You are asking about a Slave Master BMS system. Rec-BMS, Orion, A123 and a few other "Premium" types exist that do such but now your getting deep into the wallet.Would a selectable BMW be possible? Ex.
One head unit to monitor 5 16s batt packs.
I looked into some of those master/slave BMSs and thought if I was going to spend that much, I might as well buy a battery already put together.You are asking about a Slave Master BMS system. Rec-BMS, Orion, A123 and a few other "Premium" types exist that do such but now your getting deep into the wallet.
Came across this researching to understand more about Chargery's SOC readings ... & Wow, Did Not Know leaving the shunt out of a Chargery Setup was an option. You Never used that Chargery Shunt? What are the draw backs? I imagine you still have all the low cell v, high cellv , and high amp charge or discharge, and diff, and temp etc. protects, but no SOC or Amp In and Out meter via Chargery lcd ??? Did you wire up something else that might be better for reading SOC at a glance. Any further info. welcome :+)I have never used the shunt.
Not sure what you need. But have you considered Overkill BMS?I looked into some of those master/slave BMSs and thought if I was going to spend that much, I might as well buy a battery already put together.
But then I checked the price of fancy batteries and WOW! are they expensive. I'm still going the $200 BMS route.
Someday hackers on this site will make it possible for cheap.
The info about those expensive BMSs is obviously meant for large business not DIY
I am also wondering if you can leave the shunt out. The shunt is a drawback for me. I have the Victron 712 on one pack and a Bogart on the other. They are VERY good. I would never look on the Chargery for coulomb counting and I do not want the extra wiring for anything to interfere with my existing SOC system. If the Chargery can just take care of the cell level stuff I am good to go.Came across this researching to understand more about Chargery's SOC readings ... & Wow, Did Not Know leaving the shunt out of a Chargery Setup was an option. You Never used that Chargery Shunt? What are the draw backs? I imagine you still have all the low cell v, high cellv , and high amp charge or discharge, and diff, and temp etc. protects, but no SOC or Amp In and Out meter via Chargery lcd ??? Did you wire up something else that might be better for reading SOC at a glance. Any further info. welcome :+)
Yes you can leave the shunt out.I am also wondering if you can leave the shunt out. The shunt is a drawback for me. I have the Victron 712 on one pack and a Bogart on the other. They are VERY good. I would never look on the Chargery for coulomb counting and I do not want the extra wiring for anything to interfere with my existing SOC system. If the Chargery can just take care of the cell level stuff I am good to go.
Well that moves the Chargery to the top of my list. Get around the amp limitations of the others.Yes you can leave the shunt out.
I use the juntek for a coulomb counter and it works great for me anyhow.
It is the relays that turn off the power NOT the shunt. So for protection from temps or voltages etc, you need a relay [or two].I thought i had read somewhere that without the shunt you no longer have over current protection...dont know if this is important to you or not?
Without the shunt, what is measuring the current? If the shunt detects an over current condition on charge or discharge, then that activates the relay. It was my understanding that the BMS harness measures the voltages. I'm no expert...just picking up snippets as i go.It is the relays that turn off the power NOT the shunt. So for protection from temps or voltages etc, you need a relay [or two].
Not that i can think of.Any reason why the BMV712 shunt cant be installed directly before the negative battery terminal to give maximum SOC data and the chargery shunt in series next to give the cell level protections, but ignore the SOC data on it? That is my intention unless someone highlights a problem with this. Both units attached to do two seperate jobs.
Without a shunt I am not aware that you can measure the current.Without the shunt, what is measuring the current?
You're correct. The shunt is what the BMS uses for current control.I thought i had read somewhere that without the shunt you no longer have over current protection...dont know if this is important to you or not?
Well, the question is whether you would even need the Chargery shunt in that situation. You would still get cell voltage level, pack voltage level and temp protection without the chargery shunt. I don't want the Chargery shunt simply because for me it would serve no purpose the Victron does not do better and it is added connections and resistance in the circuit. (just more things to go wrong).Any reason why the BMV712 shunt cant be installed directly before the negative battery terminal to give maximum SOC data and the chargery shunt in series next to give the cell level protections, but ignore the SOC data on it? That is my intention unless someone highlights a problem with this. Both units attached to do two seperate jobs.
Yes, but you would then need to link in your chargery onto the victron shunt for over current protection....imo. Easier for me just to run the two shunts, then no compatibility/calibration issues.Well, the question is whether you would even need the Chargery shunt in that situation. You would still get cell voltage level, pack voltage level and temp protection without the chargery shunt. I don't want the Chargery shunt simply because for me it would serve no purpose the Victron does not do better and it is added connections and resistance in the circuit. (just more things to go wrong).
+1 .... A shunt is necessary for over current protection. I have a different monitor hooked to mine and have the Chargery connected to that shunt instead of using a Chargery shunt .... calibration isn't that tough if you have a way to set an accurate current.You're correct. The shunt is what the BMS uses for current control.
So. Yes I have the Deltec 500 amp shunt on one setup and the Victron smart shunt on the other. I guess I could double up on the wires on the shunt but then I would need to recalibrate the Chargery (which may be no big deal) but I wonder if it would impact the accuracy of the Victron 712. What am I missing about the overcurrent protection? I have my lines fused and my Magnum charger0inverters also have overcurrent built in. Are we just after redundancy here? I have a handle on all my risks (I think) except for what is happening at cell level and temp cut off.+1 .... A shunt is necessary for over current protection. I have a different monitor hooked to mine and have the Chargery connected to that shun instead of using a Chargery shunt.
The current measurement is also used to determine the mode the BMS is in .... but I don't know how that will affect things. It would always assume it was in storage mode.
"It would always assume it was in storage mode." Oh. Well. If that is the case then the question would be if you could double up on a Victron smart shunt or whether you would be better off putting in two shunts.+1 .... A shunt is necessary for over current protection. I have a different monitor hooked to mine and have the Chargery connected to that shunt instead of using a Chargery shunt .... calibration isn't that tough if you have a way to set an accurate current.
The current measurement is also used to determine the mode the BMS is in .... but I don't know how that will affect things. It would always assume it was in storage mode.