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  1. #1
    Wanderer
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    Default How does one test a rechargeable battery?

    I have 4 AAs from 2005 and 4 from 2010. Is there a way to find out which are the bad cell(s)?

    They still work with somethings like remotes etc. With my external camera flash the recycle times are slower, but with my film SLR after 3 days and it doesn't work.

    I have tried using a multimeter and they all register 1.4V or 1.38V I mean all 8 of them, which was the same as my brand new batteries (Panasonic Eneloop - bundled with a charger) I just got 2 days ago and the same as my few months 2x AAs (Energizers).

    My older battery charger has a discharge or test function and one set of 4 AAs registers ~1,600mah and the other set ~2,100mah.

    FWIW, the Panasonic Eneloop charger has status lights. All 8 AAs were blinking red and cannot be charged but they can be charged with my other charger. So is this a reliable enough way to say that those all 8 are bad? My brand new 4 AAs Eneloops and the few months old 2 AAs were charging fine in this Panasonic charger.

    Could it be that if the charger is discharging them to test their capacities after freshly charging them won't work b/c the batteries are freshly charged. The batteries only go bad after some days or under very high load like a camera flash?


    Any thoughts Cheers

  2. #2
    Junior Member
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    Default Re: How does one test a rechargeable battery?

    You need to test them one at a time. Will your charger do this?

  3. #3
    Senior Member pctek's Avatar
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    Default Re: How does one test a rechargeable battery?

    With a multimeter. Same as alkaline....

    Or put them in something, no go, dead battery.
    wipe your paws.

  4. #4
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    Default Re: How does one test a rechargeable battery?

    Quote Originally Posted by rumpty View Post
    You need to test them one at a time. Will your charger do this?
    Yes it does individual cells. Each of the 4 2005 cells report ~1,600mah and each of the 4 2010 cells report, ~2,100mah.
    The charger has a LCD display under each cell - there are 4 LCD displays.

    Quote Originally Posted by pctek View Post
    With a multimeter. Same as alkaline....

    Or put them in something, no go, dead battery.
    The multimeter gives the same readings. Each of the 2005 AAs are the same, each of the 2010 AAs are the same also. All these 8 batteries are also almost exactly the same as the newer batteries.

  5. #5
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    Default Re: How does one test a rechargeable battery?

    We only have a wall clock that takes a single AA. Each of the AAs work.

  6. #6
    amateur expert dugimodo's Avatar
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    Default Re: How does one test a rechargeable battery?

    Testing to 1600 and 2100 seems like they are perfectly ok, but dying fast under high load sounds like high internal resistance which is something that happens near the end of their life. Use them in low drain devices until they start to piss you off then throw them away - at 7-10 years old you've had a good run out of them already. On the other hand really low drain devices like clocks work a lot better on a carbon or alkaline battery, they can last years in Ideal situations. Trouble is they will discharge a rechargeable way too low before stopping and damage it, if you do use them make a habit of recharging every month or so rather than letting them run down.

    Nicads and NiMh naturally self discharge fairly quickly so they are best used in situations where you can fully charge them and then immediately start using them continuously until flat. That's why newer low self discharge cells like the eneloops you have now last so much better despite lower ratings, they are not flattening themselves between uses to anywhere near the same extent. In almost every situation a 2000 mAH eneloop or similar will outperform a 2500 mAH regular NiMh, within a day or 2 the regular cells have lost the extra capacity anyway and within a week they have much less capacity left.

    I have some old Nicads for my cordless drill that work perfectly when fully charged but go dead flat in under a week without being used, still ok in theory but basically useless in practice.
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  7. #7
    pcsourcepoint
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    Default Re: How does one test a rechargeable battery?

    I think you need to test each battery for Voltage (or resistance) with a MM under a load separately and compare; You may need to consider (or rather calculate) how much load (relative to the capacity of the battery) and for how long (i.e. run times), and perhaps the current draw, so as to establish some kind of ideal base line.

    So perhaps start testing at 20% capacity of a battery (whether if rated at 1800/2000/3000 mAh) This will involve using resistors (to simulate a load, and applying ohms law. Some numbers (in comments) here at indestructibles.

    I did similar for my failing 12V car battery, i.e. reading the voltage drop, when starting the engine (i.e. under load), which was low (less than the ideal 9.5 V). There are load testers for batteries.
    Last edited by kahawai chaser; 14-04-2017 at 06:17 PM.
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  8. #8
    pcsourcepoint
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    Default Re: How does one test a rechargeable battery?

    YT Vid showing a draw down test for dry cell batteries, using a 100 ohm resistor. Batteries have similar static voltage (9 V and also for 1.5 v later in the vid), until resistance (load) is applied - showing that they are losing capacity...
    Last edited by kahawai chaser; 14-04-2017 at 07:20 PM.
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  9. #9
    Zippity Fan Club Member prefect's Avatar
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    Default Re: How does one test a rechargeable battery?

    We used to test the battery on the KY28 Secure speech unit with a small load attached to it.
    Its amazing how Potatoes give us chips,fries and Vodka.

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  10. #10
    Senior Member Digby's Avatar
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    Default Re: How does one test a rechargeable battery?

    After years of using recargarables and buying several chargers and testers I decieded last year to give.

    They are just not worth the hassle of testing and charging and hoping, then wondering if it still god.

    The "testers" are just too complicated and time consuming.

    I just buy top qualirty Eveready or Panasonic when on special and have no hassles.
    So what colour is your Adkaf?
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