What Inverter Size (watts) for a Car (How to Avoid Common Dangers)?

You may need to run appliances that use AC power while you’re on the road for which you’ll need an inverter.

But what size of inverter should you use safely? Is it advisable to wire it to the car starter battery?

What precautions can you take to avoid draining the car battery so that you’re unable to start?

Read on to find out the maximum inverter size you can use in the car and truck and for tips to avoid running down the car battery.

How Big of an Inverter (watts) the Car Can Safely Handle?

Maximum inverter size for a car using the cigarette lighter socket

If you are connecting an inverter to the cigarette lighter socket, then typically the largest inverter size you can use might be 120 or 180 watts depending on the maximum current draw that can safely be handled by the car’s cigarette lighter socket. (Consult your car owner’s manual)

The cigarette lighter socket fuse will blow, and the wiring may overheat and melt should you connect an inverter whose power draw exceeds the maximum power it can handle!

What if you need to use a larger size inverter

If you plan to use an appliance with a larger power draw, you’ll need to run separate wiring direct to the battery that can handle the higher current draw and fuse it too with the right capacity fuse.

Note: Always keep the car engine running to prevent the excessive drain on the battery by the inverter and connected appliances.

Tips to Avoid Draining the Car Starter Battery

1. Keep the car engine running so that the starter battery is always replenished. A 180-watt inverter running at maximum power can discharge a 50Ah battery to 50% of its battery in about 1.5 hours only!

2. Use a secondary or auxiliary battery. Install a separate leisure battery charged by the car alternator to supply power to the inverter to avoid running the starter battery flat and getting stuck.

Why you Shouldn’t Connect too Large an Inverter

If you connect a larger capacity inverter than what the car cigarette lighter port can handle (usually 180 watts – consult your car owner’s manual), you risk damaging the wiring leading to the port. It can overheat and melt and the fuse will blow.

So, instead, connect separate and suitably sized and fused wire direct to a car battery that can handle the anticipated power from the inverter. Consult a qualified technician for assistance.

You may also be interested in this post: How to fix an inverter overload problem

Related Questions

How Big of an Inverter (watts) for a Truck

To work out how big of an inverter to use for your truck, use the steps:

Step 1. To work out how big of an inverter you need for your truck, determine first the power draw of the appliance you plan to connect.

Step 2. Select an inverter that can handle that appliance’s continuous and surge power draw.

Note, an appliance such as a fridge, microwave, or medical equipment such as a CPAP run better off a pure sine wave inverter.

Step 3. Confirm the maximum power the cigarette lighter socket can handle and plug an inverter whose continuous power draw does not exceed that.

You can use a larger capacity inverter by running separate wiring direct to the battery that can handle the higher current draw.

Closing Thoughts

If you plan to use the car cigarette lighter socket, in most cases, the maximum power rating of the inverter you can use will likely be up to 180 watts – check your car owner’s manual for the maximum power it can handle.

Do you need to run a larger size inverter? Then run separate wiring direct to the battery that can handle the higher current draw and bypasses the cigarette lighter socket and wiring.

Consult a qualified car technician. You risk damaging the car wiring or blowing the fuse should you use a larger capacity inverter than the car can handle.

Always keep the car engine running to avoid drawing down the starter battery or use a separate secondary battery in your car.

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