Is this normal behavior for the HA intelligent charger/discharger?

Discussion in 'Gen 2 Prius Technical Discussion' started by TrillingThrows, Apr 12, 2021.

  1. TrillingThrows

    TrillingThrows New Member

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    I have been reconditioning a gen 2 battery with the HA grid charger. Did an initial 34 hour soak charge and the voltage capped at 237V , seemed normal to me. I let the battery sit for an hour before discharging it. This is my discharge data :

    0830 @237V 1400ma
    0930 @200V 1400ma
    [email protected] 436ma
    [email protected] 436ma

    First question is it normal for the discharge current to drop so soon? after 1230 I stopped checking because I had to go do something but I was close enough that I would hear the beep. It took until 6pm for the discharger to beep and the interesting part was that it beeped not at 134V but at 144V. Is this normal?

    I then press the OFF button in the discharger , disconnect it from the AC and then disconnect the orange service plug and finally disconnect it from the harness. I then connect the harness into the charger , then the AC into the wall , and then press ON to ensure it's working properly and it reads 250V. Then I finally put the orange service plug back in. When I connect the service plug , the voltage reading updates to 160V as expected , because I let it sit for an hour and the voltage bounce back up , but the issue is that the amp charge reading is fluctiating wildly from 0 to 400 to sometimes 200 and 300 ma. Did I do something wrong?
     
  2. Raytheeagle

    Raytheeagle Senior Member

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    Nope;).

    Below a pack voltage of 203 volts, it'll fluctuate(y).
     
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  3. TrillingThrows

    TrillingThrows New Member

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    Thanks a lot , I need to up my thread searching game , I made sure to look up if someone had answered this question for about an hour before I posted and couldn't find out. This forum is quite literally a library of knowledge and I'm still getting used to the dewey decimal system :LOL:. Also I had read a lot of threads were they say the discharge takes about 6-8 hours mine took 9:30 does this mean the capacity or internal resistance of the pack is high? Or it taking that amount of time is still normal? Last question, is the discharger beeping and idling at 144V instead of 134V normal? Thanks for helping out a noob like me by the way , hopefully in the future I will have something to contribute. (y)
     
  4. Raytheeagle

    Raytheeagle Senior Member

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    Are you sure it didn't reach the intended target of 134 volts:whistle:?

    Usually it reaches the target then goes "idle" as it achieved its goal;).

    It doesn't stay at 134 volts long as the pack wants to be at a voltage higher.

    The lengths of the time to complete a cycle can vary as there are many factors. But keep completing the reconditioning process:).

    Good luck(y).
     
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  5. dolj

    dolj Senior Member

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    @TrillingThrows, this too would be my hypothesis of what really happened, the voltage will have jumped up to 144V in the time you heard the beep until when you observed the voltage. It will have beeped right on 134V then gone to idle. Immediately it goes to idle the voltage increases very quickly to a resting open-circuit voltage.
     
    #5 dolj, Apr 13, 2021
    Last edited: Apr 13, 2021
  6. TrillingThrows

    TrillingThrows New Member

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    That very well might be the case I will keep my eye on it next time to know for sure.
     
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  7. PriusCamper

    PriusCamper Senior Member

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    Sudden voltage drops happen most often on pack in need of reconditioning... By third round of discharge things will settle down... Also 36 hour grid charge is way too long and damages module longevity&capacity. Keep it way under 24 hours.
     
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  8. TrillingThrows

    TrillingThrows New Member

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    I'm not doubting your expertise , but HA says that anything not over 48 hours is fine , for some context this was the first charge , what I've seen others here call the "soak charge" , and it was my understanding that the longer the better as long as it didn't exceed 48 hours. Would you say that charging for an extra 4-6 hours after voltage stabilizes is a better method? And while my assumption is baseless , I also assumed that 36 hours was too much , I am literally pumping 12.6 A into , a 6.5A rated battery and while I'm aware that it dissipates as heat (and I was checking the temps they always stayed cool to the touch) your suggestion of 8-9 A seems much more sensible , especially considering it's not like it was at 0 amps when I started.
     
