Headlights dimming

Ok the headlights on my 2014 4Runner dims for a quick second when I accelerate enough for me to notice. From the responses from this group it could be a fan belt or alternator problem. Took it in and they put it on the machine and everything checked out. The only issue was that my battery had loss about 10%of it's cold cranking ability. Just turned 90,000 miles, oil changes and tire rotation faithfully. Battery is probably about 3 years old. Anyone else experiencing this? Should I replace the battery?

 

A few things...

The 2014 halogens are pretty shitty, and the front coilovers are very soft. Hard acceleration from low speed causing the front to rise aiming the headlights higher and appearing to dim as the light is no longer on the road directly in front and instead further down the road. Smashing the gas at 60 won't have this effect as the 4Runner doesn't have enough balls to lift the front at speed, relatively.

The 4Runner is extremely temperamental when it comes to the battery. Loose, corroded, rusted, battery terminal connections cause a whole host of issues. You can search this forum for a ton of threads relating to weird electrical gremlins from poor battery connection. Even if you think it's good, check it. Loosen, scrub, and tighten.

Battery life is all over the place. My OEM battery lasted six years. Some guys don't make it two. A shop can tell you if the battery needs replaced.

Start there before contemplating chasing down more complex solutions.