Lithium Ion batteries stored for nine months (PID 2011)

[biod101]

Hello,

About 9 months ago, we picked up twenty 2000 mAh lithium Ion batteries (Product ID 2011) to help us deploy a suite of solar-powered environmental monitors. The project was delayed because of staffing shortages, but we just hired an intern and are about to fire things up again.

I've been reading about lithium-ion batteries and precautions for storage-- something we hadn't anticipated or considered during the project delay. Fortunately, they have been stored in an office setting in cool temperatures.

• I now understand it is not a good idea to store these fully charged - do these come charged from Adafruit?

• I understand these will self-discharge over time. Is it possible these batteries are now damaged from having been stored too long without use or recharge?

I am particularly concerned about the second bullet since I don't want to deploy our monitors in remote areas only to have to immediately service them because of damaged batteries. I'll be collecting the batteries this Thursday - any recommendations for checking state?

As always, thanks for your insight.

[Franklin97355]

Our batteries have circuitry that should protect them from over discharge but before using them in the field I would charge and discharge them at least once to restore any chemistry imbalance and test to make sure they meet minimum specs.

[biod101]

Thanks Franklin.

Good idea - I have a programmable charger and will use the charge-discharge loop on the same. I'll post my results shortly.

Hans

[adafruit_support_bill]

Just a little clarification. The protection circuit in the cell will prevent over-discharge to an external load. But it can't stop the cell's own internal self-discharge process. Most manufacturers ship cells with roughly a 1/3 charge level: High enough to give them a shelf-life of 2-3 years. But low enough to minimize any hazard.

If you will be storing them for much more than a year or two, it would be wise to give them a bit of a refresh on the charger.