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Thread: iPhone 2g won't charge - voltage readings inside

  1. #1
    Default iPhone 2g won't charge - voltage readings inside
    Afternoon all,

    I recently managed to crack my iphone glass so decided to replace it, that wasn't a problem, and so while it was apart, I decided to replace the battery also.
    Everything seemed fine and the phone turned on and worked for a day until it ran out of charge.
    So I connected it to the mains and it vibrates, the display says it's charging, but it doesn't actually accept any charge.
    Even leaving overnight wouldn't do anything.

    I took the back off and measured the voltages that are being put out by the logic board.

    Not on charge, just switched on:
    Black --> Red = 4v
    Black --> white = 0v

    Switched on, on charge:
    Black --> Red = 4v
    Black --> White = 5v

    So the weird thing is that the logic board is dishing out 5v to the battery, but the battery doesn't appear to be taking any charge?

    Are the above voltages correct, and if so, why won't the battery hold/receive any charge?

    Anyway, I thought maybe it was a duff battery so bought another one and have exactly the same problem, and voltage readings

    Any answers will be MUCH appreciated. Currently the iphone is plugged into the wall on 85% so as not to lose any charge/completely brick on me!

    I've also restored the iPhone back to 3.0 and it doesn't solve the problem. Everything else on the phone works (calling/wifi/bluetooth etc)

  2. The Following User Says Thank You to GeeJay86 For This Useful Post:

    dysko (10-29-2009)

  3. #2
    I also have the EXACT same problem! Unit was working fine, replaced battery, now it will not charge it. My mistake was letting it drain completely before attempting to charge it, but I bet my voltage readings are the same too. I am suspecting firmware 3.0 does it, but I have absolutely nothing to back up that theory with and now I will have to go back to my original battery and make sure that it is still charging with that one! Please let me know if you find a solution...

    Edit: Confirmed, my voltage readings are the same.

    It is possible that there is a firmware failsafe built into the phone starting with 3.0 that it will flag any catastrophic power events, IE NO BATTERY, and no longer allow the phone to charge. Restoring should fix that though, unless it was not a completely restore...or what I am thinking of trying is going to 2.X firmware to see if that fixes it. There were no other problems mentioned with this until the 3.0 firmware. I may be getting ahead of myself, first I have to make sure that my old battery won't work either, and then go from there. I also am wondering if it would be hard to charge these batteries outside of the phone, ie power supply until the solution can be found.

    Well, I tried my original battery and it will no longer work. Therefore, I believe it is a safe assumption to say that there is some sort of detection and or flag in the firmware that detects a new battery and will not allow it to charge. This is most likely not a hardware flag because if it was, I believe that this problem would have cropped up by now for other people before firmware 3.0 and after searching the net I do not believe it has. Meaning that this failsafe or flag is new to 3.x firmware most likely and can probably be solved by having a battery with a full charge on it installed into the phone, and then restoring the phone with a 2.0 firmware. That is my hope anyway. I am going to talk to a guy who know Li-Ion batteries like the back of his hand about charging these batteries outside the phone, and then I plan on making an attempt at it. I'll post back tomorrow after I try it.

    Spoke with the expert about these Lithium Polymer batteries and there is a Negative Temperature Compensation circuit included in the battery which is what the white wire is. The black wire is ground obviously and the red is positive. To charge this, as with all lithium ion batteries, it should be attached to a current limiting power supply with the current limter set to 1C of the battery in this case being about 1400mA. I will set mine to slightly less 1200mA just to be safe. The red wire on the power supply should be hooked to the red wire on the battery, the white wire should stay disconnected, and the black wire should be hooked to black on the power supply. Set the charge voltage on the power supply to 4.1 volts and turn it on and the battery should start to charge and the current used should begin to drop. Battery should be charged in about an hour and a half. This is all for a 1450mAh battery (iphone 2g replacement battery). I'll go ahead and try it and post results. Also after talking with the expert, it is very likely that Apple set a catastrophic battery flag in the new 3.x firmware. Restoring to a 2.X firmware should clear the flag. This is still speculation until proven.+

    Well, I have succesfully recharged my battery using the method above and have installed it back in the phone and the phone registered it as being charged to 75%. Then I went to downgrade it and realized that I need an old version of iTunes and probably more. Trying to get that 'more' tomorrow. There are guides I am going to follow to help me downgrade from 3.0 because it doesn't appear to be an easy process.
    Last edited by bobkooney; 09-23-2009 at 08:31 PM. Reason: Automerged Doublepost

  4. #3
    Hi Bob,
    Thanks for coming back on this!
    sorry for my delayed reply, I've been away for a week.

    Anyway, many many thanks for investigating this for me/us, I'm not sure what luck you've had on the downfrading front. After many attempts and error 20's and 1601's when trying to downgrade from 3.0 to 2.x.x here's what I've managed to make work (restoring as we speak!)

    iTunes 7.5 downloaded from oldversion.com
    Shift --> Restore to the 2g 2.0.0 firmware here:

    I'll post back in an hour to see if it charges!

    EDIT 1: Restore was successful, now it's locked again, and needs at least itunes 7.7 to function lol!
    I'm going to leave it plugged in for a bit to see if it does charge before re-upgrading to 3.0

    EDIT 2: Nope, I'm down to 2.0.0 and it's still not charging, just showing that it is. Might as well try 1.1.4 for luck.
    Last edited by GeeJay86; 09-26-2009 at 10:30 AM.

  5. #4
    replace the battery, i had the same thing and replaced the battery and the problem as solved.

  6. #5
    Quote Originally Posted by amitrx View Post
    replace the battery, i had the same thing and replaced the battery and the problem as solved.
    Thanks for the reply This is my second new battery I've installed, and both have had exactly the same symptoms?

