Battery charge capacity

[SSimon]

This may be a stupid question and please know that I searched the topic and found nothing. I'm wondering what happens to the energy converted to electric when my battery is charged to full capacity. Where does it go if my battery is fully charged? Is it wasted? I'm trying to figure this out so that I know if I have to try to modify my driving technique for better energy use.

Is anyone else able to chime in?

[kDB]

When the battery is full the car tries not to charge it anymore. It will use the ICE and the disc brakes to slow the car. Any excess chare will also be spent spinning the ICE to keep from over charging the batteries. So in other words, yes, it is wasted.

If you know your going to max out the batteries on a downhill, try to lower the charge a little before. If you still are going to max it out, try going down the hill partway in B, which will save your brake pads some wear.

[SSimon]

Thanks for the info.

[John in LB]

Just to clarify, when there is no demand for electricity (such as when the battery is fully charged) the motor excitor field is reduced resulting in no electricity being generated. Simply, what that means is that although the generator is spinning on its shaft, it is just freewheeling and not making electricity.

The result is that except for the small mechanical drag, the electric motor is just coasting and not creating any kind of load on the IC engine or the wheels.

[kevinwhite]

<div class='quotetop'>QUOTE(John in LB @ Jan 15 2007, 11:34 AM) [snapback]375959[/snapback]</div>

Just to clarify, when there is no demand for electricity (such as when the battery is fully charged) the motor excitor field is reduced resulting in no electricity being generated. Simply, what that means is that although the generator is spinning on its shaft, it is just freewheeling and not making electricity.

The result is that except for the small mechanical drag, the electric motor is just coasting and not creating any kind of load on the IC engine or the wheels.
[/b]

Not quite - the Prius motor/generators are permanent magnet type so there is no field to reduce.

However although there is voltage produced the inverter can control whether any current flows into the other motor or the battery exactly as you describe.

When you apply the brakes under these conditions the engine will be spun (sometimes at quite high RPM) to dissipate energy - it is not necessary to be in B mode for this to occur.

kevin

[John in LB]

<div class='quotetop'>QUOTE(kevin17 @ Jan 15 2007, 11:49 AM) [snapback]375965[/snapback]</div>

Not quite - the Prius motor/generators are permanent magnet type so there is no field to reduce.

However although there is voltage produced the inverter can control whether any current flows into the other motor or the battery exactly as you describe.

When you apply the brakes under these conditions the engine will be spun (sometimes at quite high RPM) to dissipate energy - it is not necessary to be in B mode for this to occur.

kevin
[/b]

thanks for the clarification - I agree with you, i forgot about this particular configuration.