I'm worried that daily use of EV mode will prematurely kill the HV battery. I'm interested in how many miles people have on their original HV battery while using EV mode daily. I've got a 116k Prius which I just did the EV mod to. Thanks.
Even with the EV mod, Toyota's programming will kick you out at 3 "bars" which is a safe level. There will be a small effect, but no more so than driving in a mountainous area where your SOC goes up and down a lot.
I think that routine daily or several time daily use could have some measurable negative impact on battery life, but it would take some pretty serious misuse I think. I have almost 100k on my Prius and have had the EV mod since VERY early in the life of the car with no untoward impact yet...but then I don't use my EV button more than 1-2 times per week at most.
I installed my switch three years ago at about 25K miles. I now have 70K miles. I use it several times daily. My advice: use it liberally but properly when traffic and road conditions permit. Do not routinely use it for propulsion. I use it for propulsion only for low-speed, low-demand, limited-distance situations -- i.e., around the driveway or a parking lot. My main use instead is during braking, coasting, or gliding by forcing ICE shutdown during warmup, with a significant resulting gain in fuel economy. See this for more. These conditions affect the battery no more than normal driving does. On other hand, I suppose regularly forcing propulsion with it and repeatedly pushing state of charge as low as the car will allow could shorten battery life. To me that would meet the definition of "serious misuse." Still, the car protects the battery rather well and denies EV mode in a variety of conditions. I haven't heard any reports from overseas users, whose Gen II cars are equipped with the switch from the factory, of premature battery failure attributable to EV switch use.
