Cellular Connectivity for EV Charging Infrastructure

Cellular Connectivity for EV Charging Infrastructure

Every EV charge point that runs OCPP needs a reliable data connection. Without one, billing stops, remote management fails, and the charger shows offline to drivers and operators. Most connectivity failures on UK charge point networks trace back to the same root cause: reliance on site Wi-Fi or consumer broadband that was never intended for always-on machine-to-machine communication.

Cellular connectivity solves this. A dedicated 4G or 5G data link, independent of site infrastructure, gives a charge point a connection that the operator controls, monitors, and can manage remotely. This page covers the hardware options available – from standalone industrial routers to embedded cellular modules built into the charger itself – and the antenna and SIM choices that determine whether the connection holds in real-world conditions.

What the Connection Actually Needs to Do

OCPP (Open Charge Point Protocol) is the communication layer between the charge point and the Charge Point Management System (CPMS). It carries authorisation requests, billing data, energy metering, firmware update commands, and remote start/stop instructions. The protocol requires a persistent, low-latency connection. A session that drops mid-charge leaves the charger in an undefined state and may require a manual reset on site.

The data volumes involved are modest. A typical charge point sends and receives only a few megabytes per day over OCPP. Bandwidth is not the constraint. Reliability and uptime are. A connection that works at 99% availability means the charger is offline for around 88 hours per year – which, for a public charge point, is commercially unacceptable.

Option 1: External Industrial Cellular Router

The most common approach for commercial EV deployments is a dedicated industrial cellular router installed alongside the charge point – either inside the enclosure, in an adjacent cabinet, or on a DIN rail in the site distribution board. The router provides the cellular uplink and connects to the charge point controller via Ethernet.

This approach suits retrofits, multi-unit sites where one router serves several charge points via a switch, and installations where the charge point hardware does not include cellular connectivity as standard.

Teltonika RUT241 – Single SIM, Compact, Cost-Effective

The RUT241 is a compact 4G LTE Cat 4 industrial router with a single Ethernet port and a metal enclosure rated to -40°C. It fits inside most charge point cabinets and kerbside enclosures and runs on 9-30V DC. For single-unit deployments where one mobile network provides consistent coverage, it is the most cost-efficient cellular option. It runs RutOS with full firewall, VPN, and remote management support.

Teltonika RUT951 – Dual SIM Failover for Higher Reliability

The RUT951 adds a second SIM slot with automatic failover. If the primary network drops, the router switches to the backup SIM on a different operator without interrupting the OCPP session. Four Ethernet ports make it suitable for charge point clusters where several units share one cellular uplink via a switch. For any public-facing installation where downtime directly affects revenue, dual-SIM failover is worth specifying.

Teltonika RUTM Series – 5G and High-Availability Configurations

For high-footfall charging hubs, motorway service areas, and large depot installations, the RUTM series provides 5G throughput, dual-modem redundancy, and enterprise-grade reliability. The RUTM51 and RUTM56 support 5G with dual-SIM failover on each modem. All RUTM routers run RutOS with OpenVPN, WireGuard, IPsec, and full industrial protocol support.

Browse the full Teltonika 4G router range for charge point connectivity.

Option 2: Embedded Cellular for OEMs and Charge Point Manufacturers

For companies manufacturing EV charging equipment or building bespoke charge point controllers, embedding cellular connectivity directly into the hardware removes the need for a separate router enclosure, simplifies cabling, and reduces installation cost per unit at scale.

The Teltonika TRB series provides compact cellular gateway modules that integrate into embedded systems and custom enclosures. They connect to the charge point controller via Ethernet and provide the cellular data pipe, with RutOS running the connection management, VPN, and remote access layer.

Teltonika TRB140 – Compact 4G Gateway for Embedded Use

The TRB140 is a DIN rail or panel-mount 4G LTE Cat 4 gateway with a single Ethernet port. At 74 x 25 x 53 mm, it fits inside most custom enclosures. It supports single SIM, runs on 9-30V DC, and provides the full RutOS feature set including VPN, firewall, and remote management. It is widely used in embedded EV charging applications where board-level integration and minimal footprint are priorities.

Teltonika TRB145 – 4G Gateway with RS485 for Industrial Integration

The TRB145 adds an RS485 serial interface to the TRB140 specification, making it suitable for charge point controllers that communicate over Modbus RTU. Where the charge point hardware uses RS485 for energy metering or load management data, the TRB145 bridges that data onto the cellular network without additional protocol conversion hardware.

Browse the full Teltonika IoT gateway range for embedded connectivity options.

Antennas: Where Most Installations Go Wrong

The router or module is only as good as the signal it receives. Charge point enclosures are metal. Underground car parks are concrete. Roadside kerbside cabinets often have no clear line of sight to a mast. Internal device antennas perform poorly in all three scenarios. An external MIMO antenna mounted outside the enclosure, connected via a short low-loss cable, resolves most signal problems before they occur.

Understanding MIMO for EV Connectivity

4G and 5G use MIMO (Multiple Input, Multiple Output) to send and receive data on multiple independent signal paths simultaneously. A router has two or four antenna ports for the cellular connection. Connecting a 2×2 MIMO antenna uses both paths, improving both signal stability and throughput compared to a single antenna. For EV connectivity – where throughput requirements are low but connection stability is critical – the diversity gain of MIMO is more important than the speed increase.

Band Coverage Matters More Than Gain

UK 4G networks operate across multiple frequency bands. Band 28 at 700 MHz provides the widest coverage and best building penetration. It is the primary band used by EE, Vodafone, and Three in rural areas and inside buildings. Many antennas sold as “4G compatible” cover 800 MHz to 2700 MHz but do not include 700 MHz. If the installation site is rural, semi-rural, or inside a structure, an antenna with confirmed 700 MHz coverage is the correct specification. Confirm the antenna’s frequency range against the datasheet before ordering.

