Weird behaviour of Samsung 30Q

[pandemia]

Hi friends.

Some months ago (in fact more than a year), I purchased 8x Samsung 18650 30Q cells. And checked the voltage in the moment of receiving them (it was about 3,8 volt which is normal for a new Li-ion cell recently received from Internet vendors).

Then, as I had more 18650 available, I decided to keep these 18650 30q´s in storage condition (no use, 3,8volt and between 15 and 25 ºC)

Something weird is happening with the voltage.

After about a year with no use, and stored at the receved voltage and about an average room temp of 20ºC, the resting voltage has dropped, from 3,8 to 3,3.

This behaviour is normal?

All my other Li-ion cells (sanyo, keeppower, panasonic, etc) keep the 3,8 volt during even more than 3 years without being used, but these samsung 30q´s not.

Is normal? Are they damaged/aged or something?

I never used them! Anyone have seen something similar??

Thanks

 

[susieqz]

i'm curious about this,
no answers?
i do know that mooch says batteries in storage are supposed to
be charged up every couple of months,
that would suggest the 30qs are normal but the others aren't.

 

[zephyr]

Every battery is different

BatteryBrothers.com: https://batterybro.com/blogs/18650-.../77975750-how-to-store-18650-batteries-safely

For the most part, the maximum time for 18650 storage before recharge is about one year.

But that may not apply to you, here;

Samsung says:




This cell is a 3.6 volt nominal cell, and should be stored at 30% charge - about 3.3 or 3.4 volts. If it falls well below 30%, recharging up to the storage voltage of 3.3 - 3.4 volts is a good idea.

 

[susieqz]

thanks for the great info, @zephyr .
i'm studying batteries n i need all the info i can get.