How Much Data Does an EV Charger Use? The 2026 UK Sizing Guide
How Much Data Does an EV Charger Use? The 2026 UK Sizing Guide
A typical charge point's everyday chatter can use less mobile data in a month than one short video on your phone.
The trouble is the other days. The day a 40MB firmware update fails and restarts five times. The week the signal drops and the charger keeps reconnecting. The month someone plugs an advertising screen into the same SIM.
That is when SIMs run dry and chargers go offline. And since the Public Charge Point Regulations 2023, an offline rapid charger is not just lost revenue. It counts against your 99% reliability target.
This guide answers how much data an EV charger uses, message by message, with real maths you can copy for your own sites. It is written for the installer, the charge point operator (CPO) and the council officer about to order 20, or 200, SIMs.
👉 Already know your numbers? See GleeSim's EE IoT SIM for EV chargers →
How much data does an EV charger use? A connected charger running OCPP typically uses around 30–120MB a month in our worked examples below, including one firmware update. GleeSim's planning range is 100–500MB a month. A 500MB IoT SIM covers most single chargers with plenty of headroom, unless a screen, camera or poor signal adds extra traffic.
Two things to remember:
- Electricity is measured in kilowatt-hours (kWh). That is the "fuel" going into the car.
- Data is measured in megabytes (MB). That is the charger "talking" to its back office.
They are not linked. A charger that delivers twice the kWh does not use twice the data.
Your Charger Is a Pen Pal: The Messages It Sends
Every connected charger talks to a back-office system, called a CPMS (charge point management system). The language they speak is OCPP, the Open Charge Point Protocol, managed by the Open Charge Alliance.
Think of each OCPP message as a postcard. Most postcards are tiny. A few are parcels.
|
OCPP message (1.6J name) |
What it means in plain English |
How often |
Size |
|
BootNotification |
"Hello, I've just switched on." |
Every restart |
Tiny |
|
Heartbeat |
"I'm still here!" |
Every few minutes (your CPMS sets it) |
Tiny |
|
StatusNotification |
"I'm free / busy / broken." |
Every status change |
Tiny |
|
Authorize |
"Is this RFID card or app allowed?" |
Each session |
Tiny |
|
StartTransaction / StopTransaction |
"Charging started." / "Charging stopped." |
Each session |
Tiny |
|
MeterValues |
"Here's how many kWh so far." |
Every 30–60 seconds while plugged in |
Tiny, but frequent |
|
GetDiagnostics |
"Send me your log files." |
When an engineer asks |
Medium to large |
|
UpdateFirmware |
"Download this new software." |
A few times a year |
Large: often tens of MB |
OCPP 2.0.1 renames some of these (for example, TransactionEvent), but the pattern is the same: lots of small postcards, a few big parcels.
The rule of thumb: data is driven by how often the charger talks and how long cars stay plugged in, not by how much electricity it delivers.
The Maths: Three Real-World UK Sites
Here is a worked calculation you can copy. We have kept the assumptions simple and deliberately rounded up, so real usage is likely lower.
Assumptions:
- Each small message exchange (message, reply, network and security overhead) = 1KB
- Each reconnect, including the security handshake (TLS) = 6KB
- Heartbeat every 5 minutes
- One firmware update this month = 40MB, plus one diagnostics upload = 10MB
- 1MB = 1,000KB, 30-day month
|
Monthly data, per charger |
A. Workplace 7kW AC 3 sessions/day, 4 hrs plugged in, MeterValues every 60s |
B. Council car park 22kW AC 6 sessions/day, 2 hrs plugged in, MeterValues every 60s |
C. Rapid 150kW DC hub 30 sessions/day, 30 mins each, MeterValues every 30s |
|
Heartbeats |
8.6MB |
8.6MB |
8.6MB |
|
MeterValues |
21.6MB |
21.6MB |
54.0MB |
|
Session messages |
0.5MB |
1.1MB |
5.4MB |
|
Status and fault messages |
0.3MB |
0.6MB |
1.8MB |
|
Reconnects |
0.9MB |
1.8MB |
1.8MB |
|
Routine month |
32MB |
34MB |
72MB |
|
+ Firmware + diagnostics |
+50MB |
+50MB |
+50MB |
|
Update month |
82MB |
84MB |
122MB |
|
Share of a 500MB SIM used |
16% |
17% |
24% |
Notice something? The slow workplace charger uses almost as much data as the council charger, because cars sit plugged in all day and the charger keeps reporting meter readings.
