Could a bodyshop destroy your HV battery?

Interesting that we are starting to see reports of reduced capacity in the Leaf battery packs in states with high temperatures as well; I think there is a definite problem with lithium ion batteries exposed to, and generating high temps. I recall that some of the first lithium ion batteries that were installed in laptops tended to generate so much heat they would catch fire. Wasn’t it lithium ion batteries that exploded in the GM lab a while back? There may be more to the fact that Toyota chose not to put lithium ion batteries in the Prius Gen III, and only chose to put them in the PIP and the Prius C. It will be interesting to see if the lithium ion batteries in the PIP and the C suffer any of the problems we are seeing in the Leaf. One of the big plus points for me in buying the Gen III was that it was solid tech that has been tried and proven over a decade.

 

The C has a 144 Volt Nickel Metal Hydride (NiMH) battery.

 

Of course, just about any battery exposed to extremes of heat and cold will lose performance. If the exposure is too extreme damage will result with any type of battery. Thus don’t block the HV battery vent in your Prius.

 

Thanks for the correction. So it is just the PiP with the lithium ion pack right?

 

In the USA the PiP is the only model with Li-Ion. I think I've read that elsewhere in the world Li-Ion is used on some other models.

 

When discussing Li-Ion issues, remember that there are several chemistry families under the Li-Ion umbrella. The laptop fires were related to Cobalt, which is absent from the LiFePO4 types generally used in transportation batteries.

 

This might help:
http://www.ehow.com/video_2327592_bake-car_s-new-paint-job.html

Would you want your Traction Battery at those temps for twenty minutes?

I have also discovered through some searches that there are shops curing their paint jobs at even higher temps, between 160-175 degrees F. I would not want any of the electronics cooked at those temperatures. In one forum I looked in there was even a post stating that Chrysler computer systems can be destroyed by 160 degree F plus temperatures, along with warping of the plastic and rubber bumper parts.

So I would suggest that no hybrid or EV batteries and no car electronics should be exposed to the paint curing process. They might survive it or they might not, would you want to take that risk?

 

While there a certainly differences between different lithium ion battery types, I find it curious that they all seem to have trouble with high temperatures. I have a rechargeable string trimmer for doing the trimming around my yard that uses rechargeable lithium ion packs. They get very hot during their discharge cycle, so hot in fact, that the charger puts up a heat warning, and will not charge them until they have been cooled off. I actually put them into my refrigerator for about 15 minutes to cool them sufficiently so they will charge. There is no high speed charger for them, that I am aware of, which makes sense seeing how hot they get during discharge. I admit, I am no battery expert, but the connection between lithium ion batteries and heat related issues should not be ignored, and I believe owners of the PiP should pay close attention to their HV battery packs for any sign of charge capacity loss, or high temperatures.

Let’s look at the following from Wikipedia:

Disadvantages
Cell life

• Charging forms deposits inside the electrolyte that inhibit ion transport. Over time, the cell's capacity diminishes. The increase in internal resistance reduces the cell's ability to deliver current. This problem is more pronounced in high-current applications. The decrease means that older batteries do not charge as much as new ones (charging time required decreases proportionally).
• High charge levels and elevated temperatures (whether from charging or ambient air) hasten capacity loss.[48] Charging heat is caused by the carbon anode (typically replaced with lithium titanate which drastically reduces damage from charging, including expansion and other factors).[49]
• A Standard (Cobalt) Li-ion cell that is full most of the time at 25 °C (77 °F) irreversibly loses approximately 20% capacity per year. Poor ventilation may increase temperatures, further shortening battery life. Loss rates vary by temperature: 6% loss at 0 °C (32 °F), 20% at 25 °C (77 °F), and 35% at 40 °C (104 °F). When stored at 40%–60% charge level, the capacity loss is reduced to 2%, 4%, and 15%, respectively.[50] In contrast, the calendar life of LiFePO4 cells is not affected by being kept at a high state of charge.[51]

Internal resistance

• The internal resistance of standard (Cobalt) lithium-ion batteries is high compared to both other rechargeable chemistries such as nickel-metal hydride and nickel-cadmium, and LiFePO4 and lithium-polymer cells.[52] Internal resistance increases with both cycling and age.[53][54][55] Rising internal resistance causes the voltage at the terminals to drop under load, which reduces the maximum current draw. Eventually increasing resistance means that the battery can no longer operate for an adequate period.

