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RS 48/6000 Smart Solar Inverter - #29 overcharge protection issue

hi there!


I upgraded my system with the inverter in the title, and I have trouble setting it up correctly with my system, problems I have so far:


>solar charger will not start charging even though it has energy.

>not sure how to setup batteries, I have lifepo4 ones (4 in series) and they have a rudimentary bms, which is not accessible from the outside, no BT or CAN or similar)

>I decided to keep the solar charger (smart solar 150/70) of the prior system connected, currently it is charging the batteries, but the RS will seemingly randomly shut down


so about the shutdowns: in two days I got the #29 "battery overcharge" error code twice, yesterday noon when the solar charger (of the smart solar unit, mind you) went into absorption mode, and voltage was 56.80V, interestingly the RS showed slightly higher values than the solar charger. also the 4 series 12v batteries were not perfectly balanced yet, I have since installed 3 battery balancers from victron, and they are dead on balanced since yesterday evening.


so the second shutdown was weird though, it happened when there was little to no sun in the morning today, the batteries were at about 75% and the voltage was way off the maximum. this led me to try to dive into the menus to fix the issue, and to try to feed the MPPT of the RS instead, but as initially pointed out, I did not even get it to charge at all, not sure why.


so to sum it up, this unit is a bit weird for me, I used to have a cheap chinese inxiii 2400w 24V inverter which workes flawlessly without a single shutdown since about october in my old 24V system, with 4 of the same batteries.


what's happening here?


two thoughts I had:

>maybe I need to change battery preset to anything but lifepo4, albeit my batteries are lifepo4.

>maybe I need to find a way do disable the BMS? why does and inverter have a bms anyway? I was not aware of this initially.


any hints tips or an outright solution would be highly appreciated. if some pro could give me guidance on how to setup the battery that I have (for which there is not preset) that would be awesome.


I had no issues setting up the battery with the smart solar 150/70, but it doesn't have fancy bms tech, either, does it?


cheers,

bill


p.s.: I can't leave my home rn, as a fridge sits on this inverter, and when it decides to protect me (forced protection seems to be quite trendy these days, especially by governments) even though the BMS inside my german made (no, not german assembled, but german made) expensive lifepos is doing a nice job with overvoltage, overcharge, undervoltage, undercharage, overtemp, and undertemp protection.


p.p.s.: some more thoughts/observations:

>battery voltage measurement is exactly 0.05V higher from the RS than either the smart shunt or the MPPT150/70 during charging, I think it is about the opposite (lower by 0.05V) when discharging, but I will report back on this in the evening. what could this indicate?

>just checked in the RS' history tab, there are three errors, some hopefully due to me installing and connecting things, cause I never noticed them before, the are: #29 overcharge protection (we know this one), #10 battery low voltage (probably cause I disconnected the battery when connecting the balancers) #53 Inverter internal DC level (curious about this one). the main takaway here though is the max recorded voltage of my string of 4: 56.96V, which even if the RS shows .05V more than the other devices, is still "only" 14.24 per battery, which has an end of charge voltage of exactly 14.4V, according to spec-sheet. so again, what's happening here?

> is it possible the RS is not really designed or compatible to be used in inverter only mode, with a separate charge controller like I do? to me it seems the RS somehow "thinks" "look, the battery voltage is rising while I am not charging it, so it must be faulty? better shut it down" and then shuts down..?

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Alexandra avatar image Alexandra ♦ commented ·

@billcarson

Out of curiosity did you read the three reasons why the error 29 may be appearing? You are sort of on the right track.

https://www.victronenergy.com/media/pg/Inverter_RS_Smart/en/troubleshooting-and-support.html#UUID-e37fd1a3-4068-4e12-cf2d-c051b089e90e_section-idm232307486269475

Are the mppts and chargers in your system all set to the same battery chemistry and voltages?

For the low battery it is possible one of the batteries in the bank shut down in protection. Voltage drop over cabling is not abnormal, also a slight variation even happens between good DMM and other device readings. 0.05v is not a big problem. it is was 0.5 and above I would questions things and worry about it.

Building a 48v bank from 12v batteries usually has issues, (partially taken care of by the balancers you now have). Are you sure the battery manufacturer supports the 48v set up, not all 12v lithiums can be connected this way?

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billcarson avatar image billcarson Alexandra ♦ commented ·

well, so far no hiccups today, not sure what the reason for this was, but I noticed the RS is stick at "thinking" battery is 70% full (even though it got to 100 a couple hours ago), as it apparently can not track how much it consumes, I wonder why that is, do I need to somehow connect it to my smart-shunt which does all the tracking? how is an RS supposed to know how much it consumes if it does not know how much it produces? I might have missed something here, the RS does not know how full the battery is, albeit neither does it charge the battery, so there's that. I still would like to test its MPPT though, could not get it to work, any suggestions to what battery preset I need to change, in order to bypass the BMS, which seems to be mandatory for Lifepo4 batteries? as I said, mine have a bms, but it has no way of communicating with other devices. thanks for the reply Alexandra.


TLDR, full cycle without shutdown complete, including long (2hr+) absorption period at 56.8V, small spikes on the RS' meters to 56.85-ish, (from memory, as the RS does not seem to save "trends" over time) still no shutdowns, will keep anyone interested posted.

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Alexandra avatar image Alexandra ♦ billcarson commented ·

So we own the RS 48/6000. Have moved offgrid for over 2 years now.

It has a battery monitor complete with a peukert setting. Makes me think it is not set correctly?

I have a smart battery, that we did (not connect for comms )to it origionally as I wanted to compare the internal monitor to the battery's own monitor.

W e also added a bmv 700 later (no comms to the system). The RS is not out and neither does it go out of sync with either of the other two. I did get settings on my bmv shunt incorrect as well in the beginning. (experimented with a few settings because we can.)

Has the error cleared on the inverter? As in it is a past recording not current.

But if you have no solar on the rs inverter and it has no way of knowing there is other chargers and no way of reading from the shunt, then there is also no way it will be able to calculate SOC correctly. Since it will only see its own consumption.

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billcarson avatar image billcarson Alexandra ♦ commented ·
this is where the cerbo gx comes in, which I have laying around for about a month already, not yet installed. I almost forgot about it, duh ;) - yeah I am trying to go off-grid as well, especially for the data and surveillance aspect of it, technically it's not really allowed in my country, but they are rather relaxed here when it comes to minor infringements.


just figured out which cables I need and looks like the RS can connect to cerbo via a regular ethernet cable, which I usually make myself (with a crimp tool) the ve-direct ones connecting to shunt and solar charger I will need to order.

I wonder how well victron does the encryption part of their VRM stuff, if they send mails unencrypted, it's already a fail. I try to avoid mails at all cost, as much as paying with anything but cash, but I digress.


btw I think I figured out why the solar part of the RS would not work. and I think I dodged a (potentially costly) bullet there. I got two PV strings in parallel before they enter the 150/50, which is ok with an max input current of 50amps, the strings deliver about 20-22A max, the RS can only handle 18A. 22 might have damaged it (?) - anyways, on the website (not in the manual) among the key features it casually mentions the MPPT only turns on if it sees a voltage of over 120V, while testing my array(s) never went above 110V, so I guess lucky me. actually rather inconsiderate of me... duh

so for testing I will probably change the wiring of my 6 panels (so far) from 3s2p to 6s the amerage is low enough then not to damage the RS, and the voltage is high enough to even bother ;)

thanks again for replying! will keep anyone posted if interested.

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