Hybrid vehicle service and maintenance

Talking Automotive On Sunday

Taurayi Raymond Sewera

HYBRID CARS being imported into Zimbabwe come with several issues, which differ from one vehicle to the other.

Let us start with Toyota hybrids as our first example.

Toyota Aqua, Toyota Axio, etcetera, mostly 2012 to 2014 models, come with a high-voltage battery pack that has issues like apparent capacity loss (ACL), which basically means the cell structure has “memory loss”.

In other words, the high-voltage battery cell material has changed from beta to gamma.

This is part of the cell ageing/cell state changes, and can be reversed.

The lost capacity can be reversed in many cases.

This type of cell ageing in the form of ACL is mostly found in high-voltage batteries or the rechargeable energy storage system (RESS) made from nickel-metal hydride (NiMH) chemistry. It is not found in the lithium battery family.

Toyota warrant their high-voltage battery packs or RESS for eight years or 150 000 kilometres.

This means most of these cars from 2012 to 2014 need RESS replacement.

I have personally experienced high-voltage batteries that last way more than eight years when maintained well.

Just like we service internal combustion engines (ICEs), we are also supposed to service these high-voltage batteries to increase their longevity.

What also needs to be done on these Toyota hybrids is transaxle service.

A Toyota Aqua Hybrid, Toyota Axio Hybrid, Toyota Prius Hybrid and so on has two motor generators (MGs) — motor generator 1 (MG1), which is used to start the ICE and driven by the ICE to charge the RESS; then motor generator 2 (MG2), which is the drive motor that is used for propulsion.

MG2 is also used to charge the RESS during a process called regeneration.

Regeneration occurs when we are coasting, decelerating or when we request braking.

Depending on the operation condition and RESS state of charge, the vehicle will use kinetic energy to drive the MG2 to slow down the vehicle and charge the RESS.

The two motor generators are part of the transaxle, which is referred to as “transmission” on the traditional vehicles that we are all acquainted with.

This transaxle uses oil, which needs to be replaced before it starts to compromise the motor generators’ insulation and cause various isolation faults.

The next service we still need to do on the family of Toyota hybrids involves the inverter assembly, with DC-DC converter coolant replacement.

We need to use coolant that is non-conductive.

If you are using a concentrate, you need to dilute it with deionised water.

The high-voltage battery pack/RESS still needs service every two years, or earlier in countries with more humidity and elevated temperatures.

The next service for Toyota hybrids is on the internal combustion engine/ICE.

Most of the hybrids use Atkinson cycle engines, instead of the OTTO cycle type.

Atkinson cycle engines use 0W-16 oil.

This oil is very thin but has all the lubricity and much-needed additives.

These include anti-foaming and anti-rust additives.

The oil thinness is meant to reduce friction, which will compromise mileage.

The Atkinson cycle reduces engine pumping loss, thereby increasing mileage and saving fuel.

It uses the late intake valve closing strategy to reduce engine pumping losses.

We still need to replace engine ignition spark plugs with ones from original equipment manufacturer.

 

Using wrong spark plugs lowers the longevity of the coil on plugs. This might also compromise mileage and damage the precious catalytic converters.

We also need to service the brake system.

We particularly need to replace the brake fluid.

The fluid is hydroscopic, which means it absorbs moisture. Over time, the moisture will solidify and act as an abrasion to rubber seals in the brake system.

Neglecting brake system service on these Toyota hybrids damages expensive brake system components like the brake boosterassembly with accumulator and the brake master cylinder.

Major services on strong Honda hybrids

Honda hybrids like the Honda Grace Hybrid, Honda Fit GP5, GP6, Honda Vezel and Honda Shuttle GP7 will need service on electro-hydraulic clutch actuators (EHCAs).

These actuators use brake fluid to actuate the dual clutch.

Brake fluid has characteristics we mentioned above.

For the same reasons we noted, the fluid will need to be replaced before costly components are damaged.

When compromised, EHCAs will cause major damage to the dry dual clutch, which costs over US$2 000 to purchase, excluding costs of shipping it to Africa.

The transmission on the Honda hybrids mentioned above is manual.

Many people mistake it for automatic transmission that uses automatic transmission fluid (ATF).

Replacing the manual transmission fluid with ATF will cause catastrophic damage to the transmission, which is not repairable.

What will then be needed is replacement of the transmission.

These vehicles will still need most of the services specified for the family of Toyota hybrids.

 

*Taurayi Raymond Sewera is ASE and Auto Care Association-certified World Class Master Technician with 39ASEs, ASE Advanced Level Specialist L1, L2, L3 and L4, AMI-Accredited Master Electric Vehicles and Master Automotive Manager, and ACDC-certified Master Hybrid and Electric Vehicles Technician. He is the founder and CEO of TauRay Automotive. He can be contacted on: +263772341193, +263772357296 or [email protected]