If you’re considering purchasing an electric outboard, it’s important to understand the different types of batteries available. We aren’t getting into battery chemistry here (that’s a separate conversation—most modern electric outboards are paired with lithium batteries).
What we mean by battery type is how the battery physically connects to the electric outboard it’s powering.
There are three main types of electric outboard batteries:
- Integrated batteries (mounted on top of the motor)
- Built-in batteries (contained within the motor shaft)
- External batteries (mounted elsewhere in the boat)
Let’s break each one down.
Integrated Batteries (Top-Mounted)
Most portable electric outboards under 5hp / 3kW use integrated batteries, which sit directly on top of the motor shaft. This style was popularized by the Torqeedo Travel and is also used on newer motors like the ePropulsion Spirit 2.
Integrated batteries are designed to be simple and portable. They typically weigh around 20 pounds, or a little less than half the total weight of the motor. If you need more range, you can carry a second battery and swap it out in seconds.
Key advantage: portability and flexibility
Built-In Batteries (Internal)
Some newer portable electric outboards—like the ePropulsion eLite and Remigo One—use built-in batteries that are fully integrated inside the motor itself.
Because the battery is sealed within the motor (typically IP67 rated), there are no exposed electrical contacts that can get wet or corrode. This makes built-in systems more durable and simpler from a rigging standpoint.
The tradeoff is less flexibility. Since the battery isn’t removable, you’ll need to handle the full weight of the motor when charging. And if you need more range, you can’t swap batteries—you’ll need to recharge.
Key advantage: durability and simplicity
Tradeoff: less flexibility and more weight handling
External Batteries (Installed In Your Boat)
Once you get above ~6hp / 3kW, most electric outboards use external batteries. These batteries are not mounted on the motor—they’re installed elsewhere in the boat and connected via cables.
Motors in this category include the ePropulsion Navy Series, Torqeedo Cruise Series, and Momentum M Series. Some smaller motors (like the ePropulsion Spirit 2 and Spirit 1.0 Plus / Evo) can also be paired with external batteries using an adapter.
External batteries allow for significantly more capacity, since they’re not limited by size or weight constraints on the motor itself.
They also tend to offer a lower cost per kWh (cost per unit of stored energy). Think of it like buying a 36-pack instead of a 6-pack—the upfront cost is higher, but the cost per unit is lower.
Another advantage is flexibility. Many systems can use third-party batteries instead of manufacturer-specific ones, which can reduce overall system cost.
The tradeoff is portability. These batteries are typically not meant to be removed regularly, and most systems require dockside power for charging. Weight varies by size, but most batteries in this category weigh 70+ pounds.
Key advantage: range and scalability
Tradeoff: less portable, more complex installation, requires power at dock to charge
Which Battery Type Should You Choose?
If you’re planning to buy an electric outboard over 3kW, your only option will typically be an external battery. In that case, the decision becomes whether to use a manufacturer battery or a third-party system. You can read more about making that decision here.
If you’re looking at motors under 3kW, you’ll likely be choosing between integrated and built-in batteries.
Here’s a quick comparison:
Built-In Batteries
Benefits:
- More durable (sealed system, no exposed contacts)
- Faster, simpler motor installation
Drawbacks:
- Range can only be extended by charging
- More weight to handle at once
- May need to remove the entire motor to charge
Integrated Batteries
Benefits:
- Lightweight and portable; less weight to handle at once
- Easy to remove and charge off the boat
- Ability to swap batteries for extended range
Drawbacks:
- Less durable (exposed contacts)
- Requires handling the battery separately