Connecting solar power to a recyled GTG1200-30-3 48V power bank with quattro output inverters

Q&A and troubleshooting DESS
1

Hi,
I have a new MPPT RS 450/200 - MC4 connected to 3 old (2017) Quattro 10000 inverters and 48V battery pack ( GTG1200 -30 -3 power bank). The system is offgrid to power my remote workshop and gets solar input from 36 440W panels (4 strings of 9 panels 330 to 430V each, depending on sun light).
Because it is a mix of old and new equipment I am having some small niggles.
Initially MPPT was looking for a BMS (which I did not think existed) but I have since found there is a bmv 700 system built into the power bank (not sure how to add photos). Today’s task is to reset the MPPT to factory settings and see if I can add the BMV 700 as its BMS (I really hate all these acronyms makes it hard for us beginners).
The blue tooth app for the MPPT is really difficult to use wrt connecting a BMS (dialog box for BMS disappears when in non BMS mode requiring reset to get it back???)
MPPT connects to a Color screen on the power bank by a 8 wire VE cable and Color screen recognizes the solar charger (makes pretty graphic showing MPPT charging batteries and discharging via the quattros - 1 only for single phase AC discharge). It was all working fine and charged batteries up to 55V and went into float mode (I had only just commissioned the system and was turning inverters off overnight as it is in my workshop and limited battery charge amps to 20amp and voltage to 54V for first few days to make sure there was no overheating or gassing in the old 1200Ahr batteries). Now have MPPT set on preset for Victron OPZV batteries 56V bulk and 54V float.
Problem is with the quattro inverters. As soon as solar charge passed from bulk into float mode and the MPPT started dropping solar panel strings to reduce input current, the color screen showed fault 24 for the inverter self protection and the output AC tripped off. Manual for quattro says to restart or increase min AC charge voltage (no AC input charge voltage as charging batteries from MPPT on DC) Color screen says input AC source for Quattro’s as “UnKnown”.
Was tripping as soon as inverters were turned on but tried hard reset using EM stop button and managed to get about 10mins of AC output (batteries fully charged and MPPT in float mode - previously while charging batteries in Bulk mode I had 2 days of continuous AC output with no faults) before it tripped again and showed fault code 24 on color screen (and audible alarm).
Maybe Quattros and MPPT not singing from same song sheet regarding battery voltage (MPPT says fully charged and in float mode at 55/56V while color screen says batteries at 83% charge and lower voltage? maybe if both devices use the BMV 700 this will fix it? Multi meter over battery pack + and -, agrees with MPPT , fully charged at 55V. Can’t see settings on color screen for quattro’s. How do I raise input AC voltage as recommended by Quattro manual for fault code 24 (even if this is spurious as no AC charge input). Color screen also mentions VE comms fault - no idea, tried plugging and unplugging VE comms cable between MPPT and Color screen. I was advised to put the blue 8 pin plug (that came with the MPPT) into the spare VE port in the color screen (not sure what this plug does or if its location is correct - cannot find any mention of it in the manual???).
2nd question - how can I connect a laptop up to the color screen and quattros to see what is going on and change settings if required - like input AC lower voltage limit as it states in Quattro manual for fault code 24 -
“Should not occur in correctly installed equipment. Switch all
equipment off, and then on again. If the problem recurs,
check the installation.
Possible solution: increase lower limit of AC input
voltage to 210 VAC (factory setting is 180 VAC)”

I have sorted out the best 24 cells from 3 sets of batteries (replaced 8 low performing cells with good ones from a 2019 set, performed some sample load testing on cells with help from local battery specialists) but yet to perform a load test to determine if any cells are dropping voltage unduly on a 6KW load test over 30mins, with no charging, (was told to bin any cells that drop below 1.9V in this test). Can’t do the test as the inverter trips on fault code 24 before I get a chance. Cell voltages are all even and no heating or gassing is taking place and battery set charges ok (and was discharging normally while MPPT was in bulk charge mode for first few days, but only small workshop loads up to 1.5KW on 230V single phase.

