0.0% SOC possible? yes

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justanotherdrunk

Well-known member
Joined
Feb 19, 2015
Messages
265
Location
Silicon Valley
Curious if the Rex would start only to power the accessories (AC/ heat/ radio/ lights) while parked in the garage.

Answer: no

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:geek:
 
My understanding is the car has to be moving for the REx to run. It does continue at a traffic stop but I've not timed how long it continues to run. But I agree, I would prefer to have the REx run and provide charge even when the car is stationary.

This may justify retaining the Prius because it does preserve the traction battery SOC even when parked. This allows us to use the Prius as emergency power during a power outage. It also means we can use the Prius to provide a charge via the L1 charger to the i3.

It would be interesting if this behavior could be 'coded.' It might be a USA specific defect implemented for CARB. Perhaps some of our EU friends might test?

BTW, how did you test this? When I get out of the car, it appears to shutdown. Did you stay in the driver seat for how long to bring the SOC down so low?

Found the source in "01_I01-Product-Presentation.pdf" pp. 100:


  • 7.5.2. Automatic engine start/stop function

    The combustion engine also has an automatic engine start-stop function. To activate the automatic
    engine start-stop function the presence of the driver must be detected using the seat belt and door
    contact. As long as the seat belt is inserted and the door is closed, the driver is considered present
    and the range extender is operated with automatic engine start-stop function.

    The combustion engine is switched off under the following conditions:
    • SOC 3.5 - 6.5%
    • Speed < 10 km/h / 6 mph.
    If the speed of the vehicle is greater than 20 km/h / 12 mph, the combustion engine is restarted.
    During the warm-up phase of the combustion engine . . .

Bob Wilson
 
Are you coded to enable charge sustain mode?

I may replicate your test later today. I'll get out; insert the seat belt; roll-down the windows; and leave the key-fob inside the car. I'll start the test with the range extender engine on to preserve a significant SOC. Then check it and log the changes over time.

The training charts indicate the 12V DC-to-DC inverter has a 2500W capacity. Current tests suggest the electrical load is ~500W. If the automatic start/stop function works as expected, I'll be able to retire that last Prius unique function.

Bob Wilson
 
Mind you, it still has about 1 kWh to 1.5 kWh in the pack, it just can't be accessed. Guys, please don't purposely run the pack down this low becase you're flirting with trouble, especially if you leave it at 0% for a while. I'd recommend plugging in it as soon as you can once the SOC drops below 2%.
 
TomMoloughney said:
Mind you, it still has about 1 kWh to 1.5 kWh in the pack, it just can't be accessed. Guys, please don't purposely run the pack down this low because you're flirting with trouble, especially if you leave it at 0% for a while. I'd recommend plugging in it as soon as you can once the SOC drops below 2%.
I agree and would only add that "Battery University" suggests a full charge cycle is good for LiON batteries. HOWEVER, there are at least three LiON battery chemistries and I don't know what the i3 is using.

Beyond running the traction battery to 6.5% to ensure the REx starts, I'm not willing to explore the full range until I get more facts and data:
  • i3 LiON chemistry - I really want to know what we have.
  • sample testing - get some smaller LiON batteries of the same chemistry and 'torture' them. I have the tools and knowledge.
  • accurate traction battery capacity test - right now, I haven't found a credible source but I suspect once I start my 30 day, maintenance web site survey I might find it.

One 'wild card' is trying to separate the environmental load from the actual traction battery charge-discharge metrics. This is not a trivial NOR impossible task for the curious ... I am very curious.

Bob Wilson
 
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