What You Need to Know About Using a 3rd-party Lithium Battery with ePropulsion Electric Motors

Edit 01/01/25: added info about the Pod Drive motors.

Unlike many other electric motor brands, ePropulsion allows the use of 3rd-party batteries. However, to avoid damaging your battery or Navy motor, it’s crucial to pick the right one. Using the wrong battery can cause significant problems, given the significant power requirements of the Navy 3.0 Evo, Navy 6.0 Evo and Pod Drive 6.0 Evo.

Choosing a 3rd-Party Battery

First, we’re only considering lithium (LiFePO₄) batteries here, because the capacity to weight ratio is vastly better than lead-acid batteries, although lead-acid batteries can be used.

The lithium batteries most similar to the purpose-built ePropulsion batteries are most commonly intended for use in electric golf carts. Like electric outboard motors, golf carts have high demands on continuous high-current power draws. Because they’re not intended for boats, these batteries often aren’t environmentally sealed and don’t provide a suitable IP rating for a water-based environment, unlike ePropulsion’s batteries. You’ll need to keep this in mind when considering placement in your boat.

Key Specifications

1. Voltage: Make sure the battery you choose a 48V battery or connect the batteries in series to create a 48V system (eg. four 12V batteries or two 24V batteries.
2. Continuous discharge current: The Navy 3.0 outputs up to 3,000W and the Navy 6.0 outputs up to 6,000W. Being 48V systems, this corresponds to 62.5A and 125A respectively. Therefore your 3rd-party battery must be able to sustain a continuous current discharge of 62.5A when used with a Navy 3.0, and 125A when used with a Navy 6.0.

For all the specs that a 3rd-party battery must meet, see our FAQ What specs does a 3rd-party battery need to be compatible with a Navy electric outboard?.

Risks of Using the Wrong Battery

Batteries capable of sustaining high prolonged current draw (like ePropulsion’s own batteries) are more expensive than those that have lower limits on current draw, or those that support a high draw but only for small bursts.

While it’s technically possible to save even more money by purchasing a 3rd-party battery that doesn’t white meet the maximum continuous discharge current spec, you should be aware of the potential consequences. Neither ePropulsion nor OceansEV recommends this, for the record.

• Voltage sag: High current draws near or exceeding the battery’s limit may lead to voltage sag. If the battery’s protection circuitry kicks in due to excessive current draw, this can trigger a low-voltage cutoff on the motor and the motor may shut down unexpectedly, which could be dangerous, especially if you’re far from shore or in challenging conditions.
• Damage to Motor Electronics: Inconsistent current output from the battery—when the maximum continuous current limit is breached forcing the battery to cut output then start again—can damage the motor’s internal electronics.
• Battery Overheating: Overheating from operating at or past the current discharge limit can degrade the battery cells, leading to potential thermal damage and reducing lifespan or causing permanent damage.

Any damage that occurs to a Navy motor from using a 3rd-party battery will void the warranty.

Connecting a 3rd-Party Battery to an ePropulsion Electric Motor

There are two options for connecting the motor to the battery:

1. Direct connection by replacing default connectors: Replace the quick-connect terminals on the motor’s cable with crimp-on ring terminals. Since up to 125A of current may flow through these connections, ensure they are properly attached. Professional installation is recommended. Also keep in mind that the warranty may not cover any damage sustained by the motor if it’s determined a problem was caused by improper connections.
2. Using a bus bar and proper cabling: A safer option is to use universal battery cables connected through a bus bar. This preserves the quick-disconnect functionality of ePropulsion’s system and ensures reliable connections.

Configuring the Throttle Control

ePropulsion batteries are plug-n-play (thanks to the communications cable), but when connecting a 3rd-party battery, make sure you configure the tiller or remote throttle based on the battery you’re using, by programming the appropriate values for battery chemistry type, capacity, and cutoff voltage.

Why Choose ePropulsion Batteries?

If you want to avoid any chance of problems and like to buy the very best, you can’t go wrong with ePropulsion’s own batteries, the E-series LiFePO₄ batteries. Yes, they are more expensive, but they’re designed specifically for the Navy-series motors and offer several significant benefits, particularly regarding efficiency, safety, and performance. In addition, if there’s an issue with the motor, using an ePropulsion battery ensures your warranty won’t be voided by use of a 3rd-party battery.

