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Active Balancing for large LiFePo packs??
#4
You might want to have a look at my setup, link below.
NO - ideally *active* balancing (passive, and just 50mA/cell. But that's proven to be enough(*1) )
YES - low/high volt cut-offs (cell level and pack level, programmable in mV steps)
YES - low/high temp cut-offs (only 2x external sensors per BMS, programmable)
YES - basic reporting/history (bluetooth connection to Android/iphone App. RaspberryPi etc possible with programming)
YES - easy scalability with module groups (now using 6x BMS in parallel, planning to reach 10x by years end!)

Cost is about $50/BMS for the 60A version, but probably wise to limit usage to 1/2 ~ 3/4 that current for extended use such as in powerwalls.

(*1) My cells get charged to only 4.08V and discharge stops at 3.4V, so leaving plenty of breathing room. Balancing is set to start at 3.90+V when cell voltages differ by +/- 15mV, in order to maximize the working time for the balancer. This works perfectly fine over time, but may cause discomfort depending on the level of your OCD.
On the plus side, self discharging cells become apparent within days as the voltage of that pack starts to drift.
Modular PowerShelf using 3D printed packs.  60kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
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RE: Active Balancing for large LiFePo packs?? - by ajw22 - 05-20-2020, 12:31 AM

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