Depauwler Posted July 20, 2013 at 07:47 PM Report Share Posted July 20, 2013 at 07:47 PM Car had been charging in the garage, just reached full charge from 50+%. Temperature had cooled down after a storm, below 80f so I turned off the climate control. Unplugged and started off in L, mostly idling my way through the apartment complex. When I got to a stop, it felt like the car suddenly accelerated, as if I had mashed the accelerator when I was using the brake instead. First time I've experienced this. Was it a problem with using L and regenerative breaking with a full battery? Quote Link to comment Share on other sites More sharing options...
larryh Posted July 20, 2013 at 07:55 PM Report Share Posted July 20, 2013 at 07:55 PM (edited) L is designed to provide engine braking when going down a hill. It would normally try to use the generator to slow down the car, but your battery was full. So it would have to turn on the ICE to provide engine braking. I wonder if what you felt was the car attempting to start the ICE. With L, if you let up on the gas pedal, it will agressively slow the the car down with regen. It reached a point when it could no longer put any more energy into the battery and stopped this aggressive regen and switched on the engine to use it instead. Maybe that is what you intrepreted as acceleration, it couldn't do its aggressive deceleration temporarily until the ICE was up and running and it switched to that. I would not use L unless I needed to slow my descent down a hill. I would use grade assist first. If that doesn't slow the car down enough, then I would switch to L. For a discussion on L, see the following posts: http://fordcmaxenergiforum.com/topic/748-low-gear-regen-ive-heard-its-more-aggressive-but-how-much-any-links-and-my-experience/ Edited July 20, 2013 at 08:45 PM by larryh Quote Link to comment Share on other sites More sharing options...
Energized Posted July 20, 2013 at 09:01 PM Report Share Posted July 20, 2013 at 09:01 PM 1) With the battery at 100% the battery can't accept any regen energy (or very little). 2) With the gear shift in L, the system is in a high-Regen setting. With the above conditions met, the excess energy created by regen needs to be dissipated somewhere, it can't go into the battery. The excess energy is routed through the eCVT, where one of the two motors will physically turn the ICE. The excess energy spins the ICE, thereby dissipating the energy. The ICE will then turn on for "system performance". It does this for emissions reasons or because it thinks you want engine braking due to being in L, I'm not sure why. I've experienced this on two occasions although there wasn't any "unwanted acceleration" it's more of a jerking sensation as the system quickly changes between multiple states (Hi Regen, ICE On, Engine braking) trying to figure out what the driver wants. I've since made sure I don't use L when at 100% battery. Quote Link to comment Share on other sites More sharing options...
murphy Posted July 20, 2013 at 09:10 PM Report Share Posted July 20, 2013 at 09:10 PM L is not a low gear. There are no gears in eCVT.The sole purpose for L is to provide maximum engine braking.Page 176 in the Owner's Manual. Quote Link to comment Share on other sites More sharing options...
Depauwler Posted July 20, 2013 at 09:26 PM Author Report Share Posted July 20, 2013 at 09:26 PM Yeah, it was probably just a jerk, it wasn't hard to keep from going forward; it's not like I was stomping on the brake and still going forward. I had taken to using L because I like it better. I don't have to ride the brake to regen. I'll try to remember not to use it after topping off. Thanks for the responses. I was hoping that was what it was rather than a serious, recurring issue. Quote Link to comment Share on other sites More sharing options...
Energized Posted July 21, 2013 at 03:33 AM Report Share Posted July 21, 2013 at 03:33 AM Another sensation you may feel when the battery is full is the loss of regen 'drag'. If you are coasting down a hill and the battery fills up to 100%, the normal regen you feel in "D" goes away, and it feels like you are in neutral. Braking at this point will be through the regular hydraulic brakes, no regen. You can watch this scenario unfold on the touchscreen power flow pictorial, the energy from the motor stops flowing back to the battery. The swirly regen graphic on the battery display disappears too. If you use grade assist or "L" under this condition, the ICE will turn on to provide engine braking. Quote Link to comment Share on other sites More sharing options...
Depauwler Posted July 21, 2013 at 01:01 PM Author Report Share Posted July 21, 2013 at 01:01 PM Yeah, I bet you're right. I may have become so used to the engine braking in L, when it switched off I thought it was the throttle (does that term still apply to EV?) opening up. Thanks again all. I really want this to be a good car and hated the thought that I'd have to watch out for random acceleration or have it taken in/replaced. This isn't my first new car, but it's my first with new-ish technology. I've already had trouble with MFT (solved with a reset), and was disturbed with the threads on the 12v (bought myself a portable jumper yesterday). Quote Link to comment Share on other sites More sharing options...
Taylorjd Posted July 22, 2013 at 03:53 AM Report Share Posted July 22, 2013 at 03:53 AM Great Info All! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.