  9. dolj

    dolj Senior Member

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    Yes and is the primary guidance that HA gives in their charger instructions.
    You seem to be using Amps (A) here when you mean Amp*hours (Ah). They are not the same and your statement is confusing and even nonsensical.

    If you are using the HA charger, it will only pump 350 mA into the hybrid vehicle (HV) battery.
     
  10. TrillingThrows

    TrillingThrows New Member

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    Thanks , and I understand it's just that there is a lot of conflicting information about how long you should charge it for , but you are right when in doubt you should probably listen primarily to the guys that made the product , it was just kind of conflicting how apparently anything more than 24 hours would damage the longevity of the modules , but HA says if its under 48 hours it's fine , you have to understand my confusion ;).

    Thanks for correcting me on the proper use of terminology , I do understand that mA is a measure of current and mAh is a measure of charge , it's just that I'm a noob :cry: . Will get used to it soon(y)
     
  11. dolj

    dolj Senior Member

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    I do very much understand what you're saying. It took me quite some effort to get my head around it.
    The way I interpret that part is as a caution to not exceed 48 hours, not an encouragement to go for 48 hours.

    I'm of the opinion that less is more, so if it has been charging for 13 hours and then it stabilizes at some voltage (say 238 V) then I'm only going to charge it for another 4 - 6 hours so 17 - 19 hours in total. You will not achieve anything more by charging longer than that except to waste time and money (electricity converted to heat). The extra 4 - 6 hours is the 'soaking' part the purpose of which is to ensure all the cells that were lower in charge 'catch up' to the fuller cells.

    It is not unusual for the total charge time to be 20, 24, 30, or 36 hours it just depends on the state of the battery.
     
    #11 dolj, Apr 13, 2021
    Last edited: Apr 13, 2021
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  12. Raytheeagle

    Raytheeagle Senior Member

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    @WilDavis and @srellim234 are believers in the "if some is good, more is better" camp of the extended soak. Their batteries had seen regular Prolong sessions when these were occurring too;).

    I'm of the minimalist philosophy as a @dolj is: no need to pound on the pack if it is already achieved the desired result :).

    Good luck and keep us posted (y).
     
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  13. PriusCamper

    PriusCamper Senior Member

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    You can get away with overcharging a pack at 1/2 amp and lower... And there's plenty of debate about how long you can do it at that level. The Honda hybrid folks say as much as 72 hours and HA used to say 24hours, but now say 48 hours according to you. But after a few years of doing this I've become way more cautious, rather than less based on direct experience, as well as the science:

    "Overcharging leads to overheating and damage to the cell resulting in loss of capacity and nickel metal hydride cells are more sensitive to this than NiCds. This means that chargers need to be careful designed to ensure that overcharging does not occur, and users also need to be a little more careful as well." NiMH Battery Charging: How to Charge Them - Electronics Notes
     
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  14. TrillingThrows

    TrillingThrows New Member

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    Currently on the second discharge cycle , and I have already seen what I think are capacity improvements:

    1st Charge: 1st Discharge:
    2140 204V 0830 237V
    2340 225V 0930 201V
    0140 234V 1030 195V
    0155 235V 1800 134V
    0240 236V
    0339 237V

    2nd Charge: 2nd Discharge:
    1830 165V 1300 237V
    2030 190V 1330 223V
    0130 225V 1430 209V
    0209 226V 1500 204V
    0600 236V
    0609 237V
    0630 236V
    1230 237V

    Notable differences that make me think capacity has increased , is the first charge from 225V to 236V took 180 minutes while on the second charge it took 270 minutes a 50% increase in time , not sure how this directly translates to increased capacity. The first discharge from 237V to 201V took one hour , and on the second discharge as of writing it has been two hours and counting and it still hasn't.

    After the first discharge I also took voltages of the modules after letting them sit for 5 minutes , I am well aware that sitting voltages do not tell you the whole picture , but I'm curious as to see how much the voltage differential equalizes after subsequent discharges.

