[hstrub]

can anyone tell me how I know that the batteries in my Prius are performing as they should.
Also, what does it take to overcharge them?

 

[redwein]

If you haven't seen any warning lights, are always showing at least one bar on the energy screen and you haven't noticed any difference in fuel economy, I would say your batteries are fine. It isn't possible to overcharge them by driving/running the car.

 

[DanMan32]

I suppose a test would be to get the SOC to a certain level, then turn off all accessories and see how long it takes for ICE to have to come on to maintain charge. The only problem is, level 6 SOC has a wide low and high range with hysteresis overlap between the 5th and 7th levels.

 

[Astrowoman]

The full range on the display is much less than the full range of SOC. If you have experienced the car vibrating and running "funny" when going downhill with a "full" battery on the display, it's doing what it does to prevent overcharging and will be fine. Why are you worried?

 

[hstrub]

a) So what exactly does happen with the regenerated energy, after the battery shows full and I'm still on a long downhill run.

b) The battery has a capacity of 1300 W/h, I never seem to be able to regenerate more than 250 W/h from discharged to full SOC.

 

[MtnTraveler]

Good question on the long down hill. I finally took my car up some gravel mountain roads. The hills are long and sustained -- much steeper than any highways. Usually the speeds are in the 10-20 mph range. When descending, the battery charged up to the highest pip (I was riding the brakes). So I shifted to "B" mode.

I was surprise how little braking B mode is compared to D mode. Much different than dropping into low gear on an automatic or manual. Anyway I figured this would help keep from topping off the battery way before I got to the bottom of the hill and had to use brake pads (possibly overheating the brakes).

I wish there was a way to allow the driver to "predict the future" for the car. For example, if you know you're going up a very long road, you could set a mode to allow the battery to drain. Then at the top, you'd have a nearly empty battery that could charge up on the descent. In the event you didn't predict right, your performance would suffer because the ICE would have to charge the battery while climbing... but it would probably allow for better gas mileage.

Maybe there could be a three-way switch for the median battery level:
- low
- normal
- high

The driver would select low going up a very long hill, or driving around down town or shopping mall parking lots. Select normal most of the time. Select high going down a very long hill.

 

[DanMan32]

Whatever regen can't do to stop the car, conventional hydraulic controlled friction brakes are used. If in B mode, then engine braking is also used.

Brake system(thinging to self): Ah, master wants to slow down at 100ft/sec/sec. Lets see if the hybrid system can accomodate

Brake system to hybrid: Mr Hybrid, can you do your magic and slow down the car at a rate of 100ft/sec/sec?

Hybrid to brake: Not quite. Battery is near full. I can only give you 75ft/sec/sec brake force.

Brake to self: Ok then, I'll just have to use wastefull friction brakes for the extra 25ft/sec/sec.

 

[hstrub]

Yep, I understand that the display does only show a certain amount of the full range of the SOC, maybe 50 to 60%. I have never been able to regenerate more than 20 % of the full battery capacity, according to the regenerated W/h on the consumtion screen. - I'm in New Zealand and wonder if you guys in the US have the same software, also showing you the regenerated W/h?