# Thread: What is the fully charged voltage of NiMh batteri?

1. ## What is the fully charged voltage of NiMh batteri?

Can anybody tell me what the IMMEDIATE fully charged to capacity voltage of a NiMh battery should be? I mean either hot from the charger, or after no more than one hour after full charge (Please state which you refer to).

Thanks for any input.

2. ## Re: What is the fully charged voltage of NiMh batteri?

It really depends on the battery and the charge method.

Fast charging generally produces higher voltages. Charging Energizer 2100 NiMH AAs in an hour usually results in a cell voltage of 1.4-1.45V

However, I have a pack of 3000mAh SC cells, which after a 2 hour charge, usually results in a cell voltage of 1.35-1.4V / cell.

So if you're trying to plan for the most extreme case, plan for at least 1.45V/cell.

3. ## Re: What is the fully charged voltage of NiMh batteri?

I've seen 1.45V fresh off the charger.

I've seen close to 1.5V (1.49V or somesuch) from IC3 cells hot off the charger (as in, nearly burning yourself trying to measure the voltage)

4. ## Re: What is the fully charged voltage of NiMh batteri?

At standard charge max is @20 Celsius 1,47V.
At rapid charge 1,52V.
After 15 days storage, capasity is about 80-90%, which means 1,25-1,3V.

5. ## Re: What is the fully charged voltage of NiMh batteri?

I usually see 1.45 volts. About half of the new batteries I get show considerably less the first time I charge them. After a few charge/discharge cycles they then show 1.45.

6. ## Re: What is the fully charged voltage of NiMh batt

Mine are usually 1.43 "hot" off the charger.

Glenn

7. ## Re: What is the fully charged voltage of NiMh batt

My Maha cells come off hot at 1.45 and the C.Crane is 1.43-volts.

8. ## Re: What is the fully charged voltage of NiMh batt

Erm I'm running some NiMH 750mah Duracell AAA on the IQ328 and its reading 1.49 and not finished chargeing (its on a test cycle) should I be worried, should I take them off charge???

9. ## Re: What is the fully charged voltage of NiMh batt

Originally Posted by AnthonyMcEwen
Erm I'm running some NiMH 750mah Duracell AAA on the IQ328 and its reading 1.49 and not finished chargeing (its on a test cycle) should I be worried, should I take them off charge???
Here is a charge curve from one of my NiMH battery review:

The voltage peeks at about 1.56 to 1.57 volt, then drops when the charger turns off.

From a NiMH charger review:

10. ## Re: What is the fully charged voltage of NiMh batt

Right it looks ok then, was just surprised!

If it creeps above 1.6ish I'll start getting worried, I'll just keep an eye on it, it is charging at close to one C though (700ma on a 750mah battery)

Not hot at all just a tad warmer than warm. Thx!

Sorry for the necro but saw no point for a new thread when this one was already exactly what I needed!

11. ## Re: What is the fully charged voltage of NiMh batt

I'm not sure what charger HKJ was using for those graphs, but I have an IQ328 like you. I tend to see the voltage top out just above 1.5V (I don't think I've seen one as hight as 1.55), this is the period that the cell heats up a bit as the charge is not being absorbed but given off in heat. The voltage will then dip and be detected by the charger which switches off the charge current. Voltage then drops to around 1.46v. However I don't think I have used 700ma on AAA (tend to use 500)

12. ## Re: What is the fully charged voltage of NiMh batt

Yhea 700 was pushing it for 750 man battery, but I wanted s decent discharge rate as well so that's why I went so high, but it was still just under 1c so batterys can easily handle it, they only just warm as well barely any heat, and that's with four, I'll have to see how AA cope on same setting if I get same results, aka only slightly warm batterys I might try out the 1000 setting on four AA, but I am not holding my breath, unless they have made a change to the desinge (which I doubt) I'm not expecting to get away with it, we shall see though. I was impressed with my test though my 750mah batterys came out at 822 /810/805/782. Only 40mah between the most extream and given such batterys they were I was expecting far worse.

13. ## Re: What is the fully charged voltage of NiMh batt

Originally Posted by greeny1
I'm not sure what charger HKJ was using for those graphs, but I have an IQ328 like you. I tend to see the voltage top out just above 1.5V (I don't think I've seen one as hight as 1.55), this is the period that the cell heats up a bit as the charge is not being absorbed but given off in heat. The voltage will then dip and be detected by the charger which switches off the charge current. Voltage then drops to around 1.46v. However I don't think I have used 700ma on AAA (tend to use 500)
Are yo using the meter in the charger? It probably measures with the current turned off.
With the current on you will get the voltages I show, even a 400mA charge current goes to 1.55 volt.

On my curves you can also easily see when the dip starts and one some of them I also logs cell temperature (Usual not on the same cell as I measure voltage and current on).

Here is a curve where I measure temperature/current/voltage simultaneous (It includes curves for two batteries):

14. ## Re: What is the fully charged voltage of NiMh batt

I always use 700mA for AAs on my BC700. Sometimes I watch it terminate - they sit around 1.47v or so, then jump to 1.52 within 30 seconds or even a minute then terminate.

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