A buddy of mine has a 2019 fat boy. He is on his 3rd headlight bulb already this year. The low beam keeps burning out but the bright does not. He bought 2 bulbs from the local dealership and 1 from O'Reilleys with the same result. Anyone else have this happen and find a solution? Thanks.

 

If your friend is running hot white bulbs have him try a standard 55/60 watt bulb. The reason those higher wattage bulbs are so bright is due to their thinner filaments getting hotter. Less resistance = more current flow = brighter = vibration death sooner.
I like Phillips Motovision bulbs, made for the vibrations of motorcycles. You can buy them on Amazon.

 

Go with an LED.

 

It is probably worth checking the output of the charging system just to be sure. HD state it is alright if not over 15 volts but I think in general something around 14.6 volt max is better.

 

Yeah I mentioned an LED but he didn't really lean one way or another. I'd hate for him to spend the money on an led and have issues with that as well. I will check the charging output sometime soon to eliminate that as a possible problem.

 

If only the low beam bulb is blowing, it's not a voltage issue.
That's not how it works.

 

Most don't use their high beam for long periods of time like the low beam always on. We have had it explained that the higher wattage bulbs use a finer filament that are affected by vibration. If the charging circuit is a little hot that might exacerbate the situation. Nothing lost in just confirming something so simple to check.

 

I found that my headlight bucket had cracked and it was eating low beam bulbs like a pothead with a bag of Doritos. It was just letting too much vibration get to the bulb…