if main battery is dead will it run on gas only?

No. The high voltage traction battery powers MG1 (via the inverter) to spin up the gasoline engine when starting the Prius. So if the battery is dead, your Prius will be dead.

 

You can limp them along for a little bit by shutting off the car ,"If the engine revs up and the car jumps into neutral" than just shut the engine off and restart it and it will drive for a little bit till it does it again.. Keeps you from getting stranded..

 

No.

 

The engine in a Toyota hybrid will not start without the HV battery! It has no traditional starter motor. The 12v battery only boots up the computers. The large HV battery spins the engine to start it. No HV battery (or it's damaged), no working car.

I believe some Honda hybrids can still be run without a working HV battery (or at least a failing one), but with a loss of power and economy. The Honda and Toyota systems are very different.

 

I should have clarified my comment, If the main battery is still in the car and just one or 2 of the modules going bad you can still limp them along for a while. But you are 100% correct about the prius not working without a decent main battery..

 

I can vouch for Prius, not able to run on 12v battery alone. Very recently, was driving along in my 2009 Prius, when all of a sudden, started losing power, and all lights came on dash, lit up like a Christmas tree(even the triangle of death), had to have it towed via rollback to a friend of mines garage(he came and got it). First I thought maybe a new 12v battery, recently installed went bad, so got it replaced with a newe one(again), thankfully was still under warranty, though Auto Zone was not happy about it. Went over other day, noticed first off, the screen only was showing "1 bar", Prius started briefly a couple of times, when having jumper cables hooked to my 12v battery. So it was determined the hybrid battery, was finally gone, my Prius has 181,000 miles on it, and far as I know the battery is the original. I made a call to a place in N.C. found on E-Bay, that sells refurbished hybrid batteries, and was quoted "$800.00 and includes delivery & installation", so next week will be calling to make arrangements. I had read & heard, that Prius will run on 12v only, well so much for that theory. Just wanted to share my recent experience.

 

If the high voltage battery is still accepting some charge and the car is still running now, it will continue to run for awhile. Best thing is to get it fixed or changed out or get another car as soon as possible.

 

I'm not sure where you could have read or heard that. Any such claim here on PriusChat would be pounced upon and beat down very quickly.

Maybe from someone confusing the Prius with the original Honda Insight and Civic Hybrid, which could run on their 12V batteries.

 

I wonder if they're affiliated with (the now defunct, but working with Dorman) ReinVolt (aka Taylor Automotive)?

 

I didn't read it on PriusChat. I remember doing a Google search, awhile back, and it was mentioned, sorry for any confusion, I know the folks on PriusChat are very informed on Prius vehicles. Anyway, I have been in touch with a company in North Carolina, that specializes in re-manufactured hybrid batteries, for a good price, that includes delivery and installation.

 

If you can afford it, go for a new battery from Toyota. There are third parties selling and installing Toyota hybrid batteries. Around here there are mobile installers of new Toyota batteries for about $2300. The problem with "remanufactured" is they are not remanufactured at all. Instead they test the individual cells in the module and replace weak cells with better used cells from another module. While this will get you going, its likely you will have another failure within a year. With a new battery you will get another 150,000 miles and usually a three year warranty.

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