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Autotransformer voltage outputs are different

I am having an issue with the Autotransformer output voltages - 114V on L1 and 120V on L2 (with no load)

120V current is supplied by a Quattro 48V / 10000 / 140-100/100 to the 100A Autotransformer. I'm using the AT to provide a split-phase 120/240v supply to the 50A main break panel in my RV

I have wired the AT connections according to the diagram #3 shown on the system schematics page from the Victron website: (https://www.victronenergy.com/upload/documents/AT-3-split-phase-120V-to-120-240V-with-Quattro-120V.pdf)

The Ground Relay in the Quattro is set to ON and is correctly grounding the Neutral to earth.

Here are the voltages I read at the terminals:


The problem I have with this is that the voltage on L1 decreases a lot with load, and when occurs equipment will pull more current to compensate for the lower voltage.

Here is a pic of my RV control panel, showing the disparity in voltage between L1 and L2. Even though there are 2 air conditioners on Line2 it has only dropped 2 volts - Line1 dropped from 114v to 105v. This can't be good.


Questions: 1) - Is this method of wiring correct, and 2) what is causing the voltage discrepancy?


Aug-31: Editing this in an attempt to make the question visible again. I'm thinking of sending this AutoTransformer back to Victron as it is not performing to expectations. I have seen voltages as low as 96 volts on L1, at which point my UPS shuts down my computer, and various other circuits shut down. Not happy...

I'd appreciate a comment from anyone who has had experience with an AutoTransformer.


Pete MacLachlan asked
epuhs answered ·

2 Answers

voltage drops from solar panels once connected to MPPT

Hey guys so I have 3 sunpower e-series solar panels on the roof of my van. They are all ran into a fusebox/combiner which when the fuses are shut sends the power generated from the panels to the mppt 150/35 charge controller. When I test the voltage from the panels on the line side of the fuses I get 72.9 volts for each panel. When I close the fuse completing the circuit to the charge controller and the batteries the voltage drops to 1.9 volts tested at the load side of the fuses and at the pv +/- terminals on the charge controller. I don't get any lights on the controller, and no bluetooth connectivity. I'm not sure what is going on, I have 1 panel on each side of the van on it's own charge controller. I messed up on one and had the pos./neg. wires swapped so I accidentally blew the fuse on the 100/20 charge controller for the drivers side panel, but that passenger side 100/20 controller works fine, I can connect via bluetooth, I have lights on the front everything functions properly. So, my other small controller is bad (need to replace a fuse) but the big controller for the roof panels seems to be drawing the voltage from the panels down a lot. What can cause this?

AirborneEyePatch asked
Matthias Lange - DE commented ·

3 Answers

High grid voltage disconnect with Multiplus II in AU, why?

Lets be clear, I understand that power generators should not feed in energy if the grid voltage is already high, hence the regulations around handling high voltages. Hence the locked-in grid parameters.

I have recently has "grid lost" for short periods in the middle of the day when high voltages were sustained. Circuits upstream of the inverter were not affected by a power loss - that made it was clear that the MP2 disconnected itself from the grid. The MP2 went into "Inverting" mode.

The question is "why disconnect from the grid?". Why does the MP2 not simply go into "pass-thru" mode or a "zero-export" mode? To me this seems much more sensible. It achieves the desired outcome of removing the generator from the grid while not drawing down on batteries needlessly.

Is there any way to change this behavior in response to high (10 min moving average) voltages? (yes, ideally, fix the voltage issues but ...)

thank you,


rrroonn asked
rrroonn answered ·

2 Answers

Functional purpose of voltage sense wires?

Can someone shed some light on the intended functional purpose of the Voltage Sense wires on a Multi/Quattro?

Are you using it? If so, how/why?

The manual says loosely that it's "to make up for voltage losses across the wires".

With the volt sense wires connected or not connected, under minimal load or loads in excess of 100A, I've never seen any change in the reported voltage by the system.

This was true even before my installation of a BMV (with the lithium batts) and still so now, since SOC and voltage readings (I assume) are now coming exclusively from the BMV.

The voltage reported (by the BMV) is within .01 V of the voltage reported by the BMS on the batteries with minimal load, and within the expected 2-3% difference under heavy loads.

I'm using 2/0 (70ish mm cross section) wires and runs are around 10-13 ft to the batteries. The BMV is 5-7 ft to the shunt. 24V lithium system.

The lead-acid system prior was considerably sloppier, although still using 2/0 cable, and I still recall no differences.

Geomz asked
rjoustra answered ·

3 Answers

Voltage Sense in Multiplus when open


What is supposed to be the voltage in the V Sense terminals of a Multiplus 3000/24/70 when a is connected to battery and operating? The V Sense terminals are not connected (left open) and I see the same exact voltage as in the DC input terminals. Is this normal?