Quotable: Your charger's data bill follows the clock, not the kilowatts.
Want your own number? Swap in your CPMS's real heartbeat interval, MeterValues interval and firmware size. Your manufacturer can give you all three.
So Why Do Some EV Charger SIMs Run Out of Data?
If the maths says 30–120MB, why do some operators hit 500MB? It is almost always one of five data burners.
1. Reconnect storms (bad signal = big bills)
Every time a charger loses signal, it must reconnect and repeat its security handshake. A charger stuck reconnecting once a minute uses about 259MB a month on reconnects alone. Weak signal does not just drop sessions. It eats data. Fix: check signal at the exact charger spot, or use a multi-network SIM that can switch to the strongest network.
2. Firmware download retries
A 40MB update that fails halfway and restarts from zero five times costs 200MB. Some chargers resume a broken download. Some don't. Fix: ask your manufacturer which yours does, and schedule updates for strong-signal hours.
3. Chatty settings
Change the heartbeat from 5 minutes to 30 seconds and heartbeats alone jump from 8.6MB to 86MB a month. MeterValues every 10 seconds has the same effect. Fix: agree sensible intervals with your CPMS provider. The 2023 regulations require availability data to update within 30 seconds of a status change. That is about status messages, not constant meter readings.
4. Other devices sharing the SIM
A contactless payment terminal adds a little. An advertising screen or CCTV camera can add gigabytes. That is a different job and needs a different SIM. Fix: for charger + camera + screen on one router, size it like a business data line. See Is 2GB Enough for a Fixed IP SIM?
5. Remote engineer sessions
Remote log-ins, VPN tunnels and repeated diagnostics pulls during a fault hunt can use more data in one afternoon than a normal month. Fix: budget for it during commissioning and fault months.
Is 500MB Enough for an EV Charger?
Yes, for most single chargers that only run OCPP. Even our busiest worked example (a 150kW rapid charger in a firmware-update month) used about a quarter of a 500MB allowance. You need more only when signal is poor, settings are aggressive, or other devices share the SIM.
Use this table to pick the right fit:
|
Your setup |
Planning range per month |
Best GleeSim fit |
|
Single AC charger, OCPP only, good signal |
Under 100MB |
|
|
Rapid DC charger with contactless payment |
Around 70–150MB |
EE IoT SIM 500MB, or multi-network IoT SIM for mission-critical rapid sites |
|
Site with patchy or underground signal |
Unpredictable spikes |
Multi-network IoT SIM plus a GleeSim remote mast check |
|
Charger + CCTV or advertising screen on one router |
2GB and up |
Business data or multi-network 10GB SIM in a router, fixed IP if you need remote access |
|
20+ chargers across many sites |
Varies per unit |
Bespoke fleet quote with pooled data |
👉 Sizing a fleet? GleeSim offers bespoke pricing on 20+ SIMs. Request your fleet quote →
How to Size SIMs for 20, 50 or 200 Chargers
Use one simple formula per charger type:
Monthly data per SIM = routine traffic + (firmware size × updates per year ÷ 12) + 50% safety buffer
Worked example: 40 council car park chargers
- Routine traffic: 34MB (site B above)
- Firmware: 40MB, 4 times a year → about 13MB a month on average
- Subtotal: 47MB → add 50% buffer → about 70MB per charger
A 500MB SIM gives each charger around seven times that need. Across 40 chargers on a pooled plan, that is 20,000MB shared, so one charger having a bad month never takes the others offline. (How pooled data works: Best IoT SIM for EV Chargers in the UK.)
Buying for a local authority? See our guide to EV charging SIM connectivity for UK councils.
6 Data Questions to Ask Before You Order SIMs
Ask your charger manufacturer or CPMS provider:
- What heartbeat and MeterValues intervals does your back office set? This decides most of your routine data.
- How big is a firmware image, and does it download over the SIM? Some updates are tens of MB.
- Does the charger resume a broken download, or start again? This decides your worst-case month.
- OCPP 1.6J or 2.0.1, and is TLS security switched on? Richer messages and secure reconnects add overhead.
- Will anything else share the SIM? Payment terminal, screen, camera, site router.
