Headlights/Fog Lights
 

Alright, I searched a few different topics around here and I still have a new question on the issue. I have noticed my headlights dim just when I have the fan on even, starting to get colder here in the mornings. I read that the alt and battery have something to do with the slight dimming of the lights.

So what I am wondering, would a bigger battery solve this problem? If so what brand of battery would fit in the spot where it sits now? I know it's a small battery so finding one the same size with a little more juice might not even be possible?

Thanks for the help anyone!

the difference in brightness is due to differences in voltage over the light circuit.

All cars have a voltage regulator to maintain voltage within a certain range. As the engine speed increases voltage will increase slightly as the alternator turns faster until the voltage regulator limits the peak voltage.

As other devices are turned on (or turn on themselves, like radiator cooling fans) it can drop the voltage to the low end of the allowable range. I've noticed on mine that turning on the headlights will actually increase RPM at idle. There's some sophisticated regulation going on more than just the voltage regulator.

Some dimming/brightening is normal as the voltage changes occur and has been noticed in a wide variety of Hondas more so than other makes.

I think there are multiple regulating circuits to maintain a constant voltage to different parts of the car. I think our Fits have one on the dash lights or we'd see the dimming/brightening effect there too. The headlights don't get this treatment (maybe on other cars they do).

Putting in a larger battery won't help; voltages will still vary the same amount according to the regulator. HIDs with their own drivers probably won't dim as they have voltage regulation built in.

Historically the rule of thumb was dimming headlights at idle was an indication of a weak battery, but this doesn't apply to Hondas (or maybe any car today).

Wouldn't hurt to drop by an Autozone and have the battery checked if it seems to be getting worse...

That makes sense. Definitely nice having knowledgeable people around here that know about alternators and voltage things. I don't know a thing about that stuff, but slowly learning as I read more and spend a little more time on the forums!

I just wanted to make sure that it wasn't going to burn my bulbs out faster or not. I have zXe lights in the headlights and Nokya yellow's on the bottom. I know life span is short already on higher wattage bulbs, but didn't want the dimming to make it even shorter.

Thank you for the reply!!

Yes, dimming headlights is a way of life with a Honda, with the exception of our Pilot. No dimming lights there...

My 88' Accord didn't dim any headlights xD

Aftermarket bulbs may draw more amps, and as a result are more sensitive to changes in voltage, but these changes won't decrease their life any. But I think the expected life is less on brighter aftermarket bulbs to start with...