Elimac asked
lemonjelly commented ·

1 Answer

Usb low voltage problem - Bluesolar Pwm

Hello I have solar panel connected to car battery through Pwm, everything works fine, but after I started engine with a bit low battery, on Pwm started blinking U 0.2v, which means voltage on usb output is only 0.2 volts. Normally it shows around 5 volts. It happened me once before and after a while it went back to normal, but now it always stays the same.

Pwm is working normally, only usb is not working.

I haven't found any relevant info on this, do you have any idea what can be causing this and how can it be restored?

P.S: I tried disconnecting the module, but didn't help.

Thank you


Kubick asked
Kubick edited ·

0 Answers

Victron SmartSolar MPPT 150/85-MC4 Not showing panel voltages.

New out of the box. I connected 5 panels in series to the controller. Zero volts show up. Then I connected 1 panel to the controller. Measuring voltage across the MC4 connector is 21.0V as soon as I plug it in? Zero volts. Help?

TheSniper asked
TrinasGarden answered ·

2 Answers

Voltage and Temp monitor options

What’s the order of preference for voltage and temp monitoring? I just finished setting up my Victron solar generator for my off-grid cabin which is inclusive of a multi-plus 3000, Solar charger 100/30, BVM-712 and Cerbo GX. I have everything set up and working and trying to optimize my settings and limits but unsure which devices is best to handle monitoring or if the Cerbo GX is sharing it all either way.

Technically three of the devices are capable of the temp and voltage monitoring so should I just use one for each function or tie everything to the Cerbo since it will act as the hub? Or should I try to get each device to read as much data as possible?

An example is the temp compensation. The Multiplus has this input along with the BVM and Cerbo but since multi will charge battery when generator is running I assume it’s better to have multi manage directly. I’m hoping that the info is shared with MPPT for compensation as well through the Cerbo.

The multi also can measure voltage at the battery and compensate but then seems to make the BVM midpoint measure redundant. I only have 2 batteries in series so there isn’t much of a midpoint.

Perhaps I’m overthinking it but wanted to see if anyone else had similar thoughts.

Bob Cook asked
Bob Cook commented ·

1 Answer

What is the Multiplus output voltage?

Hi all, my first post here.

Does anyone know how to calculate the output Voltage of Multipluss II inverter?

For example, the Voltage at the property (distribution board) is exactly 230V.

If Inverter would be charging batteries from the grid then there would be some voltage drop dependng on cabeling and load, say 2%, so Voltage at the end of the circuit where inverter is connected would be 230-230*0.02=225.4V

If now we wanted to export the energy from the battery, we would have to have higher voltage at the property than on the grid side (>230V) so the output Voltage should be at least 230V + whatever voltage drop (lets say we export the same power and it is again 2%). Would that mean that Voltage at output terminals of inverter would be 230+230*0.02=234.6V? Or that plus X% or X Volts ?

Basicaly I am trying to understand how inverter decides what voltage to output when outputing AC current - is it matching the grid+X% by consistantly monitoring voltage at the terminals and making sure that generated Voltage is higher?


R2000 asked
warwick commented ·

1 Answer

BMV-712 firmware issiue?


the BMV 712, BMS 12/200 and Li-Battery is installed in a trailer.
Input (AB) fuse is 15A.

I'm trying to measure the starter battery voltage. The ground is connected through the BMS (AB) and the shunt (secondary input) is connected to the starter battery .

Is this a firmware bug or isn't it possible to measure the voltage across the BMS, because of the diode reverse current protection? Primary battery measuemend is fine.

The discrepancy is exactly 12V (24,4-12,4 = 12V), that looks a bit like a firmware issiue.








Heidi asked
Heidi edited ·

2 Answers

Controler doesn't read panel voltage

This worked all last season. No changes have been made since. Now the controler doesn't read the panel voltage correctly.

The voltmeter gives me 58v all the way to where the wires connect to controler. As soon as I connect, the voltage drops to 11v and no charging occurs.

I've redone connections with no help. About ideas?



BScholz asked
Maxxpwr answered ·

1 Answer

Venus gx VRM portal battery voltage data
Hey everyone,

I’m looking to get battery voltage data as a data point on the vrm portal, I can see the information on the 1hr chart but not on the daily or weekly information it only shows me battery capacity %age

as the BMV 712 only really give you an estimate battery capacity I like being able to look at battery voltage as data point as a fail safe. How could I make this happen? This is what I want to to see but across all points of time history.

Thanks in advance x

Ben Johnson asked
Alexandra commented ·

0 Answers

Issues with different voltages input into victron regulator

I have a victron 100/30 regulator. My two roof panels supply 48v into the regulator.

