Batteries rest at 4.06v after charging.

Hello,

I am wondering if the batteries are bad. After I charged it with both my chargers (Miboxer C2 and Miboxer C4), the chargers state it's 4.20v. After about 15-30 min rest, my batteries are at 4.06v. Is that normal?

I have 2 Panasonic ICR18650 3400mah (3-4 yrs old). After charged/discharged, capacity is at 2800-3200 mah. Charged/discharged with Miboxer C2.

Laptop savage SAMSUNG ICR18650 (I checked the voltage before charging; it's at 3.95-3.98v. After charged/discharged, the capacity at 2400-2500 mah. Charged/discharged with Miboxer C2.

Laptop savage LGDB118650, I checked the voltage before charging; it's at 3.95-3.98v. Haven't charge/discharge these cells yet.

Thanks!

If your charger gave it a proper CC/CV charge, then the battery is probably bad. Make sure your charger is giving a proper charge to other cells, and measure the voltage with a DMM if you have one.

A good cell should not drop voltage to 4.06v after a full charge. 4.16v, maybe is okay, but you're seeing something way too low. Does the voltage continue to drop?

I'm suspecting your charger is not working properly, if you're seeing this on several different cells.

Agreed with WalkIntoTheLight. I also noticed a clear drop in voltage in all my cells, even after charging with CC/CV at 1A. I measured the voltage soon after the charger stops and it's already 4.18V, and continues to drop (out of the charger) until 4.16 or 4.15V after some hours, but not below

Thanks guys. I think my DMM is broken as both my chargers show 4.17v when I tried to recharge them.

jinx626 said:

Thanks guys. I think my DMM is broken as both my chargers show 4.17v when I tried to recharge them.

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Well, put a fresh battery in the DMM and see.

Chris

Also, try measuring the resting voltage of new, known good cells to see where they stand. If the resting voltage of good cells still measures low, it could be your multimeter.