Battery SOC, EV Button, and Warranty: point to ponder

[jrawles]

I've been watching my battery state of charge(soc) while driving on the freeway and noticed something I wanted to discuss:

1. My ICE comes on whenever the SOC drops below 50% regardless of speed or acceleration. Is this normal?

2. If this is normal in a native USA 2004 Prius w/o the EV button what happens with the EV button? (how low of a SOC do you go before ICE kicks in?).

3. What actually happens with the EV button depressed? I assume it changes the algorithm of when the ICE kicks with respect to both SOC and energy demand. Does anybody no the actual figures?

4. And lastly, perhaps this is why we don't get the EV button in the US: The EV button changes the algorithm such that the battery routinely cycles down to a much lower SOC thus the battery will have a shorter life expectancy due to a wider range of charge states?

Please comment all of you hardware engineers. I'm a software guy.

-Jody Rawles, M.D.

[HTMLSpinnr]

Only point I can add is that when the screen is reporting full, half, and empty, it's only relative to the "allowed" SOC window, not 100% full, 50% full, and 0% full.

Toyota designed the system with a relatively narrow window to promote battery longevity. Even when we're down to 2 pink bars on the energy display, we're probably still above 50% actual SOC. Full battery probably isn't much above 80%. More detailed specs are available out there I'm sure.

Toyota did widen this window for the '04 since either due to the improved the battery and/or the possibility that they could have discovered that the other window was a bit conservative and that a wider window would probably still allow the battery to outlast the warranty period.

[Frank Hudon]

with one more green bar to go the actual scantool reading on the BSOC was 68%. I'm still not sure I like this BSOC gauge but can't change it so just ignoring it.