This project does not include any coding, formulas, or tables. It focuses solely on the practical side of hardware — from understanding the component’s function to building and assembling a working device using real-world considerations.
Introduction to the Project Concept
With the rising popularity of electric mobility — from scooters and bikes to go-karts — hobbyists and DIYers often build their own battery packs or retrofit existing ones. One common need in these setups is safe and efficient switching and protection of the battery pack, especially under high-current conditions. This is where the SK25DGDL126T becomes extremely useful.In this project, we aim to:
● Use the SK25DGDL126T as a high-current switching element in a small EV battery circuit.
● Integrate basic voltage and temperature protection through passive components.
● House the setup in a compact, weather-resistant enclosure.
● Provide both manual and automatic disconnect capability, offering safety for the user and longevity for the battery.
Understanding the SK25DGDL126T
Before moving into the build, let’s briefly understand what the SK25DGDL126T is and why it's suitable here. It’s a dual fast recovery diode module capable of handling substantial current and voltage — often used in inverters and motor control systems. It is housed in an insulated package and has two diodes internally configured in a dual arrangement. The fast recovery nature allows for rapid switching without much heat buildup.In simpler terms: this module can block and direct large amounts of electricity with minimal resistance and minimal delay — perfect for switching and protecting a battery in a high-drain application.
Gathering the Materials
Here’s what we need for the project:● 1x SK25DGDL126T dual diode module
● Heavy-gauge wire suitable for 30–50A current
● 60V 20Ah Li-ion or LiFePO4 battery pack (or your existing pack)
● DC breaker switch (optional for manual override)
● Thermal fuse (65°C or 70°C rated)
● High-current inline fuse (30–40A depending on your motor specs)
● Voltage-sensitive relay or battery protection relay
● Aluminum or plastic project box
● Thermal pad or heatsink compound
● Drill, screws, heat shrink tubing, and soldering tools
Building the Switch and Protection Unit
Step 1: Planning the Internal Layout
Begin by sketching the internal layout of your unit. The SK25DGDL126T module is not tiny, and because it will carry high current, it should be mounted in a way that facilitates good airflow and heat dissipation. You might want to fix it on an aluminum base inside the box, using thermal paste to help transfer heat.Place the fuse, thermal fuse, and relay nearby, allowing for short wire runs between components. Keeping wiring short and thick reduces voltage drops and heat.
Step 2: Mounting the SK25DGDL126T
Use two small bolts or metal screws to mount the SK25DGDL126T securely to the box's base. Apply a thin layer of thermal paste or insert a thermal pad between the module and the base for efficient heat transfer. Even though this module is efficient, it can get warm when carrying continuous loads.Make sure you do not overtighten the screws, as the ceramic insulation of the module can crack under stress.
Step 3: Integrating Fuses and Thermal Protection
Next, connect a thermal fuse to the module or battery terminal. This fuse should trip if the internal temperature exceeds safe limits. It can be mounted directly onto the diode module using a small dab of thermal adhesive or a metal clip.Inline fuses should be connected on the battery’s positive output wire before it enters the switch unit. Choose a rating suitable for your motor — too low, and it’ll blow unnecessarily; too high, and it won’t protect.
These fuses protect your battery and the SK25DGDL126T itself in case of short circuits or overcurrent events.
Step 4: Wiring the Switch Circuit
Now, wire the positive input from the battery to one anode of the SK25DGDL126T. The cathode of this diode should connect to your motor controller's input. The second diode in the module can be used for reverse polarity protection or omitted if not needed.A manual DC breaker or switch can be placed in series with the diode, giving you the ability to completely shut off the system manually. Alternatively, if you're using a voltage-sensitive relay, you can configure it to automatically disconnect the circuit when the battery voltage falls below a safe level.
This automation helps prolong battery life by preventing deep discharges.
Step 5: Housing Everything Securely
Drill access holes in your enclosure for wires to enter and exit. Use rubber grommets or waterproof cable glands to protect wires and seal the box against dust and moisture.Place all components inside, making sure nothing is loose. Apply heat shrink tubing and insulation tape wherever necessary to prevent accidental shorts.
Once sealed, your unit should be rugged enough for outdoor or semi-exposed environments — perfect for use in e-bikes, scooters, or other mobile applications.
Testing and Deployment
Before connecting to your actual battery and motor, perform a dry test using a low-voltage power source, like a 12V lead-acid battery or bench power supply. Confirm that:● The switch opens and closes correctly.
● Fuses remain intact under expected loads.
● The SK25DGDL126T stays cool or only mildly warm.
● There's no unexpected voltage drop across the diode module.
Once you’re satisfied, wire the unit into your vehicle. Connect the battery's output through the unit to the motor controller. If you’ve installed a manual breaker, switch it on and check if the motor responds correctly.
Now you have a compact, safe, and efficient high-current battery protection unit, using a robust industrial diode module at its heart.
Why This Project Matters
At first glance, it might seem like overkill to use a high-spec diode like the SK25DGDL126T in a DIY electric bike. But safety and reliability are paramount in any high-current application. The characteristics of this module — especially its fast recovery, current handling capacity, and rugged packaging — make it ideal for small EV battery management.Here’s what makes this project stand out:
● No active cooling is required thanks to the efficiency of the diode.
● Failsafe protection through both thermal and current fuses.
● Manual and automatic disconnect options improve usability and battery health.
● Compact, durable design suitable for harsh outdoor environments.
Additional Ideas and Modifications
Once you’ve built the basic version of the switch unit, you might want to add more features later. Some ideas include:● LED indicators to show active/inactive state.
● Current shunt and ammeter display to monitor real-time power draw.
● Wireless control using a relay and RF module for remote shutoff.
● Solar input integration for off-grid battery charging systems.
These can all be added modularly without redesigning the core unit. The SK25DGDL126T can easily handle them thanks to its headroom in terms of voltage and current.
Final Thoughts
This DIY project is a great example of repurposing industrial-grade components for personal projects. By building a battery protection and switching unit around the SK25DGDL126T, you ensure a level of robustness and reliability that’s hard to achieve with consumer-grade parts.You don’t need complex circuitry or programming to get serious results in electronics. With careful planning, quality components, and a bit of mechanical intuition, you can build systems that rival commercial products in performance and safety.
And most importantly, you learn a great deal about power management, heat dissipation, and system integration along the way — skills that will carry over to every future project involving motors, batteries, or high-power electronics.
So the next time you're gearing up for an e-bike build or retrofitting a battery pack, remember: sometimes the best tool for the job is hiding in a TO-220-sized industrial diode module, waiting to shine in your DIY masterpiece.
US 24707 
BR 24231 
GB 11999 
CA 9257 
AU 9204 
IN 8581 
IE 4507 
NZ 4469 
