Does anyone know the logic behind how the regenerative braking is supposed to work? I have tried to figure it out but it seems so arbitrary. I try to apply the brake very lightly to get it to come on, but it doesn't always do so. I am always in gear when I begin braking and try to maintain the pressure so as not to turn it off. Without changing anything it just abruptly stops. And sometimes it doesn't come on at all. It doesn't seem speed related as I have seen it work at 40 and at 16 mph. Also, it doesn't seem to matter what condition the batteries are in as I have seen it fail to work with only three bars showing. Any help in understanding would be appreciated. John

 

This is the information posted at InsightCentral.net concerning regenerative braking:

During deceleration, the gasoline engine is switched into fuel cut mode, and the IMA Motor/Generator is operated in generation mode. In this mode, the IMA Motor is driven by the wheels, generating electricity to be stored in the Battery Module, and slowing the Insight in the process. The amount that the IMA Motor slows the car is in proportion to the amount of regeneration being done. There are two deceleration modes:

• Foot off throttle but not on brake pedal - In this mode, the charge/assist gauge will show partial charge, and the vehicle will slow down gradually.
  
  
  
  
  
  
  
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• Foot on brake pedal - In this mode, a higher amount of regeneration will be allowed, and the vehicle will slow more rapidly. During light brake pedal application, only the IMA Motor/Generator is slowing the car. With heavier brake pedal application, the conventional friction brakes also come into play.<<<

When decelerating, regeneration will continue until engine speed falls to about 1000 rpm. At this point, the driver will typically shift into neutral. In many cases the gasoline engine will now immediately enter auto idle stop mode. If vehicle speed is such that it isn't clear whether the driver will most likely come to a stop, the engine may idle for a few moments before entering idle stop. If the battery state of charge is very low, idle stop will not be entered at all, and instead the engine will continue to run at a fast idle to recharge the Battery Module.

During generation, the AC produced by the IMA Motor/Generator is converted by the MDM into DC, which is used to charge the Battery Module. The DC output of the MDM is also applied to the DC-DC Converter, which reduces the voltage to 12v. The DC-DC Converter's 12v DC output is supplied to the vehicle electrical system. It is also used to charge the 12v battery as necessary.

When the State of Charge of the Battery Module is at its maximum level, generated electricity is only delivered to the 12v accessory system.

When the ABS system is controlling wheel lock up, an 'ABS-busy' signal is sent to the MCM. This will immediately stop regeneration to prevent interference with the ABS system.

I have found this info to hold true. The only other thing I could add is that sometimes I find that lightly "blipping the throttle" while slowing down will help guarantee that charging will kick in.

Regards,

 

Thanks, that was very good information, especially the fact that regenerative braking ceases at 1000 rpm. I guess you could downshift as you see 1,000 rpm approaching to throw the rpm's back up to keep regenerative braking going - I'll have to try that. But the logic now makes very good sense. John

 

What most of us have found is that the amount of regen after downshifting is not worth the wear & tear on the clutch. You're better off milking as much regen out of what ever gear you are in, then if coming to a stop, decelerate quickly to 20MPH & engage auto stop. From that point coast with clutch in to the stop.

Obviously depending on where you're driving & what your needs are, you would change that. Don't slam on your brakes & decelerate to Auto stop if there's someone behind you. And if you know you have a large climb coming up, maybe the extra regen is worth it in that instance.

 

Thanks for the helpful information. Today I did just that and coasting to a stop in neutral seem to alleviate my other issue of the engine not firing when I let out the clutch. John