Generation II Toyota Prius

311,000 miles

Is there really anything wrong

with it?

Predictive Maintenance

What is Predictive Maintenance?

It is the measurement of the high voltage propulsion system

allowing you to do long term tracking (Trending) and state of health

(SOH) to statistically measure and document the performance of

the high voltage system. PM can also provide short term SOH

analysis or analyses/diagnosis.

Predictive Maintenance

What is Trending?

Trending is a method by which data is acquired from high voltage

system components on a Annual/Biannual or Triennial intervals to

determine the SOH by comparing the test results to previous test

data.

Predictive Maintenance

Trending high voltage components is similar analyzing the state of health (SOH)

of an internal combustion engine (ICE) by:

• Performing a compression test, cylinder leak down, engine vacuum tests,

ignition test, and fuel system tests.

• Trending an engine and sub-systems can determine the overall mechanical

health of the vehicle being tested.

• This identifies any system or subsystem deterioration or rate of

deterioration.

Predictive Maintenance

Short Term State of Health

• Predictive Maintenance can be utilized for determining the high

voltage system state of health to benchmark the system

components and or component performance.

• Predictive maintenance can (and should) be used in conjunction

with OEM diagnostics before replacing a high cost component

What Components are Tested?

• Electric Machines (MG1/MG2)

• Drive Motor

• Generator

• Electric A/C Compressor

• Power invertor and control system

• Energy Storage System (HV Battery)

• DC-DC Convertor

• High Voltage Cables

Who can use Predictive Maintenance?

• “Out of Warranty” Owners

• “ In Warranty” Owners

• Fleet Customers

• Used Car Dealers

• Sub-Contracting from OEM dealers

• Salvage industry

• Collision Repair /Insurance industry

Battery Limiting and Energy Capacity Pack Power Drive Test (Five Cycles)

Battery Pack Power Limiting and energy Capacity Test (on-car)

Compare your results with these percentages SOC%:

Less than 5%outstanding

Less than 10% could be serviced (talk about this)

Less than 15% evaluate – service

Less than 20% evaluate – service

Always compare pre-SOC ______to post SOC ________

Compare V-Block high _____to V-Block low _______

Battery SOC should never fall below 13 volts

SOC% - State of Charge percentage

Always make sure that the Disconnect is removed !

Always use the proper protective equipment!

Check voltages with a CAT III DVOM.

Before jumping straight to

the battery, always spend

the extra moments to do an

inverter test!

Here we are using a Pico

Tool and Fluke clamps!

After removing the interior

pieces, we discover the

Main Battery Pack

Gloves required beyond

this point!

Make sure to use caution while

removing the cooling duct work

as these are vital components to

pack cooling.

Finally we have made it to the

electrical components!

Removing the series of

protective covers

With the connecting

bars and sensors

removed the cells are

exposed!

No Gloves required while

connecting the test leads!

Take care to make sure

no leads are crossed

First off - the Power Test!!! Well-this doesn’t look good!!!

On to the Energy Test!!!

Test leads connected.

This is a 6.5 Amp Hour pack

– all modules are drawing

down to 12 volts

Time to start cooking, but first

we must discharge the cells!!

It is vital to keep a close eye

on the battery temps through

out these processes as to

not cause a thermal incident!!

Three phase charging:

2.5 amps for 2 hours

1.5 amps for 1 hour

1 amp for 1 hour

Cooling is essential during this time.

Max temp should never exceed 50 degrees

Celsius.

After the cycling of the pack it

is wise to redo the Power and

Energy test!!

That looks much

better, all modules

are balanced!!

Now that all the cells are balanced

and everything checks out well its time

to reinstall the battery and get ready to

take it for a spin!!!

Putting things back

together!!!

Time for the

horrible gloves

again!!

Getting everything bolted

back down!!

Don’t forget all the electronic

plugs, before reinstalling the

interior panels!!

This car was in great shape for the miles

but after the Refresh we increased the

mileage by 10+ miles per gallon!!!

Before: 36mpg

After: 47mpg

• Thank you for joining me today - Ken Mays (kmays@cocc.edu)

• Special thanks to COCC Students Braddon Harrison and Pete Olson for the

photos and PowerPoint help.