The SMC SRD V4 is the latest version of SMC’s high-performance speedrun and drag racing LiPo. I tested it to see if it still holds the crown after the impressive results from the V3, which I reviewed about a year ago.
This pack is rated at 5000mAh and 250C, slightly smaller in capacity than the previous 5300mAh V3, but with the same C rating. It features 8AWG discharge leads, thicker than the 12AWG wires found on many other batteries. SMC also includes extra-long leads and a reinforced balance tap, making it easy to connect and charge safely.
At $79.95 USD, this battery targets serious speedrun and drag enthusiasts who need consistently strong power delivery.
What Makes It Unique
The SRD line—short for Speedrun Drag—is built specifically for high-current RC applications. The V4 continues that focus, but with key refinements:
- Lighter weight: 509g compared to the V3’s 578g—a 70g reduction.
- Same 250C rating despite the lower capacity, maintaining top-tier output potential.
- Custom connector options: You can order it with your preferred plug or install your own.
These updates make the V4 more efficient and easier to integrate into compact racing setups.
Internal Resistance (IR)
Testing showed identical IR values to the V3—an impressive result given the lighter build.
The V4 averaged 0.95 mΩ per cell. Using the Patreon LiPo calculator, that equates to a calculated 36.3C continuous rating, allowing for about 181A of sustained output while staying under 60°C. For context, that’s dramatically lower resistance than many mainstream packs like Spectrum’s, which measured over 4.5 mΩ in previous tests.
This consistency between generations shows that SMC has maintained cell quality while improving efficiency.
Load Test
I ran the standard 105A load test on the V4 and compared it directly with the V3.
Despite having a lower rated capacity, the V4 performed nearly identically to the V3 in runtime and energy output. The total usable capacity came out to 4806mAh versus 4860mAh on the V3—just a 1.1% difference under heavy load.
The V4 averaged 380W per cell, a 1.2% improvement over the V3. At 3.6V, it delivered 1269mAh compared to 1237mAh on the V3. Voltage at the 10-second mark was slightly lower—3.76V vs 3.80V—but within margin of error given the high discharge rate.
Overall, both packs were nearly indistinguishable in performance, but the V4 maintained comparable output with less weight, which can matter significantly in speedrun setups.
Practical Applications
The SMC SRD V4 is designed for speedrun and drag RC cars where voltage consistency, thermal control, and efficiency are critical.
It’s ideal for:
- High-load ESC setups that pull 100A+ continuously.
- Drag racers looking to shave grams while keeping peak current high and voltages high.
- Builders who want reliable output and flexibility with connector selection.
The 8AWG wires also minimize voltage drop, helping sustain stable performance throughout the run.
Final Thoughts
The SMC SRD V4 maintains the same top-tier performance as the V3 while shedding almost 70 grams of weight. The IR remains impressively low, and the pack’s ability to deliver stable power across the entire discharge curve shows excellent engineering consistency.
Even though its label lists a smaller capacity, real-world testing proves that it performs on par with the older version—if not slightly better in certain segments.
SMC continues to deliver elite-level LiPos for competitive speedrunning, and the SRD V4 reinforces that position. If you want to go fast, this is hands down the pack that will do it!
If you’d like full access to the raw data and comparison sheets from my battery tests, consider joining my Patreon community. Tier 1 members get access to the same RC LiPo calculator used in these reviews.