🔋 EV Battery Check — £79
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Mobile · Pontypridd & RCT
07896 657792
All Vehicle Types · Pontypridd & RCT

12V Battery
Check. EVs · PHEVs · Petrol · Diesel

Every car has a 12V battery — and a failed one leaves you stranded, even in a fully charged EV. PAD's professional battery load test measures voltage, cold cranking amps (CCA), and state of charge in minutes, at your door.

PHEV owners: Plug-in hybrids are especially prone to 12V failures because the engine rarely runs — meaning the alternator rarely charges the 12V battery. A flat 12V stops the whole car, regardless of how much charge is in the HV battery.
What the Test Covers

Three Measurements. Complete Picture.

A proper battery test is not just a voltmeter reading. PAD uses professional battery testing equipment for a full load test.

V

Voltage

Resting and loaded voltage measured. A healthy 12V battery reads 12.6V+ at rest — lower values indicate discharge or cell failure.

CCA

Cold Cranking Amps

The battery's ability to deliver power under load. CCA below the rated spec means the battery may fail in cold weather or under high demand — even if it looks fine at rest.

SoC

State of Charge

Current charge level as a percentage of capacity. Distinguishes a genuinely weak battery from one that simply needs charging — so you don't replace a good battery unnecessarily.

Particularly Important for PHEVs

Why PHEVs Kill 12V Batteries.

In a standard petrol or diesel car, the alternator charges the 12V battery every time the engine runs. In a plug-in hybrid, the car frequently operates in electric-only mode — which means the engine doesn't run, the alternator doesn't spin, and the 12V battery goes long periods without being charged.

The result: PHEV owners experience 12V battery failures far more frequently than ICE vehicle owners, often within 2–3 years. And when the 12V fails, the entire vehicle can become inoperable — even with a full high-voltage battery.

PAD recommends: PHEV owners should check their 12V battery annually — or at the first sign of sluggish electronics, slow window operation, or unusual start behaviour.

Warning Signs of 12V Failure

  • ⚠️
    Multiple warning lights appearing at once — especially after parking overnight
  • 🪟
    Electric windows, mirrors, or central locking operating sluggishly
  • 📻
    Infotainment slow to wake or losing settings
  • 🔌
    Charging port not opening or charge not starting correctly
  • Car completely inoperable — won't respond to key fob, won't start
PHEV Battery Health Check
Transparent Pricing

£25. At Your Door.

12V Battery Check
£25
Flat rate
  • Voltage measurement — resting and under load
  • Cold cranking amps (CCA) — compared against rated spec
  • State of charge — distinguishes weak from discharged
  • Clear result — good / needs charging / replace
  • No call-out fee within 10 miles of Pontypridd
WhatsApp to Book 07896 657792
Buying or selling an EV or PHEV? Combine the 12V check with our Aviloo certified battery health check for the complete picture. EV Battery Health Check — £79 ›
FAQ

12V Battery Questions.

A voltmeter gives a basic reading, but resting voltage alone doesn't tell you whether a battery can deliver power under load. A battery can show 12.6V at rest but fail when the starter fires or the car demands current. CCA testing under load reveals the real picture.
Around 5–10 minutes on site. We connect professional battery testing equipment to the 12V battery terminals and run the test. Results are immediate and clearly explained.
The 12V check is a standalone service for the auxiliary battery only. For EV high-voltage battery testing (SOH and SOC), see our EV Battery Health Check. For PHEVs that include both checks, see our PHEV Battery Health Check.
Very likely, yes. If your PHEV is completely unresponsive — key fob not working, no dash lights, nothing — a failed 12V battery is the most common cause. This can happen suddenly, even on a relatively new PHEV, because the alternator rarely charges the 12V in electric-only mode.