Eneloop BK-3MCCE AA best charging voltage

Batteries and Chargers Rechargeable Batteries
1

Hi, i just bought 4 of this from Nkon, i want to know, what is the best freshly charged voltage for this cells?

Li ion ~ 4.2v > nominal 3.7, what about Eneloops? nominal 1.2v - fully charged?

2

NiMH batteries are charged by constant current, not constant voltage. Fully charged NiMH might vary from 1.3V to 1.45V, depending on age, wear, manufacturer, cell’s temperature, and many other factors.

3

So there is no general volts - charge, being “good” ? interesting.

4

Shadowww is right but for fresh cells… I always thought 1.5v, same as primary AA.

5

They may be 1.5 volt in the charger with current on, but when taken out, the voltage drops to between 1.40 to 1.45 volt.

I have a charge curve included in each of my battery reviews, it shows how the voltage drops for the first hour after charge is terminated.

Here is on example (Charge is terminated at yellow line):

You can also check my charger reviews, they are also filled with charge curves, but due to trickle current the voltage will be rather high.

6

Thanks guys. What about charging current? i got Opus….500mA good for eneloops or 300 is better?

Edit, so around 1.4V is what i should get generally after some time right?

7

Sanyo recommends 1.0A, but actually their own MQR06W charger charges 2x AA at 1120mA each (or 4x at 560mA each).
Optimal range for NiMH is 0.33-0.7C (that’s 667 - 1400 mA for Eneloops), as too high of a current can cause overheating, while too low of a current can cause missed termination.

8

So 500mA should be the good option?

9

500mA is good, 1000mA is better.

10

Thanks for the clarification HKJ. So nimh relax more than lithium after charging.

11

Wont 1000mA wear out the cells faster? afaik smaller batteries need lower currents, or its changed now? thanks you as always!

12

This depends on what type of LiIon (Not lithium) you compare to:

13

1000mA is for AA.

500mA is fine for AAA.

As long as the charger terminates correctly, there is no problem using lower current, but a missed termination is not good for the cell.

14

If that were my ICR123 I would be chucking it out.

15

I charge the eneloops with NC-MDR02NU chargers, they finish charge at 1.44~1.45V…

… a week later is 1.40~1.42V

16

The battery is mislabeled, it is a IFR battery, i.e. LiFePO4 chemistry. They do have a significant voltage drop when charging is stopped.

17

Yes, I’ve noticed that with my A123’s but they have been used and abused over some years.

18

Guys, i learned that the best way to recharge 18650 is around 3.6/3.7V, but what about Eneloop? i measure the volts a minute ago, and it show 0.9V, at what point should i charge them? does damage occur same as 18650 if you discharge bellow xxx volts? thanks.

19

Completely empty NiMH will have resting voltage below 1.2V. 0.9V is well beyond that point, but unless you keep them at this voltage for a long time, I doubt they’ll incur any damage.

20

i drain it to 0.9v, the flashlight stopped working :frowning: