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About Maes

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    Here's an old post I made on the subject,

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  1. I've been using those for the last 10 years, and rarely bought any alcalines or, God forbid, Zinc Carbon ones.

    Essentially, since I started regularly using my walkman for listening to music on the move, I soon realized that it gulped batteries down pretty quickly (I always bought noname walkmans that sounded good, but consumed 2x-3x as much as a brand one).

    That's when I switched to rechargeables, in the end of 2000. At first I had to make do with some low-capacity Nicads (600-650 mAh) but even those performed much smoother than alkalines: instead of working OK for 4-5 hours and then gradually slowing down and losing power, they worked for 6 hours straight with constant power until they were completely drained.

    With NiMHs, capacity improved dramatically while still mantaining that constant current performance, going well over 10 hours with 1500 mAh cells (back then), and simplifying charging (didn't have to wait until cells were depleted to recharge them).

    In any case, since then I've exclusively used rechargeables in CD players, RC vehicles, tools, flashlight, MP3 players, and even digital cameras.

    For high-power and IT devices, they are pretty much a must: alkaline and zinc carbon batteries lose current delivery capacity pretty quickly due to their internal resistance, even if they can work for years in low power setting like, say, clocks, film cameras or remote controls. On the other hand, rechargeables perform constantly (and with way higher current output) throughout their discharge.

    The only devices that I've found to work unsatisfactorily with rechargeables, are those that lack voltage regulation and thus depend too much on some voltage threshold being exceeded by the batteries, without requiring high current. These include LED flashlights and some types of battery-to-battery chargers, like those found on some RC toys.

    (White) LED flashlights, despite being more efficient, need 3.6 Volts just to "break" the semiconductor and start working. Normal 1.5 V cells can handle that, and have some spare voltage to force enough current through them too. Rechargeables however are 1.2 V, and thus barely manage to break the LEDs forward voltage.

    Similarly, poorly designed transmitters-chargers that tap directly from the batteries without regulation may not work well or at all with rechargeables.

    Also, uses such as clocks or remote controls are not ideal, because they drain so little energy that the batteries will likely self-discharge faster than what will actually be used.

    1. Show previous comments  11 more
    2. Maes


      GreyGhost said:

      No problem if the lithium cells are CR-V3's.

      Then I see why two NiMHs won't cut it. There are some cameras actually designed to work from anything in the 2.4-3V range, but some poorly designed ones will only accept stuff closer to 3V (either a 3V lithium or two alkalines), thus we fall in the "voltage sensitive" area I mentioned before. A small step-up or step-down (with 3 cells) regulator would have fixed that, but that's overkill for this class of devices.

    3. deathbringer


      @deathbringer: this was either due to temp extreme, faulty batteries or charger. I've got a "speed charger" that tends to severely undercharge most batteries (except some brand ones certified for speed charging). Some batteries just don't work well with those, especially when not cycled several times already. In any case, using a slower charging did the trick, and got way more life out of them. I'm using most of my AA batteries in RC cars and RC helicopter TXs, which use 8 of them at a time. If there's one dud among them, the whole thing will redline after less than an hour, and the speed charger tends to mischarge a lot of them. With a proper slow charge, I can get upto 6 hours from it (in comparison, alkalines give 2 hours top, before redlining).

      Also, early NiMHs tended to self-discharge rather quickly, even 10% a day! Modern ones are more stable, almost as stable as NiCds, which however are also not suited for long storage.

      Ah, these batteries were brand new (bought about a week before the festival) and barely used, charged on an old slow charger that takes hours too. It did get bloody cold at night at the 2008 Download though, so it was probably that.

      They are brilliant in my picture camera, last for months in it. Guess this £2.99 video camera i tried them in is wierd, and badly-made. Well actually that's hardly surprising.

    4. Maes


      deathbringer said:

      They are brilliant in my picture camera, last for months in it. Guess this £2.99 video camera i tried them in is wierd, and badly-made. Well actually that's hardly surprising.

      Most of these digital devices have a "hard threshold" under which they soft-off themselves or refuse to turn on, thinking that the batteries are too weak. If said sensor was calibrated only for Alkalines (where a residual voltage of 1.4 V would indicate that they are pretty much goners for camera use), then of course it would refuse to operate (premature shutdown), even if the camera could actually work quite happily with them (that's why it's easier to see the rechargeables superiority in devices with a "hard" switch, or those specifically engineered for it.

      I have an old eTrex GPS that uses two AAs, and can accept all different kinds of batteries but its internal meter must be manually configured (or "told") each time what kind of batteries you're using, in order to give correct readings and avoid premature shutdowns.