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battery system voltage

Question about accuracy of the Voltage meters in Victron MPPT's and Smart Battery Sense?

Answering these questions should help other Victron users who notice voltage variances on their Victron equipment gauge whether there could be an issue, or whether what they're seeing is considered normal.

1) What is the Volatge metering accuracy of both the internal MPPT and Smart Battery Sense Voltage meters?

2) What is the voltage meter model/part number and manufacturer?

3) How can one be sure they're accurate if they aren't calibrated/checked every year like digital multimerers need to be, especially after 1 year?

4) Testing of equipment is a waste of time if you're not using a guaranteed in spec digital multimeter, Correct?

5) What is the minimum accuracy of a digital multimeter for a reading to be considered "correct" and/or accurate?

not-a-hard-question-to-answer asked
not-a-hard-question-to-answer commented ·

1 Answer

Lets try a second time. Whats the Voltage accuracy of Victron products?


It seems questions often arise on this forum about the Voltage accuracy of Victron units and variances between voltages measured vs what's displayed on the app.

SINCE there is zero information about the accuracy of the Voltage meters in Victron products, it makes sense that some questions be answered on this community page, which is there to help Victron users!

Elvis, Kevgermany - You didn't like my replies to you and those who commented on my previous question, before you got offended and blocked my account - Maybe go back and read the "so called assistance" that was provided and understand I'm not some completely useless person "like you all suggested" and as a result I gave blunt responses in return showing my appreciation for the RUDE/little assistance and belittlement I received for you.

I fielt my replies were warranted, considering the attitude and belittlement I got from a number of you. All because I don't have access to a "very expensive" FLUKE DMM!

• My questions of how to confirm accuracy of a DMM, fell on deaf ears.

• My questions of the products number/model number of the voltage meters in Victron products, so I could answer the above question, fell on deaf ears.

• My question about how you can all guarantee the accuracy of Victron voltage meters when you all told me that unless a DMM is calibrated every year its not guarantee accurate, so I clearly asked how and why the Victron units can/are still considered accurate when they aren't calibrated every year? This fell on deaf ears.

• How can Victron products be guaranteed to have accurate Voltage if they're not regularly calibrated?

• Exactly what accuracy percentage does a Digital Multimeter need to have to be considered accurate enought to perform testing?

^^^These are SIMPLE QUESTIONS that will help MANY future Victron users and save them from having to create posts/questions when it's already been answered (the whole point of this community according to community guidelines)...

Let's watch you delete my account again for trying a second time to ask BASIC questions all because you assume I'll abuse you - The difference is that if you actually provide clear answers and don't provide VAGUE information, or try to waste my time asking for irrelevant information and/or imply I'm useless, then my replies will be respectful.

If you waste my time again, be rude or vague you will get blunt/rude replies in return - Not sure why you're surprised by this.

* I've been told I'm blunt due to my Autism, but that won't change the sour people who have been offended at my responses to them after they wasted my time, or implied I am useless (which in itself) is very insulting to me!

^^^ You offended me and/or wasted my time first before I gave it in return...

not-a-hard-question-to-answer asked
not-a-hard-question-to-answer edited ·

2 Answers

BMV shows wrong voltage

I just changed my batteries from wet cell to AGM. It was charged for several hours and showed 100% charge. We ran the boat for an hour afterwards and the BMV showed that the batteries were receiving a charge. We sat in the sun, getting some amperage. We used the batteries for some low useage activitie, such as a small fan and of course the refrigerator. Then we ran the boat for another hour. At the end of that period the BMV showed we had used 50 amp hours, with a SOC of 92%. At that point I realized that I had not changed the battery capacity. I changed it to match the batteries. The next morning I checked the voltage using two different volt meters. They showed 25.96v while the BMV showed 24.41. I never had that happen with the previous batteries.

There are two AGM 161 ah batteries and two starter batteries. There is a Victron 24v inverter, just a year old. There is a Victron Solar MPPT 75/ 15regulator that has been working well. , The BMV is about 2 months old.

I can not find anything stating that there is a different setting for AGM batteries. Mine are made by Genois, a Polish manufacturer.

Why does BMV show the wrong voltage and how do I correct it?


garyartista asked
pwfarnell commented ·

3 Answers

Victron MPPT 100/30 and Smart Battery Sense reading 0.2-3V higher than battery

Hi there,

I have searched this fforum looking for answers or other users who have had a similar issue and have found some reports but no answers.

I have a 100/30 MPPT with a Smart Battery Sense connected to my AGM battery bank and I've noticed the MPPT na smart battery sense seem to be reading 0.2-0.3V higher than my battery bank according to two different multimeters.

I specifically noticed this last night when the Victron unit specified my battery voltage with a small load applied was sitting at 12.61V, yet when checking with my multimeter my battery bank was sitting on 12.32V.

I purchased the Smart Battery Sense due to noticing an error in the voltage between batteries and the MPPT, the Smart Battery Sense helped get it closer, but it was never exact.

