2005 Prius with 193K miles and exploded battery module

Wow. Amazing that the car ran at all after the boom
I wonder how a Li-x battery would have "performed."

 

I think you should replace modules 17 and 19 as well, because they were very likely stressed by being next to module 18 which overheated prior to blowing up.

The Prius and its passengers would probably have become a well-done barbecue.

 

never blown up but my brother has a 2005 and at about 175,000 miles ( about a month ago) through some codes regarding the battery pack. Ended up having to replace one cell and re balancing the pack. This took a few days but runs fine now. I would bite the bullet and just re balance the pack. Might as well if your going to have it dismantled

 

Wow! That really ****POPPED****​

I drove my 2005 Prius for about 1 week after the first P0A80 appeared, resetting DTC codes many times. Then I removed my HV battery. One module was at 6.62V. I replaced it with a "used/tested" module from eBay.

The bad module I took out of my HV battery showed no physical signs of damage, leaking, or overheating. I've got it on my workbench now and I plan to run some tests on it.

I also replaced 1 other module that was about 0.1V lower than the others. Since then my car has been running perfectly. No more DTC codes, and mpg improved by nearly 10 mpg (mpg for tank is currently 42.5).

 

I'd be skeptical about modules that still have < 3000 mAh capacity after cycling.

 

Your bus bars and connection nuts have a whole lot more corrosion on them than mine did.

I wonder if your corrosion resulted from the electrolyte which sprayed out of the exploded module?

My recommendation is to totally clean the busbars, the nuts, and the studs on your modules. The electrolyte inside NiMH cells is chemically "basic" (e.g., it's similar to lye). So you need to use something slightly acidic to neutralize it (a weak vinegar solution perhaps?). Or simply wash all these parts very well with soap and water, rinse them several times with clean water, and then dry them thoroughly. I've seen folks selling Prius HV busbar assemblies on eBay in case some of yours don't clean up very well.

I used the following spray-on antioxidant when I reassembled my HV pack. I've used this stuff for many years to clean contacts and controls inside electronic devices (stereos, guitar amps, etc.). IMHO it's the world's best electrical contact cleaner and preservative

Its'available here:


Caig Laboratories DeoxIT D5 Spray Contact Cleaner, 5% solution, 5 oz. | D5S-6 (D5S6) | Caig Laboratories


One can of Caig DeOxit will last for years. This stuff works best when it's sprayed on as a very thin coating.

My rebuilt HV pack is still working great after 5 weeks of normal driving. I haven't done any "extreme" tests on my rebuilt pack yet. For example, I haven't deliberately tried to discharge it. It did get down to 2 purple bars one time when I was in a McDonald's drive-up lane for 10-15 minutes with the AC running. The ICE would start up periodically to keep the SOC at a minimum of 2 bars. That seems like normal behavior to me. My HV battery regained its "normal" SOC of 6 blue bars within about 30 minutes of normal driving after I left the McDonalds. I occasionally get 7 green bars when driving with the AC turned off. But most of the time the MFD display SOC stays at 6 bars. I haven't observed any "wild" up and down variation on the MFD SOC display. So I think I'm OK at the moment.

Best of luck getting your HV battery finished and back into the car!

-EB

 

Recently happened to me. Drove and acted better after explosion did yours? I figured module went from marginal open to short thus eliminating itself from pack.

Posted via the PriusChat mobile app.

 

Forcing the car to drive with a shorted/exploded module is a bad idea.

The system will be a fire hazard.

It won't be operating in the correct voltage range and could easily damage other electronic components.

 

D5 is a great contact cleaner but a lousy product for anti corrosion on a buss bar.
Use NO OX it's designed for anti corrosion on battery terminals.
It's a heavy grease that stays where you put it.
Works good in an ac panel too. If you clean oxidation off a pure copper buss bar it will quickly oxidize again like crazy with current going thru it and presence of electrolyte gas. Apply NO OX to all surfaces of the cleaned buss bar and battery studs.

 

That happened to me too. Twice. Which way are you counting the modules. #1 is opposite the computer (BCM). I never load tested mine or balanced them, but I'm sure they shouldn't be exploding. Also, It's problematic that you can't just buy some new modules and have to resort to questionable ones. How did you resolve your situation?

 

Mine too. Drove better after the explosion. But then more trouble occurred.

What procedure did he use to balance the pack? That's important info. Did he set the modules in parallel or what? And what # module blew up? Mine was #11 from the right hand side opposite the BCM computer.
That would be 18 from the computer side. For some reason, those are taking a beating.

That's actually module eleven. The one that just blew up on mine was eleven also. And the previous one was right in that area too. Something's fishy here.

Do you know what the charge/discharge rates are for the modules when they're in the car and working?

 

Yeah, me, twice. A year ago, #11 which is what you're calling 18. and it's 2 neighbors were damaged. Replaced it and it blew again last Spring.
I had 14 codes captured but then it just settled on P0A80 to replace the whole battery. Haven't ordered a new cell (blade?) yet, as I think something is wrong beyond just the cell.
I was going to jump out the bad cell and ride on just 27 but not sure what to do with the sensing wire to the BMS (battery management system). Any ideas would be highly appreciated.
Also, what progress has been made thus far???

 

To my knowledge, the bms is supposed to take care of all that. I see videos of Dr. Prius and Torque Pro showing the voltages/charges wandering all over the place. I think the whole system is overengineered. If you balance the cells, they will rapidly become unbalance as per the bms acting the way it does. There's gotta be a better way.

 

I agree. You're the only one I've heard saying that. I don't anyone has a clear idea of what's going on. If it's corroding, it needs a dielectric grease. That's so basic it makes me wonder if all the folks out there are missing all the logic of what's going on.
Glad you mentioned that.

 

There is no BMS. The battery is balanced through recharging. Overcharging leads to heating of the modules. If there is not enough cooling, the modules overheat and internal pressure blows the roof off. In older modules, the drain valve to relieve excess pressure gets stuck.
It is necessary to check the air supply system from the fan to cool the high-voltage battery.