I have had an 09 FEH for 3 months now with about 3100 miles on it. My High Voltage battery level indicator never appears full, and rarely much above 50% charged. Now that it's spring (average highs of 40F) and I'm past the 3000 mile mark, I'm concerned about the health of the high voltage battery if it never has a charge above 50%.

Does anyone have any thoughts or experience with this - should I give it a little more break-in before having a dealer look at it?

Thanks in

 

I have seen it printed that the HV battery is cycled between about 40% & 60%.

I think Ford did this to keep safe from two things:

First an inability to start in even the coldest of circumstances.
Second to prevent overcharging the battery with attendant problems.

This is probably quite conservative but it gives them room to grow once they get more info on how the batteries do.

I believe you find this on the wikipedia site.

 

Your battery is just fine and the maximum the generator/motor will charge your battery is 52%. This allows 8% to be charged on top of that with regenerative braking to a maximum normal range of 60%. There will be times the computer will calibrate the battery to over 80% charge to keep the battery operating as long as possible in our vehicles. Ford designed this 40 - 60% operating range to get as many charge/discharge cycles as possible.

GaryG

 

Thanks for your replies.

 

Just to add my thoughts, Honda's Hybrid system allows charging up to 80% state of charge. There have been a number of individuals at Greenhybrid.com having issues with Honda's hybrid battery at the 80-100,000 mile range. The Honda and Ford system are not similar but I wonder if allowing charging up to 80% state of charge is not good for durability purposes.

 

If you look at the chemistry of the batteries they produce water tht can pressurize the cell container.

Batteries charge on an non-linear curve. My bet is that Ford chose the most linear region that would both:

a. Retain enough energy at the low end to start the engine in the coldest of environments if the engine was shutdown just before it was to be cycled on.

b. Keep the high end from damaging the battery cells if an error in the system caused some overcharging.

My bet is that they have a small program in each cars computer/controller to record data that is downloaded to Ford when you go in. They have a real need to collect battery performance data to improve their cars. If they could open up the charge band some it would give better engine off performance.

For example as I hear it the new Ford Fusion hybrid can get up to 42 mph before being forced to start the ICE. I believe that part of the performance improvement comes from better knowledge of the battery performance band.

 

Maybe you are correct. The Fusion Hybrid has a new battery composition that is suppose to provide more energy (20% is that what I read?) per cell. I understand the Fusion Hybrid can travel up to 47 mph in EV mode!

 

I don't know if things changed in 2009 *(probably not) or if GaryG made a typo...

The correct numbers for 2005 thru 2008 models:

The HV battery charges via generator to 53% SOC.
53% is the preferred SOC and the battery will remain here and only deviate slightly during crusing. It will go down to 40% and up to slightly higher than 53% during stop-n-go conditions. To get a lot higher than 53% you need a long ( many miles ) downhill stretch of coasting or braking.

HTH,
-John

P.S. I've found no "maximum" range for the battery. The 40% to 60% is quoted in some places as "normal".... but normal is really, and exactly, 53%. If you are lower than 53%, you are below normal. Higher than 53% is considered higher than normal charge.

Below 53% and the car does it's best to recharge. Above 53% and the car tries to discharge. Only at exactly 53.0% does the car do nothing.

 

I'd be interested in seeing your source. Mine was from a lengthy wikipedia article that showed much of the battery cycling. I'll go back and find it for you.

The more I see of this kind of stuff the better I understand how & why the machine does things. Once I figured out how little of the range of the battry charge they used (though I thought it to be greater than it turned out to be) I began to wonder what other software limits Ford put into this machine.

Protecting us from ourselves and themselves from lawsuits while advancing engineering for the common man!

 

My source is my car with 100's of dollars of additional instrumentation added, plus 4 years of ownership with reverse engineering, plus, something you can do as well, is read all the posts in this database and find dozens of others posting the exact same results!

What else would you like to know?
I've taken apart and studied most aspects of the 2005 Ford Escape Hybrid, and the models have changed very little over the years.