Prius Gen 3½ Ev Mode Top Speed

[PeteB]

Perhaps someone can shed some light on my top speed in EV mode.

I have a 2012 Prius T3 Gen 3 with the face lift (running lights etc Gen 3½?).

When I drove Gen 2s the EV mode worked up to around 29-30 mph,

If I recall correctly, early Gen 3s seemed to do the same.

MY Gen 3 always seemed to switch of EV mode at exactly 20 mph, until one day I noticed it still working at 27. It had just had a 10k service and I wondered if the firmware had been updated, but my dealer said it hadn't.

However, next time I tried it in the village, it maxed at 20 again, despite having 7 bars (slowing down on the dual carriage-way as I approach my village often lifts the gauge to 7 bars).

Experimentation showed that if the engine was fully warmed up, then it sometimes went up to 30.

However, a stop (at the village shop, for example) of just 2-3 minuets is enough to bring the max back to 20.

This is annoying when trying to get around the village without using the engine and someone is behind me!

Anyone know what the criteria are, speed wise please?

[Grumpy Cabbie]

The EV Mode speed is variable depending on a number of factors - mainly Battery temperature.

Cold temperatures affect the Battery so to protect it, the car will only allow ev in EV Mode upto 20 mph unless the car and Battery has warmed up, when you will probably get upto 30 mph (31 mph switches the mode off). Having your a/c on may affect why some days you get upto 30 mph and other days the car just won't have it.

Try and engage EV mode at -5c and the car just won't entertain it at all and will flash up a 'too cold' warning.

Then you have the usual EV mode issues such as the car now allowing the mode if the charge level is too low etc.+

If the battery is too warm - such as having come down a long hill - then the car won't let you engage EV Mode even if you have 7/8 bars or more. Though if you have 8/8 you might find the car does 'weird' things such as run the engine (without using petrol) to help lower the charge level or even run as an EV upto 40 mph or more with reasonable levels of EV only accelleration. This happens only for a short while and usually to help reduce the full battery level to a more 'happy' level.

[PeteB]

The EV Mode speed is variable depending on a number of factors - mainly battery temperature...

Thanks, I hadn't thought of that aspect, but now that you mention it I should have done. I was beginning to wonder if I had a fault, but that all makes perfect sense.

I suspect earlier versions may have been less choosy, as I don't ever remember Gen 2s limiting speed to 20, but maybe they just refused EV mode altogether rather than a reduced top speed.

My 2002 Classic Prius had 70k on the clock when I took it on a holiday to Scotland and saw the HV Battery max out for the first time (first time I'd seen the top bar [out of 4] on the Battery gauge lit either). Despite not even having an EV switch, once I reached the bottom of a 5-6 mile long 20% hill I could accelerate up to 60 without the ICE starting until it used up some of the charge. Don't remember it using compression though, except when in B mode.

[Grumpy Cabbie]

It has to be a long sharp steep hill (doubtful any in Norfolk) for it to really max out. There's one near me that even using B doesn't help stop it over doing it. The engine revving is similar to B mode but mainly its the HV Battery spinning the engine to burn off charge. Quite weird when the car is stationary and revving away but no exhaust.

Generally, if the car doesn't flash a warning or warning light it's fine.