Hybrid battery failure

[Chris111]

No mine haven't failed but I have been thinking about this for a while as the matter of hybrid Battery failure always gets mentioned when any prospective owner asks on this forum what to look out for on the series 3 GS450h. It is also stated that there is a higher failure rate for this model compared to other Toyota/Lexus models from the same era.

Now, I am just throwing this out there to see if anyone more knowledgeable can add to or confirm or tell me I am completely wrong about this, but I'm wondering if it isn't actually the owner of the car who has inadvertently been responsible for the hybrid Battery failure in the first place. I am only thinking this as the air intake vent to cool the hybrid Battery on a S3 GS is situated on the rear parcel shelf or package tray and a warning notice on page 11 of the owners manual states “Do not put foreign objects over the air vent. The hybrid Battery (traction battery) may overheat and be damaged.” The GS is a saloon and I have seen plenty of other makes of saloon cars with stuff on the rear parcel shelf so how many GS 450h owners may have put a coat, jacket, pet (dog!), cushions, road atlas or anything on the rear shelf without realising this and have obstructed the vent?

So my question is basically could any resulting damage from overheating ultimately lead to hybrid Battery failure?

The other hybrid models that the GS is compared to are either hatchbacks (CT/Prius) or a SUV (RX) and they don't have a fixed rear parcel shelf so obviously the air intake vent to cool the hybrid batteries is in a different place on those cars. I don't know where the vent(s) is/are on those cars but is it a place more difficult to obstruct?

As I said these are just my thoughts and I may be completely wrong but what do other forum members think?

[royoftherovers]

Good thinking Batman !

An elementary mistake which is potentially catastrophic in a series 3 GSh.

.I always keep my rear shelf clear and even put my umbrella in the boot rather than on the rear shelf.

Be interesting to learn what other Forum members think.

[ColinBarber]

Prius has them between doors and seat backs which are difficult to obstruct, 400h has them below seat base where your feet are - can be obstructed with bags etc. but in both cases they draw in air from the main part of the cabin.

Given that corrosion seems to play a part in some failures (first pic on page 2), I wonder if it draws in moist air from near the rear window and passes it across the batteries.

 

[Britprius]

Corrosion of the connecting links has been a problem on the Prius, and all subsequent hybrids. This is due to the electrolyte " a mixture of KOH & NaOH" leaking onto them. This is very caustic eating some metals copper, aluminium, some stainless steels, included, and even glass. The modules have a pressure relief valve set at 80 PSI but having done tests found over time these all stick taking double that pressure to release. This forces out the electrolyte around the seals where the terminals exit the modules, and onto the copper links. In rare cases the top of the module blows completely off 

The idea that covering the cooling vent on the GS is very valid. It has been found in hot climates the hybrid batteries have a much shorter life span due to drying out of the electrolyte. The centre modules in the Battery tend to dry out first. One cell fails with low capacity then gets  reverse charged in the series string of cells. This then goes high resistance causing more heat, and destroying other cells close to it. 

Having owned a Prius for many years I was a long term member of the US forum "Prius Chat" doing many experiments on the Battery modules including a non destructive method of rehydrating them with much success.  It is a slow process requiring the handling of the very caustic materials.

John.