I have a battery system consisting of 4 EEL DIY batteries, each containing 16 MB-31 314Ah cells, giving me a total of 16kWh. My BMS inverter supports up to 200A charging, but realistically, the packs can only handle 149A each due to a 0.5C limit and BMS protection. I'm trying to figure out a couple of things:
1. Is a 300A shunt adequate for my setup?
2. How many shunts do I actually need? Would one be enough, or should I have one for each battery pack?
Ultimately, I want to accurately monitor the health of my packs and their state of charge (SOC) using Solar Assistant. Thanks for any insights you all can provide!
4 Answers
I run three 280Ah EEL packs, each equipped with their own 300A shunt, plus a 1000A shunt from the bus bar to the inverter. It's not a requirement to have that many, but I appreciate the detailed data it gives me.
When it comes to sizing a shunt, you should match it to your max charge or discharge current. One shunt is plenty unless you're interested in tracking each pack separately. You can place the shunt between your bus bars and charging source. If you have multiple charging sources, just connect them to one bus bar and place the shunt between that bus bar and the batteries.
For my setup, I have just one 500A Victron Smart Shunt for the entire battery shelf. I mainly want to monitor the SOC of the full pack, rather than tracking each battery individually. This method works well for me!
Honestly, I think just one shunt on the combined output of your four batteries should be totally fine. It’s the plan I'm following since I have my doubts about what the BMS is reporting for SOC. Also, keep in mind that SOC is just part of the health picture—it's really about the total Ah available and cell delta at the top and bottom of SOC.
I get that! More data can definitely help in monitoring pack performance and health.