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  1. #1
    mtbr member
    Reputation: rocks'r'friends's Avatar
    Join Date
    Mar 2007

    Nite Hawk Charger question

    Anyone know if I can use my nitehawk phoenix dual charger to charge the battery for my nitehawk single phoenix. The only difference is the dual has a 7400mA rating and the single is a 3700mA, both are NiMH. Nitehawk says no, anyone know if this is true or just protecting the warranty.

  2. #2
    mtbr member
    Join Date
    Jun 2004
    Yes and no
    If they say "no" there must be a reason... my guess (and it's a guess, don't sue me)..
    the dual charger must put out a higher charging current compared to the single, and the batteries require a specific "C rate" limit for charging. The double-charger likely puts out double the C rate of the single, and both are close enough to the limit that the double would exceed the safe single capacity.
    In GENERAL, you could do what you say, as the chargers ultimately (if designed right) should cutoff based on a change in voltage/change in current detection scheme (and in fact are more likely to cutoff properly if you DID do this, because the harder charge current would cause a rapid change in voltage at the end of the cycle leading to easy detection)...
    Basically, you CAN do it, but it will likely overheat the battery resulting in degradation/shorter lifespan, or potentially killing it much more quickly. Probably NOT, but possible, which is why they say "no", just safer that way.
    How long does the double take to charge the 2 batteries fully? If 10 hours, it's charging at roughly 740mA (0.1C) (not counting losses, which would add some, we'll keep it as simple as possible though)... actually more likely it's charging in 5 hours, or a 0.2C rate of 1400mA. At that rate (1400mA), the single battery would be charging at 0.4C, which is above most "standard" NiMH charge rates, and hence their reason to say "no".
    IF however, the double pack is charging for more like 12+ hours, you probably COULD use it safely with the single, just be pushing it a little more aggressively than the proper charger. So long as you stay under a 0.2C rate of charge (740mA for 5 hours) for the single battery, you'll be within acceptable charging limits for nearly all modern NiMH batteries (many can charge at much higher rates now).
    Remember you try at your own risk, and your mileage may vary

  3. #3
    mtbr member
    Join Date
    Jul 2007
    I would say NO...

    because I have a dual, and I recall that the charging cct was pretty stupid, it was a simple timer and did not have the smarts to detect when the battery was fully charged and thus would not stop and would overheat the battery on your single Phoenix...

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