I'm very interested, and have been discussing such an add on to my Camry with a local electric car conversion company. It's not impossible, it's just difficult. Further testing would need to be done to determine if adding extra battery capacity to a camry without and EV only mode would really net any difference in MPG.

 

My TCH is my first experience with a hybrid vehicle and I am very happy and impressed with it. My daily commute to work is only 6 miles. The perfect vehicle for me would be the plug-in Prius but that it is probably 2 years away and from what I've read, the price is expected to be around $47,500. Too much for my budget. I thought if there was a plug in conversion option available for the TCH, at around the same cost as it is for a Prius, (3 to 5k) that would be the way to go. But that appears to be not the case, yet. There seems to be a market for this so we'll see what the future brings.

 

Actually, converting TCH into PHEV can be done, based on the fact of it being done for Prius. Even missing EV button could be circumvented (for example shutting down fuel pump should give you desired effect, since people who run out of gas claimed to have capability to drive some time to gas station in EV mode alone) so I didn't intend to claim it can't be achieved, it's just not very practical. Besides a lot of work and expense, the fuel savings are not that great except on short trips and with gas prices being where they're now, probably not worth it. If the gas was over $4 or in short supply, you would have people jumping over themselves to do something like that.
I just pointed out possible issues from the top of my head, but I could probably find workaround for each as well. I really wish we had some breakthrough with battery capacity to make such conversion really meaningful. For example my commute is 30 miles each way, so I would need at least 20 mile battery range to get me interested in such project. As far as battery technology, you're really talking about Nimh, Li-ion or something new like Zinc Air, older chemistry like Pb acid based are too inefficient.
BTW, I still believe such modifications, especially done by the owner will void the warranty, so after my warranty runs out I may start looking into such project, who knows by then gas might be more expensive and good batteries cheaper, but for now I will hold.

 

You have a good idea, but . . .
Shutting down the fuel pump, or anything else to make the TCH believe it is out of gas would probably not work very well either. When a TCH runs out of gas, it make A LOT of noise, things flashing,beeping, I wouldnt want to be driving a car for 20 miles that way. I think it also must be shutdown and restarted before it will clear that condition and recognize that it has fuel again, so it's not something you can switch on and off while driving.

I have discussed the idea of adding an additional pack with an EV conversion company. Every time we come up with some other way to make a TCH stay on battery, it has always required a shutdown to clear, if not throwing a check engine code that has to me manually cleared.
How to keep a TCH on battery without EV mode is a really tough obstacle.

Any conversion that doesnt take the entire remaining trunk space would have to be Lithium of some type, unless someone comes up with another viable battery technology real soon.

 

Well, how about this: ICE will start up mainly for 2 reasons
a) low temperature of engine coolant or catalytic converter
b) larger power demand
If you fool the computer that the engine and CC are at operating temperature, then the ICE will start up only when power demand is higher, kind of safety future, if you ask me. Not sure about temp sensors in TCH, but in general most are resistance based, in other words provide proper voltage on the sensor wire and computer should be fooled into state as if the car was fully warmed.
Of course the most elegant way would be to program the computer, but I think that's proprietary info and I doubt Toyota would ever release it and backtracking the code is not easy.

 

or

c) low state of charge on traction battery.

 

There is a person right now who is converting their TCH to a PHEV with an Enginer system and is getting it done at the shop that was mentioned in the first post, 3-Prong-Power in Berkeley California. (A GREAT shop by the way!)

I am assuming that the Camry is like the Prius, in that when the stock pack voltage is high that it tried to bring more battery power into the propulsion mix.

If so, then even without the EV button, while driving an add-on PHEV pack would help out mpg-wise.

 

[quote=ericbecky;220947]There is a person right now who is converting their TCH to a PHEV with an Enginer system and is getting it done at the shop that was mentioned in the first post, 3-Prong-Power in Berkeley California. (A GREAT shop by the way!)

I am assuming that the Camry is like the Prius, in that when the stock pack voltage is high that it tried to bring more battery power into the propulsion mix.

If so, then even without the EV button, while driving an add-on PHEV pack would help out mpg-wise.

I am a long way from Berkeley, California but would definately like to know how this works out and what the cost of the total installation was.

 

This thread and related side discussions with other members piqued my interest in PHEV conversion and led me to discover resources actually available for the conversion.

BREAKING NEWS:

I have ordered a PHEV conversion for the my 09 TCH.

As the project develops, I will initiate a new thread to report on progress and results.

 

I didn't think there was a conversion kit available for the TCH. What kit did you order or are you making it up yourself? Please do keep us informed with the progress with your conversion. Thanks, Rick