Does The Lower 1.2 Voltage in Rechargeable Batteries Provide Less Power Than Alkalines?

Although rechargeable batteries‘ 1.2 volts are lower than the 1.5 volts of alkalines, you need not worry about it affecting your gadgets’ performance.

In the world of rechargeable batteries, there is a healthy helping of skepticism and ignorance when it comes to all of the numbers and ratings associated with NiMH rechargeable battery technology. Voltage, the dreaded “voltage depression,” and mAh (milliampere-hour) ratings are all new technological considerations for consumers who up until very recently had nothing more to worry about when it came to batteries other than having to replace them when they went dead.

But as people become more and more educated on rechargeable batteries, this new knowledge often leads to new questions as well. A recent string of skepticism has arisen regarding the output voltage of rechargeable batteries, and how it compares with disposable alkaline batteries: while alkaline batteries output 1.5 volts of power, NiMH rechargeable batteries only manage 1.2 volts of power output. So, the question is, will that lack of .3v in rechargeable batteries negatively impact the performance of electronics?

The short answer is no. Here are the facts and realities surrounding what we might call “Voltagegate.”

First off, when we say that alkaline batteries manage a 1.5v  power output, we’re actually being quite generous: while the average alkaline battery starts out at 1.5 volts, the lifecycle of an alkaline is constantly sliding down from 1.5 to 1.0 volts before dying out. This means that the average voltage output of an alkaline battery is, in fact, about 1.2 volts. In the end, an alkaline battery only benefits from 1.5 V voltage at the beginning of its discharge. Then, it drops constantly to well below 1.2 V to around 0.6 V.  Most equipment will work happily on anything between 0.9 V and 1.5 V. Unlike alkaline batteries where the voltage drops quickly, rechargeable batteries offer a more constant voltage around 1.25 V throughout the entire period of use.

In addition, because of the discharge of NiMH rechargeable batteries, they don’t see their voltage slide down during their lifecycle in the way that alkalines do. Instead, rechargeable batteries maintain a steady voltage output of 1.2 volts.

In this way, despite the lower voltage, consumers actually get a steadier, more reliable power output from NiMH rechargeable batteries. That is why the latest rechargeable batteries will actually outperform alkaline batteries in equipment calling for a constant and high level of energy input, such as digital cameras, flashes, camcorders, computers, portable phones, CD players, toys, gadgets – well just about anything.

Some electronic devices, however, may benefit slightly from the 1.5 volt starting power of a fresh alkaline battery than the steady 1.2 volts of a rechargeable battery. A portable radio or flashlight, for example, will perform better with the initial jolt of an alkaline’s 1.5 volts. That being said, because of the steady voltage drain on a disposable battery, the performance of a radio or flashlight is going to slowly decline. The radio or flashlight using a 1.2 volt rechargeable battery may not receive or light up with the same initial intensity, but will offer consistent performance over a long period of time.

There’s another thing to consider when it comes to batteries and voltage as well. . .

The voltage of an alkaline battery drops at a very predictable rate: 1.5 volts – fully charged, 1.25 volts – 50% charged, 1.0 volts – at the end of its lifecycle. Because of this, many electronics devices, such as the Nintendo Wii, can give users accurate feedback about how much battery power is left in an alkaline battery. However, for an NiMH rechargeable battery, it remains virtually at 1.2 volts until it is nearly completely discharged. Because of this, it is impossible to track the lifecycle of a rechargeable battery.

Of course, if you’re a user of rechargeable batteries, this really won’t be much of a problem for you, since most likely you’ll have a fresh set of batteries ready to go when your Wiimote or other gadget runs out of power. But it’s always good to know what the voltage of your batteries really means.

Thanks for reading our article! If you’re ready to purchase some rechargeable batteries, battery chargers, or any other electronics accessory, then visit the Electronics Warehousewebsite and use promo code EWBLOG at checkout for 10% off your entire order, plus FREE shipping Australia wide!

8 Responses to “Does The Lower 1.2 Voltage in Rechargeable Batteries Provide Less Power Than Alkalines?”

  1. 1 Tony Sep 13th, 2011 at 2:58 am

    Excellent explanation – just what I wanted to know. Many thanks.

  2. 2 Rusu Mihai Jan 13th, 2012 at 8:06 am

    Explanation will seems valid,still dint apply v well in real world where u need banks of batteries and problem gets bigger.

