Sunday, April 5, 2009

Another Setback

Well, I certainly hate reporting the failures, but they are a part of the whole story of this conversion. Maybe the information will help someone else avoid some trouble. The first several mishaps were due to defective parts. The last two failures were totally my fault.

Yesterday during the test driving I smelled a slight burning smell. When I finished driving, I took a quick look around and checked the controller and contactor connections with my infrared thermometer. I didn't see anything out of the ordinary so I attributed the smell to just new parts "burning in". Today I was installing the new Link 10 meter and turned on the main contactor. I immediately heard a "snapping" noise in the trunk. I could also see the unmistakable blue flash of arcing, since there is no back seat in the car.

Upon opening the trunk, I found that one of the battery terminals had gotten so hot that it had melted the lead around the post. I assume this happened yesterday during my two miles of test driving. I am taking the blame for this because I have neglected to check the rear battery terminals for tightness in quite a while. After discovering this, I checked the other terminals on the rear battery pack and found a couple others that were somewhat loose. I believe this one just got too lose to handle all of the current. So I guess this means I'll have to replace the battery since the threads on the post got messed up as well. This is another lesson learned.


Anonymous said...

Sorry to see that Bruce, but good that you caught it when you did.

Can a second nut be used as a lock-nut to prevent this in the future?


Bruce said...

The posts are too short to put a second nut on. Maybe I can use lock washers but there is hardly room for those either. I'll ask the battery supplier to see if they have any suggestions. I'll also search the EV forums. Surely this problem has been experienced before.

inspyre said...

Hey not a big least the problems are becoming less and less severe!

What about applying some good ol' blue Loc-tite? Maybe even the red stuff if ya feel dangerous ;)

giganto said...

My supplier [EV America BTW] has recommended I buy the batteries with short "L"-shaped terminals. Different battery manufacturers give them different names. It's basically a 1/4" bar of lead with a hole through it. They usually come with a stainless nut and bolt though which you thread your lug and a SS split lock washer of your own. If the terminal is irreparable, you may consider a special order for a replacement battery and see how they fit in your car. The threaded one you are using isn't meant for high current loads for very long. These bugger terminals give more contact area which keeps the lead from melting.

Daniel said...

Another option might be Belleville washers on each battery post. You can get them from McMaster. You might need to figure out the proper force for them (depends on your battery post size and torque) as they can be finicky. But, if you get the right ones, I'm sure you'll never have a problem again.

Bruce said...

Thanks everyone for the suggestions. I am stuck with this post type because the local Trojan Battery supplier said that was all he could get me without a major hassle.

I have ordered belleville washers and will also use blue loc-tite. And of course now I will make sure I check the tightness of these once in while.

Daniel said...

It's been over a month now, how'd it turn out? Are you back driving again?

I'm just starting to take short trips around the block in my EV Spitfire. But, I've got a lot of restoration left ahead of me.

Bruce said...

I haven't accomplished anything in the last month but installing the new battery. I had to wait 2 weeks to get the right belleville washers. I've also kinda been derailed by the weather and my job. Hopefully I'll be able to get back to work on it soon.