Have I tweaked my Li-ion battery pack for good?

[Turbo DV8]

Earlier this evening I read in a thread (can't recall which) that a lithium-ion battery should be stored charged, and never be allowed to sit discharged for an extended period or else it will destroy it. Tell me it ain't so! Over a year ago I purchased a portable Polaroid 7" DVD player which has one of those flat Li-ion battery packs which attaches to the bottom of the player. I ran the battery through a few cycles to test play time, then consulted the owner's manual regarding proper long-term storage, since I would be rarely using this player. The manual states, "If you don't plan on using the battery for an extended period of time, discharge the battery and keep it in a dry and cool place." Emphasis is mine. Now I read here that the opposite is true, that storing Li-ion discharged can destroy it? Why would a manufacturer tell owners to store the Li-ion pack discharged?

 

[VidPro]

if you did what the manufacture suggests, then you did what they suggest
it is good to mostly discharge a Li-ion prior to storage, they are stored about 30-40% discharged in most of the stuff in the store.
it is better to not FULLY discharge, for LONG periods of storage because they will also self discharge a bit while in storage, but most devices like your dvd player will not FULLY discharge the pack anyways, so you should be good to go.

there are other issues with needlessly discharging a series pack of li-ions, but that gets rather complex.

if your worried, discharge it to 40% (its in the book) then store it.
it is better to store it low but not fully discharged, THAN to store it ALL the way charged up.

if you read that a li-ion should be recharged after taking it REALLY low, then you need to see the CONTEXT that was written in. some people/devices and uses of a li-ion can take a cell way way down, and then it should be charged up a bit before its stored, or before it stays in this VERY low state for to long.
within the context that it was stated , it was probably correct.

 

[2xTrinity]

Many devices with built-in LiIon battery packs have regulation circuits that will tell you the battery is "dead" (and shut off) when its chemistry is at about 30% charge, and warn you it is low when it is at 50% charge. They sometimes only charge up to around 90-95% capcity as well. This is done both for safety and to increase longevity (the "shallower" you cycle a LiIon battery, the longer it will last) Discharging the battery through normal use of the device will only dischage it to the manufacturers "cutoff point" rather than completely down. The battery regulators are usually a lot more conservative on consumer devices than even the protected cells that enthusiasts on here will buy -- that's because they need to be idiot-proof to be sold to the general public.

Over-discharging a LiIon is a completely different story, and that will ruin the battery. That's mainly an issue with using unprotected cells, as those lack any sort of "cuttof" mechanism like the one I described. If you completely discharge a battery, you can permanently damage it. Attempting to charge a battery that has been run completely down can lead to overheating, even a fire in extreme cases. Protected cells will generally "suicide" themselves if they're ever completely discharged as a safety mechanism.

 

[LED61]

We have a Polaroid 7 inch player just like yours. I would charge it fully, then run a movie for one hour, then store it in a cool dry place. If you use it at least once a month, I would not bother with the procedure and just charge fully after use and leave it that way.