Laptop battery rebuild service?

Discussion in 'Hardware Components and Aftermarket Upgrades' started by Raidriar, Apr 30, 2018.

  1. HubbSigns

    HubbSigns Newbie

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    I'm also interested in having a battery rebuilt, @t456 I have a Dell Studio 1569 which uses the 66Wh 6 cell Dell YY9RM battery that, as far as I can tell, is no longer made. I can't send PM's yet, but if @t456 could reach out to me I would really appreciate it.
     
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  2. KingCornWallis

    KingCornWallis Newbie

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    What a small world. I was about to post the same comment word for word.

    @t456 I am prepared to make it worth your while. Please let me know if you are up for it.
     
  3. t456

    t456 1977-09-05, 12:56:00 UTC Moderator

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    We're still busy with HubbSigns's battery pack. The difficult part is that this model uses non-standard cells, so no simple 18650s or pouch types. Did find a few suppliers of the 103450 cells we need (10mm x 34mm x 50mm). Ordered a few of them, but it is a bit doubtful they're genuine, as in 'new', rather than being re-packaged used cells. Will have to test them first; if their capacity doesn't match up then it'd be useless to re-cell the pack. Perhaps we'll have to consider 'upgrading' to pouch types instead.

    Will post an update once we have it working.
     
  4. Che0063

    Che0063 Notebook Evangelist

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    Gone are the times when upgrading laptop batteries yourself was just slotting in new18650s with some careful soldering and a dummy voltage supply :(

    I'm curious, when you are swapping out the cells, (I'm assuming you are using the original BMS) How do you wire this dummy voltage? BMSs nowadays immediately lock themselves up when they detect that one cell has gone to 0.00v (or when the cell is removed). Do you use crocodile clips?

    Does 'waking' a BMS in this locked state work anymore? I've seen and heard of three-way resettable fuses, applying a charge voltage, and 'shorting' one of the pins with a 100Ohm resistor. I've tried these methods on two Li-ion BMSs and they just don't work anymore. Any tips?

    I'm thinking of increasing the capacity of my 38Whr Li-po battery in my tablet. There is 1-2mm room between the battery and the case as well as under the palm-rest area (Think MacBook 2012-2014 era design). The current battery is just two 5000mAh Lipos wired in series. I could go for another pair of ultra thin 1000mah lipos and add them in parallel (2S2P). Any tips? Where could I go about searching for these thin li-po packs?

    EDIT: My BMS charges to 4.3v/cell. Most batteries I've seen on Alibaba/aliexpress are rated 4.2v only :(
     
    Last edited: Jan 27, 2019
  5. t456

    t456 1977-09-05, 12:56:00 UTC Moderator

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    Hmm, never had that problem. But I just remove the chip entirely and program it as a stand-alone. But if that would be a problem you might also buy a new, clean BMS and program that. Or use one from an old pack.

    There's at least one fuse on every BMS, but afaik every one of them is triggered by excess voltage, current and/or temperature, not the lack of it (that'd be very odd, indeed). This is an example of a commonly used series: SC Protector.

    I'd be careful when removing the old cells. One minor short is all it takes for that fuse to trigger and soldering heat is a no-no as well. I discharge the pack completely, strip away the cells with pliers and only solder the fully discharged cells to the pcb once they're pre-assembled with a spot welder. You could measure the fuses on those suspect pcbs and if they indeed have infinite resistance order new ones or recycle some from ancient laptops.
    That's awfully thin. Swapped an mp3 player's battery the other week and these can be pretty flat, plus there's scores on ebay/aliexpress; 3x40x40mm 500 mAh.
    All batteries can be charged to 4.3 or 4.35V, if you like. The problem is that they'll age much faster as a result (see Table 4). Smartphone manufacturers are prone to do this; it looks good on paper, in reviewer's graph comparisons and the customer will be quite happy at first. And once the warranty's over it is no longer their problem. The reverse, rather; adapter addiction would be good incentive to buy a new phone.

    You can specify the charge voltage in the BMS's firmware, but I'd prefer to set it to 4.1V instead. And, mine can't do this, but modern laptops can have a limit-charge option in the bios; if you set this to 70% or so then you'd have the exact same limit-voltage result, except retaining the option for a full charge for that extended, every-minute-counts trip. Guess a 4.35V would be pretty good to have at your disposal with such a system.
     
