Here's a picture of one of the 53 cell balancing modules I received last week from EV Works in Australia. Each module sits on a cell and monitors its voltage to ensure it stays within appropriate cell limits (2.5V-4.0V). Its signal wires (yet to be soldered on) are daisy chained to neighboring cell modules, and the whole loop is connected to a BMS controller. The BMS controller is inline with the AC line to the charger. If the charger does not taper current back when the cells reach the appropriate voltage during charge, the BMS can literally cut the charger off at the knees. There is also an audible alarm (although unclear how loud) the BMS has to warn of cell anomalies.
Note that this system only protects against over-charging. The Zilla controller already has configurable safeguards for over-discharge of the cells.
I guess I will start soldering wires this weekend. Lots of wires. Fun!
3 comments:
Be aware that if you do not have per cell monitoring on discharge, you can easily destroy cells because pack voltage is a poor indicator of cell voltage due to capacity differences between cells. Go to "evtv.me" for one persons opinion.
Hi
I have the same Batterien that you have. Many people believe that they can charge Sky Energy batteries at the same way as Thundersky, but it is not true.
See that you have a BMS that will have a peak at 4.0V but the SE cells are fully charged when they come up in 3.6V, if you charge them up to 4.0V can damage your cells
I'm not sure why the owner has not stated it already, but the EV Works BMS is configured to protect against over discharge by default.
The cell balancing modules are connected in series and each end of the this series cinnection is connected to the BMS master control unit. This forms a normally closed circuit while voltages of each cell balancing module is in between 2.5V and 4.1V.
If any cells drops below 2.5V during discharge, that cell's balancing module will then open the normally closed circuit and the BMS master control unit will do whatever it is programmed to do (ie. try and protect the cells from over discharge by limiting acceleration, or even opening contacts to stop the vehicle).
The EV Works BMS solution (with master control unit and cell balancing modules) is arguably the best analogue BMS available for Lithium-based EVs.
More information about how the BMS master control unit functions can be found at http://www.evworks.com.au/index.php?product=BMS-MCU-TS90-EV2
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