Charging Schedule Needed To Avoid Overdischarge Of Protected Lithium Ion Batteries

[saabgoblin]

Hello All,

I have been reading some of the links on Aw's page and some of the stickies in this forum and I am wondering if I am understanding a few things clearly about discharging protected Lithium Ion Batteries.

I am aware that there is a protection circuit for overcharge and over discharge scenarios and I had read that Lithium Ion batteries are shipped with a minimum charge to prevent the circuits from kicking in but will protected L-Ion batteries continue to discharge after the circuit has kicked in?

Basically, if I have some protected RcR123 and 18650's that are lying around ,in battery cases of course, and I don't use them for an extended period of time, will they continue to self discharge below the discharge cut off level and therefore become unsafe to recharge?

Thanks to all in advance.

 

[NutSAK]

You should store them at 40% charge. This will keep them from self-discharging below a safe level. This is the level that Li-Ions are usually charged to from the factory. They will also lose less overall capacity over time at this level of charge, and storing them at low temperatures will help also.

Read more about this subject here.

 

[SilverFox]

Hello Saabgoblin,

Is it possible... Yes.

Is it a practical thing to concern yourself over... No.

If you are going to store cells for an extended period of time, you should store them at about 3.8 volts. This should give you 3 - 4 years of storage before the cell discharges to the point of tripping the protection circuit. This is dependent on the current draw of the protection circuit.

If you haven't used your cells in that period of time, you need to spend more time lighting up the darkness...

Also, keep in mind that the electrolyte in Li-Ion cells oxidizes the cell from the inside out, regardless of cell usage. Eventually the cell will die due to oxidation. It is much better to use them up than to let them self destruct due to oxidation.

Tom

 

[saabgoblin]

Thanks Nutsak! I am also reading about AW'sIMR "Safe Chemistry" batteries and in a post by Lux Luthor about 18650 Safe Chemistry battery shootout, lux puts forth the IMR as having no self discharge so they may be a better way to go for my needs in the long run as long as I don't overcharge them.

I am assuming that storing these protected Li-Ions at 40% would allow them to be stored for some time before any damage would occur to the actual cell or I may just have to commit all of my EDC's to mostly RCR's with the occasional primary EDC thrown in for good measure.

I was going to say that I have had relationships that are less high maintenance than using RCR batteries but then agian when I look back at most of my relationships, I think that I'll stick with the batteries.

 

[saabgoblin]

Hello Saabgoblin,

Is it possible... Yes.

Is it a practical thing to concern yourself over... No.

If you are going to store cells for an extended period of time, you should store them at about 3.8 volts. This should give you 3 - 4 years of storage before the cell discharges to the point of tripping the protection circuit. This is dependent on the current draw of the protection circuit.

If you haven't used your cells in that period of time, you need to spend more time lighting up the darkness...

Also, keep in mind that the electrolyte in Li-Ion cells oxidizes the cell from the inside out, regardless of cell usage. Eventually the cell will die due to oxidation. It is much better to use them up than to let them self destruct due to oxidation.

Tom

Thank you for putting my overly worried mind to rest Silverfox, I am just trying to make the best decision possible in regards to the safest use and or misuse of RCR's of all sizes. Personally, I have enough EDC's that can use RCR's and 18650's so I feel that I need to branch out a little further from my NIMH and primary cell comfort zone.

Thanks Again:twothumbs

Robert