Two batteries, two jobs
A hybrid's high-voltage battery supplies the electric motor. The 12-volt battery runs everything else: the computers, the lights, the locks, the radio, and the relays that connect the big battery to the car when you press the power button. Without the 12-volt battery those relays never close, so the car can't power up, and the big battery just sits there.
Many hybrids also start their engine through the hybrid system instead of a conventional starter motor. That means a dead 12-volt battery often doesn't give you the clicking you may expect from a regular car. You get silence, or a dash that barely wakes up.
What a dead one looks like
The signs are the same ones a dead battery causes in any car, with one hybrid twist:
- The dash is dark or only partly lit.
- The car won't switch on, and the Ready light never comes on.
- The remote or the door handles respond oddly, or not at all.
- A burst of warning lights, then nothing.
Why it fails
It is an ordinary battery doing an ordinary job, so it ages like any other, and heat is hard on it. The usual triggers are a car that sits for weeks, a lot of short trips, and leaving the car in accessory mode with the doors open, so the radio and lights run while the car isn't charging anything.
A hybrid is quiet, which makes that last one easy to do. With no engine running to remind you the car is awake, it is simple to walk away from it in accessory mode or with a door ajar.
Where it is
It isn't always under the hood. Many hybrids put it in the trunk, under the rear seat or beneath the cargo floor, and provide a jump terminal under the hood in the fuse box. The manual shows both. Many of these are sealed batteries, sometimes AGM, so replace like with like.
If you can't find the jump terminal, don't clamp onto anything else under the hood. Check the manual, or ask dispatch. And leave anything with orange cabling alone. That is the high-voltage system, and none of this needs it.
What we do
We help with the 12-volt system only, and we do nothing with the high-voltage battery. A jump start is $49–$75, plus the $19 dispatch fee, added once to the job. If the 12-volt battery is worn out, battery replacement is $239–$255 for eligible vehicles and batteries, the new battery and installation both included. Dispatch confirms compatibility and tells you your total before a driver is sent.
Say in your request that it is a hybrid, and put the details in the notes field so the driver brings the right equipment.
A jump only helps the small battery. If the Ready light still doesn't come on after the jump, or the dash shows a warning about the hybrid system itself, the cause is somewhere we don't work, and a dealer or a hybrid specialist is the next call.
Common questions
No. A jump only helps the 12-volt battery. A hybrid recharges its big battery as you drive, and that has nothing to do with the jump.
Follow the manual. It shows which terminal to use, often under the hood and not at the battery itself, and a clamp on the wrong spot can damage the electronics.
Not necessarily. They are separate batteries. A hybrid can have a perfectly good big battery and a dead small one.