R25

News:

• Added option to zoom charts: use mouse wheel to zoom in/out, left click to pan, right click to reset.
  Warning: this feature is marked as "experimental" by Google, so it's disabled by default.

• Google changed some options in scatter charts: maps are working again now.
• Brakings code is now more permissive about "bad" brakings.

A common mis-B-havior

It's a common belief that B is an efficient braking solution.
Many car salesmen say that to the customers during test drives, and it's frequently stated even on car reviews: B engages engine brake (true) and charges the battery more than conventional braking (false).
Let's check it:

Scenario: car running at 50 km/h
Test n. 1: switch to B and let the car slow down only by the effect of the engine brake.
Test n. 2: stick to D and press the brake pedal with enough pressure to mimic the same slow down of the B position.

The outcome is outlined in the chart below:


The first test starts at 17:56:20 and ends at 17:56:35
The second test starts at 17:56:52 and ends at 17:56:06
Current to the battery is the red line.
Negative values represent battery charging, generated by braking.
The red area is proportional to the current generated by the recharging effect.
The second area (the one generated by conventional braking) is greater than the first area (generated by engine brake in B).
The second area is 376 units wide vs 296 of the first, so by braking you gain 27% more energy than using B.

If we add fuel flow to the chart, we can see that using B we burn even some fuel.

By looking at the RPM chart, we notice that the petrol engine spins til 20 km/h

R20

New:

• Added current statistics on the Battery Fitness page

Explorer warning

I've received reports of Internet Explorer not displaying the sidebar correctly.
Please use Chrome or Firefox.

R19

News:

• HV Fitness is now an additional analytic
  

• Resistance measurement (new PIDs required)
• Orion BMS support (select it in the options) 

• Near-critical (10% difference) cells are now highlighted

R18

New version available:

• HV Battery Fitness: check your HV battery health
• New PIDs for battery fitness: read the FAQ
• Battery Block chart

HV Battery Fitness

The HV Battery Fitness sheet gives an overview of the battery block behavior

For every battery block, the following parameters are reported:

Avg Bias: every block value is compared to the max value of the whole battery. The difference of the block value from the max value is called Bias. This is the average bias over all the trip. This should be as little as possible. High bias may be a clue of a faulty block

Max Bias: maximum observed bias in the whole trip. A high value suggest the block is fluctuating more that the others

Highest Voltage: highest voltage the block has reached. At least one faulty block has been observed having both the highest and the lowest value of the whole battery

Lowest Voltage: lowest voltage the block has reached. Deteriotated blocks may have lower voltage than the others

Std Dev: standard deviation from average value: Blocks that fluctuate more have higher deviation. This is another sign of anomalous behavior.

Avg Local Delta: each block value is compared to its neighbours

Max Bias @stress: this bias is measured only when the battery is used with high current values. This should give a measure of how well the block behave under load.

Max Resistance: maximum measured resistance. Degraded cells may have higher resistance.

%Time @MinV: Time in the whole trip, the block was the one with the minimum voltage. This parameter filtered on delta above 0.2V, as lower values are considered not significant.

Max Est. R: maximum estimated resistance

Avg Est. R: average estimated resistance

Red and green highlight best and worst blocks for every measure.
Orange values are within 10% of the worst value.

Other measures are related to the whole battery:

Long sequences of delta values above various thresholds are primary suspects of impending battery faults, as explained in this article: http://artsautomotive.com/publications/7-hybrid/140-predictive-battery-failure-analysis-for-the-prius-hybrid/

Required PIDs:

HSD3:
"Batt Pack Current Val"
"Battery Block Voltage -V01"
"Battery Block Voltage -V02"
"Battery Block Voltage -V03"
"Battery Block Voltage -V04"
"Battery Block Voltage -V05"
"Battery Block Voltage -V06"
"Battery Block Voltage -V07"
"Battery Block Voltage -V08"
"Battery Block Voltage -V09"
"Battery Block Voltage -V10"
"Battery Block Voltage -V11"
"Battery Block Voltage -V12"
"Battery Block Voltage -V13"
"Battery Block Voltage -V14"

"Internal Resistance R01"
"Internal Resistance R02"
"Internal Resistance R03"
"Internal Resistance R04"
"Internal Resistance R05"
"Internal Resistance R06"
"Internal Resistance R07"
"Internal Resistance R08"
"Internal Resistance R09"
"Internal Resistance R10"
"Internal Resistance R11"
"Internal Resistance R12"
"Internal Resistance R13"
"Internal Resistance R14"

"Temp of Batt TB1"
"Temp of Batt TB2"
"Temp of Batt TB3"

HSD2:

"HV Battery Current"

"HV Battery Block-01 Voltage"
"HV Battery Block-02 Voltage"
"HV Battery Block-03 Voltage"
"HV Battery Block-04 Voltage"
"HV Battery Block-05 Voltage"
"HV Battery Block-06 Voltage"
"HV Battery Block-07 Voltage"
"HV Battery Block-08 Voltage"
"HV Battery Block-09 Voltage"
"HV Battery Block-10 Voltage"
"HV Battery Block-11 Voltage"
"HV Battery Block-12 Voltage"
"HV Battery Block-13 Voltage"
"HV Battery Block-14 Voltage"

"Internal Resistance R01"
"Internal Resistance R02"
"Internal Resistance R03"
"Internal Resistance R04"
"Internal Resistance R05"
"Internal Resistance R06"
"Internal Resistance R07"
"Internal Resistance R08"
"Internal Resistance R09"
"Internal Resistance R10"
"Internal Resistance R11"
"Internal Resistance R12"
"Internal Resistance R13"
"Internal Resistance R14"

"HV Battery Temp 1"
"HV Battery Temp 2"
"HV Battery Temp 3"

While not strictly necessary, additional PIDs like Speed and SOC, may give a better overview of what's going on, as in this investigation.