The battery fires at ECU sense connector thread

Discussion in 'Generation 1 Prius Discussion' started by ChapmanF, Mar 19, 2015.

  1. Angry Andy

    Angry Andy Junior Member

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    pic.... friedHVbattery.jpg
     

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  2. landspeed

    landspeed Active Member

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    You should make a thread about the issue, and post a link to that thread here, as there is going to be a lot of discussion and photos etc.

    For what it is worth, the car wouldn't start if many of the blocks were truly 'zero', so it has been a short-circuit inside the engine computer (most probably). Worse, there is a chance that the remaining cells that are still giving readings could short (if the voltage sense harness is connected). When you say 5 dead cells - is that dead from measuring them? Are they the ones that were reading 'zero' on the ECU? If they are just lower voltage, it might be worth rejuvenating them ASAP (as well as the rest) with a hobby charger. The ones that shorted on mine were about 0.7v lower than the rest (the energy went into melting the wiring I guess), but they quite quickly balanced back out. I am still using the original sense harness (not the best idea), as the burning happened inside the ECU.

    Please keep the old ECU, please post photos of what happened, and do try to rejuvenate the 'dead' cells, as they might actually be fine if you charge them up!
     
  3. landspeed

    landspeed Active Member

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    Update time. I have used my Prius for a long time (maybe over a year), using my original battery, with the original burnt connector, but a new ECU. A week ago, my battery showed sudden empty charge, followed by 'overcharge' within just a mile or two. I drove gently, got home, plugged in my Wifi dongle, and I found a 0.7 volt delta (on the same modules that shorted with the last ECU).

    I couldn't find any obvious shorting, but the connector was still covered in black deposits. I replaced the HV sense lead with a known good one, and the car has been completely fine. So, the HV connector was shorting (slowly), draining some modules, but not enough to cause any check-lights to come on. I drove about 30-50 miles, and the car balanced the battery back to normal, but once I left it, it went back to a 0.7 volt delta. Once I replaced the wiring harness with a second-hand one (with corroded bus-bars, but a perfect connector), it was fine.

    So, this is another clue as to what happens (also, the ECU balances the battery by 'slowly' overcharging the cells with a higher voltage, dissipating the extra charge as heat). The ECU is kind of like 'Christine' in this way - it can fix random imbalance by itself. However, it does stress the battery. If I wasn't attentive to the car (and noticing it being a bit different that day), I could have had recalibrations every day, wearing the battery out and maybe damaging it before any warning lights came on.

    I am now the proud owner of the original HV sense harness, removed from the car, with the HV sense harness somehow discharging the same cells (1,2 and about block 10) - the same cells that shorted last time. The harness is basically a harness that is causing a discharge, and likely in the state just before a major plasma-arcing type short occurs....

    I don't have a 'megger'. Are there any particular specifications I should look for? I can get one that does 250, 500, and 1000 volts, and can show mega-ohms with +- 5% accuracy. I don't know much about them, but wonder if you had any advice around getting one (given I won't use it often, but will use it with Prius + EVs over the years).
     
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  4. ronlewis

    ronlewis Member

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    I only read a few of the posts in this long thread since it's all way over my head, but I did see black signs of heat in the battery ECU of a core I sent back to Best Hybrid batteries a couple of months ago. And I have an unburned harness that just came of another battery if anyone wants it. One sensor broke off of it.
     
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  5. ChapmanF

    ChapmanF Senior Member

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    I think I was reading Andy's post as saying the blocks were being read as zero volts by the ECU ... which wouldn't surprise me at all after burning up the connector it uses to read them.

    There's been some discussion of those animals here and here, among other places.
     
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  6. Dxta

    Dxta Senior Member

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    The 500V megger would do the magic. Getting something higher than that, could burned out any of the HV circuitry you might be testing.
     
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  7. ChapmanF

    ChapmanF Senior Member

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    Typically a megger that has a 1kV setting will also have a 500V or lower setting for when you're testing things you don't want to quite fling a kilovolt at. Some of the nicer ones will have settings down to 250, 100, or 50 volts and be usable for telecom circuits and such.
     
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  8. OBJUAN

    OBJUAN Member

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    inside the orange battery ecu connector harness and ecu, look for corrosion. Only non-gold connector on the ecu...
    condensation can run down the harness into the ecu. connector will start to corrode and develop a short between the sense wires.
    no fuses so it can cause big problems, fire even...
     
    #108 OBJUAN, Nov 13, 2019
    Last edited by a moderator: Nov 14, 2019
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  9. landspeed

    landspeed Active Member

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    I will order a megger; the ones I saw were 125,200,500v so I will get a mid- range one. It will be interesting to see what the results are, and I will post them here!

    My Prius is still going strong; the only problem is that I can get deltas of 0.3 volts if I do full charges to 80% and discharges to 40%; I drive over a large volcano, to and from work, and there are usually traffic jams beforehand, leading to low state of charge, and going down the mountain causes a full battery. The interesting thing is that the deltas are caused by the fact that the three blocks that were shorted are now even healthier; the remaining 11 blocks are the ones that drop voltage and go to higher voltage sooner; there are also very well balanced to each-other despite this. This likely shows the benefits of doing deep discharge / slow charge (Prolong etc).
     
  10. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    I have seen the same thing. You would think that would damage modules but they actually improve.
     
  11. OBJUAN

    OBJUAN Member

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    The batteries need a kick in the butt once in a while. Park, one foot-full on brake, other foot-full on gas and let it charge the battery pack full. Dr. Prius app has a process for testing battery life that wants this charge process. Then they have a controlled discharge process for you to perform for about 15 minutes. I would say the charge process stresses the pack hard and it opens up the plates to rejuvenate the cells. Course if there is a weak cell, it may fail but you will know which one. Battery #28 is next to the electronics and battery #1 is opposite end.
     
  12. dolj

    dolj Senior Member

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    You realise this is a Gen 1 thread and the information you have supplied is about Gen 2?

    And as it happens, Gen 2 and Gen 1 are different in this regard. It is not really a benefit to give incorrect information as it just adds confusion to people who don't know any better. Can we all check where we're posting and make sure what we are posting is correct. If you are not sure, then don't post.
     
  13. OBJUAN

    OBJUAN Member

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    don't know why I got threaded into gen 1, anyway same batteries same problem, so chill dude.......
     
  14. dolj

    dolj Senior Member

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    Except they are not, which is the point I'm trying to make.
     
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