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Ecobike 48V report

Sticker

  • No serial number anywhere on the battery (other than on the BMS itself)
  • Lotsa Polish text
  • EAN: 5903317865711 - same on all of them
  • Supposedly 14.4 Ah - that would mean 3600 mAh cells!
  • Supposedly Samsung cells

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Display

  • 4 green LEDs
  • Simple voltage-based SOC estimation, no coulomb counting
  • LEDs warm up significantly
  • Button is used to switch battery on

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The display board is identical to the one on the older models, but wired differently - now it is used to turn on the BMS as well.

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Old - "Ordinary protection board connection method"

1 Connect the power cord

2 and 3 are short-circuited as shown in Fig. 

4 USB output cable 

Function: The battery is always energized, and the battery panel button only controls the battery indicator light. Press the light and the light will go out after 5 seconds.

New  - "Smart protection board connection"

1 Connect the power cord

2 Connect the weak current lock control wire of the protection board 

3 Short connection as shown in the figure

4 USB output line 

Function: The battery board button can be used as a weak current switch. It can control the power output. Press the battery to power on, the battery light is always on, and press it again, and the light is off, and the battery has no output.

Discharge connector

  • 5 pins, but only the two power pins are connected
  • Signals are floating inside

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BMS

  • Made by "Sino Invent" - no hits on Google
  • Mode: HY6003-25A-13F (sic!)
  • Type: spli port (sic!)
  • SN: HYH280425210125
  • XT30 connector for connecting power to top module
  • Switched on by pushbutton impulse
  • Sandwich board, with heat sink

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Those  weird diodes and DC/DC board

  • 1N5349B zener diodes - 12 zener voltage, 100 mA zener current - 3 is series
  • Connecting to a K78L05-500R3 board that then connects to the display board to supply the USB port
    • The 5V supply board cannot take up to 54.6V input, so they drop the voltage by 36V...
    • It only supplies at max 500 mA, very poor, slow charging on the USB...
    • But it also burns a bunch of power on the diodes. Really stupid.

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Charge connector

  • The connectors inside are poor quality, crimped
  • No glue/sealing around the charge plug
  • No diode or fuse
  • Voltage is always present

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Cells

  • LG M36 cells - LGDBM361865 - NOT Samsung as written on the sticker!!
  • The cells were produced in October 2019.

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Performance

  • The batteries charge all the way up to 54.6V without problem
  • Cuts out way too early on discharge
    • One cleared maximum 5.85 Ah before cutting out and not allowing further discharge
    • Other 8.3Ah on first try, then after full charge, 8.9 Ah
  • The reason for the cutout is the BMS. When bypassing it, we could get 13.5 Ah at 7A CC
    • It seems the cells are fine, although the claimed 14.4 Ah is very optimistic
    • Similar to the others we see, that were marked as 14 Ah
  • After full discharge by bypassing the BMS, and a full charge through the BMS, it could produce 11.6 Ah through BMS. Still too little, not fully discharged. No further discharge is allowed.
  • This battery work on the new type bikes - even though the communication is not implemented, and the SOC is just guessed by the display based on voltage

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