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  1. #1
    RC Enthusiast
    Join Date
    Jan 2012
    Location
    Halifax, Nova Scotia, Canada
    Posts
    42

    Minimum Discharge Voltage - When Measured with VOLTMETER

    I've read a lot of info about minimum discharge voltages for NiMH packs. I typically see values in the range of 0.8-1.0 volts per cell.

    However, I am pretty sure those voltages are for chargers that have a discharge capacity. I have a home-made dicharging setup that I use to discharge my batteries. Thus, when I measure the voltage, I use my voltmeter. Now, as we all know, you get SIGNIFICANTLY higher voltages from a battery when you measure the voltage under no load (e.g. like using a voltmeter).

    For instance, when a NiMH comes straight off the peak charger, it will measure more than 10 volts. Obviously that is way higher than the rated voltage of 8.4V.

    Thus, I am worried that if I let cells drop to 0.8-1.0 V (measured with a voltmeter) that I could be (fairly significantly) over-discharging the cells. Does anyone know a "no-load" voltage that it is safe to discharge the cells to?

    I've estimated a pack voltage of 8V (measured with the voltmeter) as "equivalent" to a 0.9V per cell (6.3V for the pack) measured under load.

    Any thoughts/info on this would be much appreciated.

    Thanks!

  2. #2
    RC Champion
    Join Date
    Nov 2010
    Location
    United Kingdom of England land.
    Posts
    1,820
    From memory i think it was 1.1V per cell was safe, under 0.9 was on it's limits of polarity reversal. When charged they could reach 1.6V per cell but the majority is 1.4-1.5V per cell.
    8.4V is the nominal voltage of the pack, not charged voltage.
    Guide books aren't part of the packaging.

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