    I can count around me like 10 gadgets including digital cameras

    see SAMSUNG ES-9 as example will need 2 batteries
    it starts with AA alkaline DURACEL PLUS MN 1500 and wont even power up with SANYO Ni-MH 2700 model HR-3U fully charged measured at 1.22 V

    witch will not even START with Nimh or rechargeable because they need alkaline to be powered.
    if u need 4 batteries to power device up that’s a hefty 6 ,v.Nimh only can 4.8 and u can figure out the rest because 1.2 V missing is a extra battery in fact.
    I never did see a gadget require 1 battery,there might be out there, still …
    All gadgets witch specifically need alkaline and are used fairly often are a battery hog and should be avoided(wireless keyboards,mouses.. etc), i leaned that on my on pocket.
    What happens is that the device need the extra 0.3 x nr of batteries to function and that depletes fast,leaving u with the option to buy another set and the thought – that was fast to deplete –
    If u measure the batteries , u see them around 1.1-1.2 V and device refuse to work.

    I m not saying that this happens to all devices, i say that u should reconsider if a device specifically ask for alkaline type.

    My Personal opinion is :”bad design” on those devices,they got reduced volume and weight to brag out on on our expenses as they could had done a bit larger gadget to accommodate 1 more battery and a voltage regulator .

  3. 3 David Morgan Apr 27th, 2012 at 10:33 pm

    Hi there, thanks for writing such an informative article. I have a question for you. I recently purchased a solar powered light which contains 2x AA 1.2V rechargeable batteries. After the first day of charging in the sunlight they were not fully charged so I replaced them with 2x fully charged AA 1.5 V rechargeable batteries from my portable phone and the lights worked perfectly well. My question is, should I be concerned with using rechargeable batteries marked for different voltages (ie 1.5 and 1.2V in two different devices which will recharge them possibly at different voltages?

  4. 4 electronicswarehouse May 2nd, 2012 at 11:30 am

    Firstly I am unaware of any AA rechargeable batteries that are 1.5V, I would be interested to know where you got them from. Secondly 1.5V should not be an issue I have written another blog article here which explains why. You can see it at this link.


    Here is another link which explains why using regular rechargeable batteries can be problematic.


    You can find our new batteries that are designed for solar garden lights at this link.


    Electronics Warehouse

  5. 5 Dr J D Collins May 3rd, 2012 at 11:47 pm

    I bought AA batteries with charger from you to use for a Polar cadence/power detector for my pushbike. The battery compartment takes 2 AA batteries in series (ie 3V). The detector detects a crank magnet to measure cadence and chain vibration to measure chain tension which with chain movement rate is converted into power in watts. These measurements are transmitted by radio to a display on my handle bars which reads values every 5 seconds. Whilst I have no problem with normal alkaline batteries I get no readings at all using the rechargeable batteries.

    When the system has not been used for 5 or 10 minutes the operation can be checked by rotating the cranks. A light flashes on the detector each revolution as the crank magnet passes the detector and a second light flashes as the moving chain vibrates (this stops after about 30 seconds to a minute). Normal alkaline batteries show proper operation but the rechargeable batteries do not not operate the lights.

    My experience with normal batteries is that new batteries give a reading of 1.55 volts. Once I get a reading below 1.5 volts they are dead for all my battery usage applications. At a voltage of 1.2 volts they are really useless.

    If I had known they only gave 1.2 volts I would not have bought them.

  6. 6 electronicswarehouse May 6th, 2012 at 10:35 pm

    Dear Dr Collins,
    I really do not understand this. Below is a link to an article that explains why rechargeable batteries are 1.2V. You will see on the graph at the link below that rechargeable batteries supply a constant 1.2V for an extended period.
    If what you are saying is correct that your alkaline batteries die below 1.5V they would not last very long at all you will see on the graph that alkaline batteries very quickly drop below 1.5V.
    We do offer a 30 day money back satisfaction guarantee so if you are not satisfied you are welcome to return them for a refund.



  7. 7 Mark Jul 14th, 2012 at 3:34 am

    Hi Steven, I have a radio/ cd that takes 6 1.5v c size batterys. With 1.2v nimh it will not even switch on,as it is 1.8v down is there a 1.5v rechargeble available?

  8. 8 Hermie Sep 12th, 2012 at 8:47 pm

    I have a device which uses 3 AAA rechargeable (1.2 v each) batteries? Can I replace the rechargeable batteries with 3 AAA alkaline (1.5 v each) batteries? Will excess 0.9 v at start of the alkaline batteries’ lifecycle damage the circuit of the device?

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