Li-ion question

store them fully charged.......they say you can let those sit for a couple of years and you might only lose .1 to .2 of a volt even

Brad

The Schulze charger instructions say to store them discharged.

Ive li-ion battery (Nikon) for my camera and it says to store discharged.

That's interesting since I've also seen cautions that discharging below a certain voltage can permanently damage them.

Jim - AMA 501383

If lithium cells they drop below a certain voltage will not recover on charge. They should always be stored charged and then charged at least once a year. Any advice to the contrary is from an OEM that likes to sell replacement packs at exorbitant prices.

-- Red S. Red's R/C Battery Cl>

discharged.

Which would cause one to wonder if they really know anything about batteries, particularly lithium-ion/polymer. Maybe something was lost in the translation. :-)

-- Red S. Red's R/C Battery Clinic

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:> Ive li-ion battery (Nikon) for my camera and it says to store discharged.

: That's interesting since I've also seen cautions that discharging below : a certain voltage can permanently damage them.

ANd the reason is:

-Lithium batteries (both -ion and -polymer) do not self discharge (the rate is practically zero)

-It is safer to store batteries empty. In case of accidental short, the energy content does not cause external damage (although short will descharge the battery to damaging levels).

-Tapio-

An your logic has a serious hole in it.

Given: There is a voltage below which lithium cells will not recover.

Storing them in a discharged condition will allow them to self discharge (and they do have a finite self discharge rate) to below the voltage at which they will no longer be rechargeable.

I suggest you review the lithium cell manufacturers application literature - not some whiz bang charger manufacturer trying for an edge over the other whiz bang manufacturers.

-- Red S. Red's R/C Battery Clinic

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And just how does Nikon suggest you do this? Let the camera run until the lights go out? My Sony has an automatic shut down before you even get close to the threahold voltage that will destroy it's Lithium battery.

-- Red S. Red's R/C Battery Clinic

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: Storing them in a discharged condition will allow them to self discharge : (and they do have a finite self discharge rate) to below the voltage at : which they will no longer be rechargeable.

: I suggest you review the lithium cell manufacturers application literature - : not some whiz bang charger manufacturer trying for an edge over the other : whiz bang manufacturers.

Kokam claims self-discharge of 5% per six months, i.e. about 10% per year. Given that any decent cut-off logic leaves quite some headroom between the cut-off and destructively discharged levels, you should be safe storing the cells uncharged for a time period like one year. If you plan longer storage time, maybe you should sell the cells anyway to a fellow electric flier and buy new ones when you need them, with better capacity and charge/discharge properties. It still is safer to store any cells, if their chemistry allows, with minimal energy content, i.e. uncharged.

-Tapio-

-Tapio-

From the Kokam application notes:

"Kokam cells are shipped with a 50% charge and should receive charge to full capacity with the appropriate charger before use. Li Poly cells may be stored at full charge or discharged to 50% capacity for storage. "

Note they DO NOT say to store them discharged.

-- Red S. Red's R/C Battery Clinic

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From the Schulze Charger Manual:

"Maintenance: Discharge with 1C down to above listed discharge voltages (3.0V per cell). Always store these cells in discharged state. If stored fully charged, the result can be a permanent reduction in capacity."

Who are you going to believe, the cell manufacturer or the charger manufacturer?

Panasonic: "4. Storing the Batteries The batteries should be stored at room temperature, charged to about 30 to

50% of capacity. We recommend that batteries be charged about once per year to prevent overdischarge."

-- Red S. Red's R/C Battery Clinic

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:>> From the Kokam application notes: :>> "Kokam cells are shipped with a 50% charge and should receive charge to full :>> capacity with the appropriate charger before use. Li Poly cells may be :>> stored at full charge or discharged to 50% capacity for storage. "

:> From the Schulze Charger Manual: :> "Maintenance: Discharge with 1C down to above listed discharge voltages :> (3.0V per cell). Always store these cells in discharged state. If stored :> fully charged, the result can be a permanent reduction in capacity." : Panasonic:

: "4. Storing the Batteries : The batteries should be stored at room temperature, charged to about 30 to : 50% of capacity. We recommend that batteries be charged about once per year : to prevent overdischarge."

: Who are you going to believe, the cell manufacturer or the charger : manufacturer?

Three quotes, all different. Even if you decide to discard the charger manufacturer's view, which manufacturers recommendation are you going to follow?

-Tapio-

Actually Kokam's and the manufacturer's instructions are saying essentially the same thing. Store them with 50% to full charge. Schulze is saying store discharged.

I vote "no" on Schultze and will store with a charge state.

Don

: Actually Kokam's and the manufacturer's instructions are saying essentially : the same thing. Store them with 50% to full charge. Schulze is saying : store discharged.

Panasonic says 30 to 50%, Kokam 50 to 100%, so I suppose the absolute correct way to store your Lipolys is to store them with 50% of charge, right?

-Tapio-

The absolute correct way to store the battery is to NOT discharge them.

D>

I'm getting the bottom line of this thread as bad news. Maybe Red will answer this. Several months ago, I invested in a Lithium Ion battery for my laptop/notebook computer. Two days ago, while on a Christmas trip, the battery ran down just 35 minutes after I turned the computer on. Typical usage in the past has been four+ hours. I put it on charge overnight and after ten hours, the "power meter" registered 46% and still charging. My recollection is that it used to charge fully in less than three if the computer wasn't turned on, and maybe five if it was working. The 46% is not relevant, I understand that. Whatever its accuracy, it is however precise and shows 46% reliably. I think I can put a finger on the cause. I got distracted once and left the computer running on the battery and went off for a weekend. The automatic shutdown trips at 10% on the power meter, but I also know about the self-discharge phenom. So here's the question for Red, is there any way to recover/revitalize/restore the battery? Or do I go pay $120 for a new one? I haven't looked to see what alternative technology is available from the manufacturer.

Before tossing the battery I would try to charge it with another charger. Lap top computers were notorious for having poor charging systems. Seems that computer designers fancied themselves a lot smarter than lowly battery manufacturers and do a much more elegant job of battery maintenance with exotic programs.

If it doesn't come back I know of no way to "rejuvenate" a lithium battery. You might consider replacing the cells yourself rather than buying a whole new battery as the mark up on the original equipment packs seems to be the means to recover some profits in the very competitive lap top business.

-- Red S. Red's R/C Battery Clinic

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