NiMH: Trickle charge, or plug charger into timer?

Discussion in 'General Electronics Chat' started by moeburn, Aug 19, 2013.

  1. moeburn

    Thread Starter Member

    Aug 16, 2013
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    0
    I have a Panasonic BQ-390A NiMH charger, and despite the fact that it has no LCD display and only one charging light, this is apparently one of the best (if not the best) cheap NiMH chargers out there, as it has 4 separate charging channels at 500mA each (or 500ma split, not sure), with all the protection circuits you could ask for.

    I want to have my non-LSD NiMHs ready to be used at any time, but we don't need to change batteries very often in this house, about once or twice a month or so I'd say. It seems I have 4 options to achieve this:

    • Buy LSD NiMHs. I'll leave that as a last resort, because it means spending $.
    • Keep the batteries refridgerated. I haven't gotten any consensus on this yet, and I'd need someone with a very expensive charger/tester to confirm the warnings I've heard. Apparently this does help them hold a charge longer, but it also makes them crystallize faster, reducing their capacity. If anyone has a mAh capacity tester that can see if this is true or not, I'd appreciate it!
    • Keep the batteries on the Panasonic charger - I know it's just a trickle charge, but I don't like the idea of the batteries being supplied any current 24/7 for weeks at a time
    • Keep the batteries on the charger, but plug the charger into a timer - This will let them discharge a little, and then recharge a little, but probably not at trickle charge-speed. I don't know if this is a better idea than 3) or not. I also don't know what timer settings to use, 2 hours every 24 hours is one example I've heard.

    So of the above 3 (or any other ideas?), what do you think would be the best way to keep my NiMH batteries charged?
     
  2. trader007

    Active Member

    Feb 27, 2010
    222
    19
    I like the timer idea the best for various reasons, but I would set it to more like 2 hours just once a week or two.
     
  3. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    Refrigerating NiMh batteries probably isn't the best idea - you certainly shouldn't charge them while less than 0 Deg C.

    If you want to leave the batteries float charging - you should study the charger user manual carfully, some don't advise it.

    If the batteries remain warm on charge after the normal charging period, its probably better to use them rather than leave them charging any longer
     
  4. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    If you plan to leave NI-MH batteries on trickle charge continuously, I recommend not going over about C/30 charge rate.
     
  5. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    Even then, they can deteriorate if left on charge indefinitely!

    Ni-Cd cells in particular thrived on hard work, they worked better if fast-charged, but needed extreme measures to avoid overcharging damage.

    Lead acid batteries recover from mild sulphation quicker if given some hard work to do (starter motor & fast charging).

    This is less obvious with Ni-Mh - but they do like to be discharged to end-point from time to time, or they get "lazy".
     
  6. moeburn

    Thread Starter Member

    Aug 16, 2013
    31
    0
    I read the BQ-390A's manual, and now I'm not sure if it even DOES trickle charging:

    "The batteries are completely charged when the indicator light stops blinking and remains a steady green light. The auto-off feature will automatically shut off the charger when the batteries are completely charged."

    [​IMG]

    It's definitely a multi-cell charger, capable of supplying up to 2.2A total, but it doesn't say ANYTHING about trickle charge, and kind of implies it doesn't have one!
     
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