Antenna Selection by Installation Type

See the full 4G antenna range for MIMO panel, colinear, and puck options suitable for EV installations. For 5G deployments, see 5G antennas.

Read our explainer page for EV Charger Antennas.

IoT SIM Cards for EV Charging

A standard consumer or business mobile SIM is not built for always-on machine-to-machine use. Consumer tariffs prioritise handset use patterns – short bursts of high data, long idle periods. An EV charge point transmits small packets continuously, 24 hours a day, 365 days a year. IoT SIMs are rated and priced for this usage pattern.

Multi-Network SIMs for Coverage Resilience

A multi-network roaming SIM connects to whichever UK operator provides the strongest signal at the installation location. It is not locked to EE, Vodafone, O2, or Three. If coverage from one operator is weak at a specific site, the SIM connects to a better one automatically. For a charge point network operating across diverse locations – urban, suburban, and rural – a roaming SIM removes the need to pre-select an operator per site and reduces the risk of a site being underserved by a single network.

Private APN for Network Security

A private APN routes data from the charge point through a closed network rather than the public internet. OCPP traffic, billing data, and energy metering records travel directly to the CPMS without traversing shared infrastructure. Many network operators and enterprise CPOs specify private APN as a security requirement. It also enables the CPMS to initiate connections to individual charge points for diagnostics and remote commands.

Browse our IoT SIM connectivity range for multi-network and private APN options suited to EV infrastructure.

Remote Management: Running a Charge Point Network Without Site Visits

For a CPO or installation company managing charge points across multiple sites, the cost of site visits dominates operational expenditure. A router reboot, a SIM swap, a firmware update, or a configuration change should not require a van and a technician. The right remote management platform eliminates most routine site visits entirely.

Teltonika RMS (Remote Management System) provides centralised monitoring and control for all Teltonika routers and gateways in the field. From a single dashboard, engineers can check signal strength, data usage, uptime, and configuration status for every device on the network. Firmware updates and configuration changes push remotely to individual devices or groups. Automatic alerting on signal loss or device offline events means faults surface before drivers report them.

For VPN configuration between charge points and a private CPMS, see our guide to VPN on cellular routers. For detail on what RMS provides and how it is priced, see our Teltonika RMS explainer.

Frequently Asked Questions

What cellular router do I need for a single public charge point?

For a single charge point with standard uptime requirements, the Teltonika RUT241 covers most installations. It is compact, runs on the same 9-30V DC supply available inside most charge point enclosures, and supports the full RutOS feature set. For public-facing installations where downtime affects revenue, the RUT951 adds dual-SIM failover across two networks for a modest additional cost. Specify which mobile network provides the best coverage at the site before ordering SIMs.

Can one router serve multiple charge points on the same site?

Yes. A router with multiple Ethernet ports, or a router connected to a small managed switch, can serve several charge point units on the same local network. Each charge point gets its own IP address and its own OCPP connection to the CPMS. For sites with 10 or more charge points drawing simultaneous sessions, calculate the aggregate OCPP data requirement and check that 4G throughput at the site is sufficient. In most cases it is – OCPP data volumes are low. For high-density hubs, a 5G router provides headroom.

How do I get a signal in an underground car park?

Run a MIMO antenna on a low-loss cable from the router to a position with line-of-sight to the outside – a ventilation opening, a stairwell window, or a cable duct to the external wall. A 5 to 10 metre low-loss cable run is usually sufficient. The antenna goes outside, the router stays inside near the charge point. Cable type, connector type, and cable length all affect signal loss – specify all three before ordering. Contact our technical team to confirm the right combination for your site.

What is the difference between a cellular router and an embedded cellular module?

A cellular router is a standalone device with its own enclosure, power supply, and management interface. It connects to the charge point via Ethernet and handles all the networking logic externally. An embedded cellular module – such as the Teltonika TRB140 – is a compact gateway that mounts inside a custom enclosure or on a DIN rail alongside the charge point controller. It provides the same cellular connectivity but without the standalone enclosure. Embedded modules are used by charge point manufacturers integrating connectivity into the hardware at production stage, or by installers working in tight enclosures where a full router would not fit.

Do I need a VPN between the charge point and the CPMS?

OCPP 1.6 and OCPP 2.0.1 both support TLS encryption on the WebSocket connection between charger and CPMS. For many deployments, TLS alone satisfies the security requirement. A VPN adds a second encryption layer and – more importantly for private CPMS deployments – allows the CPMS to initiate connections to the charge point rather than waiting for the charger to call out. If your CPMS is hosted privately rather than in a cloud platform, a VPN tunnel from the charge point router back to the CPMS is the standard approach. All Teltonika routers support OpenVPN, WireGuard, and IPsec. See our VPN on cellular routers guide for configuration options.

Can I use the same SIM management platform across a mixed-router fleet?

SIM management is handled at the network operator or MVNO level, independently of the router hardware. If all SIMs are on the same IoT SIM platform – which routerstore.com provides – you can view data usage, signal events, and SIM status across the fleet regardless of whether the router is a RUT241, a RUT951, or an embedded TRB module. Router fleet management (firmware, configuration, signal diagnostics) is handled separately through Teltonika RMS for Teltonika hardware.

Related Products and Further Reading

Browse Teltonika 4G routers and 5G routers for charge point backhaul. For compact embedded options, see the Teltonika IoT gateway range. For antenna selection, see 4G antennas and 5G antennas. For IoT SIM options, visit the SIM connectivity section. For background on Teltonika’s own EV charging hardware, see our Teltonika EV chargers guide.