What Happens if HVB is Full and Engine is Cold?

[DrDeke]

As the new owner of a 2012 Fusion Hybrid in Michigan, I have been noticing the ICE running for increasing periods of time after I start the car in the morning, presumably in order to heat itself (as well as the catalyst, O2 sensor(s), etc) up. I have also noticed on a couple trips that the HVB state-of-charge as indicated on the dashboard has gotten very close (but not quite) to the "full" mark during this type of operation, and this makes me wonder: What happens if the HVB reaches 100% SoC (as shown on the dashboard) but the engine (or catalytic converter/etc) is still too cold?

 

In a conventional car with an automatic transmission, the excess energy produced by the engine when it is at idle and the car is stopped gets dissipated as heat in the torque converter of the transmission. But what happens to this energy in the FFH? I can't, at least off the top of my head, think of where it could go if not into the HVB.

 

Am I correct about that? If so, would the ICE stop running under such conditions? Or, would it keep running and continue to charge the HVB above "100%-as-indicated-on-the-dash" SoC?

 

Just curious, but I'm sure someone here will know.

 

Cheers,

DrDeke

[DrDeke]

A friend clued me in on this; the answer was pretty simple.

 

The ICE continues running, which causes MG1 to turn. However, the MG1 inverter effectively keeps the MG1 electrical connections 'open', thereby not allowing current to flow from MG1. This reduces the mechanical load on the ICE, and whichever computer controls the ICE simply reduces its fuel input to maintain the target RPM.

 

All energy generated by the ICE in this mode is dissipated as heat, just like in a conventional powertrain car.

[lolder]

"H" on the HVB gauge is only about 80%. When it reaches that the charge tappers down towards zero and the ICE uses less fuel until various components have reached the desired temperature. It's normal. Park you car in a heated garage if possible and don't turn the HVAC on for heat until the car has driven a while. This will probably freeze you out so just put the HVAC in auto and select the desired temperature and forget it