93 Eddie Bauer sometimes starts sometimes doesn't

[Gypsy81165]

My explorer all of a sudden decides it sometimes doesn't want to start. When I turn the key it doesn't even make a sound. The lights, radio and gauges work. It will start if I get a jump. Now this doesn't happen all of the time. I went to Autozone and they replaced a cable connector on the battery and did a test on the battery. The battery tested fine and it started up. Well 24 hours later it decides to not start again so I got a jump and took it back to Autozone and they ran tests again and they all came back good. Autozone man thinks it's a short somewhere. Could it be the ignition switch? Any thoughts?

 

[MrShorty]

I recall a similar issue with mine. It would randomly not start, though the battery tested good. After a few months of these random no starts, the battery tested bad -- replaced and all was well. I think most of the time those battery testers are accurate, but I also believe that there are a few cases where the battery is bad even though it tests good.

A short somewhere causing a battery drain is also a possibility. Standard test for this is to put an ammeter/test light in line with the battery cable somewhere. If there is a parasitic draw somewhere, the meter will show current or the test light will light up. Then you can start pulling fuses until you locate the circuit with the parasitic draw.

 

[awood]

These things are notorious also for corroded cables and wiring around the battery. The terminals may look good, but corrosion creeps under the insulation where you can't see it. It might be worth a look.

It made me pull (what's left of) my hair out getting a similar problem fixed.

 

[Roadrunner777]

Batteries can test good one day and bad the next, then be good again. I'm not sure I can explain this well... I learned it in autoshop in the 70's, but the technology is the same, so I will give it a shot.

A battery consists six lead/acid cells. They are separated physically. This is why an older battery has six openings to refill the battery. It is simply six two-volt batteries packaged in a single case.

The anatomy of a cell consists of interleaved lead lined plates, immersed in sulfuric acid. The gap between the plates is quite close. A short between the plates essentially kills the cell. Older or abused batteries tend to shed flakes of lead that short out the plates, essentially killing the cell, much like one battery kills the function of a flashlight.

But sometimes, the flake of lead clears itself or simply vaporizes due to the currents involved. This is a well known situation, and since the old days, battery designers built in a space under the cells to collect the remnants of the lead flake. Clearing the short returns the battery to normal service.

The rub is that, whatever caused the lead to flake in the first place is likely to continue, and kill another cell, repeating the problem.

I have taken far too long to explain this, but a battery be shorted, and then clear itself and test good. The bottom line is that the battery is close to the end of it's life, regardless of how long it has been in service, and should be replaced.

 

[Gypsy81165]

Thanks for all of the replies. Would the gauge in my explorer still read good also? This battery has been tested twice. I hope the battery is all it is. A quick fix.