Autotransformer Image


Batterien über Lichtmaschine Laden ?


bei einen von unseren Kunden haben wir:

- 2x Victron 160A Batterie Lithium ion

- 1x Solarladeregler MPPT 150/70 mit dazugehöriger PV-Anlage 1,6Kwp

- 1x MultiPlus 12/300/120-50

- 1x Cerbo GX, GC Touch 50


Der Kund wünscht sich gerne, das man die Batterien im Notfall über das Auto Bzw. Lichtmaschine laden kann, es ist ein Wohnwagen der an ein Auto angeschlossen wird.
Meine Idee war nun ich Baue ein Laderegler DC-DC Orion-TR 12/24-5 (120W) ein, dieser würde doch dann die Spannung vom Auto 12V hoch setzen auf 24V und gleichzeitig die Leistung begrenzen auf 120W. Kann man so etwas realisieren ? oder sollte man hier anders vorgehen ?

Mit freundlichen Grüßen


janlukas asked
nielscho commented ·

2 Answers

Isolation Transformer and/or Auto transformer?

I am fitting my sail boat with Victron equipment and I currently have a MultiPlus 12-3000-120 with two SmartSolar 100-30 MPPT controllers (one for each 300W solar panel) and a Battery Isolator for the alternator - all controlled by a Colour Control GX.

My question is this: I want to sail around the world and be able to connect safely to any marina power source and be able to plug into my boats 120v system. Obviously I want an Isolation transformer to protect me from badly provisioned power sources but also I want to be able to seamlessly run my systems whatever the power provided at any port.

I can't tell from the spec sheet if an auto transformer also acts as an isolation transformer?

Any advice would be greatly appreciated.

I have become a fan of Victron products and would like to build my boat electrics around them.

Kind Regards


whodarez asked
Rod edited ·

5 Answers

Electrolysis Problem - Autotransformer 120/240VAC-32A

I have recently installed an Autotransformer on my yacht to achieve 115 Vac power. Power is supplied by a 230 Vac Multiplus. According to the installation instructions, I achieved a Ground-Neutral bond by unchecking the Multi's "ground relay" setting and connecting ground relay to earth relay. The Autotransformer works just fine.

However, all my stanchions and other 316 stainless steel deck fittings have now started showing surface rust which is causing rust streaks down the hull. This did not happen prior to installation of the Autotransformer and is obviously unacceptable.

My 230Vac is grounded via 2 large zinc plate anodes through-bolted below the waterline. These anodes are not electrically isolated from the GRP hull. The engines, generator, watermaker, and other DC & AC electrical equipment are also all grounded to these anodes.

Any input/solution will be welcome

meshugga asked
trevor-bird answered ·

2 Answers

Parallel Autotransformers for Higher Power Neutral Forming

I'm trying to provide ~25kVA of split phase 120/240V 60Hz to a residence with two 15kVA 240V Quattro units. Even with a decent load balance, one 100A Autotransformer can't handle enough power. Can I parallel two of them? Does anyone have a wire diagram for paralleling autotransformers for neutral forming?

Am I better off just using four 10kVA 120V Quattro units (two pairs natively producing split phase) and not having the load balancing of an Autotransformer?

Also, does anyone know what the power losses are of the 100A autotransformer under load and no-load?

satiagraha asked
shaneyake answered ·

1 Answer

Multiplus AC Out is over voltage > 320VAC

I'm in the US. I have a Multiplus 230V that is connected to a Victron Autotransformer. The Autotransformer splits the 230/240V into two 120V legs which go to my breakers.

Currently at the AC1 Out terminals of my Multiplus it's measuring ~320VAC. The autotransformer is then pushing ~150VAC to my breakers/outlets.

What could be causing this? Could it be some issue with neutral bonding down the line? I have the multiplus ground relay disabled and the Earth/Ground relay wire connected from my Multiplus to Autotransformer.

Would really appreciate any help!


hummingbear asked
hummingbear answered ·

1 Answer

Multiplus and distribution transformer inverter noise

I have a Multiplus 12/3000/120 installed for a critical load panel. The output is tied to a ACME 5kVA 120/120-240 transformer. When the unit switches to inverter the inverter makes a weird noise. It does it with and without load. I have a video of the noise it makes, it's a little louder in person. I don't want to damage the inverter and I can't find anything in the book about not using a transformer and victron sells an auto transformer. What is causing this noise and will this damage the inverter?

