I have talked to a Toyota service technician and was told if there was an issue there would be an error code. Machine said no issue so that is where the assistance stopped.

Can I trust the Power Meter to indicate the level of power being generated back into the battery during braking?? If I can, then I belive I have a problem. At times this meter will depress almost to the bottom of the blue area during braking and at times it will not. The charge state of the battery seems to not have an affect on this. We believe we have noticed a drop in fuel mileage and I belive that we are not getting the full benefit from braking. It seems as if the Power Meter indicates more charging early morning and then at some point it will only very slightly depress.

Anyone know the truth on the meter?

 

This time of year, a too hot traction battery will limit the charge acceptance rate or shut it off completely, regardless of charge state. Same for too cold. Even with ideal temp, the battery frequently can't accept prolonged full regen current - eg down a long hill - without shutting down due to incipiant overheating from the huge current inflow.

I imagine the effect is worse with i4WD models with both motors generating.

Pete

 

Yesterday I had a good example of the effect of heat on the traction battery after a long ascent of Fremont Peak near Monterey - almost 3000' up to the parking lot.

On the long way down, the interior hot after a couple of hours soaking up the sun, and battery at less than 50%, no movement of the power flow needle on braking at first, then gradually more as the car cooled with the AC at full blast. Twenty or so minutes later, at the bottom, things pretty much back to normal with regen. function.

Pete

 

Thanks for the information. My issue is very intermittent and I live in Houston, so it is hot to begin with. I do see the regeneration process change with repeated breaking. The meter will indicate free movement and apparent regeneration, however with repeated breaking the magnitude of the needle deflection will reduce and then essentially stop.

My big irritation is that the Toyota dealership will not acknowledge that this is an issue. I have worn them out trying to say that it should not regenerate fine at one time then not at all another when the battery is in a state of depletion. If the computer does not indicate a red flag, there is no issue and nothing can be done. Very little immagination or idividual problem solving.

I appreciate your experience on this matter.

 

I'm afraid that this is just a characteristic of our hybrid batteries and a non-issue as the dealership has said. Stated again, at times, regen. charge acceptance is limited to avoid battery overheating and battery damage. Full regenerative braking power (kilowattage) flow to the battery is huge, and the battery can't accept this for very long without overheating. Houston summers definitely aggrevate the problem, since our batteries use reversible chemical reactions to store energy, and this process generates heat.

Pete