Cascading Battery Meltdown

[thedhgroup]

OK, first thing is first. I know, I know. I should have been more careful. To all: Follow all safety precautions and do things right. Not how I did it.

So today after work I came back to my 2001 Insight with a buddy pack installed. After opening the door I immediately smelled something and all the windows in the INSIDE were covered with water. For months I've charged at home at night and during the day at work with no issues. My charger is set to 169 for both hybrid packs. I also have 3 12 volt supplies. 1 for the 12 volt battery and the other 2 are for the cooling fans on the 2 hybrid packs. The supplies are just wall warts and one came unplugged from the power strip.

So as the packs charged one was not being cooled. It started getting hot I presume and the voltage started to go down where then the other pack said, "hey, I'll help you out" and the buddy pack got even hotter and pulled both packs down to nothing. After turning the breakers off the voltage meter read 14 volts. IMA light is on and the buddy pack looks like the plastic melted around the sticks. Possibly the shrink wrap cracked off. Not sure yet.

I'm so bummed. So let my stupidity be a lessen to others who "get it going" with temporary wiring. I used to install car stereo stuff for a living so I should have known better.

So now what?

[Willie Williford]

I praise you for accepting the fact that you did wrong. Hope everything turns out.
What temperatures were you seeing?

Willie

[thedhgroup]

I don't have a thermometer on the packs but the stock pack appeared to be cold. That is the one where the fan was still going. The buddy pack was the one with no fan going and the plastic case was pretty warm but I think the meltdown may have happened a couple hours before I got to it.

I think what I'm going to do is pull the buddy pack out and try to gently charge the stock hybrid pack back up. Since it is sitting at 14 volts I may have to put enough resistance in series to keep the constant current charger from tripping out. It would be a miracle if the stock pack came back. Looks like the buddy pack is toast. (well now I have a case for a upgrade pack)

The car is 25 miles from me now (at work). Did not dare drive it with the headlights on for 40 minutes without a charge. I'll get it back on Saturday during the day and take the back end apart.

[Willie Williford]

I would have turned off the IMA and drove it home, monitoring the 12V battery for charge.
"Only by experimenting will we find out."

Willie

[Eli]

Wow.

The IMA battery case doesn't even come close to melting at 200F(ask me how I know ). I estimate your pack must have been closer to 400 degrees. I assume you figured out that the condensation on the inside of your car was all of the electrolyte/water in the cells venting. That is going to be a nasty, nasty mess. Wear gloves and eye protection when you handle the cooked battery just in case.

I would say you're pretty lucky your car didn't burn to the ground. Scary.

Be careful out there folks!

I also assume this was meant to go in the G1 forum?

[thedhgroup]

Since it was 40 degrees F out the last thing I was thinking about was overheated batteries. Anyway, the inside glass was all wet, the seats and headliner were moist slippery, smell was awful, IMA light on and there was a brown goo around the cooling fan but it started and drove OK. (started from the 12V starter though).

Lucky is right. Although I could have used the insurance money. The downside would have been another insight bites the dust. I'll get "Bluie" going again, even if I have to disconnect the BCM and pull both packs out. Just think how light it will be.

[thedhgroup]

Originally Posted by Eli

I also assume this was meant to go in the G1 forum?

Oh, crap. Eli, can you move the thread?

[Eli]

Done.

Ambient temperature really doesn't matter. I mean it does, but a pack is going to cook without cooling whether it's 30 or 90F outside. It will just happen a little slower at 30.

Hmm..

It's a good thing the Insight doesn't use NiCd batteries. The car would probably almost need to be scrapped, if not completely stripped down and cleaned. Cadmium is really nasty stuff, and is prevalent in the electrolyte of NiCd batteries.

I don't believe there is any real toxicity risk with NiMH batteries.. not that the metal hydrides are going to be good for you, but they're not nearly as toxic as something like cadmium, and I don't believe they diffuse into the electrolyte like cadmium does in a NiCd battery.

Still, proceed with catution... This sounds messier than I had imagined. Each cell can produce several drops of fluid in a single, short venting event.. This event almost certainly caused complete venting of the electrolyte.. which causes separator dry out.. which causes cell shorting, and more heat.. etc. You managed to send your pack truly into thermal runaway! Congrats This also explains why your paralleled pack is dead(14V). It discharged itself through the shorted cells, which certainly contributed to the problem..

You need to be careful with that one too. It probably stayed cool because of the fan running, but extended reverse discharge even at low rates will vent cells every single time, if left long enough. The cells will just kinda dribble electrolyte. It's also quite possible that it wasn't a low rate event.

I'm sorry to say, it seems likely both packs are toast.

It would be interesting to weigh the cooked pack and see how much water it lost.

Oh, and PICS!

[thedhgroup]

Originally Posted by Eli

You managed to send your pack truly into thermal runaway! Congrats

Gee thanks. Do I perhaps win a set of high mileage replacement sticks? (kidding)

I don't have a lot of expendable cash so maybe I will dumpster dive behind the local Honda Dealership (also kidding -kindof- almost)

Pics after I buy some rubber gloves and a respirator mask. What a friggen mess.

[Eli]

Sorry, I was just trying to cheer up what is an overall pretty serious situation. I know this is probably a real bummer financially too, and at a terrible time of year.

You've been a great help to me in the past, so I'll help you out in any way I can. Maybe Santa will deliver a box of stock sticks. That would make a hell of a stocking stuffer!