Wednesday, July 30, 2014

R7

News:



Current Flow Chart

The Current Flow Chart shows electric current in and out of the traction battery.
With negative values, the battery is charging from braking, coasting or the petrol engine (see spot 1), while with positive values, current is actually flowing out of the battery for traction (see spot 2).
By using the EV Behaviour and the SOC Discharge charts, you can actually see where the current is coming from or going to.


Sunday, July 27, 2014

The new Google Drive and Locale Settings

If you switched to the new Google Drive, you may have experienced strange results.


It seems that new spreadsheets created in the new drive don't have a default locale setting.
When you load a CSV log file, first check "File / Spreadsheet settings..." and make sure to have "United States" selected: this is mandatory for decimal numbers usage.


Saturday, July 26, 2014

R6

News:

  • changed version number to match add-on store release number: so V57 is now really R6
  • this release is aimed at EV techniques evaluation 
  • added SOC Discharge chart, see linked page for explanation
  • added SOC loss from EV driving to Analysis page


SOC Discharge

The SOC Discharge charts may help you evaluating your EV driving style and is generated when the EV Behaviour additional analytics is selected.
The chart shows SOC values variation in different car states:



  • SOC Coasting Sum: SOC variation while coasting (accelerator pedal not pressed, brake pedal not pressed or driving in N)
  • SOC Braking Sum: SOC variation while the brake pedal is pressed
  • SOC ICE On Sum: SOC variation while the petrol engine is running (it may charge the HV battery)
  • SOC EV Traction Sum: SOC variation while the car is being pushed by the electric engine alone.

Examples:
Spot number 1: ICE is running and charged nearly 6% SOC
Spot number 2: this is a braking that recovered 2% SOC
Spot number 3: coasting gains little SOC over time.
Spot number 4: car is moving in EV and 4% SOC is being consumed to move the car.

Additional notes:
You may have negative SOC variation while coasting if driving in N.
Every time you drive in EV, battery current is used to drive the engine and SOC decreases.
The chart shows only SOC points consumed while the car is actually moving: it won't show SOC used while standing still.

Friday, July 4, 2014

Energy recovered while coasting vs braking

Here are 2 classic questions:

  • Is there greater recovery while braking or with a gently and longer release?
  • How much energy can we recover from what we used to bring the car up to speed?


Scenario:
Plain, straight, empty road with good tarmac and SOC at 60%
Test policy:
Standing start, electric traction up to 50 km/h.
Every test starts from the same location.
Electric traction is only used to estimate energy to reach 50 km/h in a way comparable to recovered energy.
Test 1:
As soon a the target speed is achieved, complete release of accelerator pedal until crawling kicks in.
Test 2:
As soon a the target speed is achieved, apply pressure on the brake pedal up to half of the CHG zone, until full stop.
Comparison criteria:
SOC gain difference, regenerated current amount, battery stress.

Test 1: coasting
Here's the chart


Speed is in blue: starts from 0, tops at 50 and then decreases until crawling speed.
SOC is in yellow: starts at 60%, decreases while accelerating and the increases again while slowing down.
HV battery current is in red: positive values while accelerating and negative while recovering.
The red positive area gives an estimate of the energy needed to bring the car up to speed, while the negative area represents recovered energy
Ratio of those two areas shows how much energy is recoverable: in this test ratio is 5.6 and recovered energy is 17.8% of the amount spent.
SOC Charge chart says that we recovered a little less than 0.8%


Battery stress is 31.03

Test 2: braking
Here's the chart


Speed is in blue: starts from 0, tops at 50 and then decreases until full stop.
SOC is in yellow: starts at 60%, decreases while accelerating and the increases again while slowing down.
HV battery current is in red: positive values while accelerating and negative while recovering.
The red positive area gives an estimate of the energy needed to bring the car up to speed, while the negative area represents recovered energy
Ratio of those two areas shows how much energy is recoverable: in this test ratio is 3.1 and recovered energy is 32.1% of the amount spent.
SOC Charge chart says that we recovered a little more than 1.5%


Battery stress is 40.43: this manouver is definitely more stressful than plain coasting.
What this could mean over the years for mileage and battery life is unknown.

Back to our initial questions:

  • Is there greater recovery while braking or with a gently and longer release?
It seems that braking gains more energy.
We have to use only regenerative braking, so no hard brakes and a road with no holes that may trigger friction pads.
  • How much energy can we recover from what we used to bring the car up to speed?
One third at best.

There's a thread about this on the Hybrid Synergy Forum: