[Guest]

I've recently noticed more and more that I rarely get full assist (or at least all bars of assist lit) even when I use WOT. It also doesen't seem to matter what my SOC is reading. I've noticed the under-assist every where from half charge to three bars from the top. Now, the weather has been colder here since I've noticed this lack of assist, is that the problem? Is it normal for the car at WOT in colder temps to supply less than the full 100A assist or the 50A assist that it usually drops to after 10 seconds or so? Are there any other conditions where the car would choose to limit the assist at WOT? Any thoughts?

 

[Insightful Trekker]

Temperature plays a significant part with what the BCM will allow going into or out of the IMA battery pack. You don't give your location or the range of temperature your now expereincing, but in general its over 100 and under 20F before these limits are "easily" seen. But there are incremental reductions as you approach these points.

Your description of the true current leaving the IMA pack cannot be reliably deduced from the dash gauge only. Remember their software driven. A somewhat "different" display of charge and assist may have no correlation to any actual change in power flowing.

An IMA reset is the first diagnostic proceedure to determine if its a learned parameter.

 

[Aaron Cake]

IMA assist will be greatly reduced in cold weather until the pack warms up, then it should show on the gauge as normal. You will find that in very cold mornings (-30C or less) that you will have no assist and forced charging for a few minutes to heat the battery.

 

[Mike Dabrowski 2000]

I happen to have a digital thermometer watching my pack temp, as well as an ammeter to watch the actual current. If the pack internal temp is <42F, assist as well as charging will be reduced. The charging system has a special mode below 32F where it charges with a sawtooth pulse to gently raise the battery pack temp. This switches to normal DC charging over 42F, and the normal assist and regen currents should be available. Since cabin air is used to control the Insight battery temp, getting the cabin nice and toasty should help to get the pack temp in the normal operating zone.

An interesting aspect of the Ford Escape battery pack is that it has its own AC and heating system to keep the 250 D cells in the best temperature range for performance and longevity. I believe we will see this in the newer generations of all hybrid cars.