I have a multiplus-II 24/5000/120 that has been running for the last month and a half. Last night I woke up because the multiplus was making a loud humming sound. When I came into the room where the multiplus is hanging, I heard it beep and I saw it was flashing the “bulk” and “absorption” LEDs back and forth. Before I got to the device though, the power cut out.
When it started back up, again the same LEDs were flashing back and forth and after a minute or two it cut out again. I enabled the bypass to take the multiplus out of the loop to prevent it from continuously starting and crashing.
The batteries showed and overcharge warning and showed 28v, even though float is set to 27.10v. Batteries were 100% full. Also the GX showed batteries at 100%, but nothing was shown in the “notifications”. The GX also didn’t show inverter use when the multiplus was humming (I looked on the UI before I went to look at the multiplus).
It was at night, so there was no solar power generated that could be pushed into the batteries, the batteries were full, so I have no idea why the multiplus decided it was a good moment to start charging the batteries. Has it gone crazy? Is it possessed?
Are there any logs I can look into to try and figure out what happened? Or any configuration that I am missing that is preventing it from showing any errors/notifications?
I have set-up Node-RED for managing battery use (I am running GX on a Raspberry PI, if that makes any difference), but that flow is not enabled yet. For charging I have not set up anything besides the normal charge configuration.
I am not using VRM at the moment; it might be a good idea to enable it for a while, I presume?
I can have a look tonight if the BMS has bluetooth, it should, but I haven’t tried it yet.
I did my initial configuration using the VictronConnect app using an MK3-USB device. There I set the charge current, voltages, float. Is that what you mean?
That should be the one, unless you somehow selected a different piece of equipment. And the settings look correct. Time to investigate other potential issues.
You have set an absorption time of 8 hours and then set it to repeat that 8 hours every hour. There is no time to be at float basically beside 1 hr in between.
Set the absorption to 1 hr and then repeat absorption to every 24 hours maybe.
You have set an absorption time of 8 hours and then set it to repeat that 8 hours every hour. There is not time to be at float basically beside 1 hr in between.
Set the absorption to 1 hr and then repeat absorption to every 24 hours maybe.
The normal absorption time is 8 hours. Refresh is done every 7 days (repeated absorption interval) for 1 hour (repeated absorption time)… right? So should be ok I think.
But why these are lead acid battery lengths for absorption?
What could be happening is the bms is getting unhappy and causing the instability as it does not need to be balancing for so long.
Another thought is to measure voltage on inverter terminals and compare that to the voltage at the battery terminals. It’s possible that the inverter is receiving different figures.
What batteries do you have exactly?
Do they have Bluetooth? Can you check the cell voltages?
My guess is that one (or more) cell is very high and the BMS blocks the charging current.
If that happens when the MultiPlus is charging with relatively high current it will cause a voltage spike and that can cause the MultiPlus to shut down.
@lxonline I’m assuming that the low SOC shutdown doesn’t affect low voltage shutdown on the inverter tab? Correct me if I’m wrong. Also for @M_Lange attention.
A tricky one. As if the soc is incorrect things don’t go as expected.
You can switch off on soc and low voltage. If the soc is higher than the low voltage the soc is used. But if soc is incorrect and the low voltage is hit it will switch off (if the battery has not done so already)
But why these are lead acid battery lengths for absorption?
What could be happening is the bms is getting unhappy and causing the instability as it does not need to be balancing for so long.
What does the battery manufacturer recommend?
It was the default recommended setting if I remember correctly. What would be a better value? 4 hrs? They are LifePO4 batteries
I had a clamp connected for PowerAssist. I have now disconnected the clamp and turned off the clamp option via de VictronConnect settings. I was told on another thread that the clamp is only needed if not all load goes through the Multiplus. Hopefully that will be less confusing for the Multiplus.
