# At what voltage are alkalines considered dead?



## Black Rose (Dec 18, 2008)

We have a call display unit next to our sofa that takes AAA batteries.
It was displaying the "replace battery" message again, so I replaced the batteries.

I checked the old ones with my analog battery tester and my DMM. 

With the analog tester, they all read at the low end of "good".

With my DMM, under load the batteries show around 1.3 volts. 
I checked the previous set of AAA batteries the unit expelled as well, and those are also showing 1.3 volts.

There is some voltage left, but it's probably not usable for long.

As stated in the title, at what voltage are alkaline batteries considered to be dead?


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## MorePower (Dec 18, 2008)

It really depends on the voltage cutoff of the device in question. A typical remote control for a TV will stop working when individual cells are around 1.0V under the load of the remote. Some (poorly designed) digital cameras will cease to function when the loaded voltage of cells is 1.2V.

In general, an alkaline cell heads downhill pretty quickly when its loaded (depending on the load) voltage hits 0.9V.

What load did you use when checking the voltage with your DMM?


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## Yoda4561 (Dec 18, 2008)

Put a load on those cells, I bet they'll drop down to under 1 volt immediately.


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## rockz4532 (Dec 18, 2008)

i used to think if the resting voltage was below 1.4 volts it was dead


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## Lynx_Arc (Dec 18, 2008)

those 3AAA caller ID boxes complain about low batteries easily and then run for over 6 months after they are *low* I gave up replacing them on mine tried nimh and a few months and it was complaining. I know have a 3AA caller ID box from GE that when it is low a tiny battery symbol flashes instead of the text blinking which is no fun. I was thinking about running 4 batteries in the 3AAA box instead with a resistor or something. Oh and alkalines are considered dead at about ~1.1v on most checkers I have taken them out of stuff and after resting for awhile that is about what dead ones rill rebound to.


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## Black Rose (Dec 18, 2008)

MorePower said:


> What load did you use when checking the voltage with your DMM?


I don't know what the load is. All the documentation for the DMM says is that the battery test function uses a load test. 

The DMM has 1.5V and 9V settings for the battery test function. I used the 1.5V setting for this.



Lynx_Arc said:


> I know have a 3AA caller ID box from GE that when it is low a tiny battery symbol flashes instead of the text blinking which is no fun.


This is a 3AAA caller ID box from GE.


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## Lynx_Arc (Dec 18, 2008)

my 3AAA one is also from GE.... blue writing on front and flashes replace battery all the time now. I leave it right by my bed where I have to turn a light on to see it and it has been flashing for over 6 months and still works you just have to read between the warning.


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## Mr Happy (Dec 18, 2008)

Black Rose said:


> As stated in the title, at what voltage are alkaline batteries considered to be dead?


This is, unfortunately, all a matter of who is doing the considering. Electronic designers are _supposed_ to consider them dead when the voltage gets below about 0.9 V or so, but many poor designers require the voltage to be higher than 1.3 V as you have discovered. Short of taking those bad designers out back and shooting them, there is not much you can do about the situation... :shrug:


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## ltiu (Dec 18, 2008)

0


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## Illum (Dec 18, 2008)

to me anyway...any alkaline that exhibit a voltage of 0.5V under load
believe it or not there are cheap cells out there that will measure 1.5V OCV out of the pkg but drops to almost nothing under the slightest load...and extra heay duty cells aren't the only exception


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## NightTime (Dec 18, 2008)

ltiu said:


> 0


 


Funny...


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## Lynx_Arc (Dec 19, 2008)

Illum_the_nation said:


> to me anyway...any alkaline that exhibit a voltage of 0.5V under load
> believe it or not there are cheap cells out there that will measure 1.5V OCV out of the pkg but drops to almost nothing under the slightest load...and extra heay duty cells aren't the only exception


I haven't seen any alkaline cells that drop like that near 1.3v and above but have had some that measures 1.0v that sag like mad under a slight load. I had some RCA manganese batteries (they were not alkalines) that measured 1.5v but my remote wouldn't work and finally I figured out on a load they were dead.
Typically if you don't have a battery drainer I would toss any alkalines that were less than 1.0v because only a few things can use the ~5% left in them.