  7. #6
    want to make it clear,
    u didn't charge the battery and then it wont charge?
    or u r trying to charge it and it's not charge from the beginning?

    i replaced the battery and didn't charge it till it ran out of charge and then it didn't charge at all..was stuck in the red battery icon.

    try to put back the old battery and check if it works.

  8. #7
    Well, you downgrade the firmware, but I believe the baseband is not downgradable, may as well try a new communications board.

    Actually I was planning to replace the battery to my 2g 3.0 iphone. Please let us know how it turned out.

    Amitrx, was your iphone on 3.0 firmware? And where did you buy the "good" battery?
    Last edited by macacophone; 09-28-2009 at 07:22 PM.

  9. #8
    Whats the latest guys ?

    I'm in the same position. New battery in, and it won't charge past red ever.

  10. #9
    Hello,

    i'm getting crazy too

    My story :

    Decided to replace my old batt in my Iphone 2G , the new batt won't charge , changed 3 wall-charger .... nothing , replaced the old batt .... all ok , the old batt charged and worked normally.

    I've bought another battery .... same thing , the new batt don't charge so i replaced the old .... the old worked just fine.

    I've decided to bought a third (different ebay seller ) battery ( this time original original ) and nothing changed : new battery does not charge , replaced one more time the old battery and all is fine again !!!!!!

    I'm getting crazy , someone help me before i throw my Iphone out of a window

  11. #10
    I am in the same boat and found this thread... I just had to chime in on this. Kinda sucks that you can't replace the battery in the old 2G phones because of this happening.

    It's all good that the old battery would still work... but the reason I replaced it was because the old one couldn't hold a charge - even worse the new one won't charge.

    I can say that when I installed the new one I did make it run down all the way just to calibrate it... then after charging it a second time and it ran down was when it would not go past the red.

    Any new info on this? Glad to see there are some people digging in on this topic.

    Hope we all get a fix soon.

  12. #11
    oh man does this happen to the iphone 3g 0.0 im planing to replace battery.

  13. #12
    ok, so i've replaced a battery on a 2G as well, and it dies during the apple boot logo. rinse and repeat.

    what to do?!

  14. #13
    got a voltage of 4.32 going to the phone (original charger). i've read that anything above 4.30 will overheat and cause problems.
    tested 'green'dot' replace for the recalled and got a 4.28. not sure but ...
    2 cents

  15. #14
    it could be that you burnt your comm board while soldering...that can happen if you don't solder it properly can't it??

  16. #15
    Default same old story
    Just installed my 3th battery...
    New battery works but doesn't charge... if I put old battery back, all works as it supposed to... Any luck?

  17. #16
    I have had the same problem with the batteries. I purchased 2 batteries from seperate sellers on Ebay and they worked when I fitted them but would not charge up, when I put the old one back in it worked and would charge up! The way I found to get round this was in the top of the old battery is a small circuit board with 2 wires or bits of metal going into the main part of the battery, Swap this with the circuit board on the new one. It is a bit fiddly but I'm a Numpty when it comes to soldiering and it took me about 1 hour to swap them over. My new battery now charges up and works perfectly. Hope this helps someone

  18. #17
    i searched and found this thread. my battery wasnt an issue but still stock.
    my problem i think is the connection port at the bottom. just moments before having this problem (wont charge) it was difficult to connect meaning id have to re-insert the cable several times before itd connect. then out of the blue i returned to a dead phone that wouldnt charge and its been that way since last night. ARRRRRRR!! now i have a dead batter, and a phone that wont charge!
    I HAVE A 3G RUNNING 3.0

    i think ill just send it to iPod Repair, iPhone Repair, and Zune Repair
    Last edited by hesaves0211; 12-25-2009 at 06:38 PM. Reason: Automerged Doublepost

  19. #18
    Quote Originally Posted by throbnozzle View Post
    I have had the same problem with the batteries. I purchased 2 batteries from seperate sellers on Ebay and they worked when I fitted them but would not charge up, when I put the old one back in it worked and would charge up! The way I found to get round this was in the top of the old battery is a small circuit board with 2 wires or bits of metal going into the main part of the battery, Swap this with the circuit board on the new one. It is a bit fiddly but I'm a Numpty when it comes to soldiering and it took me about 1 hour to swap them over. My new battery now charges up and works perfectly. Hope this helps someone

    Thanks a lot !!!

    I also swapped the charging circuit board between the old and the new battery and this solved my problem , now all works OK !
    (new battery + old circuit board )

    Best regards.

  20. #19
    hi,

    i am having this exact problem with my 3GS, i replaced the battery and now it wont charge at all even after putting the original back in so i assumed that i had missed a connector or something but it all looks fine and i'm sure i haven't done anything stupid.

    When i plug the power adapter in it goes straight to the battery full icon, when using USB it takes a few seconds then goes to it despite the level being 11%. the same charger charges my friends ipod just fine. so far i have tried restoring the firmware and scowering the board for signs of me being thick.

    does anyone have any ideas, anything at all would be good by this point i have spent 6 hours trying to get the thing to work today.

    if anyone knows anything about how the charging circuit works that would also be useful as i have no idea.

    thanks in advance

    Jacek

  21. #20
    Quote Originally Posted by miciobigio View Post
    Thanks a lot !!!

    I also swapped the charging circuit board between the old and the new battery and this solved my problem , now all works OK !
    (new battery + old circuit board )

    Best regards.
    I have the same problema whit my iphone 2g, but i can't find any "circuit bord at the top of the wires of my battery; it's soldereddirectly on the board.
    Can someone show me this legendary circuit board?? any images?

    Thanks

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