Help with paralleled batteries

[Pr4mr22]

The problem - when I connect the battery's BMS via ethernet to each other, all the lights on the 2nd battery placed in the back, including the ALM Red led, start blinking. The batteries were balanced to 54.33v exactly prior to connecting them together.

Also, when I connect the canbus to the Rosie Inverter, the MNGP2 only reads 100ah of battery when it should read 200ah.  The MNGP2 also isn't giving me any AC readings, if that's important, but the Rosie is inverting as I have 120AC inside the rig. Both the Rosie and MNGP2 have updated firmware as of last week.

My guess - Bad BMS?.. in brand new battery?

Basics of the set-up incase it helps.  2440 watt Array on roof in 2s3p configuration running to Victron 150/45 SCC - 60amp fuse on the positive cable from the SCC connected to the back battery positive terminal.  Negative cable connected to the front battery negative terminal from the SCC to ensure better balanced charging.  Positive cable out to the Rosie is connected from the front battery with T-class 350A fuse in line and the Negative cable is connected from the back battery.   

I have a Lynx Distributor but didn't think it necessary for this build.  Could the charging and output configuration be an issue?  Would a busbar solve the problem?  My research says no, but...

I left a message with Midnite Power, but have not heard back.  Last time they didn't call back.  I had to reach out to them a second time.

Any help appreciated.

Pete

[aaapilot]

I don't own these batteries, but I've seen many postings about 100 amp showing when 2 batteries are connected, so it should show 200.  It's a known issue from YouTube folks who have tested.

Just FYI, a new MNGP2 production firmware showing version 25.7.18 is now online.  I don't know what it changes, but I would check your version to make sure it was up when you updated your system last week.  Maybe it will help.  Good luck!

Dave

[Pr4mr22]

Updated software.  Still no dice.  I disconnected the BMS link cable and the lights stop flashing.  I connected the canbus cable from the Rosie to the back battery and the MNGP2 immediately gave a fault warning.  In the system it is saying BMS/ Cell over V (or something along those lines) as the fault.  Bad cell in the battery? Or bad BMS?  Front battery is fine.

[aaapilot]

So that we understand, have you connected each battery separately to the Rosie, with the other battery completely out of the system, no communication cable or power cables.  Does each battery work/display normally when the other is completely out of the system?

Dave

[Pr4mr22]

Yes, it's only when I connect the link cables that the fault occurs.  I even restarted the battery, reconnected it without canbus and then with canbus to the Rosie and independently they work.  It's only when I connect the batteries together with the link cable that it throws a fault. 

I can even have both batteries connected and on as long as I don't link them.  If I link them, the BMS throws a fault and only after I shut down the battery, turn the BMS off and then back on again does the fault go away. 

[aaapilot]

If they work independently, I would think the link cable is the issue.  Possibly a BMS that won't allow stacking, but I'd be sure that link cable is good before I suspect the BMS.   Did the link cable come with the batteries or did you have to create it yourself?  As far as order of cabling, normally the #1 battery has a specific port for the comm cable and battery #2 has a different port.  The CanBus cable to the Rosie/MNGP2 normal connects to battery #1 as well.  Be sure the CanBus is terminated properly on the Rosie & MNGP2, I.e. if there are 2 CanBus ports and one is empty, attach a blue terminator plug.

Dave

[aaapilot]

I see from your earlier thread about cables that the link cable is a 'standard' Ethernet cable (thanks Ryan) and you needed a longer link cable than what came with the battery.  Can you try the shorter cable that came with the battery just for testing purposes to rule out the cable?

Dave

[Pr4mr22]

With how these are mounted in the bays, it would be an hour or 2 long process just to get them in position to do so. I could try a different Cat 5e cable.  Or I could try to connect the 2 original link  cables with an adapter.  We are starting to get thunderstorms here though so that will have to wait until tomorrow since these are in the RV parked in the back yard.

[Pr4mr22]

Quick info... this is the fault warning the battery is giving me.