After living off the grid ina caravan for a bit over a year with this setup, I am noticing my batteries don't seem to be holding charge as good as they first did and I suspect this is due to me having accidentally run them to low as a result of the variance from the Smart Battery Sense and the MPPT.

The lowest I had taken my batteries down to was 12.24v (according to the Victron app) which would mean the actual Battery Voltage would have been close to 11.9V or 12V - Much lower that I have ever planned to discharge the batteries.

According to both MPPT and Smart Battery Sense both units are running up to date/latest firmware.

As a half assed workaround, would changing the MPPT's charging parameters to be 0.25V higher allow the batteries to reach full charge (I assume it will) but don't want to cook the batteries at the same time?

Any advice as to what the cause and fix could be.

I am running 6 gauge wire about 800mm from MPPT to batteries so voltage drop should be fairly minimal and the Smart Battery Sense should be providing an accurate reading anyway.




Hates Spam asked
Hates Spam edited ·

8 Answers

Multiplus 3000 Voltage Reading Too High


Recently had a new Multiplus 3000 inverter installed and overall it's working great. However the voltage it's reading is consistently ~0.5 volts higher than actual. I checked this 3 different ways:

- manually tested batteries using a volt meter

- victron mppt controller

- blue sea dc meter on dc panel

All others show voltage at 0.5 volts lower than the inverter.

Is there some way to calibrate the inverter to correct this?

Thank you

jcaputo asked
kevgermany answered ·

1 Answer

Batteries 92% absorption stage, battery voltage less than set absorption voltage


I have set my Quattro II with 48V lead acid (4x12V) absorption voltage setting in VE.Configure to 57,60V.

System is now:

Charger on, absorption stage.

Battery voltage 52,36V

Current 0,00A

Shouldn't the battery voltage be the same as in settings 57,60? Or is this the voltage between absorption cycles during float?

VRM/GX says that Quattro is in Absorption stage, so I would assume that those cycles (spikes in repeated absorption) happen when it reaches float stage, which it has never done yet.

My main concern is that it won't charge it to 100% level, not sure where / how it calculates the charging level. But with 0,00A current it surely wont ever get there.



Juha Tuomala asked
kevgermany commented ·

3 Answers

BMV-712 Main Voltage Showing 0.02V

I have a BMV-712 connect to 2xVictron Super Cycle batteries, today my monitor started reporting an incorrect battery voltage of 0.02 or 0.03V. This is on both the device itself and the android app (via bluetooth), nothing has changed in my system except for taking a firmware update on the app.

I've checked the voltage with a meter and its reading 13.08 from the shunt to my fuse where the power supply for the BMV is located. I also unscrewed the inline fuse and looks to be intact, just to be sure i checked the voltage from the end of the fuse to the shunt and again was 13.08V so seems to definitely be a software / device issue? I've done a number of factory resets without any joy always just displays the .02V after the reset.

Kind of out of ideas here and would welcome suggestions.


ian-doyle asked
kevgermany commented ·

3 Answers

Multiplus II 3kva 2x120v - 24 volt availability

Is the Multiplus II 12v 3kva 2x120v available in a 24 volt version or is the 12 volt compatible with a 24 volt battery bank?

I have a client that I need to install a Multiplus II.
They already bought all the equipment from a victron dealer before hiring me.
They have a 24 volts system. They currently have four 6 volt batteries in series/parallel but they will be replaced by six battle born batteries.

When going though the system while doing my homework to check to see if they really had everything I noticed that the Multiplus II the have is 12 volt and like I mentioned they have a 24 volt system.

Is the the MultiPlus-II12/3000/125-50 @X120V they purchased 24 volt compatible?

John Frame asked
ranger-rick answered ·

2 Answers

Sense wire Anomaly

This morning when i disconnected my sense wire to feed it through something i checked the voltage on my battery bank against the MPPT screen and VRM , the batteries were half a volt lower . I left the sense wire off to see when the charge controller would go from bulk to absorption and there on to float . The charge controlled did it at exactly the correct voltage shown however the batteries weren't ready , they were half a volt lower , my concern now is that the batteries will be undercharged . I dont actually need a sense wire as my cables are short and more than sufficient size and the voltage reading at the unconnected controller end of battery cables and sense wire are identical to the battery side to 1/100 volt so there's no noticeable loss . I had left the sense wire connected to the charge controller end so out of curiosity i put the meter on the other end and there was no voltage shown at all coming from the sense wire connection in the controller . Now comes the really weird thing , i connected the Meter to the batteries and placed it so i could read it and touched the battery side of the sense wire to the positive lug on battery bank and watched the voltage increase to the same as shown on the MPPT screen and VRM , it rose almost half a volt in a few seconds , taking it off and voltage dropped , it did this every time , up and down like a yoyo just by touching and removing it for a few seconds with batteries . After that i have my doubts that the higher reading is the true battery voltage , no idea why the voltages increased as it did , cant believe its possible to provide sufficient current to raise the voltage it had raced up in seconds from a cable that had shown no voltage and was only 18 awg (75 mm) . Batteries almost new AGM , Sense wire correct size and correct polarity and everything else on the charge controller functioning perfectly . Even though the sense wire isnt necessary to compensate for voltage loss in cables i have to have it connected or i undercharge batteries , even with it connected i am not confident the battery voltage is what is shows .

