Why We Recommend AGM Batteries for Electric Power Steering Systems

One problem we frequently get calls about at ePowerSteering-
The steering assistance cutting out under load when using a lightweight lithium starter battery.

Why We Recommend AGM Batteries

In our experience, AGM batteries provide the most reliable performance for electric power steering systems. That is why we recommend them over lightweight lithium starter batteries.

Our column assist electric power steering systems can draw significant current during low-speed steering. Parking maneuvers, off-road driving, drifting, autocross, and oversized tires all increase electrical demand. Under heavier steering load, current draw can reach around 50 amps or more for short periods.

That type of demand is very different from simply starting an engine.

Starting Power vs Sustained Load

Many small lithium starter batteries are built mainly for engine cranking. They are lightweight and can deliver very high burst current for a few seconds. That works well for starting the vehicle.

Electric power steering creates a different type of load. Steering systems can place repeated and sometimes sustained demand on the electrical system. This is especially true during low-speed driving and parking.

A battery may start the engine successfully but still struggle to maintain stable voltage during steering load.

Why Voltage Stability Matters

Electric power steering systems depend on stable voltage.

Even small amounts of resistance inside the battery, battery management system (BMS), cables, fuses, or ground connections can cause voltage drop under higher current loads.

As current rises, voltage drop rises proportionally

When voltage becomes unstable, the steering system may not perform correctly.

Possible symptoms include:

intermittent steering assist
warning lights
controller resets
inconsistent steering feel

Why Small Lithium Batteries Can Struggle

We most often see these issues with very small lithium starter batteries used in racing or powersports applications.

These batteries may have:

limited reserve capacity
aggressive protection circuitry
small internal cells
battery management systems not designed for repeated 40–60 amp accessory loads

Some larger lithium batteries designed for RV, marine, or off-grid use can perform much better. These systems often use larger cells and stronger battery management systems.

However, lithium battery performance varies widely between manufacturers and designs.