NiCd V's Duracell AA: NiCd produce very low mA ?

[mettam]

I have 4 AA Ni-Cd rechargable batteries puting out 6.6 Volts and .002 mA
And I have 3 AA Duracell batteries putting out 6.2 Volts and .720mA

My project worked fine with the 3 AA Duracell but not so fine with the 4 AA Ni-Cd rechargeables I put this down to the low amperage the NiCd is putting out.

Can someone explain why both batteries are putting out ~6V and yet such differant mA ? I would have thought that since both are AA in size then the Amperage should be roughly the same right ?

FYI: my project is to light 36LED party lights with 3AA batteries for 8hours. It can be done, I have kept 36 LEDs illuminated for more than 12hours on just 3AA Duracells

Also can someone suggest what kind of rechargeable batteries I can buy that will put out roughly 6V and .6mA ?

Thank you.

Justin.

 

[Nigel Goodwin]

Batteries don't 'put out' current, the current is dependent on the load - NOT the supply (as long as the supply is capable of that current).

However, your voltages are wildly wrong - 4 NiCd's are 4.8V - perhaps just other 5V when fully charged, and 3 AA's are 4.5V - again perhaps about 5V when brand new. Neither will be over 6V!.

 

[Tarsil]

I have 4 AA Ni-Cd rechargable batteries puting out 6.6 Volts and .002 mA
And I have 3 AA Duracell batteries putting out 6.2 Volts and .720mA

My project worked fine with the 3 AA Duracell but not so fine with the 4 AA Ni-Cd rechargeables I put this down to the low amperage the NiCd is putting out.

Can someone explain why both batteries are putting out ~6V and yet such differant mA ? I would have thought that since both are AA in size then the Amperage should be roughly the same right ?

FYI: my project is to light 36LED party lights with 3AA batteries for 8hours. It can be done, I have kept 36 LEDs illuminated for more than 12hours on just 3AA Duracells

Also can someone suggest what kind of rechargeable batteries I can buy that will put out roughly 6V and .6mA ?

Thank you.

Justin.

4 Ni-Cd puting 6.6V?...wow.How about 5.6V when are fuly charged and...4.8V most of the time. Where are u buing thoes cells or ....what voltmeter are u using.

 

[audioguru]

More than 2V from each duracell! I could use some of those.

36 LEDs lighted for more than 12 hours from only 3 little AA cells?

They must be nuclear cells.

 

[Tarsil]

Maybe the leds where turned on&off (on for only a very very small period:lol) . About the voltage....I bought this cheap, made in China, 1$ :lol analog multimeter. It was showing me 14.7V on a 9V bat so..... :lol

 

[audioguru]

It was showing me 14.7V on a 9V bat

Was it a duracell nuclear 9V bat?

 

[Tarsil]

Was it a duracell nuclear 9V bat?

Yup :lol. Bought from Alpha Centauri :lol or maibe the multimeter had a +-25% precision :lol

 

[audioguru]

When you talk about a cheap piece of junk, please don't say, "Precision".

 

[mramos1]

I have a meter as well, when the battery gets low if give high readings. Maybe time to drop the duracells in the meter.

 

[Tarsil]

well...a couple of 1$ junk multimeters with some twiking came in handy on my PS

 

[mettam]

I have a meter as well, when the battery gets low if give high readings. Maybe time to drop the duracells in the meter.

I think this maybe the problem (the batteries may be low on my voltmeter) I have been thinking these results are very strange too.
I noticed the other day while reading a 9 volt batery that my voltage kept rising from 7 to 14 Volts and increasing.

 

[mettam]

More than 2V from each duracell! I could use some of those.

36 LEDs lighted for more than 12 hours from only 3 little AA cells?

They must be nuclear cells.

It's true. I lit 36 LEDs in parallel with actually just 2 AA (duracell probably) the LEDs were only 25% as bright but when I got up in the morning they where still running.
Try it your self.

I cut the LEDs from a string of LED party lights.
I think I submited a photograph of this a few months ago check my history posts to see it. Its nothing ground breaking as I am a beginner.

Justin.

 

[audioguru]

36 LEDs lighted for more than 12 hours from only 3 little AA cells?

LEDs are pretty bright with 30mA. That is a total current of more than 1A and little AA alkaline cells can supply it for only 1 hour.

AA alkaline cells can supply about 180mA for 12 hours. The resulting 5mA average current per LED is not very bright.

I bet they started pretty bright, then got dimmer and dimmer and dimmer and dimmer and dimmer ......

 

[RODALCO]

I think this maybe the problem (the batteries may be low on my voltmeter) I have been thinking these results are very strange too.
I noticed the other day while reading a 9 volt batery that my voltage kept rising from 7 to 14 Volts and increasing.

I think it is time to get a new good brand DMM like Fluke.
Those readings like 14 volts from a 9 volts battery are certainly not the battery at fault, but the meter.

 

[audioguru]

I have a very good Fluke DMM and an el cheapo DMM and they both read nearly the same: 5.000V on the Fluke is 4.98V on the cheap one.

 

[Tarsil]

I think it is time to get a new good brand DMM like Fluke.
Those readings like 14 volts from a 9 volts battery are certainly not the battery at fault, but the meter.

I have a cheap digi multimeter. It's a UNI-T M830B. I've bought one for less then 10$. It has quite OK precision (I've compaired it with some more exp&acurate multimeters). It has a imput impedance of 1.8Mohm ...so for most of the voltage sources it reads ~open circuit voltage.
With 25$ u can buy a more complex one (capacimeter, noise gen, temp probe etc.). It has like 10Mohm imped.
The main diference between a low end digi multimeter and a cheap one is quality management. Like 20% of the cheap ones are junk and another 10-20% need some twiking. I've selected the 10$ one from a lot