Pentax DL - battery voltage mystery

Discussion in 'Pentax' started by Peter, Apr 4, 2008.

  1. Peter

    Peter Guest

    I've had one of these since 2005.

    It takes four AA cells, which is one of the reasons I chose it, having
    been burnt with the Sony lithium battery scandal, etc.

    I have always used four NIMH cells in it - these are nominally 1.2V
    when charged. And it was fine, taking hundreds of shots on one charge.

    Recently, it started to indicate 'flat battery' very early.

    I sent it to Pentax. After a long time (admin cockups caused by stupid
    people) and £70 I got it back. I had some trouble establishing whether
    they actually found anything wrong - apparently there is no
    communication available with the 'engineer' doing the work...

    It works the same way as it did before however. On normal alkaline AA
    cells it shows full charge. On fully charged NIMH it shows only a
    partial charge.

    What could have gone wrong?

    Products which can use either 1.5V or 1.2V cells tend to be selectable
    somewhere otherwise they cannot tell if the batteries are going flat.

    I am somewhat concerned because immediately before I sent it to Pentax
    I did use it with alkaline cells (1.5V) and they still went 'flat'
    pretty fast.

    I well remember the Olympus OM2SP scandal where the camera drained the
    battery when OFF...
    Peter, Apr 4, 2008
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  2. Peter

    ongar_route Guest

    Have you always used the same set of batteries?

    NiMH batteries have a limited lifespan, ie. they can only be charged a
    certain number of times before displaying just the symptoms you are

    I think the fact you mention it works properly on alkaline batteries
    tells you all you need to know - your NiMH rechargeables are life-
    ongar_route, Apr 4, 2008
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  3. Peter

    Peter Guest

    I do check them with a voltmeter, before/after, and they work fine in
    other applicances.

    I've got a whole collection; some old, some brand new.
    That would be logical, except that I do check them.

    The mystery is this: a NIMH can *never* be higher than about 1.25V,
    which represents a pretty flat alkalike battery. So, how did the NIMH
    ones ever work in the first place? I've done whole 2-week holidays on
    one set of them.
    Peter, Apr 5, 2008
  4. Buy a new set of NiMH batteries. You can get some quite cheaply at your
    friendly neighbourhood supermarket (Tesco, Asda, Sainsbury etc.).
    I had a NiMH set of which one cell would no longer hold any charge so I
    replaced the set.
    I tend to always have 2 or 3 sets of charged up NiMH batteries in my
    accessories bag anyway.
    Regards Mike.
    Mike Cawood, HND BIT, Apr 5, 2008
  5. Peter

    Trev Guest

    Wilkinson Have some Uniross Hybrio at £3.95 for 4 aa. These are the type
    that come ready charged and dont lose power just waiting to be used.
    Recharge up to1000 times and use again and again.
    Trev, Apr 5, 2008
  6. Peter

    Mike Coon Guest

    You won't get a useful reading from a voltmeter unless you put a
    representative load on the battery. As it ages the internal resistance may
    increase, reducing the voltage under load.

    And of course if the contacts in the camera are not as clean as when it was
    new there may be loss there too. You already appreciate that rechargeables
    may be marginal.
    Are you saying that all batteries give the same result? Suggests camera
    corrosion as the common change...
    Clean the camera contacts and then see.

    Mike Coon, Apr 5, 2008
  7. Peter

    Rob Morley Guest

    The eraser on the end of a pencil (or a typewriter eraser pencil -
    remember them?) can be handy for this if the contacts are recessed and
    hard to reach.
    Rob Morley, Apr 6, 2008
  8. Peter

    Mike Coon Guest

    I have a specialised cleaner that consists of a bundle of fine glass fibres
    in a 2mm friable casing. It fits into a 2mm collet-type propelling pencil
    and reached into awkward spaces to clean contacts...

    Mike Coon, Apr 6, 2008
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