How to test if individual battery modules are good

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by midi_ring, Dec 21, 2024.

  1. midi_ring

    midi_ring New Member

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    What do you look for? Say you have the triangle of death pop up and go through your pack module by module, and 1 just happened to go out certainly. But how can you tell if the others would be a viable candidate to go back in the pack?

    Also, id say theres different kinds of viable candidates. Some that maybe would last you quite a while, then theres some that some may say is viable that might not last as long.

    Is there a certain number of things to check out before you decide to put a module back into a battery pack? I want to find out what things i need to look out for for a "healthy" pack once I get done. What tests do I need to do on the modules to see if they would make for a somewhere in the middle. Lets just give some general numbers here. Say a battery pack nominally lasts 180k miles. Say one just happens to crap out at 80k miles on you. What tests should I perform and what would tell me what these numbers are?

    See, what I'm doing is the tests procedures I saw on one video

    Ok, so what am I getting from doing this procedure he shows?

    From what I've been seeing, his tests, which I dont know what it tells me about these packs if their subpar, or high grade, Is; using his procedure, I'm trying to find packs that can get up to a 5000mah Discharge capacity.

    But ok i see but i dont understand. What if its taking me 20 runs to get a pack to get up to that value? What if so far none havent not been able to get up to that number, but some take a slow amount of time to get up there? Out of all the ones that pass this procedure, which are subnominal and which are high grade? Is there more tests I can perform?

    I've heard of a load test. Take and put a 5amp load on the modules, after theyve been ran through the previuos procedure, and time how long they take to drop their voltage. Some peop;le just go by amount of speed. Some people do a 1 line test and see what it drops to after a set amount of time. Then theres people, like for example

    where he records how long it takes to reach certain voltage numbers between modules. He mentions that certain voltages between say 7.0 and 6.5v are more imprortant than the time it takes to drop between 8.0 to 7.5. What would be the logic behind this? WHy would the numbers he gives for importance of holding voltage during a load be more important than the other numbers? is that just how (these) batteries are? Or what voltage does the Prius begin to set the pack back to charging mode, instead of discharging in the car? If its 6.5v i could see what he's saying. but if its say 7v, but Idk. :What numbers are the most important/voltages to check for load voltage drop?

    Then theres another test I saw. Finding the internal resistance. This guy does it with a battery tester, in this video

    Also I was reading a topic here where someone was showing his Internal Resistance on his pack while it was in the car with the Dr. Prius app. Someone said that that IR number doesnt matter since the car doesnt have a load on it or a charging going on for those numbers. So, is there some way out of the car to do this, run a charge or discharge while testing for IR? Would that work with that battery tester shown in that video or would it cause the battery tester to mess or or messup maybe something in teh batteries?

    So, what do i need to look for to find the good packs, and what numbers am i trying to get? Maybe just an average from all. Should I run all three of these things? What numbers would be bad, especially on that load voltage drop test. What about IR? would that video work fine to see if the module had a bad IR or do I need to have a load; charge/discharge either or, on it to run that test to get some valid information?

    heres the thread were someone said the IR numbers from the dr prius app didnt matter unless there was a load on the car or discharge 2006 Battery internal resistance | PriusChat
    maybe tho the deal with there is that its because the battery is put together in series in the pack. running in the car. would a battery tester like in that video work to find bad IR?

    Or .. would that procedure to charge back up the pack out of the car like in the first video, suffice? I just think that maybe some of the packs can get the capacity back in them, but i dont know im just making this up myself because i dont know one way or the other, you can get the capacity back ijn them, but then they would drop that quickly, or maybe the charge doesnt get it back up enough to allow it to reach a discharge capacity again. Important thing here is, I dont know how that procedure/test works. Im just seeing numbers and not understanding anything.
     
