On July 24th we noticed a slow charge rate of 26amps from our DC to Dc charger. One engine, RPM at 2000 which should give us 45 amps. Battery state of charge at 78% and battery temperature 29.1C. After a couple hours the charge rate dropped to about 9amps. So I turned off the DCtoDC charger.
Later we tried to top up the batteries with the generator that typically charges at about 96amps depending on the system load. We were charging at only 40 amps with normal loads.
On July 22nd or 23rd we noticed a display issue on the Cerbo display; it was split half on Brief and half on Overview. After a few swipes of the display, it was back to normal. Also, on July 18th we lost our Starlink communications. Maybe both are unrelated.
So this should not be an inverter issue since the DC to DC are impacted. So this could be a Victron Lync issue or a Cerbo issue. So, I rebooted the Cerbo Menu > Settings > General and press reboot. Solar is charging at 34 amps so maybe a little low but close. Starting the generator added only 9 amps. So we seem to be limited to about 40amps or less.
I could not see any errors or alarms through the Victron Connect app. The electrical room under the bed seems cool enough. So what could be limiting our charge rate?
We have a three month old Victron based system with 4X Victron NG 300AH battery bank with Lynx 500NG, Cerbo GX, 2x MPPT, 2x 50amp dctodc chargers. It has been working as expected until recently. Any suggestions would be appreciated.
A high resistance developing such as isolator not making contact, wiring coming loose, bolts between Lynx BMS and distributors coming loose so the voltage being read by the chargers is higher than the battery voltage. Use a multimeter on the system to check.
The other thing to check is cell temperatures, there is one instance on the forum where a loose connection to one battery terminal resulted in a high resistance joint which heated up and registered a high cell temperature which then reduced charge and discharge rates. I also noticed the same happening on my NG install before it became a critical issue.
Finally, to check if it is the BMS calling for low charging current go to settings > Device list > Batteries (name will be what you have called them) > Parameters. This page lists the charge and discharge current limits (CCL & DCL), for a 1200Ah NG install these figures should be 1200A or something very high, mine normally read 600A for 2 x 300Ah NG batteries.
This is great direction, thank you.
To Check the BMS calling for low current: I have not been able to find the page you refer to. Is that through the VRM portal or Victron Connect? BMS stat is VC is Allow charge=yes and allow discharge=Y . But it must sometimes limit charge, right? I saw a reference to a log of messages somewhere but cannot find that either.
I will get my multimeter and start at the BMS and work outwards. Through the Victron Connect app the temperature of the batters seems OK at 30 to 30.6 degrees C. In Greece it is getting hotter but at 29C everything worked fine and the temp is in spec. But i will check connections.
The parameters page is on the Cerbo
Cerbo menu > settings > Device list > Batteries (name will be what you have called them) > Parameters.
Note, the list under batteries is very large and you will have to scroll down to the bottom of the list.
You see this locally on the touch screen or on remote console through VRM. There is lots of info displayed on the Cerbo for the batteries.
The other way to get to all the battery info on the Cerbo is from the overview page, click on the battery icon, then choose your lithium batteries from the list.
Solved - Cerbo > DVCC > Limit Maximum Current - Turn OFF now everything is working as before. Seems the default it 50A and that was limiting. I got ahold of out installer and sorted it out fast.
Thank you!