How to choose the right ESC for an RC aircraft
ESC selection by maximum current, voltage, BEC, safety margin, cooling, connector choice and the real load from motor and propeller.
Firma 40A Lite Brushed Smart ESC, 2S-3S: IC3 is a Spektrum product intended for surface RC vehicles, crawlers, bashers and race setups that need dependable Spektrum control electronics. This page presents the practical buying information a customer needs before ordering: fit, SKU, image, category, specifications and usage advantages.
The content is written for purchasing through RC-MODEL, without supplier prices or links to competing stores.
These guides explain the setup, safety checks and accessory choices that usually matter for this product type.
ESC selection by maximum current, voltage, BEC, safety margin, cooling, connector choice and the real load from motor and propeller.
How to match motor, ESC, LiPo battery and propeller as one complete RC aircraft power setup instead of choosing parts separately.
A step-by-step safety guide for measuring amps, watts and voltage sag so customers avoid overheating motors, ESCs and LiPo batteries.
A guide to receiver and servo power: internal ESC BEC, external UBEC, receiver battery, redundancy and large aircraft safety decisions.
Cell count, capacity, C rating, connectors, battery weight and realistic flight time explained for RC aircraft buyers.
| Technical Specifications | |
| Manufacturer | Spektrum |
| Brand | Spektrum |
| Product Code | SPMXSE40 |
| Spektrum Category | Cars & Trucks / Parts, Electronics & Accessories / Electronic Speed Controls |
| Connector Type | 4mm Bullet, IC3 |
| Product Family | Spektrum ESC and speed-control range |
| Application | surface RC vehicles, crawlers, bashers and race setups that need dependable Spektrum control electronics |
| Compatibility Focus | Check compatibility with Spektrum Smart equipment and the exact model requirements before ordering. |
| Auto Cutoff | Yes |
| BEC | Yes |
| BEC Voltage | 6V / 7.4V User Selectable |
| Forward | Yes |
| Input Voltage | 2-3 Cell Li-Po / Li-Fe; 5-9 Cell Ni-MH / Ni-Cd |
| Maximum Continuous Current | 40A |
| Motor Limit | 540 / 550 Size Motors |
| Product Height | 0.71" (18 mm) |
| Product Length | 1.41" (36 mm) |
| Product Weight | 1.69 oz (48 g) |
| Product Width | 1.18" (30 mm) |
| Programmable | Yes |
| Reverse | Yes |
| Technology | Smart |
| Amperage | 40A |
| BEC Continuous Current | 4A (Shared Between Receiver and Aux Light Outputs) |
| Low-Voltage Cutoff Programmable | Yes |
| Motor Type | Brushed |
| Water-Resistant | Yes |
| Product Application | Crawling, Surface |
| Maximum Burst Current | 160A |
| Turns | Below 8.4V; Down to 12T / Below 12.6V; Down to 35T |
Tags: Spektrum, SPMXSE40, Spektrum ESC and speed-control range, Spektrum Catalog, Spektrum Smart Technology, Spektrum ESCs, Spektrum Surface Electronics, RC-MODEL
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