Overview
The Spektrum Firma 85A Brushless Smart ESC represents a significant step forward in electronic speed control technology for RC enthusiasts in the UK. Designed specifically for 1/10th scale 2WD and 4WD surface vehicles, this waterproof ESC combines intelligent telemetry with reliable power delivery, making it an excellent choice for both experienced racers and those new to brushless RC car systems. Whether you're running a competitive buggy, a bashing truck, or a crawler, the Firma 85A offers the performance, protection, and connectivity that modern RC vehicles demand.
What sets this brushless RC speed controller apart from traditional ESCs is its integration of Spektrum's Smart technology ecosystem. Rather than requiring multiple sensors, modules, and separate wiring connections, the Firma 85A uses a single-wire telemetry solution that feeds vital operating data directly to your Spektrum transmitter in real time. This means you'll receive instant feedback on RPM, motor temperature, battery voltage, battery capacity, and more — all without the complexity and weight penalty of additional components. For RC car UK enthusiasts seeking cutting-edge electronics that simplify rather than complicate setup, this represents genuine innovation.
Spektrum, a recognised leader in RC technology, developed and designed the Firma 85A in partnership with the industry's leading ESC manufacturer, ensuring that every aspect of this brushless ESC has been engineered for reliability, efficiency, and performance. The waterproof construction allows you to tackle nearly any terrain and weather condition — from dusty track days to rainy outdoor sessions — without worry, whilst the compact design and mounting tabs make installation straightforward in most vehicle platforms.
Key Features
- Waterproof design — The all-weather, waterproof construction of the Firma 85A allows it to perform in nearly any terrain under almost any conditions, meaning your RC car electronics will keep going through dust, gravel, snow, and water without degradation or failure.
- Smart all-in-one telemetry — Without additional sensors or modules, the Firma 85A feeds battery and ESC telemetry data straight to your radio in real time through a single connection, providing RPM, temperature, voltage, balance, capacity and speed information that helps you optimise performance on the go.
- Fast, powerful 32-bit ARM M4 processor — The advanced processor produces higher resolution signal input and more accurate motor output compared to slower controllers, resulting in smoother throttle response and more precise power delivery to your brushless motor.
- High current adjustable BEC — The switched-mode BEC can be configured for 6V or 7.4V output at up to 4 Amps continuous current, or 8 Amps burst current, providing reliable power for servo systems and other accessories without requiring a separate battery eliminator circuit.
- IC3 and IC5 battery connectors with EC3/EC5 backwards compatibility — The IC series connectors are designed from the ground up to provide more solid connections, higher heat resistance, and effortless installation, whilst remaining compatible with older EC-series connectors for basic operation and telemetry.
- Multi-point protection system — The Firma 85A includes over-current protection, automatic LiPo low-voltage cutoff, thermal protection, and failsafe protection to keep your RC vehicle and battery safe during operation under varying conditions.
- Multiple programming options — Whether you prefer simple button programming at the track, detailed configuration via the Smart Firma ESC Programming Box, or advanced settings through the SmartLink USB Updating and Programmer application, the Firma 85A offers flexible customisation to suit your workflow.
- Aluminium heat sink with cooling fan — The integrated heat dissipation system maintains optimal operating temperature during sustained high-current draws, extending the lifespan of critical components and ensuring consistent performance during long driving sessions.
- Ready to install with no soldering required — The Firma 85A comes pre-wired with industry-standard connectors, allowing quick and straightforward installation into most RC car platforms without the need for soldering or complex wiring modifications.
- Compact size with mounting tabs — Measuring just 43mm long, 53mm wide, and 33mm tall, the Firma 85A fits easily into tight spaces whilst the integrated mounting tabs ensure secure installation in your vehicle's electronics tray.
Technical Performance
The Firma 85A Brushless Smart ESC delivers genuine 85-amp continuous output, making it perfectly suited to 1/10th scale 2WD and 4WD vehicles running either 2S or 3S LiPo battery packs (5-9 cell NiMH compatible). With a maximum burst current rating of 550 amps and support for motor KV ratings up to 5000 KV on 2S systems or 3000 KV on 3S systems, this ESC provides substantial headroom for a wide range of brushless motor configurations. The input voltage range of 5 to 9 volts (2S-3S LiPo with maximum 11.1V) ensures compatibility with both budget-friendly and performance-oriented battery setups. Built from high heat-resistant connectors and featuring an aluminium heat sink with an integrated cooling fan, the Firma 85A maintains optimal operating temperatures even during extended driving sessions or competitive racing. The switched-mode BEC delivers adjustable 6V or 7.4V output at up to 4 amps continuous, providing dependable power for servo systems, receivers, and other electronics. Weighing just 116 grams and constructed in a rugged plastic case with mounting tabs, the ESC is compact enough to fit modern vehicle designs whilst remaining robust enough to handle the stresses of off-road RC car driving. The 32-bit ARM M4 processor ensures high-resolution signal processing and precise motor control, whilst programmable options including automatic low-voltage cutoff, brake delay, and thermal throttling protect both your electronics and battery investment during operation.
