Cascading Battery Meltdown

[thedhgroup]

Originally Posted by smjoinsight

Tell us stories of the good ole days about a week ago "thedgroup" as to the power you had with two. I'm really taking my one better battery to the limits on a 15 mile stretch and would love that extra power (well length of power). So were you able to use that extra power easily, I mean you hook them together and when they are charged you have double the length of power?! Correct, the problem I'm seeing is how do I know where I'm at?

Ahh, the good old days... Well with 2 packs you really won't feel the g-forces. The 3 positives I can attest to is (was)

1. Assist duration (I have an assist only MIMA that has seen a lot of use)

2. A more robust overall pack. With just 1 pack and full assist events I would constantly get negative recals at about 50% on the SOC. With 2 packs that disappeared and then some.

3. Best of all was the amount of time in lean burn. On a flat with some hills I could stay in lean burn (minus the purges) for 20 miles straight. It just took about 5 to 7 amps out of the battery on average then up the hills I would juice it up to maybe 3/4 assist and stay in LB all the way up the hill. I'd get to work and plug in.

Another note is that if you are looking for more raw power, you are not going to get it. Here are my observations. Assist for me really helped the fuel economy when the engine was at lower revs. At higher revs, say above 3500 the assist really did not help much. So back to lower revs - even with your foot to the floor and full assist this car is nothing like a big V8 or a performance V6. So if performance is what your after, then just keep the revs high. But I bought this car for the FE. I had fun with it for like a week then went to work on getting the LMPG up.

[smjoinsight]

Nopen no need for power, just want the MPGs !! So you could really use you battery more, I mean it was very evident!! That is all I want I want to be able to use MIMA to its fullest as I drive a 15 miles stretch then through a 30 zone for about 4 miles then between towns then back to a 20 mile stretch to get to work. Then later back again!! I'm thinking if I can figure out how to keep from frying my stock HCH battery I would be set!

[thedhgroup]

Just got home from a short trip. I'm charging up the 12 volt battery now so it will start so I can move it to the machine shop. Not sure if I will start yanking things out yet tonight or not. My first thought was to see if the stock pack (the one that had the fan going) will hold a charge. It most likely saw a massive current cell reversal event so I'm not going to bet on it.

[thedhgroup]

Here are some preliminary pics of the meltdown (buddy pack).





And the stock pack recovery:



I put a light bulb in series so the chargers would not go into protection. Strangely however I may not have needed to. I measured 14 volts after I cut the power the day of the event. Before I plugged the charger in I read 127 and after as little as 5 minutes it read 150. Good news perhaps?

[retepsnikrep]

Nasty! Incredibly lucky that didn't catch fire, in fact I'm amazed it didn't.

[Hybrid-Battery-Repair]

Originally Posted by thedhgroup

Before I plugged the charger in I read 127 and after as little as 5 minutes it read 150. Good news perhaps?

Any sticks that suffered the reversal will likely have extremely low capacity. The fact that you're getting full voltage out of it (and probably full amperage) will mean little if you only get 500 Mah out of it. In addition, 5 minutes of use might unbalance your pack if only some sticks are bad.

At this point, I'd recommend dismantling the melted pack and extracting any non-deformed sticks. I would also recommend that you test every stick in both packs individually and it would have been better to get V of each stick before you started. I'm assuming that you have a dead short in one stick and that caused the full pack to drive into the other.

Shorted sticks will show 6V or less when charged. Reversed sticks may show less than 0V before charging or not depending on how many cells reversed.

I suggest that you test each stick individually or capacity. You may have enough good ones left to build a pack or at least most of one.

The one thing you should NOT do at this point is to run the pack in a car. Your event happened while the car was at rest, so whatever happened to cause it has not yet been subjected to the car's charging and discharging.

Test and repair it, then use it.

Let me know if I can help.

[Mike Dabrowski 2000]

All I can say is You were lucky the car did not catch fire.
Parallel NIMH is a bad idea for exactly this reason. A 100A fuse between the packs may
have offered some protection, and of course a better charger management and safety system.
Happy the car will survive, and your ok.
The vented Potassium Hydroxide may be able to be neutralized and converted to a salt with a mild acid, but I am not versed enough in chemistry to suggest the best acid to use. Vinegar?
Good luck with the cleanup, and please be more careful on your next battery setup.

[thedhgroup]

Originally Posted by Mike Dabrowski 2000

The vented Potassium Hydroxide may be able to be neutralized and converted to a salt with a mild acid, but I am not versed enough in chemistry to suggest the best acid to use. Vinegar?

Did a little investigation and vinegar will indeed neutralize Potassium Hydroxide. I sprayed all the fabric and the plastic. The dash now has a bunch of dried up white dots all over it. Will water reactivate it or should I just use a shop vac to remove the white dust?

Got the stock back up to 169 (charger set voltage) but as Ron said that probably does not mean much and I'll have to take the pack totally apart and test at the stick level.

[Mike Dabrowski 2000]

the dried Hyrdoxide is white, and the neutrilized salt will also be white, so the best solution may be to take out the seats and as much trim as you can, and just flush it with a hose and lots of water to dilute and rinse away any residue.
This is only my opinion, based on no experience.
I can tell you that when I was dissecting the cells, that the hydroxide will wash off with enough water. The test for clean is when touching it does not feel like you have soap on your fingers.
Good luck.

[Hybrid-Battery-Repair]

Originally Posted by Mike Dabrowski 2000

the best solution may be to take out the seats and as much trim as you can, and just flush it with a hose and lots of water to dilute and rinse away any residue.

And remember that the seat covers can be removed and are machine washable. You'll need a set of hog-ring pliers and hog rings ($5 off ebay) to reattach them.