  2. mr_guy_mann

    mr_guy_mann Senior Member

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  3. midi_ring

    midi_ring New Member

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    ive read a little bit of that. 130 pages.
    Im just asking for a quick tip on how to tell whats good whats bad from what ive heard. how do i know they won't just flop out, from the video i was watching example. it says; "charge them up to 5000mah discharge capacity". if they cant make it; bad. if they do; good. some of his doesn't make it. throws them away.
    But what doesnt make any sense to me, is he doesnt say why he decided to throw away and replace a couple others. Ones that even reached 5000mah discharge capacity.

    so im clueless. i dont want some that will wear down on me and go out within 2 weeks of doing all this and wear down all the batteries i charged up. this has took me 3 weeks to do with a 4x charger. at 1A discharge. you know, at searching for a 5000mah discharge capacity everytime it moves up a little bit on its way to 5000mah, that 5000mah takes 5 Hours do do.

    The only other thing Ive heard is, that other video I linked, showing using a battery internal resistance health tester. toss away high IR ones.

    But is there any thing here that people have had to figured out while working on these, that tells you that you can do a test with, that will tell me my battery module is going to be healthy for a nominal, another 100k more miles. yea their old. IM not asking for any specific to mine; would be nice, but just some general information. Or does everyone want to keep that hidden.

    Come on, give some tips without me having to read 130 pages of posts that some of them doesn't make any sense for someone to refurbish their own battery.

    Lot of people like to say, oh this isn't any good. just buy a new battery pack. ok yea sure. Then i watched a video of some guy trying to refurbish his own, he gave up and ended up taking it to a shop, that within 5 days had the whole thing put back together and running just fine. don't know how long after he made the update video

    Im thinking here about my battery specifically, its old, but its not worn out as its not be used a whole lot. Internal Resistance seems to be what i need to look for. Maybe if I can find some correlations to charge/discharge cycles and IR I may post them.

    But can anyone give me any tips. Because if not, I'll just do my own write-up here eventually. Keep it to yourself if you want to but I'm going to let everyone know everything I can find out about it. If you cant do it, or dont have the means to do it, then pay someoen to do it. but for the rest of us, please be helpful.
     
  4. mr_guy_mann

    mr_guy_mann Senior Member

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    That's just it. The whole "refurbishing" - DIY repair of the HV pack is a crapshoot.

    When a battery module fails, all of the other modules are the exact same age and statistically about the same as far as likelihood of failure.

    So beyond replacing the "obviously" bad module(s), there's not much to do as far as predicting any near future failures.

    Some here on the forums have used a grid charger to slowly cycle the entire pack at one time. (Less time but more money)

    Others use hobby chargers to cycle individual modules. (Much more time - unless you get more chargers = more money)

    You can "load test" individual modules but I didn't find any faults doing that.

    I did the hobby charger route - took over a month to complete and the resulting pack worked for 2-1/2 years.

    There is lots of conflicting info out there. Do this for charging a module at X amps and Y cutoff level. But do Z amps down to W volts on discharge. Someone else says that's wrong. But it all "works" - unless it doesn't.

    When the refurb hiccuped I bought a new pack from Toyota without a moment's hesitation. That's my tip.

    Short form is you need to do your own research then decide what you're going to do and how.

    Posted via the PriusChat mobile app.
     
    #4 mr_guy_mann, Dec 29, 2024
    Last edited: Dec 29, 2024
  5. midi_ring

    midi_ring New Member

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    Ok so I finally got them all to 5000+ discharge 7500 charge. the one bad, replaced with a brand new one. also tested it. its very good shape. charges quickly.

    Now,l Ive read your supposed to balance them... by connecting all the postives together from all the modules together and letting it sit for 2 days. also i seen differntly to connect the negatives together, too. Which way is right? im sure positives but do i need to .. teear up another coat hanger to do this with?

    how important is this and does it actually balance? what does it balance becuaes after doin gall the positives before with a battery i returned, after 2 days, they werent all the same Voltage. One was fairly higher. so it ddidnt seem like I did it right
     
  6. MAX2

    MAX2 Active Member

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    Voltage equalization is that you connect all the elements in parallel. Plus to plus, minus to minus. The voltage of each element will be approximately +-7.8 volts and they will all equalize.
    The battery uses a series connection of elements, where the voltage of each is added up and ultimately amounts to 216-218 volts.
     
