How to take care of nimh and li-Ion batteries???

[Lobo]

I have been pretty sloppy when it comes to taking care of my batteries and decided to put an end to that. But when I googled around about battery maintenance etc, it seems like everybody gives different answeres(incl battery university). It drives me crazy!
So, could any kind CPFr point me in the right direction to a link he know is true?
Or maybe a thread here? I didnt find any sticky, and when I searched I only got errors or nothing usefull. Would appreciate some help.
Cheers.

 

[coppertrail]

1. Charge between .5C and 1C
2. Full discharge every 12 - 15 partial discharges, or when you notice the cells loosing capacity.
3. Store cells in a cool place when not in use (I store them in the refrigerator)
4. Don't use chargers that "cook" cells
5. Treat your battery terminals and charger contacts with DeoxIT Gold. If that's too expensive, use a product called ISO Heet (It's actually a fuel additive found in the Walmart automotive section).

These are just some of my suggestions based on what I've learned. I agree, there are many differing opinions on how to maintain NiMH cells

 

[SilverFox]

Hello Lobo,

In addition to what Coppertrail mentioned...

You need to start off knowing what condition your cells are in. The best way to do this is with a controlled charge and discharge. Now you have a basis for comparison.

When you purchase new cells, always measure the voltage of the cells when the arrive. If they have dropped below 1.2 volts, they are older cells. If they have dropped below 1.0 volts, they are old and I will usually return them because it is a long process to get them back into shape, and they usually don't perform as well as newer cells, or cells that have been properly cared for.

I have found that cells usually come in at around 90 - 95% of their labeled capacity. Cell performance is measured by voltage retention under load, and capacity. You will find that when the capacity drops to around 80% of the labeled capacity, your cells will no longer be able to maintain voltage except for very low drain applications. This is the point where I recycle them.

Periodic testing is the most exact way to keep track of this, but informal testing also works.

Also, keep in mind that when cells exhibit strange behavior, the may no longer be capable of optimum performance. Things to look for are cells that have charged fine before, now are heating up a lot while charging, physical damage, and leaks. Once again, cells that exhibit this behavior are ready to be recycled.

NiMh and NiCd cells should be stored in a discharged condition, and should go through a charge/discharge cycle every 30 days.

You can get away with discharging a NiMh cell, then putting around 20% back in and storing it for roughly 90 days.

The low self discharge cells, like the Eneloop cells, seem to be a little different. They can be stored at a full charge. While they can last a long time, I have noticed that my Eneloop cells that were stored for 6 months have a slightly higher impedance than the ones that have been in service. This is brand new technology, so we don't know what is going on with them. I think they should be cycled every 6 months, but have no basis for that recommendation.

Storage is hard on NiMh and NiCd cells, so just get enough to handle your needs and use them often.

Li-Ion cells should be stored at around 40 - 50% charged and do not need any form of cycling or break in, unless they are going to be subjected to very high current draws.

Tom

 

[Lobo]

Oh, that was a lot of info.
Will have to reread it, but just some additional questions.

1. How low is dangerously low for NiMhs?
2. How high is the voltage when the batteries(NiMh are full? I'm not sure how good my charger is, so could be good to now if it charges my batteries full or not.
3. Should or should I not discharge my NiMhs every time before loading them? I have a discharge function on my loader, and it goes pretty quick, so I have been using it from time to time.
4. How should I store my old cellphones? I rarely use them, but it would be nice to know that they could be used one day. The batteries are Li-Ion, should I just charge them to 50 percent and them forget about them?
5. Not a question really, but I'm a bit puzzled over my Sony digicam-batteries, they are Sony branded 2100mAh NiMh, and they have been rarely used for almost a year, and I havent charged them for at least 6month(probably more). Just picked my camera up, and they still have about 20% charge according to my camera. Is that unusuall?

Thanks for all the helps guys, it's appreciated.

 

[Turbo DV8]

NiMh and NiCd cells should be stored in a discharged condition, and should go through a charge/discharge cycle every 30 days... Li-Ion cells should be stored at around 40 - 50% charged...

Now you can add me to the confused list! I was led to believe that NiMH love to be kept charged, not stored discharged! I have two portable DVD players, one with NiMH battery pack, the other with Lithium Ion. The instructions with the NiMH state to keep the battery pack in a fully charged state at all times when not in use. The instructions for the Li-ion state to store the battery pack fully discharged, not partially charged. I guess there is a reason I have no hair. :hairpull:

 

[SilverFox]

Hello Lobo,

Remember that batteries are a perishable item with a limited life. The better care you give them the longer they will last, but eventually you will have to replace them.

Dangerously low for NiMh cells is 1.0 volts resting. You can run cells lower than this under load, but the voltage should climb back up to usually around 1.2 volts within a few minutes. At lighter loads, the voltage will not climb as high.

The voltage at the end of a charge is dependent on several things. With the ambient temperature at 68 F, relative humidity at 55%, charging at 0.1C, and brand new cells, you can see an ending voltage of around 1.46 volts, hot off the charger. By the time the cells have cooled off, they are usually at around 1.42 volts. As cells age, their ending voltage increases.

NiMh, and NiCd cells, do not have to be fully discharged with every use. NiMh cells should go through a full discharge/charge cycle every 30 - 50 cycles, unless they are being stored. NiCd cells benefit from a full discharge/charge cycle every 10 cycles. Keep in mind that depth of discharge is a factor in cycle life.

Li-Ion batteries are supposed to last longer when stored at 40 - 50% charge in cool temperatures. Seal your phones against moisture and store them partially charged in the refrigerator.

Your Sony batteries sound about normal. When you calculate out the self discharge rate you come up with around 28% capacity remaining after 6 months. A couple of actual tests show that to be slightly higher, but in the same ball park.

The problem is that you will not get the same performance from your battery pack until you have gone through around 5 complete charge/use cycles. The reason is that the chemistry is a little changed due to the extended period of self discharge. If you are interested in getting the best performance from your pack, you would be better off storing them in a discharged state, and doing a charge/discharge cycle every month. If you are more interested in cycle life, and can give up some performance, you can store the pack charged, and know that it will take a few cycles to get them back up to good performance again.

The second method us usually recommended because it gives you a better chance of having power available for a spontaneous use of your camera.

Tom

 

[SilverFox]

Hello Turbo DV8,

Battery packs compound the problems of individual cells.

Storing your NiMh pack will give you a longer period of time to remember to charge it, but the cells in the pack will go out of balance and your performance will suffer. A good compromise would be to store it at around 50%.

Storing a Li-Ion battery pack in a discharged condition for any length of time could result in a ruined pack depending on where they cut to voltage off at. If they are using a high voltage cut off, you may be OK for the short term. If you have a way to measure the voltage of the pack, it should be around 3.7 volts for proper storage.

Tom

 

[Lobo]

Thanks for the help, Silver Fox, seems a bit clearer to me now.

Cheers!

 

[User name]

3. Store cells in a cool place when not in use (I store them in the refrigerator)

And the humidity?

 

[coppertrail]

And the humidity?

Each cell stored in a separate snack sized ziplock bag.

 

[LuxLuthor]

Take a few minutes and read Chapter 4 of Buchmann's guide here.

 

[coppertrail]

Thanks Lux, that's batteryuniversity.com in an easy to navigate format

 

[LuxLuthor]

The other thing I'm liking about this new Hyperion 1210i charger I got is I can set the charging to end at a certain capacity of a Li-Ion. So if I want to store them at 60%, there is a way to set that percentage....or if I want to more quickly charge at higher rate up to 85% of capacity, you can do that too. Maybe all the Triton/Schultze type chargers do that.