Bad cable equals expensive battery replacement for Club Car EZGO Golf Cart

I mentioned losing a battery in our Club Car EZGO electric golf cart at my "How to repair a broken battery terminal". That repair didn't last long; I soon had to buy a new battery.

I initially thought that the damage shown in the pictures below had come from accidentally leaving the battery cap loose. As it turns out, I was wrong about that.

Well, not entirely. Leaving the cap loose would have been a careless and unthinking act on my part. The actual cause was a different careless and unthinking act on my part, so while I was wrong in the specifics, the top level cause was dead on: it was my own dumb fault.

I'm kicking myself extra hard because I know better. I noticed this problem, knew it was a problem, but I didn't act on it instantly. That cost me $148.00 and may end up costing me another $148.00 before I'm done.

Basic Electricity

Resistance in an electrical circuit causes heat. Everybody who has ever done even the most cursory study knows that. Heck, you might even know that if you never learned anything about electricity.

I certainly know it.

I know it very well, in fact. I've burned my fingers more than once building little electronic circuits and have smelled burnt resistors from my mistakes more times than I'd like to admit. Electrical resistance creates heat, that's basic. That's how electric heaters work, right?

Small current flows create a little heat, but even a 1.5 volt battery can heat up a thin wire enough to burn your finger. Six eight volt batteries wired together produce a good amount of electrical current and the amount of heat that current can generate if it hits resistance is quite impressive.

The original meltdown

The picture at right is the original meltdown and explosion that happened shortly after my post repair. Note that this was not the repaired post that blew; it was the other terminal.

As I said, because my discovery of this came when I heard a loud "bang" under my seat, I thought that perhaps I had left the battery cap loose after checking the water levels. Loose cap, hydrogen gas bubbles out, a tiny spark ignites it, flame melts lead and plastic, more gas, and "pop".

Nope. That's not what happened at all.

Rust isn't such a great conductor

As the second picture shows, one end of the cable for that battery had a good deal of rust.

I noticed that. I even made a mental note to get new cables. I even called the local auto parts store to see if they had short cables like this (they didn't).

I ignored it.

Which is totally stupid, yes. Rust is not a great conductor of electricity. At the very least I should have taken some steel wool or a file to this and cleaned it up to get some shiny metal. But I did not. I just tightened it down and forgot about it.

That wasn't a good decision.

With enough heat, the lead melts

So.. apply a nice 48 volt current through some unexpected resistance and you get heat. Enough heat to melt lead. That's what had happened to the original battery and it melted enough lead and burned enough plastic to open the battery right up as we can see in the pictures.

And now it was on its way to happening again. While driving down to get our mail, I smelled something burning and stopped. I flipped open the seat to see the batteries and touched the terminal. That burned the tip of my finger.  Just a little, I expected heat so I had touched it very lightly.

It had been raining, so I had a damp paper towel handy; I touched the terminal with that and it sizzled like water splashed on a frying pan. Hot, very, very hot.

I cooled it down with the wet towel, tightened up the nut (which was loose because of the lead melting underneath the cable) and drove it home, stopping frequently to cool it down and retighten.  

Salvage?

I don't know. I have ordered new cables ($25 plus shipping from Buggies Unlimited) but I'm not sure if I can file the lead down flat enough to get a good solid connection.

You can see in the photos at right that the cable was actually broken - rust, heat, who knows, but that wasn't helping any.

My tardiness in replacing these cables may cost me another $148.00 and that annoys me greatly. If I didn't know any better to start with, I'd just call it a life lesson leaned, but I DO know better, so this was completely unnecessary.

I'll be having a long talk with myself if I do have to buy another battery, that's for sure.

Auto battery cables are different

I've never seen an auto battery cable that wasn't a ring clamp as shown in the final pictures. I wonder why golf cart battery cables aren't done that way - it seems like a better design to me, less apt to loosen up and cause this sort of problem.

Oh well: it will be what it will be. I have ordered the new cables and hope not to have to buy another battery. It's getting on toward winter, so I'll be putting the cart away soon, but it has to be charged every few weeks to keep the batteries from freezing, so I need to have this all corrected before that.