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Duration of 1st charge of drill battery

Discussion in 'Electronic Components' started by Aloma, Mar 1, 2007.

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  1. Aloma

    Aloma Guest

    My portable Tesco drill has a 9.6V 1000mAh battery pack. I don't know
    what type of battery it is. The power supply "brick" outputs 12VDC
    400mA to the charging stand which the battery sits in.

    The instructions say to charge it for about 5 hours each time it gets
    run down ... not to carry on charging because the charger does not
    switch off when the battery is full ... 10 hours is the maximum
    permissible.

    Should the first charge be for a longer time to equalise the cells so
    they are all fully charged. Maybe, 16 hours? Or would this be too
    damaging?
     
  2. Dave Platt

    Dave Platt Guest

    My portable Tesco drill has a 9.6V 1000mAh battery pack. I don't know
    16 hours looks like a substantial overcharge. If the DC supply is
    actually delivering 400 mA, then a 1C charge time for a 1000 mAh pack
    would be only 2.5 hours... throw in some losses and inefficiency and
    I'd expect that 4 hours probably tops the cells up pretty well. The
    5-hour number they give is probably quite reasonable. Anything much
    beyond that, and you're simply trying to force current through
    fully-charged cells, and heating them up as a result.

    Even if the cells aren't *perfectly* matched in the pack, I'd expect
    them to be within perhaps 10% of one another. A 6-hour charge ought
    to be adequate to ensure full charge even if there are differences
    between the cells.
     
  3. ehsjr

    ehsjr Guest

    Follow the manufacturer's instructions.
    Ed
     
  4. Guest

    almost certainly low end NiCd
    lord no, 5 hours is a heavy enough charge already
     
  5. Most of these cheap drills with even cheaper chargers seem to recommend a
    stupidly long initial charge. Perhaps they want to make certain the rot
    sets in early.

    A 5 hour charge type suggests all the 'control' consists of is a series
    resistor between an unregulated DC supply and battery, so the likelihood
    of overcharging is pretty real.
     
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