Which battery are we talking about?
| 12-volt battery | High-voltage battery | |
|---|---|---|
| What it does | Wakes the car and runs its electrics | Drives the electric motor |
| Which HS has one | Every HS | Plug-in hybrid and Hybrid+ |
| MG's cover, first registered from 1 July 2025 | 24 months, manufacturing defects | 7 years or 150,000 km, including capacity below 70% |
| Who handles it | A local mechanic | A mechanic trained on high voltage, or MG |
Signs the 12-volt battery is tiring
Slow cranking on a petrol HS, a car that won't wake up, or several warning lights appearing at once. On a plug-in hybrid, a full high-voltage battery doesn't rule out a flat 12-volt one, so don't assume the charge reading tells you everything.
Ask for a battery test and a charging check before anything's replaced, as a fault elsewhere can flatten a new one. If the car won't start right now, flat battery help comes first. Battery replacement explains the job.
Which HS do you have?
The HS arrived here in November 2019 with a 1.5-litre turbo petrol. A plug-in hybrid and a 2.0-litre turbo with all-wheel drive joined in March 2021.
The second generation launched on 3 September 2024 with a 1.5-litre turbo. The Super Hybrid PHEV followed in June 2025 and the Hybrid+ in July 2025. Tell the mechanic the year and the badge, because the answer to most HS questions starts there.
When is an HS due for a service?
Carsales lists the 2021 HS at 12 months or 10,000 km, and CarExpert listed the HS PHEV the same way in 2021. MG's suggested schedule on the 2025 HS is longer, at 12 months or 15,000 km. Those two figures are why you should read your own Service and Warranty Booklet rather than copy a neighbour's.
A plug-in hybrid that mostly runs on electricity still needs its yearly visit. The engine, oil and brakes age with time as well as distance, so don't skip one because the kilometres look low.
We don't list prices. What sets the size of an HS service is the items due at your kilometres, the oil the book asks for, and anything worn. A written estimate will show all three. Logbook servicing has more.
Battery, warranty and an independent mechanic
On an HS first registered from 1 July 2025, MG says a suitably qualified Australian repairer can service the car under standard cover of 7 years, unlimited kilometres. The record must go to MG's online portal within 10 days, and parts must meet MG's engineering specifications, which applies to a replacement battery too. An independent service does end eligibility for the extended cover of up to 10 years or 250,000 km.
Tell us it's an HS, the year, and whether it plugs in. A local mechanic who specialises in your car.
What you can do on an HS
You can
- Note exactly what the car did when it wouldn't start
- Photograph any warning lights
- Keep a plug-in hybrid charged if it's going to sit
- Read the booklet for your service gap
Leave to the mechanic
- Testing the 12-volt battery and charging system
- Fitting a battery that meets MG's specifications
- Everything on the high-voltage side, including its orange cables
Our take on an HS battery
Have the 12-volt battery tested first, and ask for the result. If the car's under MG's 24 months and the battery is the original, raise it with MG before paying for a new one. If it's older, a local mechanic can test it, fit one to MG's specifications and check the charging at the same visit, with the invoice kept for your records.