What does connecting all the battery com cables together do exactly?

[PhantomF]

I have an EG4 6500EX inverter connected to 3 EG4 48V LL V2 (6pin) batteries pictured below. The top battery is connected in closed loop communication to the inverter and they communicate and give me the SOC. My question is what additional benefit do you get from connecting the green com cables between all the batteries? I don't notice any additional or different info on the inverter display when the cables are hooked up or not. Do the batteries talk and better manage charge and discharge current between them to balance total system SOC better? Does this communication between batteries still occur even if the inverter and first battery are not connected in closed loop? Also, how do you know if the com cables are hooked up correctly as I've seen some installs have the com cable going out from the top com port and into the bottom com port of the battery below and then some have it out the bottom port and into the top port below? The manual is not completely clear in showing this either but I believe it should be from out the bottom port and into the top port below.

 

[sunshine_eggo]

It's the difference between the inverter thinking it has 100Ah or 300Ah of capacity when making SoC decisions. A single battery will report SoC based on 100Ah. Three in communication will report SoC based on 300Ah.

When connected together, the "master" battery passes aggregate data to the AiO and can issue controls based on all individual cells in the system, i.e., if ONE cell in ONE battery hits high limit, the master BMS can instruct the controller to back off charging before the battery in question engages full BMS protection.

 

[PhantomF]

It's the difference between the inverter thinking it has 100Ah or 300Ah of capacity when making SoC decisions. A single battery will report SoC based on 100Ah. Three in communication will report SoC based on 300Ah.

When connected together, the "master" battery passes aggregate data to the AiO and can issue controls based on all individual cells in the system, i.e., if ONE cell in ONE battery hits high limit, the master BMS can instruct the controller to back off charging before the battery in question engages full BMS protection.

Ok that makes sense. So is there anyway to confirm the battery com cables are hooked up correctly and the inverter sees the 300Ah total?

 

[Jarrett_Mccool]

I have an EG4 6500EX inverter connected to 3 EG4 48V LL V2 (6pin) batteries pictured below. The top battery is connected in closed loop communication to the inverter and they communicate and give me the SOC. My question is what additional benefit do you get from connecting the green com cables between all the batteries? I don't notice any additional or different info on the inverter display when the cables are hooked up or not. Do the batteries talk and better manage charge and discharge current between them to balance total system SOC better? Does this communication between batteries still occur even if the inverter and first battery are not connected in closed loop? Also, how do you know if the com cables are hooked up correctly as I've seen some installs have the com cable going out from the top com port and into the bottom com port of the battery below and then some have it out the bottom port and into the top port below? The manual is not completely clear in showing this either but I believe it should be from out the bottom port and into the top port below.


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@sunshine_eggo hit the nail on the head. If we want the inverter to know the amount of amp hours we have through BMS communication, you need to connect them via the battery comm ports