I want to add in portable panels when the roof panels are in the shade, but these will be 24v input into the same regulator.

Any foreseeable issues with this setup?

Jcee Bull asked
tilo answered ·

1 Answer

Solar Laderegler Mppt 75/15 lädt nicht.


Ich habe den Laderegler Mppt 75/15 neu eingebaut.

Er zeigt mir immer eine Solarspannung von ca. 12-13 Volt an.

Ich habe die Leerlaufspannung gemessen ca. 21-22 Volt die Kurzschlussstromstärke beträgt ca. 3,5 Amp.

Ich habe gelesen das die Solarspannung mindestens 5V höher sein muss als die Batterie Spannung.

Aber das Gerät zeigt nur eine Solarspannung von 12-13V an obwohl eine Spannung von 21-22 Volt vom Panel kommt.

Ich hoffe es kann mir jemand helfen.

Schöne Grüße


RAHSS asked
qwame answered ·

7 Answers

Venus gx VRM portal battery voltage data

Hey everyone,

I’m looking to get battery voltage data as a data point on the vrm portal, I can see the information on the 1hr chart but not on the daily or weekly information it only shows me battery capacity %age

as the BMV 712 only really give you an estimate battery capacity I like being able to look at battery voltage as data point as a fail safe. How could I make this happen? This is what I want to to see but across all points of time history.

Thanks in advance x


Ben Johnson asked

0 Answers

Autotransformer output not 120v

Hello. Is my brand new 100a autotransformer defective?! It is putting out 120v and 114v on each leg.

Can I fix this? What do I do?

GeorgeV asked
Pete MacLachlan edited ·

1 Answer

Adding a step up for my 230V boat. Help!

I have a European 230V boat that is now in America. All my systems will run on 50 or 60HZ so that isn't an issue. I just need the easiest and most cost effective way to convert the dock voltage from 110v to 230v. Do I use the isolation transformer or the auto transformer?

Mixman1 asked
Bathnm commented ·

2 Answers

Argo FET 4.4V voltage on input terminal with no alternator running

I have acquired a yacht wired with three 12V batteries on outputs. With the engine shutdown and no alternator running I have 4.4 Volts on the Input terminal and alternator circuit - I am not wiring the "energise" terminal. Is this usual or indicative of defective isolation as I am experiencing battery capacity leakage on one battery bank when not using the system for several weeks.

pmdent asked
vga commented ·

2 Answers

Is it posible to set an alarm with two separate conditions

Hello everyone,

as my batteries already twice caused a low voltage alarm (although above 80% SOC) after some days with little sun, I would like to set an alarm for the voltage in combination to the current, i.e. "voltage < 24V while current < 10A". Anybody can think of a possibility to set such alarm or should I send a feature request to Victron?

Greetings from Colombia,


chasen asked
Jaco Reinecke answered ·

1 Answer

Charge limit voltage (CVL) precision

I have a question about Charge Voltage Limit (CVL) when using BMS connected via CAN bus. In my system (VenusGX and Multiplus II) I'm using BMS connected via VE.Can (Batrium BMS). I would like to set Charge Voltage Limit (CVL) to 56.75V, but it looks like precision is fix to just one decimal place, so I need to set it to 56.7V or 56.8V. Is there a way to have 2 decimal places (e.g. 56.75V). All settings in VE Configuration tool have precision to 2 decimal places, why CVL (and CCL as well) is different???

Kind Regards

Mysik asked
Daniël Boekel (Victron Energy Staff) commented ·

1 Answer

High voltage on MPPT 75/15 battery output, when BMS closes due to temperature

Dear all,

I try to figure out, if the behaviour I see is per design or not. In my van I have installed a Victron LifePo4, a BMS12/200 and a MPPT75/15 with 2x110W solar panels. Due to the current cold weather conditions (<5°C), the battery and the BMS shutdown the battery charging.

Whenever there is sun available, the voltage on my BMS load and the MPPT battery output increase to ~17V. I assume this is due to the battery shutdown for charging. As soon, as the battery is open (>5°C), the voltage decreases to a normal level.

Is that expected? I thought the MPPT will reduce somehow the voltage when there is no charging in progress.

Why I am asking the question? If put the MPPT battery charging minus on the BMS load pin, where all my other load is also connected to. Now I have ~17V on all my devices, as long as the battery is shutdown. Is my design correct or do I need to change something?

best regards,


Fabian Pagel asked
KevP answered ·

5 Answers

BSC IP67 Volt und A Anzeige fehlerhaft?

Hallo Zusammen,

habe hier ein BSC IP67 Ladegerät an einer Victron 90Ah LiPo hängen. Ladestand der Batterie ca. 50% (BMV-712) bei 13.11 Volt (Multimeter). Wie dem Screenshot zu entnehmen ist das BSC IP67 da anderer Meinung.


