Does hybrid battery never fully charge?

[bav401]

While running in EV+ and Eco-cruise mode, my battery display will charge to approx. 70% on ICE then run on battery till 25% remaining. I have never seen a fully charged battery icon, how do you (if even possible) achieve this?

[plus 3 golfer]

The battery symbol does not represent the State of Charge (SOC) of the high voltage battery but rather the usable operating range of the HVB.  The PCM algorithms appear to limit the SOC between 30% minimum and 70% maximum (for reliability reasons and should extend the HVB life). So, when the battery symbol shows full including the battery symbol tip (which can be achieved by going down a steeper hill for several miles), the SOC is only 70%.  I monitor the SOC frequently via the OBDII port and rarely see below 40% SOC (EV+ operation can take the % below 40%) which will look like about 25% or so on the battery symbol.  In typical driving, the SOC will vary between about 40% and about 56% which will look like about 75% full on the battery symbol. If one is running at around 56% at high speed and slow down via braking regeneration to a stop the charge may increase up to the 70% level.

 

I'll look for the posts which show the relationship between SOC and the battery symbol.

 

Here's two links.  

 

http://fordcmaxhybridforum.com/topic/3673-how-to-get-rid-of-this-mix-mode/?do=findComment&comment=41851

http://fordcmaxhybridforum.com/topic/1927-interesting-information-on-the-high-voltage-battery/?p=18222

Edited September 25, 2014 by Plus 3 Golfer

[LizM]

On one of the routes that I take when going home...it's fairly rolling, with more long stretches of downhill than uphill.  My battery symbol gets full every time on this run. 

[fotomoto]

  My battery symbol gets full every time on this run. 

 

Your indictor may show full but the battery isn't and never will be.  The computer programming doesn't allow it to completely fill as that is bad for battery longevity in the long run.  Once the indicator is full yet more charge is coming in (say coasting on a very long downhill road), the programming will kick in the ICE to burn off that excess charge instead of sending it to the battery.  In my Energi with its much larger battery, I can recoup that excess charge and accumulate 20+ miles of EV charge assuming the descent is long enough but it too has its limits and will eventually do the same thing.

[ScubaDadMiami]

When in the mountains, I've easily seen the icon fully topped off when coming down long stretches, especially when using Downhill Assist. As said, what you see is only showing the operating range, not the actual state of the HVB charge.

[John Sparks]

I usually achieve a full battery gauge on the way to work. After about a 2 mile 2000 rpm burn I have about a 90-95% charge I then drop to EV and coast to my turn with some regenerative braking just before I turn. As I am turning many times the tip of the battery will fill. Only to immediately drop as I start to accelerate in EV.

 

Having this full battery allows me to make it over the next two hills and quite a way down the other in EV. Then it's back to a 2000 rpm burn up the next hill.