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  7. dolj

    dolj Senior Member

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    What do you mean by a brand-new one? This is not a good idea. You need to match the capacity of the replacement module to your other 27 modules for the chance of the best outcome. Also, what do you mean by it charges quickly. From empty? Charging fast (from empty) is not a good sign.
    You can save your coathangers and your time. As MAX2 said, you are talking about equalization and it does not do anything meaningful.

    Balancing is a whole different ball game and you've already done it by the multiple discharge/charge cycles you've done.
     
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  8. midi_ring

    midi_ring New Member

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    what do you mean?

    I just made up about charging quickly. i have no idea how long it took to charge. it took as long as any of the others to charge up.

    I hear about the "matching capacity" or something like that in putting them back together in pairs. I have no idea what that means. 0. Nothing. SO i just flipped them inside out, while taking the new one and setting it in the dead middle.

    How am I supposed to find equal batteries as my used one with all these "inserts ebay auctions descriptions - 7.8v battery. B-grade battery. 3000mah battery" None of this means anything except its not dead to almost nothing at all to 3000mah? mine are 5000+.

    So, could you elaborate? Ive already spent a lot of time working on this, paying for this new cell, to hear its a bad idea. How?

    Let me see if i got the idea. every time a cell fails a little bit, and from my charging with a hobby charger, this is the idea i get. Sometimes they would give me a 4000mah discharge, next run it would drop 400mah -3600mah. or between sets of 3 runs it would do that 400mah loss. but the next run it would go up to beyond where it was before it dropped. The only idea i can get is if you lose a little bit then it never comes back. ever. because the best one in the pack charges up before the others ever get fully charged.

    But I think hows does that matter if the batteries better? Its going to keep up with discharge rates. And they should all eventually equalize after some runs to getting up more charged. They are all discharging. Even that brand new one, only gave me a 3000mah discharge capacity on its first run. They would all eventually drop like that if the car sat for a while.

    Whats the big problem? I am really going to ignore this unless this is a big problem. I never hear anybody say this and give a full explanation.

    I think from seeing this battery get run down from the bad battery, that they do get a low discharge capacity some of them do and do not want to come back up for quite a while. 1 even took 30 runs to get up to 5000+ but it got there. But one, out of the original battery, hit 4900 discharge capacity on the first run and hit charging capacity.
    --------------
    What test are you talking about running? Are you talking about where they are in packs of 2? i put the new one with the one that got to 5000mah on its first run
     
  9. dolj

    dolj Senior Member

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    Making things up is not helpful if you expect help from people. It is better to be factual and if you can't or don't know just say nothing,
    Well, you can't do it easily with the buying process. What you would do is buy more than you need and hope that one of the ones you buy will be close after you use your recondition process on them.
    No, I am talking about determining relative capacity by doing a basic load test on each module. There is a description of how to do a basic load test here. You don't need to buy their load test kit, you can easily make your own.
    So you mean a new-to-you secondhand module, not actually a brand new straight-from-the-factory module. If so, this is good news.
     
  10. midi_ring

    midi_ring New Member

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    It charged up capacity not at a faster speed, but in less cycles and went higher. almost hit 6500mah on 2nd run discharge / 7500 charging.
    Also, yes its a brand new from the factory new old stock 2 year old module.

    So, Ive run into a problem. Yea. I put it back together. Didn't know what to do to balance them. I basically swapped them inside-out. The DrPrius app, while the batteries were a little cold mind you, told me that 3 of the sets weren't balanced. Little bit later 15m at the most, it didnt' complain. Maybe nothing.

