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A 750 watt inverter is more than capable of running various household appliances, electronics and power tools. But what exactly are its capacity and limitations? Can you run a refrigerator on this system? And if it is connected to a battery bank, how long before the batteries are totally drained?

A 750 watt power inverter can run laptops, a TV, cameras, radios, lights and other appliances. These inverters also have a 1500 surge watt capacity, which allows it to run a refrigerator, a microwave and various power tools.

What Appliances Can a 750 Watt Inverter Run?

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These inverters have a maximum capacity of 750 running watts per hour and up 1500 surge watts, which it can supply for a few seconds at most. If you want to buy one right now, we recommend the Ampeak 750W Power Inverter as it is designed to run various applications with ease.

These inverters can run any combination of appliances as long as it is less than 750 watts per hour total. The newer inverters are 90-95% efficient, so the actual available watts will be 675 to 712 watts.

By combining that information with an appliance wattage chart we can determine what appliances the system can and cannot run. Now you just need to compute the power requirements. Appliance power consumption is measured in watts, though the draw is sometimes listed in amps as well. The amps drawn per hour will depend on the voltage.

The conversion formulas are:
Amps x volts = watts
Watts / amps = volts
Watts / volts = amps

A 750 watt inverter with a 320 watt load running on 120V AC power will draw 2.6 amps.

320 / 120 = 2.6 amps

Another 750 watt inverter running a similar load on 24V batteries will pull 13.3 amps.

320 / 24 = 13.3 amps

If the power load is in amps and you want to find its wattage equivalent, multiply amps with volts. The conversions are not exact, but the results are always rounded off so it is not an issue.

13.3 amps x 24V = 319.2
2.6 amps x 120V = 312

These results are estimates. You should look up the inverter efficiency and factor that in with the runtime. Multiply the total watts by the inverter rating to get an estimate. Pure sine wave inverters are the most efficient, so we suggest the POTEK 750W for best results.

If you have a 450 watt load and a 90% efficient inverter:

450 / .90 = 500

That 450 watt load will use up 500 watts. Obviously the lower the efficiency the more watts will be used up. This is one of the reasons why it is never a good idea to run an inverter at full capacity. It not only is dangerous but there probably just isn’t enough power available.

Inverter Running Watts and Surge Watts

The rule of thumb is the inverter surge / peak capacity is double the running watts. For a 750 watt inverter that would be 1500 watts. This means the inverter can run this watt load for only a few seconds

An energy efficient refrigerator might use 500 running watts a day, but it requires 1000 watts to start up. With a 1500 surge watt capacity the inverter can power the fridge. Any appliance with less than 1500W peak requirement will run.

Blenders, portable fans, small microwaves, small sump pumps, a 1/2 inch drill, 1/4 HP motors and garage door openers can run on a 750W inverter.

Air conditioning units, clothes washers, dishwashers, furnaces, air compressors, circular saws and other power tools need more than 1500 watts to start up, so a larger inverter is required.

How Long Will a 750 Watt Inverter Last?

An inverter can run on an electrical source (usually 110V/120V) or batteries. If the inverter is on AC, it can run indefinitely as long as there is power available. If it is battery powered, the runtime depends on the remaining charge.

To get the most accurate estimate, list all the appliances, tools and devices you will run on the inverter. Add the watts and this will give you a good idea of how long the power is going to last.

750W Inverter Battery Runtime Guide

If you are in a hurry, here is a quick guide to various power loads that you can run on the inverter and for how long. This guide assumes the system runs on batteries, which will be completely drained at the of the runtime.

• Laptop, printer, speakers, router, portable fan, LED lights: 2 hours
• Refrigerator: 8 hours
• 40 inch TV with movie player: 5 hours
• 600W microwave: 1 hour
• Well pump: 1 hour
• Slow cooker: 3 hours
• 60W ceiling fan: 12 hours
• 60W light bulb: 12 hours
• Blender: 1.5 hours

Some notes on this guide.

• The power consumption listed above are estimates. The laptop in this example uses 200 watts, which is typical for running business applications and web browsing. A gaming laptop will need more solar power.
• Many appliances have variable usage. A blender will use up about 700 watts in an hour, but in reality they are only used for a few minutes or seconds at a time. The same with other appliances and tools so their usage is not as high as it seems.
• The chart assumes the inverter has 750 watts of power available. That is equal to a 62.5 12V battery or a 31.25ah 24V battery. Rounded off to the nearest size that would be 75ah 12V or 35ah 24V.
• You can mix and match the appliances as it matches your requirements. There is no one size fits all solution here because no one runs appliances or tools identical to another.
• Because of the differences in manufacturing, the power consumption may vary among appliances. Even if the specs are the same, some appliances will be more efficient than the others.
• Inverters will perform better when short, thicker wires are used. The shorter the cables between the inverter and the batteries, the less energy will be lost during the conversion.

And this brings us to the next point, how many batteries you will need for the inverter. And as you will see, the math is not as difficult as it might seem.

How Many Batteries Do I Need For a 750 Watt Inverter?

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If you are on a grid tied system you do not need a battery bank. The inverter will run off the main power. As long as there is electricity your appliances will keep working.

But if you are in an RV or solar powered mobile home, the inverter power supply will come from the battery bank.

To find out how many you need, use this formula:

Appliance watts x runtime = total watts
Total watts / DC volts = amps

Suppose you have a 12V 750 watt inverter. If you place a 750 watt load, the inverter will run for an hour or so, depending on its efficiency rating. The system will pull 62.5 amps (750 /12 = 62.5). If you have a 75ah battery, the runtime will be 1.2 hours (62.5 / 75 = 1.2).

So you can run the inverter on a 75ah battery for 1.2 hours, but this will result in a complete discharge. This is not advisable for FLA batteries as they are supposed to be recharged at 50%. If you follow this rule it would take a 12V 150ah battery to run a 750 watt load for 1.2 hours.

Inverter Battery Capacity Sample Calculation

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Let us us another example. You add up all the load and it comes up to 400 watts. You have a 750W inverter and you need to keep this load running for four hours. The formula is the same as earlier: total watts / battery voltage = amps

If you have a 12V system the numbers would look like this:

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400 / 12 = 33.3

A 400 watt load draws 33.3 amps an hour so you need 133.2 amps to run it for four hours. Rounded off that would be a 150ah 12V battery. But to avoid draining the battery completely, you should double the battery size to 300ah.

With a 300ah battery bank the inverter can run your load for four hours without going under the 50% discharge rate. If your battery has a different discharge rate, adjust your calculations accordingly.

You can use the same calculation with a 24V or 48V inverter system:

400 / 24 = 16.6 amps an hour
16.6 x 4 hours = 66.4 amps

Multiply 66.4 by two equals 132.8 or a 150ah 24V battery. The higher the voltage, the smaller the battery size required. This is why majority of inverters have support for 24V batteries a they are becoming more common.

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Conclusion

A 750 watt power inverter is a good choice for RVs, boats or small homes that do not use a large system. Because they are capable of running various tools and appliances, it should serve your needs for years to come.