Multiplus voltage differences

Question

question

dirk-s asked Jun 5, '22

Multiplus voltage differences

Hello,

I'm reading in this community for a while now and get many help/hints to setup my storage system. But now I have a questions and didn't find this kind of topic in this community before.

I have just changed my installation from a Multiplus II 3000 GX to a Multiplus II 5000 GX. It is an grid connected ESS System with 5* Pylontech US3000C. Everything works well so far.

But there is one issue that bothers me a bit. The Multiplus have a voltage difference of 0,30 V between the Multiplus itself and monitored in VRM Portal "VE.Bus DC Voltage And Current" and the real voltage. The BMS from Pylontec and all the other voltages monitored and shown by the GX device shows 0,3 higher voltages. I also messured everything with a multimeter and the higher voltages are correct. If I messure also directly with my multimeter on the DC terminal of the Multiplus directly (without calble and inverter/charger are off) the voltage ist 0,3 Volt higher than monitored by the Multiplus.

As the Multiplus uses this messured voltage to steer everything, the real voltage is everytime higher. For example I need to set charge voltage limit to 50,0 Volt to get 50,3 Volt in reality. Also if I don't limit the charge voltage, the real charge limit will be not 52,4, but 52,7.

It may be that these deviations are normal and are the usual variations of measurements. In this case it is ok. But as I still have the possibility to return the Multiplus and to get a new one, I want to be sure. My former Multiplus II 3000 had a deviation of 0,1V.

What are you experiences and values? Are your messured DC voltage by Multiplus the same like messured from BMS/Multimeter/reality or do you have also these kind of deviations?

Many thanks in advance.

Bye Dirk

Multiplus-II voltage

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Modifications Space

Node Red Space

Answer 1 · 2022-06-07T10:34:58Z

dirk-s answered · Jun 07, 2022 at 10:34 AM

Hi all,

Does nobody from this Community use a Multiplus II 5000 GX who can check this on his/her installation?

Would be very helpfully for me to know.

Thank a lot.

Dirk

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 2 · 2022-06-07T13:27:06Z

JohnC answered · Jun 07, 2022 at 01:27 PM

Hi @Dirk_S

I've an earlier Multi 48/5000 and see a V difference of up to 0.2V. It varies for some reason, maybe a Temperature thing? I 'fixed' it by using DVCC to pass on to it a better V from a Smartshunt.

With your Pylons I don't think you can do that, but the Pylons should be controlling everything anyway if set up correctly. What the Multi reads itself shouldn't really matter. But I've little experience with the Pylons, so check this out for yourself. With managed batts (at least the Victron-supported ones), if they say they're happy, then all should be good.

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 3 · 2022-08-10T20:08:34Z

anieuwstadt answered · Aug 10, 2022 at 08:08 PM

Picked up a similar problem. The chart below shows differences between the VE.Bus (MultiPlus) and the BMS (Freedomwon). Conditions: no load, no charging, no solar. The variance is sufficient to put the system into Absorb charge when the BMS battery SoC is being reported as 49%. In the large (6 month) chart, the difference between the voltages is increasing over time. In April at the start of the flat line section, the MP II firmware was updated. Going to confirm the bus voltages using a meter to confirm which is more correct, the BMS or the VE.Bus

1660160936566.png (70.7 KiB)

1660161270221.png (13.4 KiB)

1660161854823.png (110.0 KiB)

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 4 · 2022-09-21T04:57:24Z

cedricr21 answered · Sep 21, 2022 at 04:57 AM

Bonjour, j'ai un problème identique. Mon multiplus II indiqué 51,8v alors que la tension de batterie est de 50v. J'ai mesuré la tension réelle au borne du multiplus elle est de 50v mais le multiplusII indiqué au cerbo 51.8v. Quelqu'un sait-il comment résoudre ce problème ou si je dois l'envoyer en réparation ?

Merci

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 5 · 2023-03-01T15:48:47Z

Jörg Becker answered · Mar 01, 2023 at 03:48 PM

Same problem here now.

