HVB discharge while not in use

[openair]

I always come back to the vehicle with less charge than I left it.  With some ev range left on the HVB, I'll lose about anywhere from 2% to 10%.  With the HVB depleted into hybrid mode, it'll drop from 50% on the hybrid portion to 10 or 0% inside 3 hours.  I figured, and some posts around here implied, this was normal.  The hvb cooling, the difficulty of estimating remaining charge on a battery that has a load drawing a discharge, etc.  But this post from the hybrid forum says it is not.

 

http://fordfusionhybridforum.com/topic/10547-hvb-drain-from-45-to-0-while-parked-during-workday/?do=findComment&comment=100749

 

Is it normal or not?  Are the HVBs in 2012s and earlier just better at holding a charge? The larger battery of the energi leaves more room for variance? 

[murphy]

When an Energi is turned off the HVB is disconnected from the car by contactors.  If the ambient temperature goes down the battery capacity will go down.  If you want to try an absolutely disconnected test, fold down the right rear seat back and open the door you will find there.  Behind the door is the manual disconnect for the battery.  All rechargeable batteries are subject to self discharge but I would expect the rate to be very low.

 

I have not tested but it is possible that accessing the car using MFM may reconnect the battery to the car.  I do know that an MFM access puts an over 10 amp load spike on the 12 volt battery.

[openair]

How about with no MFM use and little to no change in ambient temp? Do others routinely experience this or is it rare or not all?

[murphy]

My 12 volt battery drops all of the time but the HVB does not drop at all unless it gets really cold outside like it did last night.  It dropped from 26 to 25.

[Fat Fusion]

Mine drops.  Right in the range you describe.

[Hybridbear]

This is because the car cannot accurately measure discharging while driving. The BECM thus overestimates the SOC. When the HVB rests, the voltage stabilizes and thus the BECM can calculate a more accurate SOC.

[storksb]

This happens to my FFE, not as extreme as the OP. At the end of my commute the SOC will be reported as approx 55%, when I return to the car 9 hours later it typically show 46%. I put this down to two things, the HVB cooling down and the BECM being able to calculate more accurately. The only thing I am really concerned  about is range, do I get what I am expecting, SOC is just an estimate.

[jeff_h]

Same as all those guys above said, mine does the same.

[openair]

Same as all those guys above said, mine does the same.

Except for Murphy. Wonder what's different there. Thanks though guys.