Any suggestions greatly appreciated.
Have tried seller for MPPT but problem lies with older quattro and currently can’t read this unit by blue tooth, laptop or remotely with modem (I do have a modem on one of the other battery packs and will try installing this onto the set currently in use). Also don’t have software to read or change quattro settings or send data files to dealer (who is unfortunately away for 2 months and unable to visit the workshop in NE Scotland).
Is there anyone reading this with useful knowledge in Aberdeenshire?

Regards Alistair

2

Hi , A couple of updates since my post above last week. When discharging even on single phase all the inverters ar eon and when fault code 24 appears (which it does now as soon as you turn inverters on) the same diode flash sequence (for fault code 24 as per the manual) appears on all 3 inverters. Only 1 inverter turned on when charging using single phase AC. First trick is to determine which inverter is faulty. I suspect the fault lied within one or more of the quattros in the reverse current protection relay. Possibly this was under sized for the previous application when the batteries were bulk charged with 100amps at 400V from a gen set or mains (not solar as in this new application). I cannot find any photos or schematics of the Quattro 10000 140 inverter but the Quattro 5000 inverter manual mentions this reverse current relay and has a very basic schematic (which I would attach if I could). I am in the process of downloading software and purchasing interface cables for both the quattros and the bmv 700 (which I am told is not a bms… but just a shunt to read current to assess charging state, and I guess battery voltage - what a BMS might do I have no idea).
So I hope to be able to pull appart a quattro and post pictures of the damaged reverse current relay - if this is indeed the problem - I fired up another battery pack - after shuffling and charging yet another set of 24 good cells, and guess what - straight to fault code 24. I suspect this is why the previous owner dumped all these GTG 1200 units to auction and I hear on the grapevine they were not a very successful design - I suspect because the overnight charge rate was too much for the 3 x 10K quattros. More to follow - can someone advise how I can post photos please. I may have found it with the upload button on the ribbon above.

Battery bank solar charger
Battery bank solar charger1920×2560 329 KB

Regards Alistair
relay H for reverse flow protection.pdf (1.8 MB)
Error 24 diagnosis.docx (17.3 KB)

3

One thing is slightly puzzling, these GTG1200’s were built in large numbers (over 20 units - maybe 50 - at a cost of about £80K each) so the makers must have been pretty good clients of Victron and complained bitterly when they all failed and went to fault code 24.

Therefore it is my deduction is someone at Victron knows exactly why these units faulted and knows exactly how to fix or de rate them - why has no one from Victron answered this post?
From the 2 auctions I observed at least 15 units were sold off late last year and this year - mostly to people like me who saw them as cheap way to get 3 inverters and maybe some good batteries - so there will be another 15 people in the UK with exactly the same problems that I am having and looking for a solution.
Any assistance greatly appreciated.

Regards Alistair

4

In Between posts 2 and 3 above I did get a period of 5 hrs running out of the battery bank with ac discharge as normal (before the inverters died completely at the end of that day). So I did get to perform the load test on the batteries and the 24 best cell performed excellently on a 40 min discharge with no charging through a 6Kw load and all cells registered almost exactly the same drop in voltage of 2.2V per cell to approx 2.12V percell after the test (before recharging). There is a constant draw of about 3 to 400W from the solar charge controller, over what is being used as output ti inverters for AC loads but I assume this is acceptable heat loss in the inverters and batteries. I’m sure Li Ion batteries would do better but these 1000/1200 Ahr cells were basically free, so no complaints. I don’t think battery condition is a issue wrt the fault code 24 I am experiencing. A quick way to deduce which inverter has failed would be a bonus as they are packaged very tightly and access to terminals is very difficult to carry out the diagnostic attached above (found on the internet - from, I guess, originally a Victron publication, but no reference was given (found by AI). I will fix these things (and publish a solution) but pretty sure Victron could make it a lot easier.
I have spent a lifetime in the reuse business and the best brands are the ones that stand by and repair their equipment and not just sell new kit. Automotive brands like Toyota and Mercedes did not get where they are by turning their back on customers problems - no matter how old the machine or how much they stand to profit, or not, by the repair.

Regards Alistair