Some BMS Questions for my New Solar Shed Project


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TheStealth

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Oct 29, 2020
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I've started collecting and processing 18650 cells that I will be integrating into a 7S##P battery in my solar shed project that that will be based around a MPP Solar LV2424. Any feedback on my design below would be much appreciated.

Solar Shed.jpg
I have also started to do some research on BMS solutions, but am getting a bot confused with all the possibilities. For my project I would like the BMS to:
  • Over/Under Charge Protection
  • Over/Under Temperature Protection (under temp protection is critical since winter temperatures often go below -20C))
  • Active Balancing
  • Configurable
  • Stats
To date I have narrowed my choices down to the following:
  • Daly SmartBMS (not really a great choice from what I can tell)
  • JK BMS (seems there has been some success using these)
  • DIYBMS (need to build it, but I like projects)
  • Batrium (a bit too high priced for my small project)
  • Another suggestion?
A solution like the JK BMS is a nice all in one solution, but the downside is no individual cell temperatures and Bluetooth only.

I like the idea of building a DIYBMS, but this is not an all in one solution. I do have some outstanding questions regarding this type of solution:
  • From what I can tell I would need to either add some sort of battery disconnect controlled by DIYBMS (shunt trip, contactor, other?) to shut off the battery in case of a problem. What is the best/most efficient way to do this?
  • Do I need to add some sort of disconnect to the solar panels as well? or will the MPP take care of this?
  • Do i really need a shunt to measure battery current? What if I omit this?
  • Are there any thing else I need to consider?
Thank you all in advance for any feedback.
Mike
 
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