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Dear All ,
I have a peculiar issue that the inverter even with hard coded lower voltage cut-off at 18.7V
and alarm at 20V ( Via VictronConnect and latest FW )
and still the inverter cuts off at 24 V exactly.
The current shunt and MPPT controller reports the same voltage during the shutdown
I hope someone could provide some light ?
Thank you
The Harvester
What voltage is shown in the inverter via VictronConnect?
What load is running at that moment?
Can you measure the voltage at the battery terminals of the inverter?
What wire gauge is used from the inverter to the battery and how long are the wires?
My guess is a high voltage drop due to a loose connection somewhere or to thin/to long wires.
Well the shutdown happens at 5,6am in the morning I am not awake to go look.( I will check if the VRM keeps track Voltage from the Inverter )
The running load is a fridge and a NAS ( 95W on compressor run and 20W standby PSU all in all 115W the loads are a joke and I have a huge Inverter )
I can't because the system is on a remote location that At the moment I do not have access to.
Wire gauge used as per the manual 50mm^2 at less than a meter, 1.5M tops(if I don't remember correctly 1.5M is top length I think) from the battery.
Loss connections are impossible because everything was torqued down to spec as per the manual and inline fuses are sized as per the specifications of the inverter.
But other times of the day I had a look on the voltage from the inverter and also from the shunt and the voltage drop was almost negligible.
I will look again , but from 24V from the battery have 18.7 V at the inverter meaning I have a 5.3V voltage drop ? I find it very improbable/ impossible with proper crimped cables and proper cable used... as per the recommendations of the manual.
Thank you in advance for your input
The Harvester
Dear Sir ,
I just checked now
and with a 27VA load the voltage shown is 27.13V from the Inverter ( though the VictronConnect app )
the shunt( though VRM) shows 27.16V that's 0.03V voltage drop.
When the Fridge will start up I will re-check the voltage.
But I am sure its going to be fine I made the install on the proper specifications.
Thank you in advance
The Harvester
Dear @Matthias Lange - DE
Now the Inverter is under "Full" load : (138VA)
and I see on the Current shunt battery voltage 27.17V
and on the inverter battery voltage 27.11V
so 0.06V voltage drop from Shunt to inverter.
I consider this normal.
Any other insides ?
Thank you in advance
The Harvester
what kind of BMS are you using?
because, the detected values of the BMS will always count in the end (LTP).
if you are using a BMS which is configured seperately - by software or DIPswitch etc... - those hard coded parameters will overwrite any fixed parameter which you have set in the ColorControl / (even in the inverter itself) or whatever you are using for display / control.
example: assuming you have set a value for charging up to 27.6V in your inverter but you have set the BMS to start balancing at 3.6V for each cell, your MAX charge voltage will rise up to 28.8V before the system will enter absorption mode - 3.6V x 8 (in a 8S system).
the same will happen with battery low voltage: if you have set a parameter in the BMS to cut-off the batteries at 2.8V or lower, the system will continue to discharge until 22.4V
in your case the parameters might be set to around 3V / cell - that at least would explain the 24V cut-off.
Thank you for your input.
No there is no BMS as I am running a 2 x 12V AGM batteries 150AH to make 24V system.
Thank you though.
Thank you in advance
The harvester
Dear All
I woke up today at around 5am the inverter was off on alarm. I started it and voltage didn't drop lower than 24v from the victronconnet and then re-alarmed and stopped.
So there is something wrong with the inverter FW. (its on the latest version) i will try to rollback 1 version.
Please advice how to move forward?
Thanks
The Harvester
A small hair dryer or kettle? Something to have 500-1000W load on the inverter?
It's hard to troubleshoot if it only happens in the middle of the night.
It can also be a problem with your batteries.
During the day the MPPT helps to maintain the batteries and during the night the batteries are discharged slowly.
At some point the inrush current of the fridge compressor drops the voltage below 24V.
At the moment I do not have physical access, But even if that happens it needs to be tested at the end of the night before reaching that critical point.
Yes indeed is very had and the strange thing that the Inverter does not even reset when the MPPT start to charge the batteries
Well the batteries are of some age ( at lest 3/4 years ) but even at that I didn't see any irregularities with the other pure DC loads that are running 24/7 plus going from 24 lower than 18.7 ? I find the difficult to believe ..( and I have no idea how fast the Current shut measures voltage but the rest of the Victron stuff does not realise that there is such a massive voltage drop. )
I just saw on the current shunt at 6AM when I tried to clear the alarms it started inverting for a short while 6 seconds and the current shunt measured the voltage
I had from 24.35V went down to 23.54-23.95V ( I have the mix data enabled )@ 10A
So even at that voltage sustained for 6 seconds I find it adequate for the inverter to keep on producing power and it literally stops 2 hours before sunlight ( yes not the best solution due to in case the sun does not come out for 2 days I would be dead in the water ) and with the lower limit of cut-off at 18.7 I can't imagine that its hard to archive.
Never the less I need to find a solution for this ASAP or else I need to either upgrade my battery bank or shed loads.
But this inverter works out of the intended specifications and that is annoying. VERY.
Thank you in advance
The Harvester.
Old batteries sometimes can hold the voltage pretty good for a while (even with bigger loads) but suddenly the voltage drops fast.
It is also possible that only one battery is nearly dead and pulls down the other.
But if you think everything is fine with your installation and you blame it on the inverter than you have to contact the Victron dealer from whom you bought it and ask him for checking/repairing/exchanging the inverter.
If you consider to "upgrade" your battery bank don't add new batteries to the old ones that won't work for long. You have to replace the old ones.Dear @Matthias Lange - DE
As far as I know I did everything by the book 50mm^2 cables 150A fuses both - / +
short run of 1.5M total , batteries have a 50mm^2 jumper between them , everything is rogued down properly , and jumper from the shunt to the battery same size.
I don't get it... plus the current shunt managed to record 6 seconds of voltages. at the shunt .. of 23.5V so again based on the details on the inverter that supposedly it should stop at 18.7V , this is misbehaving/ not following the guidelines of the own FW..
The voltage drop from the inverter to the batteries / current shunt in measured and is negligible even underload( from VictronConnect ).
What's left is the inverter. Period. Now what I suspect is that the inverter does not keep the values I give to it from the Victron connect app and keeps the default that cuts out at 24V .. This is a real suspicion of mine.
The issue is how to find out if this is the case remotely ?
I was thinking to disable the service on the VRM running raspberry pi and open the serial console of the inverter and manually see what is the response / stored options .
but I didn't manage to get around that yet. but is the next step for me.
Regarding upgrading the power bank of course I will change it completely(and return the AGM batteries they had very low discharges in the past I was barely using 1A per H total of 24Ah/day) for a new Lithium version at 48V and I will buy a new inverter at 48V most probably some of the quartos .. but If I don't get down to the bottom of this I will move away from Victron all together.
Yes the VRM is nice to have but I wouldn't care much for that IF the actual hardware is having systemic issues.
Never the less thank you for your input , and I will try to sort it somehow.
If you have any more ideas about the serial interface please be my guest and provide some input.
Thank you
The Harvester.
1 battery being dead its a bit far fetched because they wore the same day and lot purchase yes some time there is a voltage deviation but then it gets back to 0.1%
for example during 30A charging there is a deviation of 2% tops and I find that normal.
Never the less even at that the current shut didn't describe a total battery break down. If that was the case I would had a 18V output if the 1 battery was completely dead.( 1 battery would be at 13V and the other at 9 or 10V )
Thank you in advance
The Harvester.
