Hello good people,
its been a while since I setup a pure backup system (there are no options for putting PV)…
So 2 x US3000C and Victron MPII 3K, do I need to install ESS assistant (setting it to “Keep batteries charged”) or not?
If not, do I simply configure charger/inverters settings and enable DVCC?
The desired goal is a pure backup (UPS) system, when load shedding is on - use batteries, when grid comes back - charge batteries to 100% and keep using grid.
Sorry, I understand its a “dumb” question, but I haven’t done new setup in over 3 years.
If ESS is needed or recommended, I do know how to setup parameters as well as enable DVCC and configure it…at least something
Don’t forget that PylonTech require the batteries to be cycled daily to maintain the warranty. So I would configure ESS and set the minimum SOC to 85% or so.
One way is to leave it in ESS mode with a scheduled charge slot that keeps it charged 23 hours and 30 minutes of the day, so it discharges the battery slightly just before midnight, and then recharges it again.
That said. I personally don’t like using ESS in backup systems. I know it works and that sometimes it is the only option, but let me explain. It opens the door to a heap of unnecesarry issues, such as the overload-when-grid-fails issue (only affects some ESS systems), and getting generators to tie properly with the Multi (also harder if the Multi runs ESS). It is far simpler, and more reliable, to run without ESS in a backup system.
Are we absolutely sure it is still a requirement to cycle the batteries? I would check that first.
What I did on his, I increased it to 35A and the charging became as intended @35A so the two US3000C’s charged fairly quickly.
I thought that pylontech manages all this but then thinking again, this shows that it is “Maximum DC charge current” because when battery % came to around 95-98% it dropped down and charged at lower amperage.
Should this value be based on the inverter in question, e.g.
MultiPlus II 48/3000/35 - this should be set at 35A and on MultiPlus II 48/5000/70 should be set at 70A?
I watched videos and was digging in google but didn’t find a clear answer
That is the charge limit that your batteries can handle and you should set it to something equal or smaller than your battery recommend.
When it’s only the Multiplus this value will be used. But when you add a link to a GX device you can override that. Then if your battery is linked to the GX and the DVCC option enabled then your battery will override that.
It’s always better to set each value in place, even though the Victron system do have many checks to prevent problems. There are still some rules where this value is king.
I also though it will work like this but it doesn’t
We both have Venus GX
He has 2 x US3000C and I have 4 x US3000B
Now for a single US3000, recommended charge current is 37A but a question now, if there are 4 batteries in parallel, should it be 37A for the complete bank or 37A x 4? (obviously up to the maximum current based on the inverter model)
I guess the latter part of my answer begs exactly this question
EDIT:
Ok, so I did find the answer to that question
Since recommended charging current for a single US3000 is 37A, when we have 2 or 4 in a bank the charging current needs to be multiplied by the number of batteries.
That said, in both scenarios it should be set to the max. DC amperage each Victron can produce since the banks are 37A x 2 = 74A and 37A x 4=148A, but the max amperage is 35A and 70A respectively.
Now to put a stamp on all this @plonkster@JacoDeJongh am I correct with the above or will I be burning something?