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## Illum (Dec 19, 2008)

I need to get another DMM soon...my last one sprout legs while I left the garage door open. I'm reading from an analog and the needle is near halfway below the 1 tick mark whenever I measure voltage through a load...something like a 2.2K resistor.

to me OCV means nothing...cr123As measure ~3V even when the ZTS says its dead, Silver Zinc will still say ~1.3V when they won't light an LED up two in series.

I've tested a couple batches of Duracell's [Mar 2008 all the way up to Mar 2015, AA, AAA, D] this way and yes, most don't go below 1V. at the moment I'm trying to figure out how to extract all the juice from them, using low current LED drivers and using them around the house instead of the AC LED nightlights.

With the current expenditure per year of batteries we as a household only yield about ~20AAs, even less on AAAs, and about half a dozen 9Vs from the smoke alarms and alarm clocks...which the Pak-lites doing a good job eating them. For the AAs I've rigged up a 5V boost circuit using the Max756 and ran CREEs on them, at 100ma CREEs are pretty bright actually. I dunno what to do with the AAAs, and about 30CR123As/year  ...


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## Lynx_Arc (Dec 19, 2008)

I must have 8 Dmms. I was given a craftsman autoranging dmm as a present and got 3 harbor freight cheapos on sale for $3 each and then my father passed away and he had done the same thing. I currently use the guts of a 3AAA headlamp that the case broke to light up my keyboard using weak batterie. I use rechargable AAs to help drain the weak ones when I don't have 3 of them. I have a AAA to AA adapter I made from a 2AA light that hade a 2AAA tube in it. I find I can get batteries under0.4v with a load and rested they measure about 0.7 to 0.8v or so. draining batteries this low will have about 1/5 of them leaking so I have a battery holder and don't put them in anything nice.


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## Black Rose (Dec 19, 2008)

I have a few 3xAAA battery holders for powering those LED projects I have yet to start 

I'll keep those cells around to use/drain with those projects.


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## Lynx_Arc (Dec 19, 2008)

at one time I had a single 5mm LED wired to a variable resistor and hooked up to 6AA batteries that were all *dead*. I would dial it down till it read 4-5ma and leave it on as a nightlight and every so often I would check and dial it back up to 4-5ma when it got down too low. I have had batteries so low they reversed in the set, they were the *undead* batteries


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## jerry i h (Dec 19, 2008)

Black Rose said:


> ...As stated in the title, at what voltage are alkaline batteries considered to be dead?


I guess it depends on what gizmo the batt is in :hahaha:
I have a Stanley Maxlife 369. I took some dead batts from the recycle bag, and stuck 'em into this thing. ALL of them light up the torch, and also lit up the red LED saying your batts are dead.


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## Lynx_Arc (Dec 19, 2008)

jerry i h said:


> I guess it depends on what gizmo the batt is in :hahaha:
> I have a Stanley Maxlife 369. I took some dead batts from the recycle bag, and stuck 'em into this thing. ALL of them light up the torch, and also lit up the red LED saying your batts are dead.


that is the beauty of LED lights...... you can use 3 batteries direct driving that are dead out of incans and most non LED devices till they are dim then put the batteries in devices that have boost circuits and use them some more.


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## etc (Dec 21, 2008)

When I used alks, I ran into the problem of them dropping to some voltage like 1.2V, too low to power what I wanted but not dead yet. In time I accumulated a colleciton of mostly-discharged cells.

I did find that CMG Infinity ran on these cells for a long while... but at a reduced lumens, which is pretty bad as it's low even on fresh cells.


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## Stereodude (Dec 21, 2008)

Black Rose said:


> As stated in the title, at what voltage are alkaline batteries considered to be dead?


When the device they're in no longer works.


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## MrAl (Dec 21, 2008)

Yeah that's about it 

If you have cells that dont work in one device sometimes
you can take them out and use them in another device and
get a little more life out of them.

I find that 1.2v doesnt run much though, so i only keep cells
that are 1.3v or above now.
One exception is one of my digital thermometers, but then
again if the cell reads 1.2v even though the thermometer
still works it doesnt last very long with that cell anyway,
so it's almost a waste of time in the long run.


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## Black Rose (Dec 21, 2008)

Stereodude said:


> When the device they're in no longer works.


 

Why didn't I think of that!!!!!


