Hi guys,
I installed a Multiplus 5k together with a MPPT 150/85. They charge a total of 8 pieces of 12V batteries with 130Ah, there are 2 x 4 pieces in series so that I reach the 48V.
My problem is the following, the batteries are never fully charged to 100% and are never discharged below 70%.
What could be the reason? I hope you can help me.
Here you see the battery SOC graphic
Ther problem is If the batteries fall below 70%, the inverter simply switches off.....
Kind regards.
Harry
Hi Harry. Guessing here somewhat, so I'll need correcting if I'm wrong.. but we don't bite, so please do.
It appears you're using the 'onboard' SOC calculator, not a BMV. If so, please understand that it has *very* basic functionality and accuracy. Adjustments to it are basic and quite coarse. We can go there if you want, maybe later.
What is your batt V doing when the inverter trips? Is it very low, and perhaps coincidental with the 70% SOC?
Do you have any 'assistants' loaded, perhaps ESS?
Maybe not much point going on until you confirm..
Hi John, yeah you guessed right. :)
The system has no BMV installed, is it absolutely necessary for the system to function correctly?
The problem is that we have to look for the fault in the system because the installer does not find the fault.
Since we haven't installed any Victron devices ourselves so far, this is unfortunately not so easy.
Since the alp is not so easy to reach, I wanted to know beforehand which errors could be present.
I have now downloaded the VE Configuration Tools software and ordered the MK3 USB adapter so that I can check the configuration on site.
Ok. The system should work fine without a BMV. Nice to have if you've exotic batts or dc loads, but not essential in a simple setup.
You suggest remoteness. Is your system web-linked, so you grabbed that graph from VRM? If so, you already have VE.Config available remotely, and you could effect changes that way. The MK3 is needed locally for firmware updates to your Multi though, so keep it.
How much weight you apply to SOC as a determinant of your batt management is up to you. I don't use it at all for my own pb's, and much prefer to see V and the charge progression through it's stages.
Your system itself may not be faulty *at all* actually, and if you have that VRM access, you've plenty more graphed data available which may even be more suitable to monitor than a calculated SOC.
The main issue with using the Multiplus internal battery monitor is that it does not refer to the 'tail current' at the end of absorption phase to resyncronize regularly - it only assumes a particular SOC% at the end of bulk phase and if your usage is irregular it can be hard to tune the setup parameters for the calculated SOC% to read accurately.
To confirm if your battery bank is truely getting recharged back to 100% SOC, the best measure to look at is the charge current that the battery is receiving at the end of the absorption phase, just before it switches into float phase. If the 'tail current' drops to about 1 to 2% of your battery bank capacity (for example: 2 to 4A for a 200Ah battery) while the absorption voltage is being maintained, then you can consider the battery bank as fully recharged and SOC to be 100%.
If after doing this check it seems that the battery monitor is actually under reporting the SOC%, then you can try to tune the battery monitor setup parameters by;
A) increasing the 'charge efficiency' setting
B) increasing the 'SOC% when bulk finished' setting
Perform any reconfiguration gradually in small steps / over several days so that you can monitor the effect of your changes to decide what if any further adjustment is necessary.
Obviously also confirm that the correct battery capacity has been configured.
Also note that you can now use the VictronConnect app with your phone, tablet or PC to configure a Multiplus, but you still need to use a MK3 to USB adaptor.
https://docs.victronenergy.com/victronconnect-vebus.html#warning
I have only a "shared" Link: https://vrm.victronenergy.com/installation/42297/share/e6ad833f
I don't have access to the configuration, the installer will still have it. I have to ask the customer if he can get it for me.
