Finally fixed my flickering lights

[robdtoyota]

I have a 2000 Avalon, 112k miles. A few months ago the lights started to flicker rapidly. Not a loose wire flicker - a rapid fire flicker only when the car was running - did not do it when the lights were on without the engine running.
Here is how I fixed it: I cleaned thoroughly the pos and neg battery terminals. These terminals are not solid, they have 2 round bands instead of the usual 1 large solid band. They had some corrosion on them, but the corrosion was not visible while the terminals were tight./ I cleaned the connections of the ground wires as well. All with vinegar and water. Then I cleaned the connection to the alternater.
Putting the battery back in, I noticed it is much smaller than my Sienna's battery. I compared the 2 batteries and the Sienna has a more powerful battery (cranking, etc) that the Avalon. So I switched the 2. Now the flickering went away and there are no starting or running issues w/ the Sienna or the Avalon. The Avalon battery was of course not the original. They are both Autozone Gold. They haven't flickered in 2.5 weeks now.
Rob

[Riick]

More likely cleaning the connection to the alternator is what did the trick.
Would be interesting to know whether the Avy battery was fully charged, no way to tell now.

[robdtoyota]

Riick:
I don't knwo if the battery was fully charged for sure, but I switched the Avy battry with my Sienna - and I use the Avy battery in the Sienna every day and it is fine. So my guess is that the battery was ok - maybe too small for the Avy, i don't know.

[Jigg007]

Looks like your culprit was a funky corroded battery connection. It only did it when the engine was running was due to vibration, I'd imangine. And the sienna won't show any signs because you just cleaned and re-torqued the battery posts.

But cleaning your battery posts is a good practice, as it would of built up so much where one day the car wouldnt crank.

Infact, what was happening is that the connections were breaking loose to the battery (can be corrosion, or just a loose terminal) And Even though the cars electrical is hardwired to the alternator, the battery acts as a buffer. when you remove this buffer and immediately pull current from the alternator it will dip untill it catches up. With the connections to the battery being intermitent the effect will repeat.