question

ffvictron avatar image
ffvictron asked

48v 60v High voltage alarm: Alarm out of nowhere, no changes? TEMP shows -25C

48v system 2 sets of 4x12/200Ah total 400Ah. Aokly GEL

SOLAR: Two strings de 200v 10amp
Cerbo GX v2.92
Quattro-II 48/5000/70-2x50 v500
MPTT 250/70 v3.13
Smartshunt 500A v4.12


The alarms have started since this Monday and never seen them before, no changes have been made lately until today I started checking out the settings.

The alarms are being triggered when it goes from Absorption to Bulk from what I saw on the stats on Monday and Tuesday.


I updated and reset the parameters for the MPTT again as I was updated to 3.13 but I am not sure where to look at as they look OK to me.

I have turned off the charger as I was triggering the high voltage alarm again.

I also noticed the MPTT temperature shows -25C which is wrong. maybe it causing the problem?


is there anyway I can reboot the Quattro remotely? if that helps I am not onsite.


any suggestions what should I check next?


today-alarm.png

mptt250-70-3.png

mptt250-70-2.png



mptt250-70-1.png

smartshunt-3.png

smartshunt-2.png

Temperature Alarm
today-alarm.png (43.7 KiB)
tuesday-alarm.png (44.8 KiB)
mptt250-70-1.png (51.7 KiB)
mptt250-70-2.png (102.0 KiB)
mptt250-70-3.png (27.5 KiB)
smartshunt-1.png (35.5 KiB)
smartshunt-2.png (86.7 KiB)
smartshunt-3.png (27.5 KiB)
3 comments
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klim8skeptic avatar image klim8skeptic ♦ commented ·

@ffvictron It is likely that the -25c reading at the mppt has combined with temperature compensation to raise the charging voltage to alarm levels.

What device is feeding the mppt temp values?

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ffvictron avatar image ffvictron klim8skeptic ♦ commented ·
that's my thought as well, that the MPPT has something going on that is causing the problem. I have no temperature sensor attached to the MPPT. The only temp sensor is connected to the Quattro. The Quattro, shunt, and MPPT are all hooked up to the cerboGX.

I managed to ask somebody to go to the site and cut off power from the PV and the batteries to reset the MPPT and the -25C went away.

I will be monitoring closely today if the alarm gets triggered again.

I'm thinking it maybe necessary to install an additional temp sensor to the mppt to prevent this issues.


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klim8skeptic avatar image klim8skeptic ♦ ffvictron commented ·

The Quattro, shunt, and MPPT are all hooked up to the cerboGX.

Have you read the DVCC manual ? Might be applicable for your problem.

Also if you have nothing connected to the SmartShunt's AUX input, make sure that NONE is selected.

smartshune-none.png


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3 Answers
Alistair Warburton avatar image
Alistair Warburton answered ·

I am fairly sure that the bad temperature reading is to blame...

I do not know if the 'normal' point is 20C or 25C but in either case with a reading of -25C and compensation set as it is bulk/absorb will be more than 60V, 60.12 and 60.44 respectively.

Disabling compensation will help until you get the sensor fixed but unless you know the battery temp, by some other means, you are risking damage, although probably not as much damage as continually overcharging, or not charging at all, will do.

If you have to manage it manually, push the float to the max permitted in normal conditions and do an EQ periodically. That will at least top them off, for a controlled period, without creating a continual overcharge.

If you are picking voltages manually you probably need to check the battery specs carefully first. I am no expert in that respect. Checking DVCC shared temp is a good plan, what sensors do you have connected?

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christianf avatar image
christianf answered ·

Did you eventually use USB to VE-Direct cables? I remember there was the same issue in one off grid garage episode where it turned out that the cables were directly connected with no galvanic separation. Changing the cable -> error gone.

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ffvictron avatar image
ffvictron answered ·

@christianf No. we use only VE-Direct cables. MPPT to the Cerbo GX.

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