2x SmartSolar MPPT - Diferent battery voltage problem

Q&A and troubleshooting
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1

Hello.
After more 5 years with the SmartSolar MPPT 250/100-Tr in one array of solar PV without problems, now I verify differences in battery voltage problems.

The problem is the higher voltage report in the MPPT create a permature absorvation/float in the MPPT production when exist solar avaliable and the baterry is not full charged…
The other MPPT (250/60) have the correct value and continues to try to fill the battery…
This situation create an cut of solar production, when exist capacity to store more energy in the battery.

The solar system is made with:
2x Victron Multiplus-II 48/5000/70-48 [id:2623] in parallel mode (test in firmware v502 and v556);
1x Venus GX [id:C002] (check in firmware v3.00 and v3.55);
6x Pylontech US5000
1x SmartSolar Charger MPPT 250/60 [id:A05D] (check in firmware v1.61 and v1.64);
1x SmartSolar Charger MPPT 250/100 rev2 [id:A065] (check in firmware v1.61 and v1.64);

The problem is the 250/100 MPPT read an “incorrect” value of the battery voltage (higher value then report by the Inverter, Battery BMS and MPPT 250/60).

I already check the cables connected to the bush bar (made with Victron Lynx Power In) and the MPPT 250/100 with a multi-meter and verify the diference of +/- 1.5 to +/- 2 volts (MPPT/multi-meter value).

The measures with the multi-meter to read physical values of the voltage where made in the connections of the MPPT 250/100 (battery screws), and the multi-meter read the correct voltage in the bush bar (copper bars) corresponding to the same as reported by the MPPT 250/60, Multiplus and BMS in the software (with +/- 0.2 volt of error).
The voltage drop from bush bar to MPPT 250/100 screw connection is +/- 0.0 V.
Same situation for the MPPT 250/60, voltage drop +/- 0.0 V.

I shutdown all installation more then 10 minutes, recheck all screws and physical connection and not verify any physical situation. Power on again and the problem maintains…
I decide to update all the firmware’s in the system to the last versions and again, the problem maintains…
The configuration is the default for Pylontech battery’s in the Victron Page. All parameters are the same and where working during more the 2 years withou any problem with the MPPT…

The charge voltages are force in MPPT too, like recommend by Victron (Abs 52.00V; Float 51.00V; Equal 48.00V).
Nevertheless, the MPPT are controled by external control (venus GX).

Is possible to help to identify this higher value of baterry voltage in the MPPT250/100 ?
I have access to other solar installation with Victron and with the same MPPT 250/100, and the values in the multi-meter and MPPT are OK…

Thanks

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2

As always:

Bad wiring
Loose connectors
Bad fuses / cirquit breakers

Check plus and minus from charger to battery…

3

Thanks, but already check, as explain in the text.
No problem and no voltage different in multiple points measure from bush bar to MPPT…
Inclusive check connectors of the MPPT and no sign of corrosion or other physical problems…
And start to change the voltage only in last months after 5 years working well…

Apparently, the MPPT have something inside… or not !!!

4

Is bluetooth active in the smartsolar ?

5

No network via BT. Only comunication cable connect to Venus GX.
Bt is enable to access via victronconnect

6

Then you should disconnect the mppt from the cerbo, and check if the displayed battery voltage goes down, and/or current is going up

7

I disconnect the VE.direct cable in the MPPT<->Venus GX and after some seconds, the MPPT pass from External control to Float, and the results are:

VE.direct cable disconnect (alone, enter in float mode): Battery voltage = 51.53V, current = 0.0A (MPPT cut production).
VE.direct cable connect (external control): Battery voltage = 51.66V, current = 24.00A
This difference in voltage is normal (battery charge oscillation).
No battery voltage values drop to battery/inverter values happen during cable disconnect (+/- 49.70V)

In the battery BMS, inverter and the other MPPT250/60, the system report +/- 49.70 V (Battery SOC at 37%).

8

Ok,

if the mppt is less then 5 years old, contact your supplier and return if for warranty exchange..

Otherwise your only possibility would be to set your charge parameters higher, match it to the displayed voltages.

You’re up 2v from the battery, so you should also set absorb and float up by 2 volts.

BUT…is ever the MPPT decides to return to the correct values…you might get a problem

9

Change the MPPT internal parameters is not a solution, because is controlled by the DVCC.

About the warranty… my unluck… it’s pass +8 month after 5 years warranty… bad for a not cheap MPPT…

It’s possible the MPPT see the battery voltage from other source and follow this source, because I have at least 3 other correct values for the battery voltage ?

Thanks in advance.

10

Not if you pull the ve.direct cable

11

Are you using ESS assistant or not?

The most interesting part is…

  1. The mppts are under external control, so they should not be using their internal algorithms.

  2. Dvcc should be forced on by the pylontecs which will probably be requesting 53.2v
    3.. When dvcc is enabled the voltage being used is the battery voltage when it is set at the monitor and SVS is on.

In conclusion I do find it quite strange they aren’t producing.

But since this seems to be a new thing a warranty check may be in order, since the product is not behaving as expected.

My only other comment is on 3.55 that venus will be struggling though. I would dial it back to around 3.4/2.

12

Its only ONE mppt thats not producing, they should get the same data from cerbo…

13

Thanks for the info, but I disconnect the ve.direct cable and the MPPT enter in float mode, same battery voltage (with +2V) and 0 Amps production. I need to see is there is some manual selected curve in the MPPT… or is need to restart the MPPT.
Conclusion, with ve.direct cable disconnect the MPPT enter in float mode.

14

I’m using Virtual Switch with AC network as backup only. This avoid sync with the network and adjustments to the network when I have enough energy in the battery. When SOC <15%, AC input suport the home until the SOC level to disconnect again the network.

1.The MPPT in fact are in external control, but according Victron documentation for Pylontech battery is recommend as security to force the same limit parameters in the MPPT.

  1. DVCC is forced with Pylontech and SVS Shared voltage sense is ON forced by configuration.
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Regarding output, this is decreased because the additional effect of another 1.5v to 2.0v added to the battery voltage associated with the relatively flat charging curve of Pylontech batteries means that this MPPT enters absorption mode more quickly than in reality.
Thus, the MPPT’s output is cut off early, even though the batteries are capable of receiving more energy…

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About the VenusGX with 3.55, this problem happen with 3.0 version and I update last weekend because Victron always say to update the firmwares for the last version to clear errors… And is not documented by Victron to not update the VenusGX with 3.5 version (at least I try to find and don’t see nothing and in VenusGX version scan was defined the 3.55 (standard) version…

Thanks for your informations and time.
Is possible the MPPT see the voltage directly from the BMS ?

Thanks.

15

You’re up 2v from the battery, so you should also set absorb and float up by 2 volts.

16

The battery sends charge and do not charge based on what it wants the widget for bms limits will show what it is doing and requesting. DVCC is the mechanism used. That is why it is forced on
Recently there have been alot of control changes for the pylontecs. If i find the thread i will link it in.

17

No, one is, the other not.

THAT is strange…

18

I saw your previous comment.
Which is why the link is there. If something is wrong with the product then the next step is a warranty claim.

19

Tough luck ?

20

@PMB
I see you have Charge limit on the one graph posted. Where is that set?

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