after I pitch them I may be more in line with what you say.

I do keep a good stock of alkaline, and just started keeping some lithiums in car lights and backups in with them. I want to build up a reasonable number of the lithiums and not quite as many alkalines.

Hopefully you'll be like the Energizer bunny, and keep going....and going....and going....

Thanks for all the help and advice, it is greatly appreciated.

Steve