Hybrid battery balancing

Discussion in 'Gen 2 Prius Technical Discussion' started by Jonscheets, Sep 26, 2017.

  1. mr_guy_mann

    mr_guy_mann Member

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    The discharge limit got me as well on the first charger I got- turns out that the specs are for a maximum number of WATTS that it can dissipate. So it can do 3 amps at a low voltage so long as it doesn't exceed 7 watts (typical for the cheaper chargers) . As voltage goes up then amps go down.

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  2. C Wagner

    C Wagner Junior Member

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    I hope DSC to 7.0v (you wrote) is a typo. I think that's too high a low cutoff value. In your work, did the battery health return? I'd suggest 6.0, which is what most of the others used. Some went below, but recall that you're pulling down 6 x 1.2v cells and stress occurs below about 1.0v per cell, I've read somewhere.
     
  3. TMR-JWAP

    TMR-JWAP Senior Member

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    And don't forget, the charger setpoints use the voltage at the charger, not the voltage at the module terminals. During a 1.4ish amp discharge, my terminal voltages are about 0.2 volts higher than at the charger. My low is 5.8 volts (as sensed at the hobby charger) I use 16ga speaker wire, so your results may vary.
     
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  4. R-P

    R-P Active Member

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    Whenever charging or discharging, this is very important. Know the voltagedrop in your cables.
    When I bought a new 12V battery for the Prius, it tested fine but when I loaded down the battery with a single 12V bulb (some 4A draw) and it dropped to 6V, I was about to pick up the phone and start yelling at the seller.
    Turned out the cheap crocodile-to-banana plug ready made cables I used had coaxial microhone cable instead of normal ~16AWG cable... Teaches me to buy the cheapest Chinese crap... (Works out to about 34AWG, they only had the inner wire connected, nog also the shielding-strands)

    But I still haven't learned: Also check your charger's measurement accuracy!!! I just bought a new charger that displays a normal value but actually would charge my LiIons to 4.3xV instead of 4.20V. NiMH are more forgiving, but LiIons could burst into flames because of this.
    Decent chargers will have less of an issue or even decent calibration procedures to adjust this. My Chinese knock-off doesn't.
     
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