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  6. Che0063

    Che0063 Notebook Evangelist

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    Funny you should mention. I have a faulty BMS - the battery will charge to a (seemingly) arbitrary value before refusing to accept any more charge. It used to charge only to 25%, then I somehow coaxed it to accept up to 50% before terminating the charge. Now it charges to around 60-70%. I've measured with a multimeter and the charging process goes fine up to, e.g. 7.9-8v, then the voltage suddenly spikes to 8.6V and charging stops. I assume the BMS has just cut-off. I'm yet to use it at school - 60% could be enough to last through a day but I've soldered a bypass wire from one of the cells directly to the motherboard with a switch. It probably means I lose undervoltage/overvoltage/short circuit protection but I'm yet to test that. Another option is to add a diode so that the charging process goes through the bypass wire, but discharging must go through the BMS. Just a thought.

    Unfortunately I do not have the tools nor the knowledge to program a chip :( I can't even de-solder a chip from a board without losing my temper and/or destroying the chip entirely lol
     
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  7. t456

    t456 1977-09-05, 12:56:00 UTC Moderator

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    Heheh, yeah ... well, if you have the patience to re-cell a pack then that shows pretty good temper-control, I'd think.

    It's probably the wear level that's hindering the full charge. In a properly-working battery this value will be adjusted now and then in order to have an accurate %-left reading (otherwise it's that '4hrs left -> 4 mins later -> shutdown' thing). After a re-cell you'd have to reset it to get the stock charge back right away. But fortunately the pack's wear level can also decrease (...). They probably do this in order to prevent having a crippled pack resulting from a single bad calibration. The up-side is that your new pack will get better and better for a while; try to re-trigger that 25->50% calibration run and check whether the wear level has decreased (HWiNFO can show the current value).

    Not sure what you want to use that bypass wire for? If you hook it up straight from the cell to the mb's connector then you won't gain anything if the cells still won't be charged fully.

    The small voltage spike at the end is normal, btw; a circuit behaves differently under load (dis-/charging) then when at idle and you'll get different measurements in these situations.
     
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  8. Che0063

    Che0063 Notebook Evangelist

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    It happened when the laptop was brand new. I'm sure its the BMS. I've done many discharge cycles. I've also checked that the BMS has balancing - Each cell is within 0.01v of each other so its not individual voltage lockout or anything. I've never modified the battery other than the bypass wire.
    upload_2019-1-29_11-20-3.png

    All software reports my battery being 50000mWh. That's false. It's 5000mAh x 2 x 3.8v = 38000mWh Also, the voltage always stays reported as 7600mV no mattery what. Chemistry: "Real". Serial number: "123456789". Manufacture name: "Intel" BS. It's a cheap Chinese Teclast tablet. I'm yet to determine the actual capacity - The cells themselves are likely genuine. Unfortunately the BMS will never set the 0% and 100% flags so it will never calculate the actual capacity. The 'Full Charged Capacity" has remained exactly at 50330 forever. I will test it with my imax b6

    Also, my motherboard handles the CC/CV charging, not the BMS. My guess the BMS's sole purpose is as a protection chip. Thus, the bypass wire goes directly from the motherboard header to the battery, and the motherboard feeds the current to the battery via the wire. It works fine to charge the battery to 100%. Each cell goes to 4.30v precisely. But when I don't have the bypass wire, the batteries charge to about 4v each before cutting off. The open-circuit voltage is about 3.85v per cell, which is in line with the 50-60% estimated capacity.

    It's not a voltage spike sorry, I meant that the voltage jumps to 8.6v and stays there. The moment the voltage jumps, the laptop stops charging. The voltage I'm reading is from the motherboard connector. The moment I disconnect the AC power, the voltage drops down to <8v or whatever the cells were before.
     
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  9. K46tank

    K46tank Newbie

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    I realize I'm reviving an old thread but I'm newly registered on the site and can't send PMs yet. I have an Itronix ix325 that needs the batteries rebuilt and was hoping t456 might be up to the task.
     
  10. seanwee

    seanwee Notebook Evangelist

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    Would it be possible to make a custom lithium ion battery with over 100whr capacity? (just assume that size is no constraint)

    How do airports even determine if your laptop has an overly large battery anyways?
     
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