• To power larger devices, such as electric cars, connecting many small batteries in a parallel circuit is more effective[56] and efficient than connecting a single large battery.[57]

{Electronics 101 resistance increases with temperature. High temperatures will reduce the capacity of even the LiFePO4 battery.} My comment.
Safety requirements
If overheated or overcharged, Li-ion batteries may suffer thermal runaway and cell rupture.[58] In extreme cases this can lead to combustion. Deep discharge may short-circuit the cell, in which case recharging would be unsafe.[59] To reduce these risks, Lithium-ion battery packs contain fail-safe circuitry that shuts down the battery when its voltage is outside the safe range of 3–4.2 V per cell.[35][47] When stored for long periods the small current draw of the protection circuitry itself may drain the battery below its shut down voltage; normal chargers are then ineffective. Many types of lithium-ion cell cannot be charged safely below 0°C.[60]
Other safety features are required in each cell:[35]

• Shut-down separator (for overtemperature)
• Tear-away tab (for internal pressure)
• Vent (pressure relief)
• Thermal interrupt (overcurrent/overcharging)

These devices occupy useful space inside the cells, add additional points of failure and irreversibly disable the cell when activated. They are required because the anode produces heat during use, while the cathode may produce oxygen. These devices and improved electrode designs reduce/eliminate the risk of fire or explosion.
These safety features increase costs compared to nickel metal hydride batteries, which require only a hydrogen/oxygen recombination device (preventing damage due to mild overcharging) and a back-up pressure valve.[47]
Now let’s look at this chart of capacity loss against storage temperature:



Source: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

 

I wouldn’t say that entirely. Batteries can be destroyed by impact shock as well as heat, so without being able to inspect and test the battery after the accident, but before the paint job, it’s impossible to answer that question.

I would suggest, that before any paint work is done, that the shop be told not to expose the sensitive batteries and electronics to a curing oven. Realize that this will mean more disassembly of the car, either to remove the electronics from the vehicle or the damaged body panels from the vehicle for paint curing. It is my understanding that at least here in the US many shops do not bake the paint that is applied for accident repair. Maybe this is different where you are.

This just highlights one more reason to have a Toyota dealer do any work that needs to be done on a Prius, or a Nissan dealer for the Leaf. “Fred’s Garage” most likely doesn’t have the knowledge to properly repair a complex vehicle like a modern hybrid or EV. I am not trying to knock small repair shops, I’m just saying these cars are different.

 

I was addressing only the safety issue of battery fires from thermal runaway, and did not mean to suggest than any Li-Ion chemistry doesn't have performance problems with high temperatures.

Also from Wikipedia (Lithium-ion battery):
"Handheld electronics mostly use LIBs based on lithium cobalt oxide (LCO), which offers high energy density, but have well-known safety concerns, especially when damaged. Lithium iron phosphate (LFP), lithium manganese oxide (LMO) and lithium nickel manganese cobalt oxide (NMC) offer lower energy density, but longer lives and inherent safety."

... also (Lithium iron phosphate):
"Avoiding the lithium cobalt oxide cathode leads to a number of advantages. ... LiCoO2 also can lead to problems with runaway overheating and outgassing, making batteries that use it more susceptible to fire than LFP batteries."

My other handy references, while a bit dated now, are still tied up by NDAs.

 

Actually I don’t think we are in any disagreement per se’. I agree about the cobalt problem with the battery fires. All I am saying is there is a definite correlation between reduced performance of lithium ion battery tech and high temperatures, and I still say if you own the PiP watch your HV battery health and heat exposure closely.

 

How soon would you know if there is any damage to your battery? I was rear ended in Jan 2012 and the rear bumper was replaced. i haven't noticed any difference.​

 

I think you would have noticed, at least reduced capacity by now, if your HV battery had been damaged. Sounds like your battery is OK.