- Does it need SMS? Some chargers use texts for wake-up or configuration. GleeSim's EE IoT SIM is text-enabled.
Bring the answers to GleeSim and our UK team will help you size the right SIM for every charger type.
Why Data Allowance Is Now a Reliability Issue
Under the Public Charge Point Regulations 2023, rapid chargers (50kW and above) must be available 99% of the time, averaged across the operator's rapid network each year.
The guidance says a charger with malfunctioning or broken communications equipment counts as out of order. Only exceptional network failures outside your control may be excused, and you must prove it.
A SIM that runs out of data on the 28th is a charger that's out of order on the 28th.
Sizing data correctly is the cheapest reliability insurance you will ever buy. At GleeSim's listed price, it costs pennies a day per charger.
(Choosing between 4G and 5G for chargers? See 5G IoT SIM for EV Chargers. Unsure why chargers use SIMs at all? Start with the EV Charger SIM Card complete guide.)
Why UK Operators Choose GleeSim for EV Charger Connectivity
GleeSim is a boutique UK telecom company based in Livingston, Scotland, part of a business that started in 2009, with a team bringing 30 years of combined telecom experience. We build bespoke connectivity for SMEs, corporates and enterprise: M2M and IoT SIMs, mobile broadband (MBB) and business mobile contracts, with or without hardware.
For EV charging, that means:
|
What you get |
Detail |
|
EE IoT SIM for EV chargers |
500MB/month, text-enabled, plug and play, no APN setup needed |
|
Listed price |
£2.50/month on 24 months · £2.90/month on 3 months (ex VAT) |
|
Fleet pricing |
Bespoke quote for 20+ SIMs, with pooled data options |
|
Multi-network options |
For underground, rural or mission-critical rapid sites |
|
Fixed IP options |
When your back office or engineers need to reach the charger directly |
|
Hardware |
SIM-only, or supplied with routers when chargers share a site connection |
|
Support |
A UK team in Scotland, not an overseas call centre |
FAQ: EV Charger Data Usage
How many MB does an EV charger use per month?
Most connected chargers running only OCPP use roughly 30–120MB a month, based on the worked examples in this guide. GleeSim plans for 100–500MB to leave headroom. Firmware updates, poor signal and extra devices on the SIM are what push usage higher.
How much data does a rapid charger use?
A busy 150kW rapid charger with 30 sessions a day used about 72MB in a routine month and about 122MB in a month with a firmware update in our example. Rapid chargers send meter readings more often, so they use more than slow chargers, but still fit easily in 500MB.
Does a faster EV charger use more data?
Not because it is faster. Data depends on how often the charger reports and how long cars stay plugged in. A 7kW workplace charger with cars parked all day can use almost as much data as a 22kW public charger.
How much data does an EV charger firmware update use?
It depends on the manufacturer, but firmware images are often tens of megabytes. If a download fails and restarts, the cost multiplies. Ask your manufacturer for the file size and whether the charger can resume an interrupted download.
Why is my EV charger using so much data?
The usual causes are weak signal causing constant reconnects, firmware retries, very short heartbeat or meter-value intervals, or another device such as a screen or camera sharing the SIM. Check the signal first, then your CPMS settings.
Does OCPP 2.0.1 use more data than OCPP 1.6?
It can. OCPP 2.0.1 messages carry more detail, and device-model reports can be larger. The difference is usually small next to firmware updates and reconnects, but check with your CPMS provider when sizing a large estate.
What happens if an EV charger SIM runs out of data?
Depending on the plan, the SIM may be slowed, barred or billed for extra data. If the charger loses its connection, payments, app starts and remote monitoring can stop working. Ask GleeSim what applies to your plan before you order, and use pooled data on larger estates.
Size It Once. Stop Worrying About It.
Most EV chargers need far less data than people fear. The chargers that go offline are the ones nobody sized properly: weak signal, chatty settings, or a screen nobody mentioned.
Do the maths above, ask your manufacturer the six questions, and pick a SIM with real headroom.
GleeSim gives UK installers and charge point operators EE IoT SIMs from £2.50 a month, multi-network and fixed IP options, and bespoke fleet pricing from 20 SIMs, backed by a UK team in Scotland.
👉 Order your EE IoT SIM for EV chargers → 👉 Get a bespoke quote for 20+ chargers →