Charging best practices

[cegarbage]

Has Ford, or anyone, compiled a list of best practices in regards to getting the  most out of the plug in?

 

I'm looking for something like this, but from a FFE point of view.

 

http://www.plugincars.com/eight-tips-extend-battery-life-your-electric-car-107938.html

 

[Hybridbear]

There has been lots of discussion along these lines in the OBD data for HVB thread.

[rbort]

Ah, this is just Perfect!!  The article pretty much agrees with all I said in my HVB Best Practices on the Cmax forum I posted back in April.  I'm going to steal the link and add it to my thread  :happy feet:

 

-=>Raja.

[cegarbage]

Raja, I like yours. Please add if you find anything relevant!

The other thread is white-paperish. I wish I could go back in time and be an engineer.

I'd like to sit down and read it when I have time to follow along. Thanks!

[rbort]

Thanks Ce!

 

You might enjoy reading this thread also:

 

http://fordcmaxenergiforum.com/topic/3669-getting-a-good-range-out-of-your-ev-driving/

 

All the best,

 

-=>Raja.

[larryh]

I would add one additional item to the list.  Avoid over-stressing the HVB.  This means, while in EV mode, avoid excessive acceleration, driving at high speeds on the freeway, or ascending a steep hill rapidly.  Also, avoid hybrid mode until the end of a trip. 

 

The following chart plots HVB power (red line) and SOC (green line) vs. time for a 60 mile commute.  The blue indicates the voltage variation between cells, which is a proxy for stress on the HVB.  When there is significant voltage variation between the cells, the weaker cells are doing a disproportionate amount of the work making them even weaker.   Weak cells impact HVB performance.  To function correctly, all the cells need to be the same strength. 

 

While the SOC is above 22.5%, i.e. the car is not in Hybrid mode, the blue line is generally well below 20 mV.  It spikes above 20 mV when the HVB outputs more than 20 kW of power (about 2 bars on the empower screen).  When in Hybrid mode, as the SOC continues to fall at the end of the trip, the blue line rises to about 40 mV.   The increases in variation indicate the greater stress on the HVB when it outputs high power or when the SOC is low. 

 

Edited June 27, 2015 at 08:36 PM by larryh

[JATR4]

I would add one additional item to the list.  Avoid over-stressing the HVB.  This means, while in EV mode, avoid excessive acceleration, driving at high speeds on the freeway, or ascending a steep hill rapidly.  Also, avoid hybrid mode until the end of a trip. 

 

The following chart plots HVB power (red line) and SOC (green line) vs. time for a 60 mile commute.  The blue indicates the voltage variation between cells, which is a proxy for stress on the HVB.  When there is significant voltage variation between the cells, the weaker cells are doing a disproportionate amount of the work making them even weaker.   Weak cells impact HVB performance.  To function correctly, all the cells need to be the same strength. 

 

While the SOC is above 22.5%, i.e. the car is not in Hybrid mode, the blue line is generally well below 20 mV.  It spikes above 20 mV when the HVB outputs more than 20 kW of power (about 2 bars on the empower screen).  When in Hybrid mode, as the SOC continues to fall at the end of the trip, the blue line rises to about 40 mV.   The increases in variation indicate the greater stress on the HVB when it outputs high power or when the SOC is low. 

 

Won't the blue line go above 20 mV if the vehicle is in EV later?

[larryh]

I started out in EV now mode for the first third of the commute.  I was in EV later mode during the second third of the commute, when the green line levels out around 50% from time 11:34 am to 11:57 am.  For the last third, I was in EV Auto mode until the HVB was depleted and the car entered Hybrid Mode. 

 

In EV later mode, the cell variation will rarely exceed 20 mV.  When high power is demanded, most of it will be supplied by the ICE rather than from the HVB.  So the HVB doesn't have to work as hard and will be less stressed (vs. EV Auto or EV Now mode).  The actual SOC of the HVB must exceed 22.5% (the car displays 0% on the MFT screen when the actual SOC is 22.5%) to be in EV Later mode. 

 

When the HVB actual SOC falls below 22.5%, you enter Hybrid mode.  The battery now struggles more to provide power than when the SOC was higher.  During hybrid mode, the car will limit the amount of energy that can be provided by the HVB to 35 kW.  The HVB is weaker in this state and is more easily stressed. 

[cegarbage]

Raja,

I don't see any reference in your article about waiting for the car to cool off to charge it. Do you do that?

I thought it would be easy to incorporate by changing my setting to "value charge". However, I notice value charge still immediately charges my car up to about 40%, then does the rest at the value charge time

[rbort]

Best practice I've found is to charge the battery 1/2 now 1/2 later.  This way the temp doesn't go up as much while charging.  But yes I do wait when I get home before charging it, then I plug it in around 9pm or so and unplug it before going to bed.  Then I will charge it up the next day before I need it from storage charge up to 100% if need be, and less if not.

 

Value charge should wait until the window before charging.  If your battery is charging to 40% right away, then something is not correct with the setup, maybe your window is too small and the car is trying to charge some now and finish the rest during the allowed window.

 

-=>Raja.

[cegarbage]

Yes, my window may be too small. Other best practices i read state to not let it charge up to 100% completely, I was trying to get it in the 90% range. I may have reduced my window to four hours in the middle of the night. If that's the case, Ford doesn't design the software to accomodate partial charging.

[rbort]

No the best advice is to delay the charge window until 8am or whenever works for you and you just wake up and unplug the car before it gets to 100%.  Either that or you charge it the night before to storage levels and leave it there.  Around 60%.

 

-=>Raja.