AAA vs. AA

[Ray_of_Light]

I am still playing with the new Arc AA. I like very much the fact that it stands upright, to the point that I am now using it as nightlight.
I originally intended to replace my Arc AAA that I have all day on a neck lanyard. I changed my mind due to the the AA bulkiness (it do not hide well) and... for the run time.
While for the size there is nothing to say, it is much smaller than the CMG Infinity and not bigger than the AA cell itself, I think there is room for improvement on the runtime side.

All my AAAs draws about 180 mA from a fresh alkaline cell. Since the current draw decreases with the voltage, I an get up to 7 hours of good light before "moon mode".
My two AAs draws 250 mA off a fresh alkaline AA cell, and the current keeps fairly constant while the battery voltage drops. To this effect, I get about 10 hours of good light before "moon mode". With a lithium L91, I get 15 hours instead.

There is to note that the brightness of the Arc AAA Premium is about the same of the Arc AA... this fact let me think that the LED is of lesser grade, or the inverter is less efficient.

This said, I am very satisfied with the AA. The slight higher power consuption, and the different V/I curve are minor nuisances, or subject for improvement.

Anthony

 

[djpark]

[ QUOTE ]
TheProphet said:
All my AAAs draws about 180 mA from a fresh alkaline cell. Since the current draw decreases with the voltage, I an get up to 7 hours of good light before "moon mode".
My two AAs draws 250 mA off a fresh alkaline AA cell, and the current keeps fairly constant while the battery voltage drops. To this effect, I get about 10 hours of good light before "moon mode". With a lithium L91, I get 15 hours instead.


[/ QUOTE ]

I start suspecting the accuracy of my DMM.

From the same fresh (unused) GP Ultra Alkaline AA battery with 1.56V, my AAA-P and AAA-S draw about 160mA, while AA draws about 155mA. The AA appears to be slightly dimmer than AAAs.

The battery was kept for a while in the store, so 160mA of AAA current seems acceptable considering the natural discharge, but the 155mA of AA current from the very same battery seems way too low compared to your AA (250mA).

Can my AA be actually having a QC problem?

Perhaps, I will do a few more current test.

Meantime, if anyone else have some battery current draw data of AA (and AAA), I would appreciate.

DJP

 

[Ray_of_Light]

I took again the measurements, this time with a professional 4 1/2 digit professional bench meter, and I read 250 mA with a fresh Duracell M3. I tried with a new Energizer L91, and the reading is 230 mA.
Internal impedance of my ammetter is 0.1 ohm.

These readings are true for both Arc AA I own. The AA drop to moon mode at about 0.8 V, after 11 hrs, on a plain coppertop Duracell.
Of course, this is a sample of two. I do not know if this is a common behavior to all Arc AAs, or is a "peculiarity" of mine two. Peter may have the right answer...

DJP, check the internal resistance of your ammetter. If you use a cheap DMM, you must select the 10 Amp range, since the lower ranges uses a 200 to 500 mA fuse that has an high internal resistance.
High internal resistance ammetters will show lower current value than real.
Also, as you suspected, the lower reading may be caused from am high - impedance AA cell, so try with some different ones.

Ultimately, your Arc AA and mine may be different, or just at the opposite edges of the design tolerance. At 155 mA, your AA should last 15 hrs on a plain coppertop Duracell...

Regards

Anthony

 

[djpark]

Thanks for the advice. My DMM is actually a cheap and small one.

When I measured with 10A range, I got 220 mA for AA with Duracel which came with the AA at 1.54V. Perhaps, I might waste a pc of battery for runtime test.

OTOH, my AAA-P and AAA-S (measured with 10A range) draws 300mA from the same AA battery, and also from a new AAA battery.

No wonder I keep thinking my AAA is brighter than AA to my naked eye.