    But, now after reconditioning all of them. getting them up to 5000+discharge and hitting charging 7500 capacity. The car doesn't sit very long before it turns the motor on. And my MPG is pretty low, at about 39mpg. drove it about 60 miles and it is still the same.

    ? is it the new battery? I could not find one that gave 5000+ mah discharge with actually hitting the 7500 charging capacity after looking through 4-5 pages on ebay. Everyone sells them, 3000mah+ or 7.8v or something like that. That doesn't tell me nothing.

    Oh also I was looking at the battery as putting it back together and seen a 2013 date wrote on it. This is a 2005 car. So it's been serviced before. Car only has 83,0000 miles on it.

    So what have I messed up, or not messed up? Is it possible to mix this new module in there with the rest of my modules? If I could could I just pair it with one with similiar balancing characteristics?
    is that how you pair them? with similiar load test characteristics together?

    What about discharge capacity? Since ive got that one that i bought used that only has 4500mah and doesnt even reach charge capac gets to @ 6500.

    Think maybe theres another one in there going out?

    IS that all i really need to do, is do this load test, and measure which ones are dropping the quickest and replace them if there way off from the rest of the pack?

    That one test I linked that some guy did, he was load testing at 5amp discharge and said the important numbers to him - were from 7.2v to 6.5v. Is that sound, alright? or ok?

    last thing, my hobby charger, discharges the cells. Couldn't I just use it, start discharging. Wait 2 minutes then record the value? put it on (1) amp discharge, it does it at a certain voltage that it runs too. Or is the h4 light bulb use different values? Would I not want to put a different voltage or am I just thinking about this wrong and maybe that charger doesnt have that (setting: discharge voltage)? be impossible? But it also can discharge at up to 5 amp. so wouldnt it work either way.

    Final note: whats weird, is they all show a 5000+mah discharge capacity, all teh way down to 6V but toss them all together and they don't use the capacity in the same way. Does this sound right? Or maybe this problem I'm having is from the odd New battery in there with the rest of them. I just don't know how they work together in ?paralllel or however there set up.
     
  11. midi_ring

    midi_ring New Member

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    What im saying there :Final note - .. is that, wouldn't you think if they all had a 5000mah discharge capacity after I ran them multiple times; when id first start them up, 4 at a time. after an hour theyd all start at 8.0V then i'd go in there and look and 3 would be at say 7.3V and 1 of the others would be at 6.9V. but by the time i ran them through their cycles and stuff, they would all go from starting 8.0V to 6.0V in 5 hours, (drained at 1amp) giving me 5000mah capacity.

    So if this balancing thing shows anything, then it would show that some of them hold the voltage up under load at a higher capacity more than others. Which is odd because they all discharge; at the end, 5000mah by the time they reach 6.0V. How it's different, and what a balancing test would do.

    IDK. Any kind of tips on what to look for,k what to do, to make sure one of these doesnt, possibly, do just fine at 7+Volts but then suddenly drop like an absolute rock and die off under that, down to 6.5quickly.

    There was one test, I'd linked before, that one guy said 7.2V to 6.5V was the most important load to check on. ?
     
  12. midi_ring

    midi_ring New Member

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    another question. What do I match together for balancing? Load drop times? Or capacity? That link says nothing about balancing.
    This
    says to match by capacity ... O K there is NO WAY I'm going to run those d/c cycles on all of those to see how high up I can eventally top them all off at. They are all 5000+. If they reached that in 3-4 or less, I got them to 5000Discharge and stopped. Some went a little longer cause at firs ti was trying to get them to hit 5000+/7500 d/c on one cycle. Any that took 10+ times to get there, I ran again to pump them over 5000 a bit to make sure they werent topping out. and everyone that I did this too, hit 5400+ up to 5700. One took it 30 times to get 5400mah Discharge. At 1 Amp discharge rate, that was a 5 hour discharge ..

