Author: Shawn – Battery Engineer – Power System Design

Standard off-the-shelf battery packs often fail under real-world conditions. This is especially true when you design power systems for outdoor motorized equipment. I am a dedicated battery solution designer at Himax Electronics. My primary objective is to engineer custom battery architectures that eliminate these pain points.

As a dedicated battery solution designer at Himax Electronics, my primary objective is to engineer custom battery architectures that eliminate these pain points. Today, I want to take you behind the scenes of a recent custom project. We specifically engineered a 25.2V 13Ah (327.6Wh) IP67 waterproof lithium-ion battery pack to reliably drive a 24V 350W motor for outdoor equipment in the UK market.

Cell Selection: Why We Chose DMEGC 18650 2600mAh (3C Rate)

The foundation of any high-performance battery pack is cell selection. For this specific project, our client needed a solution capable of outputting at least 15A continuous discharge current. This current powers a 24V 350W motor, especially when the trolley climbs muddy inclines under heavy load.

Instead of chasing the highest possible capacity, we prioritized discharge capability and thermal stability. We built a 7S5P architecture utilizing DMEGC 18650 2600mAh cells with a 3C continuous discharge rating.

Here is the engineering logic: A 3C rate on a 2.6Ah cell allows for roughly 7.8A of continuous discharge per cell. With 5 cells in parallel (5P), the theoretical continuous discharge capability of the pack safely exceeds 39A. This provides a massive safety margin over the required 15A continuous draw. This ensures the battery operates well below its thermal limits. It drastically reduces voltage sag during motor startup and extends the overall cycle life of the pack.

Rugged Enclosure & IP67 Waterproofing

When deploying equipment in regions with unpredictable weather like the UK, water ingress is the number one cause of battery failure. A standard PVC shrink-wrapped battery was out of the question.

You can see this pack in the reference photo (25.2V 13Ah(1).jpg). We engineered it inside a highly durable, rigid black AG enclosure that measures precisely 175mm x 125mm x 100mm. But the real engineering happens inside the box.

To achieve a true IP67 waterproof rating, we fully seal the entire internal assembly using a specialized potting compound. This assembly includes the 7S5P cell matrix and the BMS. This potting process makes the internal electronics impervious to water immersion and heavy rain. It also acts as an excellent shock absorber. This protects the spot welds and nickel strips from the continuous mechanical vibrations of the trolley rolling over rough terrain.

Smart Interfaces and Dual Safety Protection

A well-designed battery should communicate seamlessly with the end-user while protecting the equipment it powers. We integrated two specific external features to enhance usability:

1.Flush-Mounted LCD Display: Users can instantly read the exact battery capacity percentage and real-time voltage. They don’t need to power on the main equipment or use external meters.

2.Weatherproof XT60BE Connector: We utilized a panel-mounted XT60BE male connector equipped with a custom black rubber cover. This keeps the high-current connection dry and free of mud and debris. It does so even when you detach the battery for charging.

For safety, we need a standard Battery Management System (BMS). It prevents overcharge (max 29.4V), over-discharge, and short circuits. Outdoor motors can stall if a wheel gets stuck in mud, causing massive current spikes. Knowing this unpredictable nature, we integrated an additional 18A resettable fuse. If the motor stalls and attempts to draw dangerous levels of current, the fuse will trip instantly. This protects both the motor controller and the battery pack. Once the fault is cleared, the system easily resets.

Partner with a True Battery Solution Designer

At Himax Electronics, we differentiate ourselves by being more than just an assembly line. We are an expert battery solution designer. We understand that the battery cannot be an afterthought. Whether you are building heavy-duty tracking equipment, outdoor mobility tools, or sophisticated portable power stations, this principle holds.

If your current battery suppliers fail to meet your environmental, mechanical, or electrical requirements, then it is time to upgrade your power architecture. Get in touch with our engineering team via our contact page to discuss how we can design and manufacture a custom battery solution tailored exactly to your product’s demanding specifications.