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iphone 6s battery misreads and random shutdown

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  • iphone 6s battery misreads and random shutdown

    (DCPS after inserting power 5v reverse polarity - soon after I disconnected and reconnected correctly - failure wasn't immediate but later on when trying to boot)
    1. USB- Verified with known good charge flex, battery and screen - 0mA Not booting via USB
    2. DCPS -0mA Before Prompt to boot. prompt to boot with tweezers -0mA -230mA -330mA - up to 450mA(split second) back down to 330mA - 0mA (screen turns on with Apple logo during this 'booting sequence')

    Replaced TRISTAR! With known good parts charge port flex, battery and screen above problem gone and now the phone boots but has gas gauge problem, intermittently misreads 73% charged battery(verified 73% constant with known good motherboard) as 1% and randomly shutsdown!

  • #2
    Sounds like batt_swi problem—om 6s it can be nearly invisible damage to the connector. Press on connector to check. If not, then change tigris

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    • #3
      Thanks for the response. I checked the motherboard's battery connector under the microscope comparing with the battery connector from the known good motherboard. Looks fine. Tested for spongy connections with my tweezers - firm.
      Replaced Tigris. Now with my known good parts
      1. charge port flex
      2. battery 73%
      3. screen
      No longer booting thru USB
      Boots with battery on prompt to boot with tweezers
      Battery level misreads, random shutdowns and reboots
      Connecting to USB whilst powered on(after powering on with prompt to boot via tweezers)
      battery charging symbol is displayed but USB ammeter shows zero current draw.

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      • #4
        Reballed Tigris - retested no difference.
        Replaced Tigris with another one from a different supplier - Rossmann Group.
        Behaviour is as with the previous Tigris. Battery misreads, random shutdowns, reboots with the exception that you can now prompt to boot from USB. However, still doesn't charge, pull the charging current you'd expect for a 73% charged battery - current draw is low and constantly changing.The only other two components I can see on the SWI to Tigris are a 56pF 1005 cap sitting between the line and ground and a resistor. The cap is non polarized and rated at 16v so I can't see how 5v at reverse polarity would have damaged it. I am attaching a picture of the battery connector at magnification.
        Attached Files

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        • #5
          hello l2l, Jessa and all.

          what about Tristar? Can you read its status?
          ​​​​​​​

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          • #6
            Hello tojaert thanks for the reply.
            Not sure what you mean about reading tristar's status. If you are asking whether I have a Tristar tester, then no.

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            • #7
              I've replaced Tigris, twice. I think I've ruled out Tigris, but I'm still getting the gas gauge issue. I COULD just do another TRISTAR replacement and 'see' if that fixes the problem but would be doing so like 'a monkey' without any real knowledge of what I'm doing. In order to diagnose Tristar properly I think I need to understand better what Tristar does and develp a better understanding of the charging circuit.
              The following is a link taken off the blog of aonemobiles, a treatise of iphone charging from Bill Saith/ Ben Duffy. It's mega! I think Jessa and Mark know these guys......

              https://www.aonemobiles.com.au/2018/...ging-analysis/

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              • #8
                Did you do what I suggested? PRESS on battery connector. Press on it and see if anything changes. Apply pressure the entire time.

                Also--you said you got a tigris chip from Rossmann Group. Be cautious buying chips from people that do not use those chips. Tigris chips from China are often wrong because China thinks the PN style will work and they will not. Your chip must say SN. Check--does yours say SN?

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                • #9
                  Yes I did press on the battery connector - for 5 seconds but entire time was the magic word I needed to hear, which you said just now.. so this time I did press on the battery connector for a long time...and after a time the charge level jumps from 1% to 90% AND the charging current looks normal at 170-200mA. I cross checked this with my known good motherboard - it is correct.

                  Yes the first Tigris was from China, said PN, and yes the result it gave was crazy, the second from Rossmann Group said SN and behaved better and I'm keeping the original ... looks like it's NOT faulty after all... and the ones from China are going in the bin! I guess my next job is to swap over the battery connector. Well I'll be buggered..... I put it beside a good connector and I still can't tell it's faulty just by looking at it. You're a Guru!

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