ako asked
ako edited ·

1 Answer

Dc ripple

Hello everybody

I have a system made up of multiplus II 5000/48, pv inverter fronius primo 4.0, 6 Q-cell panels (580 watt each), and a 4 kwhr BYD lithium battery.

I am suffering from rebooting of the system for few repetitive times (3 to 4 times per day, each time may reboots about 5 to 6 reboot) whenever the battery is full, i noticed at the same time with this issue there is a High battery voltage alarm and High DC ripple.

What i should do to solve my problem?

khaled asked
khaled commented ·

8 Answers

Lithium battery voltage below < 12 volt @ 41% SOC and BMS shutdown @ 39% SOC / 11.2 volt

I have a system with 2 x 330AH smart lithium batteries = 8 kW

12 volt system

I thought i could discharge to 5% SOC, but at 40% the voltage drops below 11.2 Volt and i have a BMS shutdown. With no big loads connected at the moment.

Charging from 40% to 100% was done in 2 hours @ 195 amps = 4.6 Kwh

Which means the capacity of my victron smart lithium batteries is comparable to lead acid batteries.

Is this a manufacturing problem? or could it have anything to do with my parameters.

The batteries where fully charged a couple days ago and both balanced.
Decreasing the BMS shut down voltage does not look to make any difference, with this rapidly declining voltage.

From 45% SOC the batteries voltage is rapidly declining, so it's looks very empty.

So it looks like i got batteries of 200 AH instead of 330AH.


Below some graphs, the shutdown was @ 05:51

The characteristic of this new batterie looks in no comparison to the graph from the manual.




2022022401 - Bootschappen-1.pdf





Frank asked
seb71 commented ·

1 Answer

12 Volt oder 24 Volt System?


Solarmodul 110Wp 5,9 A 22,3 Volt Leerlaufspannung

Victron Mppt 75/15


3 Solarmodule 330 Wp mit 66,9 Volt Leerlaufspannung.

Was ist besser.?

Eine 24 Volt System mit Victron Mppt 75/15 oder

ein 12 Volt System mit Victron Mppt 100/30.


aki asked
aki commented ·

1 Answer

How to reset voltage detection on MPPT 75 | 15

Hi, I have been battling for a week to find information on how to reset the automatic battery voltage detection on MTTP 75 | 15 .

I have a bank of large individual lead-acid cells which I connected as 24V. The Victron detected this and autoset to 24V charging cycle. However, I now need to connect this a 12V bank and the regulator's "automatic" detection only work once and keeps trying to overcharge my battery.

I have found a MTTP 150 manual which states it can be reset by shorting the "output" and applying an input for several seconds. This does NOT work on MTTP 75 series. ( I'm guessing they mean the battery output , not the load output since this is not specified ).

The same manual tells me this can be set by computer but FAILS to say how this can be done. I'm guessing , again, that this can be done via but without a specific command and value setting this is no use.

Automatic voltage recognition can be switched off and a fixed
12/24/36 or 48 V sy stem voltage can be set with a computer or
a Color Control panel.

I have a working USB connection via FTDI cable and can see the status output from the regulator. I do not have a smartphone.

Can anyone tell me what command I need to send to the MPPT 75 or where this documentation can be found. I've downloaded everything I can find but have not been able to locate this gem of information.


vickly asked
klim8skeptic commented ·

2 Answers

Voltage ratio of 8 times on MPPT 450/100: error #18

I have a DC source at 393-335 V (a battery) on the In side, and a 48V battery on the Out side (41-52 V).

I have discovered that when the source battery is fully charged and the target battery discharged, the DCDC shows error #18 "charger excessive current". And that there is a limit of 8 time float voltage on the In side.

Is there a way to circumvent this issue, or is it simply that the In can't be 400 V on a 48V battery ? If so, I suggest to make this very clear in the labelling and specsheet of the device, as this info is far from evident. When I read 450V In and 48V out, I take it as granted !...

jeanbaptistesegard asked
jeanbaptistesegard answered ·

3 Answers

Inverter Battery Voltage drop on startup…


I have a Victron 800w 12V inverter connected to Lithium Ion cells. 4S configuration totalling around 16.4 volts.

On startup it sometimes takes a few attempts with very little load like an iPhone plugged in. The low battery alarm keeps coming on even though it’s set to 12V…

Is this normal or is there an issue?



Mathew Hamilton Green asked
Alexandra answered ·

3 Answers


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