I love slowing down and seeing the needle drop to EV, sitting at stoplights with no gas engine running, etc. What I can't figure out is why this sometimes does not happen. Normally, anytime I slow to 30 miles per hour the FEH goes into EV mode. Once in awhile, though, I can't MAKE it go into EV mode. Even when I come to a complete stop the gas engine keeps running. I can't see anything different. The ambient temperature is the same as it was the day before (when the FEH went into EV mode regularly), I've been driving the same as always, the message center says the available energy is NORMAL (I've never seen it say LOW), the vehicle has been running long enough that the engine is definitely warmed up, and I'm not running AC or defrost.

Does anyone have any idea why this happens? I don't have the NAV system so I have to rely on the message center for my information. When this happens it goes on for most of my drive to work or home again (a 35 minute drive). It's very frustrating. I keep thinking of all the unnecessary gas I'm using!

I have the same problem you describe jnr. I have the nav. system and know that sometimes when the battery gets all the way full, this happens. What I do is stop the FEH and keep the brake on till the engine shuts off (a few minutes at most). After this, I'm good to go as if the computer reset. I run in the EV mode as much as I can and this seems to be a problem every so often. I now have 4,500 miles on my FEH.

Thanks, Gary. That makes sense. I'll try that next time it happens.

If it's anything like the Prius (and it's pretty close!), there are computer algoritms that control the whole energy system, to keep it optimized, even at times running the gas to maybe get the engine back up to clean emissions temp, or to top off the battery when the power requested from your right foot says there's extra energy available to charge and not needed to propel you forward.

I know at times my Prius runs the gas when I'd like it not too (similar situation as the above poster). But, I chalk it up to the system knowing what it has to do in order to keep everything efficient, etc. Smart cars!

PS In the Prius there are 5 stages of hybrid operation that happen, depending on many variables (temp, battery charge, time spent stopped, time spent warming up, etc.) Do a search on Priuschat or Priusonline. It's pretty amazing the software built into the Prius (and the like Escape hybrid) that controls energy, giving you the best efficiency and performance.

'04 Seaside Pearl #7. Fumoto oil drain, mudflaps, rear bumper scuff protector & rear warn system, compass mirror, EV mode button, 8" subwoofer in right rear cubby & 6" subs under seats, power lumbar in the front seats, Coastaletech hitch w/ Aspen bike/snowboard rack. iPod2car, 2 amps, Alpine component speakers, and DVD video, solid 47 MPG @ 70000 miles.

Likewise, from time to time I have this same problem. EV will come on normally and the FEH will work as it should. Then, for some strange reason it won't go into EV, even sitting for 5+ min at a stoplight. Sometimes I'll try shifting to N or P and that will cause EV mode to engage. Other times this didn't work, so I shut the engine completely off and the FEH behaved normally after that (EV mode <30 miles per hour). Weird.

It hasn't been that obtrusive, it has happened only 3x in 1400 miles thus far.

Nate

I believe the FEH computers run a battery conditioning program from time to time that requires the ICE run for a fixed period of time. I would not worry about it or try to bypass it, just trust the computers and let them do thier thing.

Simplying having the ICE running won't make a huge differance in your fuel economy, the engine consumes very little fuel at low RPMs and 5 minutes of idleing won;t make a big differance. Running at high RPMs even for a minute or two will however have a big impact on economy.

Chris Brown

It could also be that the battery is above optimal charge, at that point the motor generator will spin the ICE just to run down the battery a bit.

There's a lot of reasons why the ICE might be running when you think it "shouldn't" but that's because there are a lot of factors the PCM takes into account when it makes its decisions.

I agree with you Steve and thats why I said when the battery has a full charge. One factor after the battery is fully charged by the ICE, we must remember the brakes can still force an over charge situation. Nate said its happen 3x in 1400 miles. It happens to me sometimes three times in one day of 50 miles. Sometimes I can reset at a stoplight but if there are no stoplights ahead, I pull over and hold the brake. The best way, is not let the battery get to a peak charge.

In the routes I travel almost every day, I charge and drain the battery about 12 times in about 30 miles of travel. I don't think my battery will make it 100,000 miles before Ford will have to replace it.

I have no worries about the life of my battery. I run about 2 maybe 3 discharge cycles a day. I have seen pure EV cars go 80,000 or 90,000 miles on one battery and that is with them going to 100% discharge frequently (on older model batteries). On the FEH I would guess the system does not let the battery get below 40% discharge. In general I think the FEH does not work the battery nearly as hard as the Prius (Gen I) that I drive at work. Our Prius is at about 50k with no battery issues at all (and it probably sees 3 discharge cycles per trip).

My guess is that the FEV fuel milage could be improved by working the battery and the electronic motor harder, but at the expense of thier respective lifespans.

All the research that I have read shows that the life of a battery is measured in the number of complete discharge/recharge cycles. Discharge cycles that do not get get below 10% or so have much less impact on the battery life.

Chris Brown

I need to correct what I said about charging from the brakes causing an over charged battery. After some research in my FEH manuals, I found it is the generator which is slowing down the vehicle in place of the brakes. Brake pedal switches trigger the Transaxle Control Module to use the turning axle as power to turn the generator for charging. This said, the over charge protection is the same as for when the engine is used to charge the battery. The manual said this system is regulated based on the battery level and the need for a charge. I would think that if the longer you keep the battery drained, the longer your brake pads will last.

I did find out in the manual that the D/C to D/C converter takes high voltage D/C current from the generator and converts it to low voltage D/C to charge the 12 volt battery for running the bells and whistles. This takes the place of an alternator on the FEH. It would make sence that the engine would keep running to top off the 12 volt battery or keep the fans running for the rear large battery to cool.