Note that we’re not advocating for or against ePropulsion batteries. We recognize that there are some benefits associated with genuine ePropulsion batteries and some risks with using a 3rd-party battery, they also carry a higher cost (although not as much as you might think).

Optimal Performance

Genuine ePropulsion batteries are designed to work seamlessly with ePropulsion motors. They ensure consistent power delivery, avoiding fluctuations that could harm the motor or reduce performance. The battery’s performance is calibrated to provide the appropriate voltage and current for efficient motor operation, enhancing the motor’s lifespan and reducing wear.

Safety Features

ePropulsion batteries feature a robust BMS (battery management system) for safety (arguably the most important component of a high-capacity lithium battery). The battery’s BMS communicates with the motor to provide real-time status updates, such as charge level, temperature, and health. The BMS in ePropulsion batteries come with built-in safety mechanisms, such as overcharge, over-discharge, short circuit, and temperature protections, ensuring safe operation. Accurate power management avoids sudden power loss, especially during critical operations.

While all lithium batteries will have a BMS, the quality of the BMS can vary greatly, and this is the component that is typically compromised by some manufacturers to achieve a lower price point.

The BMS in ePropulsion batteries are specifically tuned to the requirements of ePropulsion motors, reducing the risk of damage or accidents.

Real-time Communications Between Battery and Motor

One feature that comes with the genuine ePropulsion battery is the ability for the battery to communicate directly with the motor via the communications cable.

The cable allows the motor and the battery to exchange real-time data, such as battery charge status, voltage, current draw, and temperature. This information is displayed on the motor’s interface, enabling the user to monitor system performance at a glance. By communicating precise power requirements, the motor ensures the battery delivers energy efficiently, reducing wastage and optimizing run time.

The cable enables the motor and battery to work together to implement safety measures. For example, the motor can reduce power output or shut down if the battery is overheating. It prevents the motor from operating when the battery charge is too low, protecting both components.

Advanced features like range estimation and energy consumption tracking rely on the data shared via the communications cable. These features improve the user’s ability to plan trips and avoid running out of power unexpectedly.

Some batteries provide built-in Bluetooth wireless and a free smartphone app to monitor information that would be accessed on the tiller display or remote display when using an ePropulsion battery and the communications cable. The app will display real-time data such as power draw and remaining capacity, and via the phone’s GPS data, estimated range remaining. This at least partly compensates for not having that battery-motor communication, but requires you to keep your phone handy. Without Bluetooth and an app, 3rd-party batteries will usually build a simple LED gauge directly into the battery, and this gives you a rough idea of remaining capacity, but nothing else.

Some 3rd-Party Batteries to Pair With a Navy 6.0 Evo and Pod Drive 6.0 Evo

We’ve compiled a list of some batteries that meet the specs required of the Navy 6.0 Evo and Pod Drive 6.0 Evo. We chose the Navy 6.0/Pod Drive 6.0 because of their higher power and continuous current discharge requirements…finding batteries with the required specs is not as easy as batteries for the Navy 3.0, which are far more plentiful.

The prices in the table below include the cost of the universal battery cables and the bus bar, as this is the recommended method to connect a 3rd-party battery. If you didn’t want a quick-disconnect option and prefer to crimp/solder your own ring terminals, you would just reduce the cost by the price of these two products (about CAD$438).

Note that we aren’t recommending any of these batteries (except for the ePropulsion battery) and make no claims about the quality of them.

Make/Model	ePropulsion E163	BigBattery 48V HUSKY 2	Relion RB48V100	Epoch 48V 100Ah Battery	Vatrer 51.2V 105Ah Lithium Golf Cart Battery
Max. continuous current discharge	150A	150A	200A	150A	200A
Capacity (Wh)	8,345	5,120	5,120	4,800	5,370
Price including charger and connection components (CAD$)*	$7,195	$4,354	$9,469	$3,734	$2,797
Price per watt-hour	$0.86	$0.85	$1.85	$0.78	$0.52
Weight (kg)	76	45	62	44	46
Bluetooth + App?	No	No	No	Yes	Yes
Link	Visit	Visit	Visit	Visit	Visit