how? when? charge my NIMH batteries

jally

12 years ago

Hi, my questions concerns when, and how best, to charge ni-mh batteries via choice of options available to me now.

Here's what I have:

Four 1,2v 2000 mAh Duracell NI-MH batteries
(including CEF14nc charger)

as per this pic:
Duracell

Also, I have:
A very old "Universal Ni-Cd Charger" (made in China)
...which is most similar to this:

I have been using the batteries inside a mini flashlite, and inside a mini-lantern which holds Three AAs. Though I've seldom been using the flashlite & lantern, occasionally, i've been removing 2 batteries at a time from the lantern for use in my digital camera. But i've never kept track of WHICH 2 batteries i've been transferring to my camera at any given time.

That explains why the 4 batteries have different charges.

As follows: The battery readings on multimeter are:
.92
1.21
1.22
1.25

Questions:

(1) Which of my chargers would be safest to recharge the NIMHs on?

(2) Can I safely place all of them at once inside [whichever-charger] even though they're different charges?

(3) for how long a duration is safe to charge them?

btw, I spent hours trying to find the answers to these Qs on search engine, Ehow and Youtube. No dice.

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Comments (3)

toxcrusadr
12 years ago
It is best to use a charger rated for NiMH batteries, NOT an NiCd charger. The two types of batteries have different charging profiles and the circuitry in the chargers is a little different.

As to whether you can charge them all at once, it should not be a problem. Each will charge as far as it needs to and the charger will stop there. NiMH batteries have less of a memory problem, so charging them when they aren't completely dead does not reduce their lifetime like it does with NiCds.

Finally, your volt meter will not really tell you how much charge each one has, since it reads voltage and not current output capability. Voltage stays almost constant until the battery is about dead. The first one on your list is about totally discharged. The other ones could be at 80, 60, or 20%, hard to tell from a voltage reading.
jally
Original Author
12 years ago
thanks toxcrusader!

So basically, if I charge the 4 NiMH batteries on the Duracell value charger they came with, I can keep all of them in the charger for even (say) 48 or more hours, and it wouldn't be a problem?

Once they're all charged, would the red light know to shut itself off?
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jally
Original Author
12 years ago
Update:
Last week I'd stuck them in the charger overnight (approx. 10 hours).

When checked on multimeter, they were at approx. 1.4 charge, which I guess is near the danger zone.

Naturally a smart-charger is on my "to buy" list among a zillion others, such as wire cutters, yada yada, not to mention research for each of them such as can they cut branches too.... Huge headache.