    So what is the thing you do to balance them? My DrPrius thing told me 3 of them were unbalanced. One I believe was the one with the new module in the set.

    The problem I think has got to be that I have another 1 or 3 that are on their way out and not holding up on any load; but maybe doing that weird thing I talked about up there, holding load at lower voltages.. idk why but whats the point of load testing, I see it work, but the capacity is 5000mah+.

    I know from one thing in reading about and hearing about batteries is they don't hold capacity the same. So just someone tell me I'm wrong about that and they don't discharge at the same rate at different Voltages (on their way down). Or what is going on with batteries in general

    Also one last note; so that noone get confused along the way here is: The one bad module I replaced, i knew it was bad because it dropped voltage out of the car and when left alone, quickly. all but it; and drprius was complaining about that set it was in too, had a 8.1V when I tessted them a day after the last time I ran it, except for that one in that set, it was reading 7.5V. After sitting for 2 weeks untouched, it was at @ 6.6V.
     
    #12 midi_ring, Feb 3, 2025
    Last edited: Feb 3, 2025
  13. MAX2

    MAX2 Active Member

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    Using a charger, you can select modules with the same capacity. But that's not all.
    The charger loads with a weak current of 1A.
    When working, the hybrid part operates the battery at very high current values, both during discharge and during charging. 50-100-150 A.
    And then the internal resistance in a pair of modules is interesting.
    If the internal resistance of the modules is approximately the same, then at a high current in pairs of modules there is approximately the same voltage drop, which is measured using the ECU of the high-voltage battery.
    That is, for a real measurement of the voltage on pairs of modules, a large load is required.
    Then you compare U1 U2 U3 ... U14.
    If there is a large difference in voltage, the ECU will consider this an error and you should shuffle the cards in the deck so that this voltage is equal to each other.
     
  14. midi_ring

    midi_ring New Member

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    that doesnt make sense, to me, because.
    2 modules in a pair. the computers not going to know anything about 1 or the other to "error" becuase all its going to know is the addition of the voltage between them.

    say 2 moduels -voltages - in a pair. they are supposed to be 7.5v at max. of course a little higher we know but. adding 2 of these gives 15V. so say one drops quickly to 6V and the other still sitting pretty at 7.5V. that would be 13.5V. I would think that that would be the minimum the car would see to then start charging them, since their in pairs, because below 6V would be dangerous to these 7.5 volt modules; if one stayed at the 7.5 nominal voltage they are new after a load on them for a bit.

    can i just use an h4 headlight bulb, do i need to use the bright light side, to load test the modules with?
    do i need to recharge them, do charge/discharge cycle back up to @ 5000mah discharge again before I do a load test on them?

    do i pair them based on times it takes to discharge them? and get rid of any bad apples out of the bunch?

    how does the car charge and discharge these batteries? they are in pairs so, idk. Is there a rundown anywhere here ive tried looking on how to make a load tester and couldnt find anything. Like say if i can assume that the car would begin to charge them once they were loaded and discharged to 6.5V, a module, what im trying to look for is, what voltages are they used to? whats their operating range? IM trying to find what to load test them down to. In a worse case, nominal, scenario
     
  15. MAX2

    MAX2 Active Member

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    All modules are connected in series. The same charge or discharge current passes through them.
    It's simple.

    The voltages of a pair of modules are measured. If, with the same discharge current, a pair of modules begins to quickly lose voltage relative to their neighbors, this is a sure sign of a high-voltage battery error in the future.
     
  16. dolj

    dolj Senior Member

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    Yes you can, but it must be halogen not HID or LED. You use both high and low-beam circuits to draw the highest current.
     
  17. vvillovv

    vvillovv Senior Member

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    a module that charges fast is usually not a strong module. It's usually the opposite. Fast charging modules usually also discharge faster than slower charging modules.
    connect them any way you feel comfortable, than take readings to confirm what you expected to see. You do need to have some expectations to look for from the process before you begin.

