Replace battery pack in Out of gas mode

Discussion in 'Prius PHEV Plug-In Modifications' started by menardsy, Oct 25, 2013.

  1. menardsy

    menardsy Junior Member

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    Thanks Jim,

    I will do that this weekend, I am a bit busy until the end of the week...

     
  2. menardsy

    menardsy Junior Member

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    Hi Eric,
    I did some manual balancing (by turning on the bms switch forced balancing). The fact is that the cells are perfectly balanced when no under load or when under light liad(30 amps). When the load is 80A, the firsts 8 cells (I assume they are all in one half of the pack) are dropping to 2.900V compare to the other half wich stay at 3.200V.
     
  3. ericbecky

    ericbecky Hybrid Battery Hero

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    Clearly your 2.9v drooping batteries are limiting the rest of the pack.

    When I say manual balancing, I mean to physically take a separate charger and charge each cells individually.
    Don't trust the bms. In these systems, it turns out that the BMS can actually part of the problem.
    Also, I would double check the integrity of the sensing wires.

    Just because it is the same voltage, does not necessarily mean it is at the same state of charge.

    Do you have the tools to individually charge the drooping ones to be sure they get completely full?
    Do you have the tools to load test those separately from the rest of the pack after you have them full?
     
  4. menardsy

    menardsy Junior Member

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    Hi Eric,
    I only have an IMAX B6. I don't want to invest too much for another charger / balancer unless there is a good probability to save the pack. I was thinking of inverting the 2 left / right pack balancing cable on the BMS.
    Do you think it could help?
    Thanks!
    Sylvain
     
  5. ericbecky

    ericbecky Hybrid Battery Hero

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    Hard to know from here how bad things are.
    You can use you charger to just charge those drooping cells. Then do a load test on just those cells while watching to see if they still droop.
     
  6. glyndwr

    glyndwr Member

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    Menardsy,

    I purchased a mean well 3.3v switch mode power supply from ebay for less than £10 and I use that to top up individual cells on my pack. There is an adjustment voltage pot on the pcb that allows the voltage to be tweeted to 3.6v therefore charging the cell but not overcharging it.
    I used to have an enginer system and when I had it, I disabled the balancing function of the bms, also, I wired in 2 cell loggers that I used to stop the charger at 3.5v, as the older enginer systems charged all the way to 3.8v.
    My enginer bms was still in circuit but in reality all it did was report individual cell voltages to the lad display in the cabin and stop the converter at 2.6v.
    I then used the meanwell charger to top up individual cells to manually balance and use a 25 w resistor to bleed down high cells again in manually balancing.
    From speaking to shushil at pluginautos I was led to beleive the new bms systems were very good.

    I now have 76 cells and a plug in supply control pcb system that I installed myself, I still rely on the cell loggers to monitor all the cells and I manually balance, it's something I don't mind doing as I'd rather kill the cells myself than rely on faulty electronics or poorly designed bms software systems.

    Once the cells are close to balance ( I do have about 3 weaker cells that go high and low early) I don't spend much time now on them, maybe an hour or so once a month just fine tuning.

    Anthony.
     
  7. glyndwr

    glyndwr Member

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    Hi again,

    I just went onto the plug in auto website, and on there I read the battery has a 5 year limited warranted, so I would for sure contact shushil and ask him to resolve the problems you have with the 1 24v pack, see what he suggests to overcome the issues.
    Also the other parts are covered by a 2 year warranty, so you should be ok there.
    There is a chap called Dan lander who helped me enormously when I first got my kit, I uploaded my charge/ discharge curves to him for analysis on a few occasions, he is very helpful, but that is something that shushil and the battery supplier should be doing on your behalf.

    I would peruse shushil, I have met him in person once, he visited my home and looked at my plug in supply kit, I did view the new mdtech kit in his prius, he does seem a genuine helpful person, but as always, the service you reive after the supply of the goods is the gauge of a good or bad company, so I hope he fixes your issues.

    Anthony.
     
  8. sushp

    sushp Junior Member

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    Been a while since I logged in.
    To update on the menardsy problem. The BMS has an error that it does not update when discharging on the right pack circuit. The version he has was not a version that went out in Europe. It was sent out during the closure of MD-Tech before everything was turned over in Acrel. After some investigation the BMS will be replaced by Acrel.

    There were long delays last year when MD-Tech got into difficulty after Enginer failed to pay for a delivery (still in dispute). These delays have now disappeared under Acrel.

    The new Acrel BMS is working well and is under version control. Attached is a picture showing some of the latest features, BMS has temperature protected balancing circuits. Balancing is always on now. BMS temperature is shown on the monitor screen. 4 cells balance at any one time if there is a hi-Lo difference of 60mV, they are also shown on page 4 of the monitor.
     

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  9. sushp

    sushp Junior Member

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    Just to note: I can only guarantee products brought directly from my company, "Plug-in Autos", Plug-in Hybrid Conversions - Plug-in Autos. If you go directly to Acrel, you get an Acrel guarantee. Although I am providing support while they get to know the kit and customer history.

    As menardsy points out his problem is limited to one issue, over 217 days of use. The converter is running fine. This is something of note which has not been picked up by the naysayers here.

    I find Dan Landers opinions to be a bit off. After sending him some of the latest BMS data he seems to think that nothing has changed, he misses the point that HVC is now 3.55V and LVC 2.75V both described in specifications to have a 0.002V accuracy. Also he misses seeing from the data that the balancing is working to keep the pack within a tight range and spec. So if you cannot read data or graphs don't ask him for analysis, post it here for everyone to see.

    Anything else is a clear case for a warranty claim. There have been no other warranty claims on BMS accuracy from any of my customers, so menardsy's issue appears to be limited to menardsy and as I said above Acrel will be replacing it within the next 14 days. There has been a recall of BMS's following the discovery of a different software glitch caused by an overheating BMS, also known as BMS burnout. BMS burnout is an issue that can arise when balancing packs in series. A BMS protection circuit is now employed that prevents overheating and other software upgrades have removed the issue completely. All BMS's were replaced with an upgrade, free of charge, as you would expect.

    Acrel are eager to develop this kit so any requests for changes are welcome.
     
  10. menardsy

    menardsy Junior Member

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    it has been awhile since I've been here too.

    Sushil have been very helpful and involved in the diagnostic of my BMS issue.
    I have no issues the converter itself.

    I am really looking forward to get my replacement BMS!

    Sylvain
     
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