2009 Ford Escape Hybrid Sluggish Acceleration on Hot Days

Y’all were really helpful with diagnosing my Fusion’s AC compressor problem, so maybe you can give me some pointers with an issue I’m having with my Escape.

Some background:

  • 2009 Ford Escape 4WD 4 Cylinders 3 2.5L MFI Hybrid DOHC
  • ~100k miles

BLUF: Sluggish acceleration on hot days

In the electrical power system menu, the battery always shows between 40-60% capacity. On hot days, it has really sluggish acceleration from a full stop or a slow roll right after starting the engine. This lasts for about 5 or 10 minutes, sometimes longer depending on how hot it is. Also, during this time of sluggish acceleration, the car won’t switch to electric at stop lights or low speed and the “Charge / Assist” indicator on the instrument panel doesn’t move.

Two questions:

Could the car be dangerous or unreliable to drive with an issue like this, especially over long distances?

Where can I start troubleshooting? I’ve heard the battery cooling system could cause this.

Did you ever find out anything about this problem? I have a very similar problem. Problem is intermittent and seems to go away after the car has been driven for 5 or 10 minutes. Problem also seems to be worse when the vehicle has not been driven for a few days.

I solved a sluggish acceleration problem with my 2011 MKZ hybrid a couple of years ago by resetting the ‘birth date’ of the battery, Ford cut back on hybrid battery use after 7-8 years for some reason, resetting the battery’s age eliminated that problem. I recently got an offer for the dealer to reprogram the car to achieve this.