Here is the info on the transformer:


  • Multiplus 12/3000/120 2x 1/0 AWG DLO battery cables per terminal.
  • 50A AC feeder, 6 AWG THHN
  • 50A AC breaker for transformer, 6 AWG THHN
  • 1200AH 12v GBS lifepo4 battery with EMUS can bms
  • Cerbo GX

arghhh40k asked
arghhh40k edited ·

0 Answers

Can two 100A autotransformers be connected in parallel for a 200A split phase output?

Hi VE Experts,
Can two 100A autotransformers be connected in parallel for a 200A split phase output? The system will have two Quattro 15000 240V units. This is for a 240/120V, 50Hz system so we cannot use two 120V Quatto units in parallel as the 120V is only for 60Hz output.



lalith asked
satiagraha answered ·

2 Answers

Autotransformer/Isolation transformer.

Hi, I’m hoping for some clarification please. I built my system for my truck using a single Quattro 5000 230v for a trip through Africa however plans have changed and we are now going to Canada. My system is primarily solar fed, a buckboost to feed whilst moving, a generator for those dull non moving days and the ability to hook up to shore power. My problem is I’ve confused myself with which step up transformer is best suited for my build, idealistically I want the ability to plug into any shore power with the transformer then feeding my Quattro on the AC leg. I’m not worried about the HZ and all my appliances are UK specification wiring that work perfectly with my current set up but for the odd times we will be hooking up to shore power can anyone advise to the best unit?
Sorry for the simplicity of this but I’m going round and round with this one, many thanks Will.

whick89 asked
kevgermany commented ·

2 Answers


I just installed 2 Multiplus 12/3000 120vac in Split Phase and running the outputs of those through a 100a Autotransformer. The idea was to Balance the output off the 2 inverter/chargers. I have they system wired per the manual, tying the output neutrals together from the Inverters. The system works OK when NOT inverting. But once AC mains are taken away and the system is inverting, one unit shows negative amps and the other shows positive amps. All AC load breakers are turned off and still using just over 40 amps of 12vdc per the BMV-712.


jerrytidwell asked
jerrytidwell answered ·

1 Answer

Ground Relay on autotransformer with 3rd party inverter and grid input

I am attempting to add the 100A autotransformer to my Sol-rk 12k setup for balancing the load (single-phase 240v). My setup most closely resembles 2.3.1 "Balancing a Generator or Stacked Inverters" in the manual except that my inverter supplies the load from the grid when sun's down and batteries are empty.

What's the recommended way to maintain that grounded neutral path back to my main panel at the service entrance since I'm creating a new Neutral at the AT? The manual isn't clear on how to utilize the ground relay with non-Victron inverters.


yamlcase asked
Kevin Windrem answered ·

3 Answers

Autotransformer Ground


I have purchased two Autotransformers with the intent to balance loads either on shore or generator. The boat is supplied with 50 AMP (240), a 9KW Generator and an Aims 4K Inverter. Half of the Air Conditioners are 240V, the other are 120V.

The goal is to use two separate autotransformers to power 2 air conditioners (120V) and 120V Battery Chargers. Both autotransformers will have 240V either from shore or generator as the source. (Planning on stepping down 240 to 120V)

Reading through the documentation I am a bit confused on how the ground is setup. Will the autotransformer create a "Fake Ground" thus any fault from an appliance will return to the autotransformer? I am guessing I should not connect the autotransformers ground to the boats central ground. Can someone confirm?

I noticed some information in the documentation recommending I remove the Neutral - Ground bond on the generator. This is not doable in my case since some of the 240V and 120V appliances will not pass through the Autotransformer.


daveinfl asked
yamlcase answered ·

1 Answer

100A autotransformer hot without load


I have just installed Quaddro 15kW 230V and I have 100A autotransformer on the output to convert 230V to split phase 120V for my house. I connected inverter and tuning batteries for a while and connected autotransformer input to inverter output, but I haven't connected autotransformer output yet (there is a bypass switch) so there is no load. I left it overnight and today morning I found that temperature LED is on and transformer body quite warm (not hot though). Is there a problem that there is no load connected or I have faulty autotransformer?

rglory asked
rglory commented ·

0 Answers

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: (

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
wolf commented ·

5 Answers

Autotransformer- shunt trip

I am using the Autotransformer to provide a neutral for off grid application. I have a loss of neutral circuit and I want to trip the breaker if it detects a loss. What do I need to do to trip the breaker?

rfbuehler asked

0 Answers


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