MP II measures 56,8V when the real voltage over the terminals is only 55.6V. The BMS measures 55.6V, the MPPTs show 55.6V but the Multiplus shows more than 1V more.

Anything I can do about it?

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 6 · 2023-03-08T14:58:58Z

anieuwstadt answered · Mar 08, 2023 at 02:58 PM

In my case, there was an inverter hardware issue, and an update to the Venus OS resolved the problem.

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 7 · 2023-10-13T03:25:15Z

craig1 answered · Oct 13, 2023 at 03:25 AM

My Multiplus II 48/3000/35-32 has about a 5.1% error.

Actual battery voltage read on the Multiplus terminals is 54.0V (Confirmed with two multimeters). Reading in VictronConnect shows 56.84V. I also tried with VSense (Kevin connection) and no different.

I just disabled VSense in the charger settings and the battery voltage is pretty much spot on. The setting has a comment "For diagnostic purposes only" - What is the practical implications of leaving this setting on?

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 8 · 2023-12-05T17:49:49Z

proton answered · Dec 05, 2023 at 05:49 PM

@dirk-s:
Exactly the same situation here, Multi II and Pylontech US5000, just a few weeks old.
Battery-BMS reports around 0,3V more as VE.Bus DC (independent if load/idle/sharge). Meassured with two Multimeter, the Battery BMS is the correct one.

Did you ever got a solution? I think in another thread a user reported that Victron was able to re-calibrate the DC-sensor by a remote session.

Kind regards,

vebus-dc-vs-bms-values.png (57.3 KiB)

3

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Alexandra ♦ commented · Dec 05, 2023 at 05:57 PM

@proton

Disabling V sense sorted it for a user on a different thread.

0 ·

proton Alexandra ♦ commented · Dec 05, 2023 at 06:02 PM

Thxs, forgot to mention, i already tried this (disable Vsense), but it still exists, aboth graph is with disabled V sense and i light load (4A)

0 ·

dirk-s proton commented · Dec 06, 2023 at 03:38 PM

No, still no solution. But also not worse or better. I live with this and adjusted my voltages in the configuration of DVCC and Multiplus VeConfigure configuration by this differences.

0 ·

Answer 9 · 2023-12-13T15:14:07Z

anieuwstadt answered · Dec 13, 2023 at 03:14 PM

This may have something to do with the voltage variances seen with Pylontech.

Checked a site with Pylontech UP2500 and saw voltage variances between VE.Bus and battery BMS. When fully charged, the variance is consistent at 0.2V. I don't see this at other non-Pylontech sites.

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom

1702480104838.png (41.2 KiB)

2

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

dirk-s commented · Dec 13, 2023 at 03:28 PM

I don’t think so. If I measure the voltages directly at the Multiplus (plus and minus terminals) I have the same differences.

0 ·

proton commented · Dec 13, 2023 at 07:05 PM

I don't see the link for our issue with the victron link you posted, the cutting to 52.4 V will only happen for charge voltages reported from the BMS to DVCC above that level (during charging).

Can be found inside venus-os, watch out for _pylontech_quirk:
more /opt/victronenergy/dbus-systemcalc-py/delegates/dvcc.py

But the voltage measurements had this differences through the complete range.

0 ·

Answer 10 · 2024-04-11T05:15:16Z

kaypea answered · Apr 11 at 05:15 AM

Just came across this post as I have the same problem with around 350mV discrepancy between measured and real voltage. Did you ever get to the bottom of the problem? It obviously a wide fault/issue.

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 11 · 2024-04-11T06:19:08Z

onrbikes answered · Apr 11 at 06:19 AM

I asked similar a while back and have something odd to add.

I have an easysolar 24v 3000

I had 12x2v 500ah lead acid batteries that would always read .3v less than the easysolar. Now I would think a voltage drop and might get less at the Easysolar.

The cables are 500mm long and well sized. No shunt installed.

Then recently I changed to 8 x 3.2V 200ah self build Lifepo4. This is connected to a Daly then a new smart shunt. All with the same cables.

Now the voltage reads exactly the same at the batteries, the Daly and the Easysolar.

Go figure?

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

question