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Battery Corrosion Can Make Good Parts Look Bad

My wife called across the kitchen to me “our friend at church says her car’s alternator died, can you go save her?” Once word gets out that you are a “Car Guy” this kind of thing is normal. Luckily my wife understands that my mechanical gift must be shared, so the project begins. A quick phone call to the young lady nets the year/make/model of the car (a 2006 Toyota Matrix) and the suspected problem. The car was electrically dead at the moment, but the previous night she noticed that the headlights were growing increasingly dimmer as she drove. Sounds like a classic case of a dead alternator (or voltage regulator, but they are almost all internal today).

Once the alternator stops recharging the battery it is up to the battery to supply power for ALL the electrical systems. This usual works for a little while but eventually things start to go wrong (like the headlights getting dim or the turn signals slowing down). The best you can hope for is to make it home before the battery goes below the voltage level necessary to trigger the fuel pump and ignition system.

I quickly jump on Google to look at pictures of that vehicle’s engine compartment, belt routing, and watch a YouTube video of someone swapping out an alternator on the same car. Luckily this gave me the list of tools that I’d need for the job, which is great considering I would be working in an apartment parking lot with only the tools I brought with me.

After a brief fight through city traffic I pulled into the apartment parking lot. She had managed to get the car jump started, which I found odd if it were a bad alternator. I pulled out my voltmeter and checked the battery which read over 12 volts and change. When I attempted to crank the car though I was only met with a series of clicks (makes sense, not enough juice to kick over the starter fully). No problem, as I carry a jump box anyway. It wasn’t until I went to attach the jump box that I noticed the high degree of corrosion on the battery terminals. Not quite to the point of being furry, but definitely on the way.

I asked the young lady to tell me more about what the car had been doing. The previous morning when she tried to crank it she was also greeted with the clicking of a starter solenoid. The battery was only three years old, but those nasty connections were starting to look very suspect. Unfortunately I’d left my battery brush at home so a length of fraying stranded copper wire was pushed into service. After a few minutes the battery terminals and clamps were looking a bit better. But was that the problem?

I started the car with the jump box then quickly disconnected it. I needed to see if the car was running on its own (and it was). A check of the voltage at the battery terminals showed a solid 14+ volts, which also matched the voltage at the output lug on the alternator. Next up was the stress test. I turned on every possible electrical system and waited for the car to warm up to operating temp (so that the radiator cooling fan would kick on). With the whirr of fans motors mixing with the stereo I checked the voltages again: 14+ volts.

I turned the car off and then ran it through a few start/stop cycles. Every time it cranked and ran like a champ. Case closed.

There are times when the real problem is simpler than it appears. Corroded battery connections are a common problem with an easy solution. If you are ever greeted with a suspected dead battery, always give the battery terminals a twist. If they are loose you will know it instantly, but also the twisting motion can break up the battery corrosion enough to let the juice flow again.

I won’t lie, I learned this lesson the hard way after having my first car towed home due to a “dead battery”. I extolled to my Dad how it was for sure a dead battery and that I needed a ride to the store to buy a new one. My Dad popped the hood, twisted the battery connections, and fired the car up.  He then chuckled, patted me on the back and walked away. Touche’….

Photo courtesy of Morgue File

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