Load testing modules

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by midi_ring, Feb 11, 2025.

  1. midi_ring

    midi_ring New Member

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    How many amps am I putting on a module if i put 1 12V lightbulb at 65watts on one of these prius gen II modules?
    Whats the important voltages that the modules are used the most at in the car? It runs them in pairs, right? Anyone know either of the numbers that the car runs the modules down until it starts charging them again?

    How many amps is ok to put on one of these modules?

    I tried to put one 12v 65watt bulb on one of these modules and it took 3minutes almost 4m before I gave up because it only got it down from 7.9v to about 7.75v. i didnt want to sit there that long I want to run them all the way down to 6.5v becuase i have 28 to do.

    side note: i refurbished all of my batteries; then replaced the bad one (cause i had the red triangle of death) with a brand new module. all of them got back up to 5000+ discharge capacity, charged up and put together and back in the car. I wasn't getting 35-40 mpg at best. The car wouldn't sit for 30 seconds before it would turn on the motor and start charging up the battery.
     
  2. PriusCamper

    PriusCamper Senior Member

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    To calculate amps, you can use the formula Amps = Watts / Volts. You can also use a calculator to do this.
    Steps
    1. Determine the wattage of the electrical device or system in watts (W)
    2. Determine the voltage of the electrical system in volts (V)
    3. Divide the wattage by the voltage using the formula A = W / V
    ---------------------------

    Keep in mind that this is just a rough estimate because the temperature of the filament defines how much resistance and thus amps are draining the module. The difference is significant when the bulb is super bright and module is at full charge compared to when its drained and bulb is dim.
     
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  3. midi_ring

    midi_ring New Member

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    is there such thing as too many amps or watts on these batteries?
    I tried one headlight bulb, bright side, which is 65watts. but took the battery @4min to reach from 8.0v to 7.75V. too long of a wait for me. about right for me would I'd think be using 2 or 3 of these headlights. maybe 1 on the low light.
    IDK i wouldnt think so and am getting ready to go for it. I just want to cut my time in less than half waiting for the voltage to drop to @6.6V or so..

    what voltage does the Prius look for in the module sets before it starts to turn the car into charging the battery again? It would help me to know what voltage the batteries are in use at the most.
     
  4. midi_ring

    midi_ring New Member

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    that equation doesnt really seem that correct. according to it, a 12v bulb at 65watts in a 12volt system would be pulling 5amps.
    but on a 7.5v system, seems the amps would increase to 8.6amp and get even higher as the battery drained since you'd be diving by less each time.

    can someone explain this voodoo to me? according to it, if i put this 180 watts on the battery im going to be pulling 25amps, only getting higher as the battery drains.
     
  5. MAX2

    MAX2 Active Member

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    To measure current, smart people invented the ammeter.

    When you connect a light bulb, you apply resistance to the module, not voltage and current.
    When you apply the same resistance to different voltages, the current will also be different
    I=12/R will be greater than I=8/R


    The less voltage remains in the module, the less current will flow through the bulb, and it will eventually stop giving light.
     
  6. midi_ring

    midi_ring New Member

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    ok yea. i did some looking found that the car will at the most apply around 9 amps to each module. my 4 car headlight bulbs were discharging them at 34-35 amps.

    What I don't get is, "After replacing the bad module in my hybrid (set) battery with a NEW one, why did I only see 30-35mpg?
    - How do you "pair" these modules back into the battery?
    - What is or was the problem with me putting a new module in that bundlef
    Good luck finding something matching on ebay, based on discharge capacity, or any other thing you might see from your set of batteries.
    THe thing is is everything I've seen, I understand about nothing about this.

    I bought a battery that seemed close to mine, was supposed to be a 5500mah discharge battery. Guy sent me 3 (for 1). THey are all getting 6000mah within the 2nd discharge/recharge cycle. Didn't even check for more.

    Is this giong to do as poorly as my try before? 30-35mpg? WHy does it do that?

    -HOW do I pair these modules together (in sets of 2)- was that the issue?

    I read one guy said to pair the best with the worst. Someone said it might damage a poor module. Wouldn't this be what might happen anyway? Wouldn't the car detect something before something (pretty) bad happened? (at least these aren't lithium).

    I could ramble on all day long but i seen some people link to a post that was a 300 page topic. I read through some of that, and it seems, maybe, there is some app that will show you the voltage drop of "sets" or pairs of modules compared to the rest of them..

    So wouldn't it make sense to put yoru worst ones with the best ones when you PAIR them together (in (they call them) blades). sets of 2.

    the computer would read (2) them as 1.

    I was hoping someone who had done a bunch of tests would read my message and respond to me with something. IDK man think i just need to see if i can get that app and find this visual representation for myself. And determine it myself.

    I'm wondering why putting the new module hurt the MPG. I don't understnad how it would do that. they are ran in parrallel. From hooking up bulbs to the batteries, i found out what that means (by seeing it). -bulbs were dimmer when I hooked up more and more. basically spliting the module votage between how many bulbs I had hooked up to it.
    but its not clicking why the new one in this set would done anything liek this to my MPG.

    What I saw when I took the hybrid battery back was, I did a discharge/recharge cycle on each one of them. And the first discharge cycle each one of them were around 3500 mah left in the battery, up to 5000mah. The new cell was at... 5800. I Wrote it all down

    I had betwen 3300mah to 4800mah on all of my cells after they came out of the car when I did the first discharge/recharge cycle on them, at the state they were at. THe new one was at 5800mah. (the new one was new and charged up to full capacity (6350) after running 2 d-c cycles on it whne I got it with my hobby charger).

    IDK I'm gonna pair the best with the worst and toss these 3 6000mah cells into the hybrid (battery) again and take it for a spin. Maybe try to get that app that I saw them using showing the voltage drop between different pairs of (cells) modules.


    IF anyone reads this and could throw in some thing I could use,. it would be really appreciated.