What protocol to recharge NiMH batteries?

Discussion in 'Mac Accessories' started by Pndrgnsvc, Jan 31, 2011.

  1. Pndrgnsvc macrumors 6502


    Jun 13, 2008
    Georgetown, Texas
    I use NiMH rechargeable batteries with my trackpad.

    When I get the notice that the batteries are running low, I replace them. Then I fully recharge the (just) spent batteries and put them back in the queue for reuse.

    So the question is: Am I doing this to best advantage, or is some other protocol recommended?
  2. beige matchbox macrumors 6502a

    beige matchbox

    Mar 16, 2005
    Oxfordshire, UK
    Ideal is to take them down to 1V per cell, but no lower then recharge at 1/2C.

    However, with regular super market type chargers you don't have much say as to what happens, so the best you can do is use them until the indicator gets low and put them on for a recharge.

    Oh, and recharging asap is a very good thing, as the cell will continue discharging even outside of a device :)
  3. Pndrgnsvc thread starter macrumors 6502


    Jun 13, 2008
    Georgetown, Texas
    I really should have mentioned this in my post: I am using the Apple recharger. Alas, this does not provide the true rate, depth of discharge, etc.

    Also, I have three pairs of batteries, and they last about 2-3 weeks before I get the "Replace Batteries" alert. So after I have (re)charged them, they remain dormant for about 4-6 weeks before it is their turn back in the Trackpad. But now I wonder, should I recharge them (again) immediately before use?

    And of course, many thanks for your reply.
  4. BigRedOne macrumors regular

    Nov 29, 2007
    Leaving them fully charged for 4 to 6 weeks is not a big deal. If your serious about getting your monies worth, then you might want to consider a smart charger instead of the iMac charger, My batteries are over 3 years old and they keep coming back to life, have yet to through one away. I own about 20 of them or so.

    A smart charger like the TITANIUM SMART FAST 8 BAY AA/AAA BATTERY CHARGER, form Battery Junction, charges each battery independently in each bay. Plus after you have charged your batteries 15 or twenty times, the smart charger has a built in discharge button. The discharge brings the batter to an almost zero state and then the charger automatically charger the batter back up to the full 1.5 volts.

    I purchased an 8 Bay smart charger for $27.95, but I think you can buy the same charger with a 4 bay cheaper. Big plus, the charger (my 8 bay anyway) come with the DC charger so I can take it with me on the road and keep my batteries fully charged. I use the same batteries on my iMac things, MM or key board, plus I have flashlights that use this same chemistry, so it all works well for me.

    You can charge a NIMH's and leave for 3 months unused with no problem at all. After about a year or so, it will start to drop, but should be good to go with a least an 80% charge. I try to catch my batteries right around the 40% discharge although I have had some go down to the 20% mark and it did not hurt them. I charge each battery around 15 to 20 times then I drain each battery using the discharge button and then go back to fully charging them.
  5. mchalebk macrumors 6502a

    Feb 4, 2008
    I bought the Apple charger (with 6 batteries) for my wife's wireless keyboard and magic mouse. When I decided to get my own magic mouse, I decided to buy four Sanyo Eneloop batteries, but no charger. This left us with four unused batteries and a charger that can only charge two at a time. So, how to handle this?

    After reading about how well these batteries maintain their charge after being removed from the charger, we have settled on the following routine:

    1. The batteries that are removed from a device go in the charger,
    2. The batteries from the charger go in a drawer, and
    3. The batteries in the drawer go into the new device

    I wanted to make sure that we could handle the scenario where two devices need new batteries at the same time (as unlikely as that might be).

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