I was trying to clean the battery terminals but I didn’t realize I had to loosen the positive terminal clamps first. I stared loosening the positive terminals and my wrench hit this other bolt (indicated by green arrow) several times and created a few small sparks. After I while I got too freaked it to continue so I stopped trying to loosen the clamps. I couldn’t loosen the negative terminal clamp so I left the positive terminal clamp loose and decided to wait for a mechanic to come check it out. Is there danger in leaving the positive clamp lose if I’m not starting that car at all? Also, if sparks were created is it certain that I blew out all my fuses/electronics? Is it possible that I didn’t fry my (brand-new) battery? enter image description here

1 Answer 1


When performing tasks that involve direct connections to the battery, always disconnect the negative terminal first and avoid contact between the wrench, the positive terminal and the negative terminal. Once the negative lead is disconnected, accidental contact between the positive terminal and any other part of the vehicle will not generate sparks.

The sparks you saw are the result of a poor connection between the clamp around the battery post. The electricity then attempted to flow between the battery post and the marked location, which it would do in ordinary circumstances. You probably caused zero problems other than an elevated heart rate.

Before you stick a wrench in there again, disconnect the negative terminal. Once that is accomplished, you can continue with your tasks. I see no need to have a mechanic examine the "problem" as there is really no problem.

When you've completed your cleaning, secure the positive terminal before the negative. Expect some small sparks when attaching the negative terminal, as most cars today draw some current even when turned off.

  • Good answer, but I suspect the small sparks were a result of the voltage drop between the terminal clamp bolt and the B+ lead hold down bolt. The very reason a good cleaning of ALL the parts, bolts, nuts, and threads is a worthwhile endeavor.
    – SteveRacer
    Mar 15, 2018 at 3:13

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