[ClassicCrazy]

Quick info... this is the fault warning the battery is giving me.

That means it is detecting that one of the cells in a battery is ovp Over Voltage Protection either that is the warning or if it goes above the warning setpoint it should shut down the charging for that battery. I don't have those batteries so don't know what the bms in it is programmed for. Are you charging the battery when you see that ?  At what voltage is the battery at ? Usually you would see that when the battery cells are at the very top of their charge and the cells are a bit out of balance. Turn off the charging and put a load on your system and you should see that go away. It takes time for cells to balance and you will see the warning first when they get to that stage. But I have no idea how the bms or what setpoints those batteries are .
For example on my battery with a different bms , the ovp warning could be set for example to 3.50v per cell, and the ovp protection set to 3.55v per cell . When any cell gets to 3.50 you would see the warning. When it gets to 3.55v the bms will shut off charging but will keep on the discharge.
So put a load on your batteries. Most likely they are full and don't need any more charging.
Hard to analyze unless you give more info on your charging setpoints.
Larry 

[ClassicCrazy]

I looked back through some of your previous posts - so still not sure if you are charging when you see this message or not.
Do you have software that will show all the details of the battery and show the voltage of each cell ? Or does your mngp2 on the Rosie show that ?  Also some batteries have a reset button on them for the bms . If your battery has that try pressing that to reset the bms if you truly don't have any cells in over volt alarm or protection. That should clear it and put the bms back to default.
Larry

[Pr4mr22]

I see from your earlier thread about cables that the link cable is a 'standard' Ethernet cable (thanks Ryan) and you needed a longer link cable than what came with the battery.  Can you try the shorter cable that came with the battery just for testing purposes to rule out the cable?

Dave

I will try different cables after I sort out the current MNGP2 issues I'm having.

[Pr4mr22]

I looked back through some of your previous posts - so still not sure if you are charging when you see this message or not.
Do you have software that will show all the details of the battery and show the voltage of each cell ? Or does your mngp2 on the Rosie show that ?  Also some batteries have a reset button on them for the bms . If your battery has that try pressing that to reset the bms if you truly don't have any cells in over volt alarm or protection. That should clear it and put the bms back to default.
Larry

Thank you for chiming in.  Does this video help answer some of your questions?

[aaapilot]

I see from your earlier thread about cables that the link cable is a 'standard' Ethernet cable (thanks Ryan) and you needed a longer link cable than what came with the battery.  Can you try the shorter cable that came with the battery just for testing purposes to rule out the cable?

Dave

I will try different cables after I sort out the current MNGP2 issues I'm having.

I would also suggest changing out the MNGP2 cable, it also uses just a standard Ethernet cable.  I made a separate cable for the MNGP2 run to my Rosie using Cat6E shielded.  It's suggested to use a Shielded cable so any stray interference doesn't scramble the signal.  Lastly, try switching/plugging the cable into the unused CanPort.  I saw Ryan suggest this on another thread, though the ports are all interchangeable, just makes sure the existing port you are using now doesn't have a bad pin, etc.  Hope you find the right combo.

Dave

[ClassicCrazy]

I looked back through some of your previous posts - so still not sure if you are charging when you see this message or not.
Do you have software that will show all the details of the battery and show the voltage of each cell ? Or does your mngp2 on the Rosie show that ?  Also some batteries have a reset button on them for the bms . If your battery has that try pressing that to reset the bms if you truly don't have any cells in over volt alarm or protection. That should clear it and put the bms back to default.
Larry

Thank you for chiming in.  Does this video help answer some of your questions?

It looks like you don't have any load on your batteries ? Is that correct ? Also  you could make a video when the batteries are at the top of their charge - like when just going into absorb so we can see the voltage and current.
It seems like your batteries are full with no load. That is why you get the ovp alarm.
Also , do you have any software that shows you the data from your battery ? Something that displays each cell and any alarms ?
Larry