Battery pack issues

Discussion in 'Technical & FAQ' started by grahamx, Mar 8, 2018.

  1. grahamx

    grahamx Finding my (electric) wheels

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    DSC_3411.JPG DSC_3412.JPG DSC_3413.JPG DSC_3415.JPG DSC_3417.JPG

    Back story....

    • Battery cells are confirmed ok and registering 42V per multimeter at outlet

    • Sans Charger appears ok registering 42.1v per multimeter at outlet. see this thread

    • Issue is trying to get battery to charge. I am seeing a green light on the charger when it should be red. I am only able to see the light go red when manipulating the battery (by turning over/ upside down on worktop and giving a gentle tap) : Suggest loose connection somewhere within battery case.
    • Note: battery cells appear to move/ rattle within the battery case which is particularly noticeable when riding over uneven surfaces or when the battery is manipulated. This rattling has been getting worse with continued mileage - currently at 184miles.
    Oxygen are not aware of this issue with their packs and although out of warranty have kindly offered to look at the battery if I courier it to them but cannot guarantee a repair. I am somewhat concerned with the battery surviving two couriers & repair attempt together with the associated costs for what could be a possible straight forward loose connection issue.

    Am considering carefully taking the battery pack apart to see if I can see what the issues are and effect my own repair before taking the risk of sending it off.

    Has anyone here experience with these issues in a battery pack or indeed dismantled the oxygen battery pack and can assist? Pics included to show the packs ports/fuse & visible screws.
     
  2. There's a fair chance that you have damaged the charge socket. have a look in there with a torch to see if you can see any sign of burning. be careful about trying to clean it with anything metal because you'll short it out and make lots more sparks and burning.
     
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  3. grahamx

    grahamx Finding my (electric) wheels

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    Thanks will double check the charge port particularly the outer "sprung" part. will attempt a clean tomorrow and point taken regards the use of metal in vicinity.

    That said no fiddling so far prior with the connector gets the pack charging....only manipulating and tapping down the battery pack on the worktop can I get the pack to charge.
     

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    #3 grahamx, Mar 8, 2018
    Last edited: Mar 8, 2018
  4. Thit doesn't look too bad in that photo.

    Is the fuse for charging (5A) or discharge (20A)?
     
  5. grahamx

    grahamx Finding my (electric) wheels

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    Gave both the charge socket and charger male connector a careful clean and removed a little dark coloured oily residue. All looking shiny and clean. Issue still persists.

    The Fuse is 30amp removing kills the output of the battery. Have checked the fuse and terminals all appear to be fine.
     

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  6. grahamx

    grahamx Finding my (electric) wheels

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    I am able to get the battery to charge but only after a short period of manipulating the battery case.

    I'm noticing shifting movement within the case both top to bottom as well as from side to side (particularly at top of case) Have done a video clip which may explain it better. Note: may need some extra volume to hear the issue.



    I got the bike at 36 miles and the charging issue/ ratting battery case was not an issue but now at 180 miles the rattling has become much more noticeable on the bike particularly over uneven ground.... possible cause of the charging issue?
     
  7. Rattling a battery like that won't do it any good. I think your only option now is to open it and check the wires.

    I have opened one before, but it was a while ago. I seem to remember that something wasn't as straightforward as it should be, but I can't remember the details. It's possible that it was that it needed heatshrink to be cut or something, which I didn't want to do because it was new and still guaranteed.
     
  8. grahamx

    grahamx Finding my (electric) wheels

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    Thanks. I am somewhat concerned about the movement within the battery certainly not healthy to have play like that for the long term life of the pack.

    Have removed the fuse &carefully opened up the case . Concerned at minimal attempt within the pack regards padding between cells/bms/case.

    Removed fuse & checked connections and so far unable to locate anything obvious when checking/ moving the wiring.

    Connected charger & pack is showing 42.1v at the internal connections of the charge port while charger led GREEN. On the one occasion when moving the cells the charger randomly turned led RED getting 37.3v at this connection. The red and black wires from the charger port then go to the bms with the red wire also linked into the main Live before the fuse connex.

    Next port of call I guess is pulling apart the bms?.......3 circuit boards bolted together.
    20180309_182728_resized.jpg 20180309_182143_resized.jpg 20180309_182206_resized.jpg 20180309_182223_resized.jpg

    Of course any advice appreciated.
     
    #8 grahamx, Mar 9, 2018
    Last edited: Mar 9, 2018
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  9. Before disassembling further, check the voltages on the pins of the multi-pin connector. Anything wrong with the cell-pack will show there.
     
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  10. grahamx

    grahamx Finding my (electric) wheels

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    Cheers @d8veh appreciate your assistance

    Cells are charging up to 42V when I can get the pack to charge.

