When a hybrid won't go into 'Ready' mode, it's almost never the high-voltage traction battery — it's the small 12V auxiliary. The main pack can't wake up the inverter without it.
We jumpstart safely from the correct terminals (never straight to the traction battery), and if the 12V is done we fit a like-for-like AGM sized for the boot or engine bay position.
Key facts — Hybrid cars (12V)
- What actually goes flat
- 12V auxiliary AGM, not the traction pack
- Jump point
- Under-bonnet stud on Toyota; boot-mounted on many Lexus
- Typical size
- 45–55Ah AGM
- Do NOT
- Attach leads to the orange HV cabling anywhere on the car
What we actually see on these jobs
- Prius 12V lives in the boot on Gen 2 and 3 — we know the routine.
- Auris and Yaris hybrids: under-bonnet jump stud, not the visible battery terminal.
- We won't touch high-voltage orange cables — that's dealership work with the correct isolation kit.
Who calls us for this
Prius mini-cab drivers on their day off, Auris and Yaris hybrid owners after a fortnight's holiday, and Lexus CT and RX owners with a car that clicks but won't 'Ready'.
How the callout works
- 1
One call, one price
Postcode, vehicle and symptom on the phone — you get a fixed price before we set off.
- 2
On-site test
Voltage, load and (where relevant) alternator field test at your location.
- 3
Jumpstart or replace
If it holds, you drive off. If it doesn't, we fit the correct battery from van stock.
- 4
Coded and warrantied
BMS coding included where required, warranty paperwork by email before we leave.
Hybrid cars (12V) — specific questions
Q.Can jumpstarting a hybrid damage it?
Not if you use the correct 12V jump points. Our process is documented — we never go anywhere near the HV orange loom.
Q.My Prius clicks but won't go into Ready. Is the traction battery dead?
Almost certainly no. That symptom is the 12V aux battery 9 times out of 10 — a jumpstart usually gets you 'Ready' immediately.
Q.Do you replace the 12V AGM on a hybrid?
Yes — we carry the small 45–55Ah AGMs used on Prius, Auris, Yaris and CT200h.
General questions
Q.Do you code new batteries to the vehicle?
Yes, wherever the manufacturer requires it — BMW, Audi, VW, Mercedes, Ford, Vauxhall, Peugeot/Citroen. OBD-level coding included with every fit that needs it.
Q.Are you insured?
Yes — fully insured with public liability and goods-in-transit on every callout and every battery we fit.
Q.Can you invoice on account for businesses?
Yes — 30-day account terms available for fleets, lettings, dealers and repeat trade customers. Single monthly PDF invoice.
Related guides
In short
Hybrids fail on the 12V, not the pack. We know the jump points, we carry the batteries, and we don't touch anything orange.