After installing a backup camera for my 2004 Mazda RX-8, I wanted to look into an engine stall problem I've been having. As I approach a stop sign or red light and release the throttle pedal, engine speed will drop as expected. Usually it'll settle at idle speed, but every once in a while the engine would drop all the way to zero RPM and I would have to restart the engine... which sometimes would stop again immediately unless I use a bit of throttle to keep it at a higher RPM.

According to the workshop manual, there are many potential explanations for this symptom. The cheapest and easiest thing to check is my battery connection. I guess the alternator doesn't provide enough power at idle so the battery needs to pitch in?

Well, my battery terminals are pretty old. There have been several batteries throughout the car's 20+ year life and a few of them have leaked battery acid to corrode these terminals. The plating is long gone, and some of the core metal has been eaten away as well. They are due for replacement whether they are causing this problem or not.

I first tried a set of "universal" terminals from AutoZone. I think they probably suffice from an electric continuity standpoint, but they are a little bit longer than the previous units.

For the positive terminal, they're too long for the protective cover to close. For the negative terminal, the extra length pushed wires against the battery strap and I worry about abrading wire insulation. I don't think these are going to work well long term.

Now that I have learned length can be an issue, I measured length of the old terminal and found these units on Amazon with the correct length. (*) I confirmed the length with a quick test fit, but the test fit found another problem: they are too loose to clamp tightly on my battery posts.

To solve this problem, I cut away the center red plastic tongue to give it more room to clamp down. I used the cut-off piece of plastic as nut washer/spacer so my socket wrench could grasp the hex nut for a properly tight fit.

Once installed, these terminals appear to give me the same fit as the earlier units. The negative terminal no longer pushes wires against the battery strap.

And now the positive terminal protective cover closes properly.

I'm happy I fixed this particular eyesore under the hood, but soon after this swap, my engine stalled again. Old corroded battery terminals weren't the cause, so I need to continue working down the workshop manual's checklist of potential causes.

(*) Disclosure: As an Amazon Associate I earn from qualifying purchases.