Habe jetzt auch mal alles von der Batterie abgeklemmt und nur das Ladegerät angeschlossen. Gleiche Situation.

Hat wer eine Idee?

CaEike81 asked

0 Answers

Are my MultiPlus II VE Config charger settings correct for 4 x Omnipower 200Ah batteries?

Just want confirmation on my settings. Help will be appreciated. The ones in bold I'm most worried about.

Stop after excessive bulk checked

Lithium batteries unchecked

Storage mode checked

Use equalization (tubular plate traction battery curve) unchecked

Charge curve Adaptive + BatterySafe

Absorption voltage 57.60 V

Float voltage 54.60 V

Charge current 35 A

Repeated absorption time 1.00 Hr

Repeated absorption interval 7.00 Days

Maximum absorption time 8 Hr

Temperature compensation -72.0 mV/deg

Battery Specsheet: Omnipower-240.pdf

The system is a MultiPlus II 48/3000/35-32 with 4 x OmniPower 240AH batteries as a backup system. I'm using the BMV700 as a battery monitor. Venus GX.

jond asked

0 Answers

MPPT 150/85 TR uses wrong battery voltage

How do I get the MPPTs to get battery voltage from the batteries themselves, the lynx shunt, or the CCGX? All of these things have the correct voltage but the MPPTs are sensing 14.x

I have the following setup. CCGX, Victron LiPo 300amp batteries, Quatro 5000, Lynx Ion 1000 shunt, 2 MPPT 150/85 TR, D400 Wind Generator, dual Balmar 220 amp alternators.

My MPPTs are sync'd in a Bluetooth network and connected to the CCGX via USB. I thought they would get the batteries state from the CCGX. For some reason they detect 14.x voltage and go to absorbtion way too early. Any ideas?

Thanks in advance,


Jon S asked
Jon S answered ·

2 Answers

Solar charger 12v to 24 v

I want to change my mppt controller (150/60 mc4)

From 12 v to 24 v. I will use the same lead acid battery. Do I need to change settings in the controller or will it do it automatically?

Duncan asked
Duncan commented ·

1 Answer

Help with MPPT SmartSolar #39 Input shutdown due to battery over-voltage when connected to DC Power Supply

Image screenshot here https://photos.app.goo.gl/pQbGShgg3Jn73MGc7 (photo would not upload)

This error is occurring ONLY when connecting MPPT to a 12v single or string.

Using MPPT charger to perform distribution tests on parallel wiring.

Power source is 48v bridge rectifier, error reiterates with 24v 1500w switch mode.


Battery voltage is indeed switched to 12v, error reiterates with another AGM battery in the exact same way. No error with 24v or 36v strings, MPPT starts bulk immediately.

Have also tried with another MPPT out of the box, same problem.

Battery voltage is 11.50v

Thank you

Renz asked

0 Answers

Smart solar 100/30 Voltage Too High Momentarily
I turned off a device connected to my solar setup today and when it powered off I heard a beep. Upon further inspection I realized it was the high voltage alarm on my inverter turning on momentarily. I turned the device on and back off and realized from looking at my battery monitor that the voltage was jumping up to 15v or more for a split second (my lifepo4 battery is charged to 14.6). when I the load goes away. I also charge this battery from a sterling battery to battery charger, so I turned off the solar charge controller and started up the vehicle to start using that charger exclusively. When I turned off the device, this time the issue did not happen.

I should also mention that when the load is turned off and the voltage spikes, the three lights on the front of the charge controller flash.

It seems to me that the solar charge controller is causing the problem? It only seems to be happening after the latest update? This is a brand new problem. We have been using this device for a couple of months without any issues till now. Very strange! Any advice would be appreciated. I have to disable it for now which stinks, but at least I have a backup charging method.


abeausoleil asked
kosio86 commented ·

2 Answers


2 issues have occurred a few days ago.

1. App does not find device until solar panel disconnected and reconnected. Both iOS and android tried.

2. Battery voltage fluctuates widely (5-15v) util light is turned on then it settles.

I have tried 3 min reset. All wiring checked. It all worked for months before.

Any ideas?

Thanks Julian

JulianG asked

0 Answers

Victron 712 not showing voltage

I recently installed the Victron 712 in my RV, I have 4 6 volt flooded batteries connected, I found a diagram on your site showing the correct configuration to the 6 volt batteries and I am set up with that configuration. The issue I'm having is that the app only shows 0.03 volts on the Voltage. I've checked the voltage with a volt meter to see the output and it correct. Any help would be appreciated

tugetorg asked
tugetorg answered ·

1 Answer

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