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Knowing the right cable size for inverters is essential to get the best possible performance from your system. The cable wires are responsible for transferring power from the battery to the inverter, so having the right size is a must. If the wires are too small, the inverter might not run at all.
The inverter and battery cable has to be as short as possible, preferably less than 6 feet. The longer the cable used, the greater the energy loss will be, and at 10 feet or more the voltage starts to drop due to resistance. If you need to use a cable longer than 6 feet, get the thickest gauge wire possible.
Inverter Cable Size Guide
Always use the shortest and thickest wire recommended by the manufacturer. As the cable length increases, the longer the power has to travel, and this results in some losses. If the battery and inverter cannot be installed in proximity, use the thickest wire suitable. The following are the recommended AWG wire sizes for various inverters.
|Wtats Capacity||Maximum Input Amps||AWG Cable Wire Size|
|Watts Capacity||Maximum Input Amps||AWG Cable Wire Size|
|Watts Capacity||Maximum Input Amps||AWG Cable Wire Size|
This guide is for general recommendations only. These are mainly for inverters that use one cable set (negative and positive). Other inverters may require two or more cable sets and necessitate other AWG wire sizes.
Cable size requirements may vary by manufacturer, make, model and brand. The exact size will be specified in your owner’s manual. Refer to it before you buy a cable wire set. You should also check the battery instructions if it requires a particular cable size or type.
The cable sizes for the inverter and battery are not necessarily the same as those for the solar panel and battery. Refer to the proper documentation or owner’s manual for the recommended wire gauge and lengths.
How to Calculate Inverter Wire Size Requirements
If you follow the tables here you don’t even need to do any manual calculations. But if you want to do the numbers by hand, it is easy enough.
Divide the inverter watt capacity by the voltage to find its amps, then use the table above to find the equivalent wire size.
Suppose you have a 1500 watt 12V inverter, the WZRELB Pure Sine Wave. for example. The calculation is like this:
1500 / 12 = 125
The inverter draws a maximum of 125 amps. Using the chart as a guide, you can see that an AWG wire size 2, 2/0 or 4/0 is ideal. Do not worry if the wire sizes are not an exact match with the inverter. These sizes are recommendations only, and you can always go one larger.
However you should never go one size smaller. The worst thing you can do is use a long, thin wire as it will generate heavy resistance and adversely affect system performance. if you need a 4 AWG wire, we recommend the Spartan Power Cable Set because they work with these inverters.
Bottom line: do not use a smaller cable size than what the manufacturer recommends. This could damage the inverter or even cause a solar arc fire.
Cable Sizes For Small Inverters
Inverters less than 500 watts are usually bundled with cables that can be used directly with batteries. Most also have a cigarette lighter adapter which can be set on the cigarette lighter socket of any vehicle.
Inverters with bundled cables save you the trouble of figuring out what wire sizes to use. However you are stuck with the cables provided unless you use an extension cord.
Inverter cigarette lighter adapters are plug and play. Once plugged in your vehicle it should work. However you won’t be able to use the maximum power. From a 500 watt inverter, the lighter might pull only 250 watts. But if portability is your main prioerity,, then this should be an issue.
Larger inverters (500 watts and above) are the ones that need the wiring. Some of them may come bundled with cables, but usually that is a separate purchase.
How Far Can an Inverter be From Batteries?
The maximum recommended distance between an inverter and a battery is 10 feet. Beyond 10 feet and the voltage starts to drop. This can be remedied by using a thicker wire gauge, though they are more expensive.
This guideline – use short, thick wires – applies not just to the inverter and battery but every cable connection in your solar power system. In some cases this is not possible – rooftop solar panels for instance – but keep the distance as short as practically possible.
You can also place long cables on the inverter AC side instead of the DC. Use an extension cable if necessary. The energy / voltage loss may be reduced though it depends on the inverter design. This is a good option if you have a large inverter and want to install it near the battery bank.
Your inverter manual might offer other suggestions on how to offset the issues with lengthy cables. Follow whatever suggestions the manufacturer recommends.
Why Inverter and Battery Cable Distance Matters
In theory you can install an inverter anywhere and from any distance from the battery bank. But the bigger the inverter and the further it is from the battery, the larger the voltage drop. In fact the voltage may plunge so low the inverter will not even run.
This drop might also trigger the low voltage protection integrated in these systems. When an inverter senses the voltage has fallen below acceptable levels, it will stop running any load connected to it. If the cables are too long and not the right size, it might not even accept a load.
The biggest factor here is the gauge or thickness of the cable. A thick enough wire might be able to overcome the distance problem and run the inverter. This is the reason why if you cannot avoid using a long cable wire, make sure that it is the thickest available. This can also try this with inverters that keep shutting down.
If you notice that the inverter is consuming more power than what the load should, or that it is not performing as expected, this might be attributed to the inverter and battery being too far apart from each other.
Can You Use an Extension Cord with a Power Inverter?
Yes you can use an extension cord with an inverter. If the distance between the inverter and the battery or appliances is too far, an extension cord will work. Just make sure the cord specs are suitable for the inverter and load.
The question is how much of a signal / power loss there will be. As stated earlier, inverter and battery cables should be kept as short and thick as possible to prevent power loss. However there are some extension cords that claim no signal loss even over a hundred feet distance.
This might be true with regards to the performance of the load. A washing machine running off an inverter with an extension cord should run fine, for instance. But due to the cable length, the energy wasted would have increased.
If you are not sure, check your inverter owner’s manual for more details. There should be information stating what type of extension cord can be used and up to what distance. just like with everything else, you should only use what the manufacture recommends.
One way to avoid using an extension cord is to plan the installation first. Make sure the inverter and the battery bank have proper spacing. The battery must be the right size too. The location must not only be well ventilated, but there should be space for the cables to go through and reach the appliances and each other.
By planning the installation ahead of time, you can determine where the inverter and batteries have to be so they can be as close to each other as possible. Doing this will reduce the amount of time required to configure the cables so they are in the right position.
Having a large, powerful inverter is not enough, and neither is having a battery bank. The cables, wires and connectors matter just as much, so make sure that your system has the right set of cables connecting each component. If the cables are the right size and length, you can be confident of the results when you start running the inverter.