    01 6.48V
    02 6.26V
    03 6.50V
    04 6.55V
    05 6.34V
    06 5.48V
    07 5.43V
    08 5.43V
    09 6.46V
    10 5.57V
    11 5.44V
    12 6.51V
    13 5.55V
    14 5.23V
    15 4.93V
    16 5.14V
    17 4.92V
    18 5.59V
    19 5.39V
    20 5.52V
    21 5.83V
    22 5.53V
    23 5.48V
    24 5.30V
    25 6.40V
    26 5.62V
    27 5.98V
    28 5.29V

    Slightly unrelated question at what voltage would it be safe to be able to start the car again. Reason I am asking is because this takes a lot of time and was wondering if it is feasible to force charge the battery to the max the prius allows it to , then proceed with the grid charger and likewise with the discharging process simply putting it in neutral drawing power from it and shut down the car as soon as the engine kicks back in and then proceed with the discharger.
     
  15. PriusCamper

    PriusCamper Senior Member

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    Yep, as capacity increases it's takes a painfully long time to recharge at under a 1/2 amp. I usually speed the process up by charging each module with a hobby charger if pack is out of car or by using car to force charge pack (foot on brake, car in drive, floor accelerator) if pack is still in the car. Of course if you have the time a slow trickle charge is slightly more beneficial.

    As for how long to wait to start car, 1/2 hour works, sometimes less if I'm in a hurry. Have never had any issues with this particular precaution, so am growing more skeptical of it.
     
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  16. TrillingThrows

    TrillingThrows New Member

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    Just so I'm clear after fully discharging the battery to 84V then charging it for 1/2 hour with 350mA is enough for me to start the car? Thanks for the help by the way.

    I have completed the second discharge round and while I expected the resting voltages to be more equalized , the dV actually increased by a significant amount . I suspect this might be due to lower discharging levels really stressing the modules and magnifying their deficiencies , although a proper answer would be appreciated.

    Second discharge resting module voltage:
    01 1.32
    02 5.61
    03 5.56
    04 5.85
    05 5.50
    06 5.00
    07 4.82
    08 4.62
    09 4.79
    10 3.96
    11 3.99
    12 6.19
    13 5.12
    14 2.15
    15 1.15
    16 2.13
    17 3.00
    18 3.44
    19 3.23
    20 5.00
    21 5.37
    22 4.88
    23 3.23
    24 4.35
    25 5.58
    26 5.16
    27 5.98
    28 0.41

    Before attempting the reconditioning process I load tested the pack by force charging it and then drawing power for 15 minutes then looked at the graph and determined 5 modules had to be replaced , however after looking at these voltages module 1 , 15 and 28 seem excessively low and my initial diagnostic didn't pick them up. My question is how indicative of a failed module are resting voltages after a deep discharge? If I were to use the same parameters of not exceeding a dV of 0.3 ,over half of these modules would be scrapped.
     
  17. jerrymildred

    jerrymildred Senior Member

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    Why did you remove the orange plug. Am I right in assuming you're doing this on the bench? Normally, when the battery is in the car, you don't even need to see the battery, much less remove the safety plug.

    I have. I know you condition batteries a lot, so I'm surprised you say this. Apparently the battery is much more forgiving in Pacific Northwest weather than in FL weather.
     
  18. PriusCamper

    PriusCamper Senior Member

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    I've never looked at individual module voltage after discharging a whole pack rather than discharging modules, but it's an interesting data point in terms of finding bad modules that I've not yet considered. Are you sure pack was fully charged and balanced before you discharged and ended up with those numbers?

    As for skipping to force charging once you have enough power in the pack to get the engine started, please let us know the lowest voltage you can get that to work?
     
  19. TrillingThrows

    TrillingThrows New Member

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    Yes you are correct , I'm not sure if I have to remove it but I like to make sure I do as an extra precaution step.


    Absolutely sure ,it was actually fully charged up and top balanced twice before , that's why I was expecting more equalized resting voltages compared to the first discharge where it had only been top balanced once. Once the battery is completely reconditioned I will also run another load test with hybrid assistant to see if individual module voltage was actually indicative of something.
     
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  20. Albert Barbuto

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    I've done just what you are doing, except I measure the individual module voltages while under load. ( 84v - 88v ) This will give an accurate reading of module comparison. Any module found significantly weaker will be cycled individually via a hobby charger, in an attempt to get all modules equal.
     
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