Cell-logs as LVC BMS

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In the video below you can see my latest creation.

It’s a low voltage cutoff that uses cell-logs.

Cell-logs are battery monitors for lithium batteries. They display the voltage of each single cell in a battery pack. Each cell log can be connected to up to 8 cells. Cell-logs can also send an acoustic alarm if one or more the cells is above or below the preset voltage. This voltage can be programmed by the user.

On top of the acoustic alarm, the cell logs have an alarm port that closes or open (like a switch opening or closing a circuit) if the alarm is triggered.

In my project I exploit the alarm port of the cell-log and use it as a low voltage cutoff.

Because the alarm ports of the cell-logs are not isolated, it’s not possible to connect the alarm ports together if you are using more than one cell-log in your battery pack.

Therefore I designed and produced a board that isolates the alarm output of the cell-log with an optocoupler.

Using my board you can connect as many cell-logs as you like, connecting the output of the optocouplers in parallel.

This video explains how it works:

Using this system has many advantages, some of them are:

  • Can be adapted to any lithium chemistry
  • It’s programmable, the alarm can be triggered selecting several options
  • The single cell is monitored
  • Can be used with any current drain
  • Can be used in large battery packs
  • It’s more flexible than the standard BMS
  • It’s portable, the same system can be disconnected from one battery pack and used on another, even if they have different chemistry and capacity

This system saves your cells and your batteries from being over-discharged, saving them from getting damaged.

Feel free to comment or contact me using the site contact form (on the top right).

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