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## Lynx_Arc (Dec 21, 2008)

there are entire threads talking about people sucking the last drop of electricity out of cells... I once thought of an idea of a smart boost circuit and charger to take weak and dead cells and use the remaining power to top off another battery but decided it would be a lot of time for little savings. spending a bunch of money you could spend on more batteries to not waste a fraction of what would be saved by getting that extra drop of gas out of the nozzle by shaking it one more time sort of thing.


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## FLT MEDIC (Dec 23, 2008)

For 1.5v AA or AAA primary batteries, 1.3v "under load" as tested by your DMM is considered dead.

For 1.2v Nicad or NiMH AA or AAA rechargeable batteries, 1.0v "under load" is considered dead.


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## jerry i h (Dec 23, 2008)

not sure.


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## Lynx_Arc (Dec 23, 2008)

FLT MEDIC said:


> For 1.5v AA or AAA primary batteries, 1.3v "under load" as tested by your DMM is considered dead.
> 
> For 1.2v Nicad or NiMH AA or AAA rechargeable batteries, 1.0v "under load" is considered dead.


I have a battery tester that has 3 load settings on it.


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## Mr Happy (Jan 31, 2009)

I found a battery vampire. I have an Oregon Scientific weather station that had been displaying the low battery warning for a few months but was still working fine. Well today I noticed it was no longer picking up the signal from the remote sensor so I thought I had better check the batteries and see what's what. The three Duracell AA batteries were each down to about 0.7 volts! (And one had started leaking.) Now that's what I call extracting the last drop of energy from batteries.

Given the leaky battery, I think we can say 0.7 V is a bit too low when it comes to considering batteries dead.

I replaced the alkalines with rechargeables this time, but now I will have to pay attention to the low battery warning so I don't over discharge them. I don't want my Duraloops being sucked down to 0.7 V!


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## Lynx_Arc (Jan 31, 2009)

I have found when alkalines get below 1.0v they tend to not be able to power anything over about about 50ma for long till they sag to where the device dies. If I were to *guess* this is my estimate:
1.5V 95%-100% capacity
1.4v 80% 
1.3v 60%
1.2v 40%
1.1v 20%
1.0v 10%
0.9v 5%
0.8V 2%
This is just my own thoughts and this is resting voltage sitting long enough for a full recovery. Recovery times vary and I would say take about half the percentage for the percentage of current it can supply under load so if it can put out half an amp at full capacity at 10% it will put out 0.10 x 0.5A x 0.5 or about 25ma at most. Probably a lot less than this IMO.


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## Mr Happy (Jan 31, 2009)

Yes, I'd say the batteries were pretty dead. They were reading above 0.7 V when installed in the weather station. After removal they were reading about 0.77 V open circuit, and the voltage dropped down below 0.7 V when using the battery test function on my meter. The battery test function draws 5-10 mA, so they were certainly not capable of supplying much more than that.

If an AA cell has 2000 mAh, then for the weather station to last a decent time between battery changes it must be drawing less than 1 mA. But perhaps not a lot less, since the batteries seem to run down more frequently than I'd like -- which is why I just put rechargeables in it.


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## fireguy (Jan 31, 2009)

Have to agree with the "depends upon the device" answer. I have an Oregon Scientific atomic clock that always reads "LOW BATT" no matter what batteries are in the unit. I've had a set in it for a year and it still didn't go dead. My "Weather Channel" remote weather unit had some NiMH and they were running for almost a year. I had put some cheap 2700 cells in it, and I'm not sure if I charged them first? Probably did, but this was the first device they were put into. It read LOW BATT about a week after I put them in. When I removed them the 2 cells read 1.21 and 1.22v on a DMM (not under load).


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## Russel (Jan 31, 2009)

In most devices that I use, or see used, will work down to 1 to 1.1 Volts. There is that pesky digital camera at work that refuses to operate below 1.3 volts per cell...but that is the only device that I can think of that won't drain AA batteries completely. (And it refuses to work for more than a few photos with fully charged NiMH batteries!)

I hate discarding AA primary batteries that arn't completely drained, so I usually save them and use them up in low power demand devices such as wall clocks. I have found that most wall clocks will keep working with AA alkalines down to about .8 to .9 volts.


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