i know they sag at start ,hmm this is answer from company that did my battery
They’re all welded in the middle 
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I must say that I don’t see the reason why the phisical position of the cell group would have anything to do with measurement difference🤷♂️
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This is my biggest issue with cell holders.
Any pack modification after the fact sucks, but as soon as you put them into holders like this, it’s done.
The amount of work it would take to replace a group in something like this would be comparable in price to just building a new pack.
I’ve been toying with the idea of designing holders for each individual group that just slot together, so that in a worst case scenario, the workload is heavily reduced should something like this occur.
Sorry this has happened to you dude, hopefully the builder can get you sorted.
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ok I’m very much not an expert, I have only built one half decent battery. But I have 2 thoughts here that could be useful:
- I think the reason the physical location matters is because the connection from groups 1-2, 2-3, etc is a fairly big nickel strip welded pretty well. But from 6-7 seems to be a much longer cable, rather than a tiny strip of solid nickel. Resistance is still very low, but at 160A dropping ~0.2V seems sort of expected. Do you have pictures of the assembled pack other than what you showed?
- To test if a cell in that group is defective, run the pack at high currents and see if it gets hotter. If it is in fact the connection and not the cells, the cable will get warm. If a cell is unhealthy it will likely get a lot hotter than the others
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No production P42B’s out there. There can be a few samples though. 
Edited to make it clear that my original reference to samples meant that they can be in the hands of some people but none are in production.
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That guy is overrated. 
I think you guys covered the possibilities well. If the app is giving correct readings (are we assuming anything here?) then it unfortunately it looks like the pack will need to be opened. If temps are to be checked then it needs to be carefully done while running since the nickel strip could cool a lot in just seconds.
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Oh rly? I have some unobtainium at work then 
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You’re saying they were purchased from a retailer or distributor and are production cells, not samples? If so that is contrary to what I was told by those who know about Molicels.
There are none available for purchase anywhere, it’s not listed as an available cell on the E-One Moli web site, and both Molicel and NPE have said that the P42B is not going into production and is being passed over for the P45B. 
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Nah we got samples to test 
Currently evaluating some EVE and molicells. Think the P45 is in there too.
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Ahh…okay. I mentioned samples being available in my post so I still stand by it. 
I have edited it though to try to be clearer about what I was trying to say.
A couple of the EVE’s have tested pretty well IMHO, especially considering their price. The P45B I won’t say anything publicly about yet (just to my patrons) but the testing I’ve done the past few weeks has been verrry interesting.
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We run weeklong cycle tests in our rigg with about 20 cells, so might be able to confirm your findings 
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Don’t no l know if anyone has said this yet but the design on this pack is awful and I’m not that supprised that it’s failing.
Many of the parallel sections have imbalanced capacity, imbalanced current flows through cells and probably huge voltage imbalances which can’t be balanced out.
EDIT:
Think I may have misunderstood the pictures. Looked like one side was front and back, but I now realise that these are just a mid build and finished build picture.
If that’s the case is not as bad as I thought.
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The top floor and bottom are connected with cable , that is way polish do,That group works normal, when is charged battery has 0.001v difference just that group is quicker on discharge and drops 0.176v i both packs has same temperature in bms app
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That guy builds batterys for years high end ebikes,i think is just one damn cell, we will see,but Molicell are saging more then i expected …
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For 160/180 amps peak and 80 cotinius it will be enough !
Thanks for the picture, can you show the cable that connects the floors? Because it is indeed a cable rather than nickel, I think my guess that it is just voltage drop across that cable is correct. If you have a way to draw a high current from the pack and measure the voltage on that wire, or directly on the cells in group 7, you can get an accurate answer.
If you have a multimeter that can probe directly across the wire and you find that at high current it’s dropping 0.2~0.3V then you know that the cells are fine. If you can’t access both ends of the cable safely, but you can access the cell terminals then you can also measure the positive and negative of group 7. I can draw a diagram if that’s not clear, describing batteries in text can be messy
In Poland all high end ebikes company that make high discharge battery do it like that way,because you must use o+minimal two or three floors and tje only way to connect it is by cable,because you cannot fit all pack together in same time in frame,but that is not a problem they did hundreds of them,cable is not a problem.I will show you now how that looks ,this battery on picture is 300 amp discharge and no problem ! We will see one cell or something alse not cable …
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Man they should really look into the copper sandwich technique. Would save them so much time
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