Sizing and Choosing Inverters to run AC Loads

EPEVER IP-Series Inverter Range

An inverter can be installed to convert 12V DC or 24V DC to 230V AC to power AC loads.

The most important consideration when choosing an inverter is to ensure that your battery bank will support the load.

In a camper or RV, an inverter of 350W – 500W is quite suitable for light AC loads such as a laptop charger (65W-100W), phone chargers (45W), or even small rechargeable power tools.

A load of 200W at 12V is 24A, which a couple of large AGM batteries can sustain for a few hours after dark. It’s a great idea to recharge any AC devices during the day to harness your solar power and save your battery power for the lowest loads after dark.

Many customers assume that larger loads will work with their battery systems by simply adding an inverter to the system. This is a mistake. A system should generally be designed from the ground up around the inverter.

If, for example, you wanted to charge two e-bikes for 6 hours, you would consume a whopping 450AH.

Here’s that power formula again…

450W charger / 12V = 37.5A x 2 bikes x 6 hours = 450AH!

At 20% DOD, you would need 2,200AH of available battery. This would also likely be a 24V or 48V system with enough battery power in parallel to deliver enough current from 10 large AGM batteries.

Put another way – if you connected a 2000W electric kettle to a 2000W inverter in a 12V system, this would draw a whopping 166A, which may likely overload/ damage the inverter, overstrain the batteries and probably cook wiring, blow fuses or trip circuit breakers in a system that is not designed to handle that amount of load.

Inverters designed for large AC loads like house appliances (washing machines, ovens, kettles, toasters, microwaves, etc.) are generally connected to large battery arrays. They are 48V systems and may have 8, 16, 32 or more deep cycle batteries or multiple large lithium batteries, making this application physically impossible and uneconomical in a van, RV, caravan or boat.

Other AC loads with large inductive currents can quickly overload or damage a system. For example, a 3-way fridge plugged into an inverter has a massive inductive startup load when the compressor motor starts up. This continuous start-up current draw will quickly render a house battery flat or damaged.

We would always recommend gas for cooking, kettle and hot water in an RV, Camper, Van or boat. 12 or 24V DC for lighting and RV-style appliances such as TVs, compressor fridges/ freezers, stereos and a SMALL 350-500W inverter for low current AC loads such as a laptop, broadband router or phone charger.

No coffee machines, no kettles, no toasters, no microwave ovens 😊