My INR18650-29E drops to 4.12V after a full charge

Batteriapan

Member
Joined
Feb 20, 2017
Messages
35
I have this collection of 40Samsung INR18650-29E thatbehave strange according to me.

After charging them to 4.2V they drop to 4.15V in a matter of minutes. After a few hours they drop top 4.12V and seem to stay stable there "forever" (only had them for so many weeks). If I recharge a 4.12V cell to4.2V my Lii-500 tells me that it managed to charge it with some50-100mA.

Otherwise the cells are great. 25-75mOhm internal resistance, 2750-2950mAh capacity @500mA discharge. And I've tested them quite a bit.

I don't dare mixing thesewith other cells in parallell, afraid they'll discharge the others. Not a big problem since I've got 40 of them, which also happens to bethe size of my packs. Also, I normally nevercharge my packs to more than4.05V, but sometimes I top them off.

But what's up with this? I've never seen something like this before.
 

daromer

Moderator
Staff member
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Oct 8, 2016
Messages
5,573
Sounds like normal bounceback to me. Most cells will bounce back. Almost ALL of my cells drop to 4.10-4.15 within days and thats normal nature and due to the fact that we test and charge with a charger that stops all from 4.15 to 4.25.... ;)
 

thunderheart

Active member
Joined
Apr 4, 2018
Messages
275
Batteriapan said:
I've never seen something like this before.
Maybe you've never checked before? I'd be surprised to see a cell which doesn't drop the voltage after taking out of the charger))
 

Generic

Member
Joined
Oct 23, 2018
Messages
210
Could be the chemistry. Most of my power tool batteries will drop to 4.00-4.03 after a day or two and will stay there for ages. Some of my really good laptop batteries only dropped to 4.18 after a year. If you set up your powerwall for daily charge/discharge, and will not be charging all the way to 4.2 anyway, I think you will be fine to mix. Otherwise, keep them separate.
 

Wolf

Well-known member
Joined
Sep 25, 2018
Messages
1,390
Its definitely battery chemistry,

INR - NMC - Lithium manganese nickel
This chemistry adds nickel to the IMR chemistry above, making it a "hybrid" chemistry. It combinesthe safety and low resistance of manganeseand the high energy of nickel.

ICR - LCO - Li-cobalt
This chemistry delivers thehighest specific energyof any 18650 battery chemistry.

Sample of my INR18650-25R I know that they are not 29E but I don't have any of those yet Chemistry is INR though and notice the V and IRon all of them.
Right where yours are showing up.

image_ilosap.jpg


Wolf
 
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