    To be ~ SAFE ~ take two modules that have the biggest difference in voltage and connect them in parallel for a day or two. Than after separating them take there voltage readings.

    The key I believe in you position is to find the modules ( if any ) that reached your (good specs readings) in the first cycle(s) you ran them through on your CQ3. Those should be your strongest modules.
    The others will be weaker as it took more cycling for them to meet your chargers settings for ( good specs readings).
    There is no substitute for experience. Instructions are all over the place. You have to find someone that explains what they've experienced in a way that makes sense to you. And learn as much as you can about why it works that way.

    Not many of us truly understand why what works for us works well sometimes and doesn't work every time the "same way". ( ants are marching red and black and antennae wavy).

    Back to that 130 pages of posts thread since you have a CQ3 I've found for me that the best descriptions of how that charger works, it's setting to use, how to run the cycles, what the charger doesn't detect when cycling NiMH modules and
    not so much but some of how his
    rebuilt packs perform when reinstalled in the car
    is @TMR-JWAP
    he has 4 or 5 CQ3's and has been refurbishing for some time.
    Gen II Prius Individual Battery Module Replacement | Page 123 | PriusChat

    Keep in mind that when at the beginning he states "In the big picture" he's talking from experience of already knowing what a "healthy module' looks like in his sleep. Many of us struggle to know exactly what a "healthy module" actually looks like both right after it comes out of the car and even after it's been reinstalled in the car after being cycled and balanced.
     
    #17 vvillovv, Feb 8, 2025 at 10:13 AM
    Last edited: Feb 8, 2025 at 10:21 AM
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  18. vvillovv

    vvillovv Senior Member

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    Also , you haven't mentioned it yet, I think that is Because not enough people remember to even talk about it.

    Self Discharge

    It can be observed at both per module as well as the pack level, it shows mostly at the pack level when you have two full packs that are rotated in and out of the car. But you can often see it clearly at the module level if you let each module rest a week while others are cycling.

    There's a lot more to self discharge than gets into most instructions.
    When cycling most voltage ampere watts reading are done in the chargers, but in the good ole days most of our reading had to be taken on volt / multi meters.
    Self discharge is still one of those things you have to keep track of manually.
    In a nutshell
    self discharge is how much voltage a module looses on it's own while sitting with no load (or not connected to anything ) for a day, a week, a month, and during testing by the manufacturer when new (a year)
    It should be listed somewhere in the batteries spec sheet provided by the manufacturer of the batteries.

    Measuring it can be tricky due to the fact that many NiMH modules will hold a "surface charge voltage" that is not it's true working voltage. And figuring out how to remove the " surface charge " is as much of an art as the entire process of cycling Prius Packs.
     
    #18 vvillovv, Feb 8, 2025 at 10:31 AM
    Last edited: Feb 8, 2025 at 10:50 AM
  19. dolj

    dolj Senior Member

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    N/A
    This process will do nothing useful. There is not enough potential difference between the modules to move any meaningful quantity of electrons one way or the other. This process is called equalization. Don't waste your time with it.

    The most useful thing anyone can do to find the relative capacity is a load test. Either measure the voltage drop over a set time (2-3 mins) or, the time taken for the voltage to drop from say 7.2 V to 6.6 V. The specifics don't matter so much as to do the same process for all modules. Taking longer (within reason) is better than shorter. At no point should you carry on the load test below 6.6 V as shortly after that the voltage will freefall and you can damage the modules very easily by discharging high current (relatively) after the cliff-drop point.

    [EDIT]
    One last thought, it is important to take the termination voltage while still under load and the easiest way to do that is to make sure both the timer and voltmeter are in frame, snap a picture, and then terminate the load. You can then refer to the photo at your leisure to transfer the data to your log.
     
    #19 dolj, Feb 8, 2025 at 9:44 PM
    Last edited: Feb 8, 2025 at 10:09 PM
    Brian1954 likes this.