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rithym1964 avatar image
rithym1964 Suspended asked

RS 450/100 throttling down current on both trackers way before Absorption reached

Recently installed RS 450/100 at my home and I straight away noticed a problem where the controller throttles both strings down to under half the rating whilst the controller is in bulk mode. I wondered if there was an issue with cloud shading but this morning has been perfect blue sky and still the RS throttled down the current on both arrays more than an hour before absorption voltage was reached. I also have an mppt 150/85 on the same 48V system both controllers have identical charge settings and are showing as not networked in standalone mode in the Venus GX menu. DVCC is also off. So far the two controllers switch to absorption & float within a few minutes of each other as expected but I am curious as to why the RS is not producing full power when still in bulk mode. It can be clearly seen on the graph below I am getting no error codes from either controller



graph.jpg


vrm.jpg


controller-data.jpg


Any help much appreciated

Jinko KM330-60 Tech Sheet.pdf

Scheuten P6-54 210W Tech Sheet.pdf


inverter rs
graph.jpg (4.6 MiB)
controller-data.jpg (5.6 MiB)
vrm.jpg (18.0 MiB)
jinko-km330-60-tech-sheet.pdf (610.5 KiB)
scheuten-p6-54-210w-tech-sheet.pdf (528.8 KiB)
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4 Answers
mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi all,

We made a mistake in the derating of the MPPT RS. Actually, two mistakes:

1) the charger derated too much, too early. Which is addressed in firmware v1.09, coming next week. New derating: The Charger set-points (float and absorption) can be set to max 60V. The output voltage at the charger terminals can be higher, due to temperature compensation as well as compensation for voltage drop over the battery cables. The maximum output current is reduced on a linear basis from full current at 60V to 5A at 62V. The equalization voltage can be set to max 62V, the equalization current percentage can be set to max 6%.


2) The datasheets were not clear about this limitation, which can come as a surprise as most of our other chargers are able to charge at higher voltages. We have updated the datasheets and other documentation to be more clear on max configurable charge voltages as well as to include above sentence. More details in a comment further in this thread.


My apologies for this! And for anyone whose MPPT RS can't meet the charging requirements of the used battery technology, please contact your distributor for a solution.


Best regards, Matthijs


Ps. I'll accept this answer, to make it show up first in order to help anyone looking for this info.


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Thierry Cortassa (Victron Energy Staff) avatar image
Thierry Cortassa (Victron Energy Staff) answered ·

hello is it junko 330 half cut ?

if yes i think it's probabli normal. the junko 330 have a isc and i mp uper than the rs450/100 can received if you have 2 string in parallele !


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rithym1964 avatar image rithym1964 commented ·
Thankyou for your reply. I have added above the tech sheet for the solar panels. The Jinko 330W are 60 cell with a ISC 10.31 & IMP 9.77 I have 2x strings of 8 panels in parallel.
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JohnC avatar image
JohnC answered ·

Hi @rithym1964

This looks suspiciously like temperature derating output. I don't know the RS and how it behaves, but you have reached the 100A output (and exceeded it, perhaps briefly), then the output has backed off. Maybe look at ventilation of the unit?

And Thierry is right that you have overspecced the panels on the Jinko tracker. Not by much, and the data suggests that the Imp and Isc limits haven't been reached in practice, but still something to keep an eye on.

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rithym1964 avatar image rithym1964 commented ·

Perhaps a temperature issue would explain the throttling down of both trackers rather than just limiting the current to 18A as I would expect to happen. No alarms though? I never fitted the bat temp sensor that came with the RS as the Venus GX has one fitted so I assume it shares this info with all the devices connected to it. If the temp issue is internal to the RS unit then I should hear the fans come on once it starts generating high power... will check that next sunny day.

I noticed when I use VictronConnect on my LAN to view the RS live data that the bat temp & current are not displayed so it seems that the GX was not sharing this info with DVCC disabled. I have now enabled it and I can see bat temp & current in both controllers live data view.

Update 12.30 hrs - It's a hazy chemtrail sky today so the RS is still in bulk showing about 10A produced by each array. Both the bottom fans are working and the air forced out the top of the unit is 39 C It seems logical to me that the temp inside the cabinet is over 40 hence the throttling. This is quite worrying because the RE cabin is only 23 C now but in the Summer here it gets well in to the mid 30's. I may have to investigate forcing more air through the unit

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Thiemo van Engelen (Victron Energy staff) avatar image
Thiemo van Engelen (Victron Energy staff) answered ·

Hi,

The MPPT RS 450/100 has, besides a temperature derating, also a battery voltage derating. This is unfortunately not yet mentioned in the datasheet, which will be corrected. The datasheet should contain the following footnote regarding the battery voltage: The charge current derates above 57V

Kind regards,

Thiemo van Engelen

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rithym1964 avatar image rithym1964 commented ·

Okay, that makes even more sense than the temp derating because since a couple of days that I posted this problem I have removed the main top cover from the RS and directed a large high power fan directly onto the inside components which blows just before the controller makes 60A total. This has made no difference to the derating of the current which continues to drop dramtically after reaching 57V. My absorption voltage for these FLA batteries is specified as 60v (with temp compensation of -120mV) so why would Victron release a charge controller that severely reduces current above 57V ???

I can easily improve airflow and cool the internal components if necessary but I cannot control the severe voltage limitations in the software. I hope this problem will be corrected with a firmware update quite soon.


57v-derate.jpg

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Related Resources


Inverter RS Product page.

Inverter RS Online Manual.

Inverter RS Datasheet.

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