Voltage converter in the mobile home with 230V
The inverter makes it possible!
It doesn't matter whether you live in your camper or only use it for short trips. There are things like a voltage converter in the mobile home that we don't want to do without at this time either.
Charging the laptop and mobile phone or the electric toothbrush are classics.
Turn 12 V into 230 V - that is the job of a voltage converter, which we then need. So that
no unpleasant surprises happen on the way, I would like to show you what to look out for when buying a voltage converter in the motorhome or where you can save money.
Do you need an inverter?
Most important question: Do you even need a voltage converter in your motorhome?
Most important question: Do you even need a voltage converter in your motorhome?
Having 230V in a mobile home sounds exciting and necessary. Expecially, over the years its price became more and more acceptable, it turned out to RVers' standard equipments list.
How do 12V become 230V with a voltage converter in the mobile home?
An inverter in the mobile home takes the 12 V direct current provided by your on-board network and turns it into 230 V alternating current, as the word "voltage converter" already says.
You get a pure sine wave from the socket at home - however, a pure sine wave does not come from every voltage converter if you don't buy the right one.
There are big differences here. From the modified sine curve to a pure sine curve, which you often have to pay for with a higher-priced voltage converter.
In order to provide a low current for the 230 V, the voltage converter needs a high current from the battery.
Therefore, the correct wiring and the size of your utility batteries play an important role.
The power consumption losses cannot be swept under the table either - if the voltage converter runs all the time, it permanently eats a few watts and if 230 V electricity is required, an inverter works with an efficiency of approx. 85% - 90%.
It is therefore an advantage if you can switch off the voltage converter in the motorhome after use using a switch as shown in the picture.
Wave form: pure or modified sine wave?
Differencies between pure / modifed sine wave?
So that you understand what the whole thing looks like, I would like to show you in a small picture.
Here we have placed a modified sine over a pure one.
This is where you can see the differences and better imagine that for sensitive electrical equipment it is not beneficial to use a modified sinusoid.
With your laptop, the charger may get warm or even hum quietly. Batteries that have to handle complicated charging processes can also be damaged.
If a device does not get the power it needs, the batteries may be charged incorrectly or not fully.
With devices such as a Flex or a coffee machine, it does not matter whether the curve is pure or modified.
In the case of high charging currents such as a Flex, you also need a correspondingly large voltage converter. In this case I would take a closer look to see whether that is necessary.
You don't always need the large voltage converter in the motorhome. You can start here and possibly save money.
Do you need a pure or modified wave inverter?
Short conclusion: Depends on what you want to use on RV.
You don't always need the large voltage converter in the motorhome. You can start here and possibly save money.
Wattage
What power must the voltage converter in the mobile home have
You can of course always buy an extremely large voltage converter with 2000-4000W. But that doesn't make much sense. Therefore, you can easily calculate the performance.
So that you can work out for yourself how big your voltage converter should be in the motorhome, I would like to show you an example.
For example, my laptop charger needs 85W. With an efficiency of 85% we end up with approx. 100W, which is taken from the battery.
At 12V this results in a current of 8.3 A - this over three hours of charging time, we achieve 24.9 Ah, which you take from your battery.
In order not to buy a voltage converter that is too small, you should always plan a reserve. Take the power of your largest consumer and multiply it by 1.3.
So your voltage converter does not always run at its limit. These devices also have continuous current and peak current information.
However, you should only call up the peak current for a few seconds. This is important, for example, when you switch on devices and they need a certain starting current.
Battery for inverter
The right battery for your power inverter
To be able to imagine how long your desired inverter can be operated with your battery, there is also a simple way.
t (operating time) = ( V (voltage) x Ah (battery capacity )) / W (power of the converter)
In my case it would look like this, for example:
t = (24 V x 220 Ah) / 600 W = 8.8 h
This means that you can only run my small inverter for just under nine hours until my usable battery capacity is used up.
WIRING
The wiring is important for a voltage converter in the motorhome
In order to provide a small amount of current for the 230V consumer, the voltage converter in the mobile home needs a lot of current from the battery.
For example, if you operate a 1000 W voltage converter with an efficiency of 90%, a current of 91 A flows through your cable. It should be designed and laid accordingly.
Here it makes sense to choose short distances from the battery to the voltage converter and to dimension the cable thickness correctly.
How to calculate the cables cross-section for power inverter correctly??
How big should the cable cross-section be in my motorhome?
The right cable cross-section for your cables in the motorhome regularly creates uncertainty for many self-builders when researching.
I have provided you with a standardized table for a simple calculation and an online configurator with which you can calculate your cable cross-section for the mobile home expansion.
The simplest thing is, you just follow this table for 12V devices. For 220 V you can always use the cross-section of 1.5 mm2 for normal consumption.
For a double check, I have created an online configurator for you that you can use to check your values in the table.
Why did i do this If you use cables that are too small, it can lead to a cable fire in the worst case.
What do I enter how?
1) How long is your cable? Enter the number of meters here.
2) Enter amps. Look at your device and divide the wattage by volts (12V or 220V). My example: 110 W / 12V = 9.16A (rounded up to 10A).
3) You can derive the loss factor from my comment below.
4) The voltage in volts is always "12" or "220". It depends on which power source you want to connect.
Explanation of the loss factor?
When electricity flows through cables, losses in the form of heat occur. The declared aim is to keep these losses low, because heat production costs energy and this is known to be in short supply in mobile homes.
You have to consider your loss in the calculation of your cable cross-section. There are practical indications for this. With devices such as solar systems or the like, you can expect a voltage drop of 1%. You can orient yourself to these values. Devices such as televisions and similar electrical devices have a practical value of 4% for the maximum voltage drop. If you want to install LEDs or other lights, you can calculate a loss of 10%.
- 1% for solar systems
- 4% for devices such as televisions, refrigerators, LEDs, lamps
- 10% for devices such as LEDs, lamps
Calculation example
The refrigerator in your bus is connected from you personally. So you're wondering how thick the cable should be !? The device says that the power consumption is 110 W and that the device should be connected to the battery with 12 volts.
You ran a cable, which was run about 3 m through your camper. How we calculate the cross-section of the cable will be reproduced using the example of the refrigerator:
After this calculation, we need a cross-section of 2.19 mm2 according to the online configurator:
Since cable cross-sections are standardized for certain sizes, you can simply take the next largest cross-section with 2.5mm2.
Would you like to find out a lot more about the subject of converting a camper ?: Download the sample chapter here and learn everything you want to know about converting a camper on over 250 pages.
ATS, DC Breaker
The right battery for your power inverter
To be able to imagine how long your desired inverter can be operated with your battery, there is also a simple way.
t (operating time) = ( V (voltage) x Ah (battery capacity )) / W (power of the converter)
In my case it would look like this, for example:
t = (24 V x 220 Ah) / 600 W = 8.8 h
This means that I can only run my small inverter for just under nine hours until my usable battery capacity is used up.
440 Ah with 24 V are installed in my Mercedes truck , of which I use a maximum of 50% of my battery recommended by the manufacturer.
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