Does An Onan Generator Charge Its Own Batteries?

Whether the Onan Generator can charge its own batteries is a common question among novice RV users. This is because users often don’t want two generators that are ultimately charging the same battery. So, does the Onan generator charge its own batteries?

The answer is no; it does not. But this does not mean that you have to obtain a separate generator to charge the Onan generator batteries. Those batteries are simply charged through the converter.

Before we dig more into this, let’s understand a few things about RVs. 


What Are RVs?

A motor vehicle or trailer with living space intended for lodging is referred to as a recreational vehicle and is sometimes abbreviated as RV. RVs come in a variety of styles, from the functional to the opulent, with amenities like air conditioning (AC), heating systems, televisions with satellite receivers, and quartz worktops, for instance. 

Although double-deck RVs are less common, single-deck RVs certainly remain common. Larger RVs sometimes include expanding sidewalls (also known as slide-outs) or canopies which are deployed while parked in order to maintain a much more compact design when in travel. 

RVs are most frequently used as temporary housing when traveling. Instead of staying in a hotel room, some people may decide to take a road trip in an RV. When they get to their location, they could even choose to tow their car behind the RV so they can use it to go about more readily. Although temporary lodging while traveling is an RV’s most popular use, some individuals make it their permanent home. 

Types Of RVs

Motorhomes, trailers, and truck campers are the three basic types of recreational vehicles. A motorhome is a hybrid of a house and a car. This implies that they don’t require a tow vehicle to be driven. But on the other side, trailers need a second vehicle that can pull them. 

Finally, there is the little truck camper. This is neither a towable trailer nor a motorhome. It’s a compact cabin that’s also made to adjust in a pickup truck’s bed. You frequently discover a sleeping space, kitchenette, and dinette in a truck camper.

RV Systems to Know About

Let’s look at some of the important RV systems that every RV owner should be aware of.

Auxiliary Battery

Want to keep your RV’s appliances and lights running even while it isn’t moving? An auxiliary battery is therefore required, enabling you to turn off the automobile’s engine while maintaining electricity inside. These are frequently solar-powered, enabling longer off-grid periods.

Black Water Tank

The phrase “black water” refers to the discolored water from your RV’s bathroom. It’s critical to understand the black water capacity if you are using a black water tank.

Cassette Toilet

Smaller trailers and RVs can include cassette toilets, which are self-contained toilets that can be taken out and cleaned.


The motorhome’s structure is known as the chassis.

Freshwater Tank

Your freshwater tank is where you store clean, usable water.

Gray Water Tank

Wastewater from the bath and basin is called gray water. This flows into the black water tank or, in certain situations, the gray water tank inside your home.

Leveling Jacks

You must make necessary adjustments to the leveling jacks beneath each side of your RV for it to sit flat on uneven terrain.

Origin of Onan Corporation


Onan Corporation was started by David W. Onan, a resident of Minnesota. David, who disliked school, left at the age of 14 to help sustain his family when his father died. His first position was assisting with the construction of a power plant for Niagara Falls Power and Light.

The Reinhard Electrical Repair Department was his next post, where he oversaw 50 mechanics who completed 100–125 repairs daily. He worked on mechanical innovations in his own time while teaching mechanics at the Dunwoody Institute in Minneapolis throughout the First World War. His classmates frequently referred to him as a technical genius.

The automobile business did not have the level of service it does now in the 1900s. A defective component was supposed to be removed by the owner and sent for maintenance or replacement. David established his new business in the 1920s from his house, working primarily at night on tools and gadgets for the automobile sector.

Do Onan Generators Have an Internal Battery Charger?

The short answer is no. They do not. There are a few reasons for this. First, the generator lacks a charging circuit because it is intended to be used in an RV, which has an active converter/charger whenever it is exposed to 120 volts of electricity (irrespective of the source of 120 volts: generator or shore power). 

This would sound right that the Onan’s charging circuit will be turned off or not used in an RV if it did in fact exist (for usage in another installation type). Second, the generator’s battery is charged by your power converter. As you may have already seen, the generator shuts off when the battery runs out of power. 

This is due to the fact that the generator must travel a considerable distance—through the transfer switch, the converter, and back to the battery—to produce 12 volts instead of directly from itself. As a result, it’s crucial to connect the coach batteries to the generator batteries and never to disconnect the battery when operating your RV.

Do Onan Generators Have Alternators?

The majority of Onan generators contain an alternator, and inspecting it is a pretty simple process. Simply open your generator’s entry hatch to get started. Onan generators consist of an indicator light on top of the STOP/PRIME switch, which is located inside the top left or lower right edge of the generator, depending on the type and model. 

The alternator is broken if the indicator light is flickering. The alternator is in good shape, though, provided the light is always on.


And there you are. In this article, we discussed important information about RVs. We also talked about whether Onan generators can charge their own batteries. So, the bad news is that the generator does not charge its own batteries. But the good news is that it doesn’t need to, given that the generator batteries are connected to the coach battery.