What's in the Box
- 1x Spektrum Firma 85A Brushless Smart ESC
- 1x Spektrum Smart sticker sheet
- 1x Product manual
What You Need to Complete
- Spektrum surface receiver (compatible with your transmitter)
- Spektrum transmitter with Smart technology compatibility
- 2S or 3S LiPo battery (IC3/IC5 or EC3/EC5 connector)
- Brushless motor (2000-5000 KV recommended based on battery configuration)
Frequently Asked Questions
- Is the Firma 85A Brushless Smart ESC suitable for beginners in RC cars? — Yes, the Firma 85A is an excellent choice for newcomers to brushless RC vehicles. The ready-to-install design requires no soldering, the straightforward button programming makes initial setup simple, and the comprehensive protection systems (low-voltage cutoff, thermal protection, failsafe) mean your battery and motor are well-protected. However, you will need to pair it with a Spektrum transmitter and receiver system to access the telemetry features that truly set this ESC apart.
- What battery does the Firma 85A need? — The ESC is designed for 2S or 3S LiPo batteries, supporting voltage ranges from 5 to 9 volts, with a maximum input voltage of 11.1V. You can also use 5-9 cell NiMH batteries if you prefer. For optimal performance on 2S, use brushless motors rated up to 5000 KV, and for 3S setups, stay within the 3000 KV range to avoid exceeding the ESC's current limitations.
- Does the Firma 85A work with my existing battery and charger? — If your battery features IC3, IC5, EC3, or EC5 connectors and is a 2S or 3S LiPo or 5-9 cell NiMH pack, it will work with the Firma 85A. The ESC's IC series connectors are backwards compatible with older EC-series connectors, though you'll only access full telemetry features if you're using a Spektrum Smart battery with IC connectors and a compatible Spektrum transmitter.
- How does the Smart telemetry system work? — The Firma 85A uses a single-wire connection to transmit real-time data directly to your Spektrum radio, eliminating the need for separate sensor modules or additional wiring. This telemetry feed includes RPM, motor temperature, battery voltage, remaining battery capacity, individual cell voltages (when used with Spektrum Smart batteries), and more — all displayed on your transmitter screen whilst you're driving, allowing you to adjust settings and monitor performance instantly.
- What makes this better than a standard brushless ESC? — Unlike traditional electronic speed controls that either store data for post-run analysis or require multiple separate components to achieve telemetry, the Firma 85A integrates telemetry into a single all-in-one package using Spektrum's Smart technology. This reduces weight, simplifies wiring, improves reliability through fewer connection points, and provides real-time data transmission that allows you to optimise your vehicle whilst driving rather than after you've finished.
- Is the Firma 85A waterproof? — Yes, the ESC features a waterproof design that allows it to perform in nearly any terrain and weather condition, including dust, gravel, snow, and water. This makes it suitable for both dry track racing and wet outdoor conditions typical of UK RC car enthusiasts.
- Can I use this ESC with a non-Spektrum transmitter? — The ESC will function as a standard brushless speed controller with any receiver that features standard servo-type pulse width modulation (PWM) output. However, you will not be able to access the Smart telemetry features, as these require a compatible Spektrum Smart radio system.
- What protection features does the Firma 85A include? — The ESC incorporates multiple layers of protection: over-current protection prevents damage from excessive motor load, automatic LiPo low-voltage cutoff preserves battery lifespan and safety, thermal protection throttles the motor if temperatures climb too high, and failsafe protection ensures safe operation if radio signal is lost.
Why Buy from RC Model Shop?
RC Model Shop is a trusted UK RC retailer and authorised dealer for all the brands we stock, including Traxxas, ARRMA, Losi, FTX, Hobbywing, Spektrum and more. Based in Walsall, we have a physical store where customers are welcome to come in, view products and purchase in store. Whether you are a seasoned competitor, a weekend basher, or just discovering the world of RC for the first time, our team of experienced RC enthusiasts is here to help you find the perfect setup and provide ongoing support. Order the SPM Firma 85A Brushless Smart ESC: Promoto-MX O-SPMXMXE85 today with confidence, knowing you are buying from an authorised retailer with genuine products, expert knowledge and a commitment to customer satisfaction. Shop online or visit us in Walsall — we look forward to helping you get the most out of your RC experience.
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