And he said the only one they had was a good condition 2007. I said great, can my mum get a test drive. He said no, the battery is flat. I said, what, both? He said not the 12v, only the hybrid battery. Also lock wasn't working. He said it has to be charged under the driver's seat Is it true that Prius can't start engine if main battery dead but 12v ok?
On a Prius the large hybrid battery uses one of the motor-generators to start the engine when needed. The 12 volt battery just powers the computers and accessories. It closes the switch to the hybrid battery when the computers say everything is ready. The hybrid battery also recharges the 12 volt battery. If the hybrid battery is dead the car is not in good condition. Run away and look elsewhere!
They are a car dealer who franchise Toyota and Hyundai. So just to clarify here: A typical Prius (2007, not a brand new one), if the 12v battery is charged it cannot start the engine itself. The hybrid battery is the energy source to the starter motor. So if your 12v is dead, it's not a problem because the hybrid charges it up. But since the 12v powers the computer and accessories, I'm surprised the Prius can start wirhout it (as computers are usually a fundamental part of the operation). So the bigger question here is, is it difficult to drain the hybrid battery? I thought it was easy to do this because you're often using that battery as you drive and it fluctuates from low to high. Seems strange it is this battery which is the only one able to start the cars engine. One would think the Prius would have one dedicated battery, like the 12v, to start the engine. From there, the engine can charge the hybrid battery.
not quite. the 12v boots up the computers. if it is dead, the hybrid battery cannot charge it. so you need a good 12v and a good hybrid battery.
On a properly functioning Prius it is difficult to drain the hybrid battery. In normal use charge varies between 20% and 80%. If the car is malfunctioning trying repeatedly to start it can drain the battery. It is also possible the battery is worn out if it is still original. That is why I said go somewhere else. Either they do not know the condition of the car or they are lying to you.
just as an aside, if you are looking for a car so cheap that a 2007 prius with a dead hybrid is in your price range, you may want to consider a non hybrid.
If they ran the car out of gas and then all that was left was a 10 year old battery, it could be an explanation. But if this issue is there now, it will be a project later. At least you found out about it before dropping the money on it.
I'm in the far south west (Cornwall) so I don't know any dealers further upcountry. I suggest you ask around about friends, neighbours, colleagues etc for recommendations. If you meet a Prius driver at the pumps or in a store car park, ask them about it. Chances are they will enjoy telling you this and suggest, or advise against a certain dealer. Good luck, but walk away from anything that doesn't work and have at least two working key fobs. It's a chore, but keep us informed of your progress and don't hesitate to ask for advice on here.