    How do I test voltage on the pins (assume you mean the white multi-pin connector in pic) Do I need to pull the connector apart first ? & where should I place my black multimeter lead when taking readings from the pins?

    Thanks 20180310_141804_resized.jpg 20180310_142049_resized.jpg
     
  11. Measure between ground and each pin. it doesn't matter whether they're connected or not. You need to use the cell-pack ground (B-) not the output ground (P-).

    If the battery has charged to 42v, they'll all be at 4.2v, so no need to test. You only test them when it won't charge.
     
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  12. grahamx

    grahamx Finding my (electric) wheels

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    Many thanks for the clear instructions.

    Pack is currently discharged to 37.8Volt measured at output

    Unscrewed the top section of the bms to identify Ground B- on the circuit board. removed some of the white silicone obscuring the connections

    Readings as follows from the 11 multi pin connector wires red wire first (see pic)

    2018-03-10 20.33.38_1520714049148.jpg

    37.8
    34.1
    30.3
    26.5
    22.7
    18.9
    15.1
    11.4
    7.6
    3.8
    0.00

    Inexplicably after the process of getting the reads upon checking the charger red led came back on steady for a good 5 minutes then after powering off the charger then switching back on the green led returned.....possibly heard a click from the bms at switching to green? Seemed quite random as so far unable to get charger led to change by manipulating wiring or connectors.
     
  13. Woosh

    Woosh Trade Member

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    you need to check the battery output voltage when the LED on the charger is green.
    If it is less than 41V then the BMS needs replacing.

    examine the BMS PCB for a dry joint before buying a new one.
     
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  14. grahamx

    grahamx Finding my (electric) wheels

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    Thanks for your reply . Although was able too get the board charging by giving the pack a knock I'm unable to find a specific area of fault. Can't see anything obvious with the 3 circuit boards of the bms though you guys are welcome to take a look..

    DSC_3522.JPG

    top:
    DSC_3512.JPG

    middle:
    DSC_3429.JPG DSC_3438.JPG

    bottom:

    DSC_3451.JPG DSC_3458.JPG

    Additional question: is it possible a dry joint issue further up towards the cells could cause this charging issue?

    If it is the BMS may be it is possible that I can source identical unit and only need to replace either the top or middle board as they do not require solder. That bottom board soldering may be beyond my 30w iron?
     
  15. spanos

    spanos Finding my (electric) wheels

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    I can't open the photo but I've repaired several packs now where the welded nickel strip on the cells itself comes off. Sometimes a connection is made through pressure , then a knock separates again

    I'd look at all the welds carefully for a loose one
     
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  16. Nealh

    Nealh Pedelecer

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    I would first check the charge point of the battery and the wiring joints, then various main wiring continuity checks after you can simulate it in non charging mode.
    Then move on to the sense wires for continuity and good sound solder joints to the cells.
     
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  17. grahamx

    grahamx Finding my (electric) wheels

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    Thanks guys very much the advice. Will be un-wraping the pack for access to cells wiring as my next job and check the wiring and connections. So far the pack all appears well put together aside from the rattling issue which will be next on my list once the charge issue solved.
     
  18. grahamx

    grahamx Finding my (electric) wheels

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    Update:

    No issues located with nickel strip welds
    Balance lead connections all ok and checked continuity
    Also took the opportunity to try another 42v2a charger = issue remains

    One interesting area of note is with the 2 non soldered boards disconnected (bms and controller?) the charger led will turn red

    Unfortunate not good news from recent call with Oxygen...they have confirmed batteries are assembled in china and they offer no repair to batteries or supply spare parts. That's a shame because the bms and top board (controller?) would be a simple swop over no soldering.

    Oxygen are only able to offer me a new battery pack @ £400.

    Oxygen did advise that there are companies that can possibly repair battery pack i.e. bga reworking.
     
  19. Nealh

    Nealh Pedelecer

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    The cell voltages are fine from your earlier post, so I would disconnect the BMS and solder in a new single one.
    Plenty on ebay or Ann/Annpower on Aliexpress are highly recommended, you should find one that will fit.
     
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  20. grahamx

    grahamx Finding my (electric) wheels

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    Thanks for your advice.
    I think I will need to keep the bms board in situ as part of the 3 board unit as it has power pins to connect to the soldered board as well as rf (which i believe connects to handlebar screen/ controller?)
    DSC_3429.JPG DSC_3438.JPG


    Very little room left within the pack to add new bms. Am thinking........
    • disconnect or remove existing sensor wires
    • drill case
    • extend or install new sensor wires with external male connector
    • install new +/- wiring to battery pack and external xt60 connector (would need advice on where best to connect)
    • connect above to new bms /w existing charger externally for charging cycles only
    • disconnect new bms once charged
    Thoughts on whether this is likely to work ?

    thanks
     
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