Lawnmower LED Light Bulb - Failed A Third Time!

My new bulb(s) came in the mail today. BTW, the eBay seller that sold me the 85 SMD LED bulb gave me a full refund. Here’s the defective bulb (I count 8 LEDs bad):

Here’s the defective replacement bulb with the lawnmower lens on (left) and lens off (right)(10 sec, F/20, ISO 1600):

Here’s the new bulb with the lens on (left) and lens off (right):

Again, here’s the defective replacement bulb with the lawnmower lens on (left) and lens off (right)(10 sec, F/18, ISO 1600):

Here’s the new bulb with the lens on (left) and lens off (right):

Here are my observations:

  1. The new bulb gets a lot warmer than the defective bulb.
  2. The new bulb is significantly brighter.
  3. Even though they are both cool white, the new bulb is less cool and shows the green of the grass better.
  4. The lawnmower lens kinda sucks. Even though it helps disperse the light, there are streaks that are noticeable with the new bulb.

The new bulb is certainly much better than the original bulb that came with the lawnmower. Rarely do I end up mowing in the dark, but it’s nice to have the extra light when needed.

Thank you Lightbringer/BLF for your help.

No worries, glad to help.

I’m betting that the (facetted) lens is meant to take all the light that’s bouncing around in that 5-sided cube (ie, 6th side missing) and just scatter it as best it can. Enough random bounces, and it’s “smooth”.

The bulb with a brazillion discrete LEDs all over, around, on top, everywhere, similarly threw light everywhere, to again bounce around the mirrored cube and out the front lens.

Now with a single point-source throwing light just out the front, the front lens is acting like a chopper for those pyroelectric person-detectors (alarms, auto-on lightswitches, etc.), ie, a “fan” of individual beams directed all over the place. So now, all those light/dark areas show up really well. :smiley:

If you can stick just a clear piece of plexiglass or something over it, to keep out grass clippings and other filth, you can have that nice smooooth light courtesy of the bulb’s aspheric lens. :smiley:

Good idea ! But It’s just to be beautiful. I think the effect is not high

Thanks for the suggestion. Another option would be to put something inside the lawnmower lens to smooth things out. Or if I really wanted to be experimental, I could sand down the inside of the lens, but that seems too risky. I’ll see what I have to put inside the lens and see if that helps.

Good luck with the latest leds. Its bound to be mentioned, DC fix though in this case it may not work.

Last week I noticed the headlight was no longer working on my lawnmower. So I pulled off the headlight lens (it’s glued in) and looked at the LED bulb.

Well no wonder why, the LED fell off the MCPCB (see bottom left corner)! Wow, that must’ve gotten very hot in order to do that. My guess is that MCPCB must have dislodged from the bulb shelf due to the lawnmower vibrations and overheated. I see there’s nothing to secure the MCPCB to the shelf.

So it was my first opportunity to reflow a LED. I don’t have solder paste, so I tinned the MCPCB and put some flux on the bottom of the LED. Held it over my heat gun and as soon as the solder melted I took it off. It looked pretty good.

Since the bulb is essentially a hollow shelf flashlight, I wanted to improve the heat management. I found a washer that fits on the shelf, made some notches for the LED wires, flattened both sides, and used some thermal compound next to the MCPCB. I then used 2 very small screws to wedge the MCPCB and washer against the bulb shelf.

I also sanded down the aspheric plastic lens and made it frosted. The beam was too narrow before and showed lots of artifacts.

I’m happy to report that my reflow worked and the beam looks much better. Time will tell if my heat management mod actually makes a difference.

You sure that socket is a steady 12 volt dc? Might be running off the ac side of the stator and that could be the cause of some of your issues.

Poll: how many BLFers have mowed their lawn in the dark with flashlights? haha. (I have)

Guilty………A headlamp and two S2+’s duct taped to the mower. I was headed out of town the next morning and forgot to mow.

Not surprised a bulb like this will fail when operated as a headlight, even if the power supply is good. These are not engineered to last, at least at $6 a piece.

I guess these bulbs were mostly meant to replace a reversing light - an application where they will typically not be on for very long periods at once. If not meant for that, it’s where these shine(no pun intended).

Some of these do work very well in many vehicles that have a very low powered and dim incandescent bulb that’s mostly a signal for others. In dark and rainy places an actual projector that helps to see a little is very necessary and one of these sometimes helps - even through the original diffuser of the rear lights assembly. Mostly it’s an illegal modification but may also be legal in some machines not operated on a public road - this will depend on jurisdiction and a bunch of details. I don’t endorse illegal modifications to vehicle lights, but this is worth noting and has served me well in an off road application. It’s nowhere near actual auxiliary reversing lights, but it gets some light behind the machine for $6, requires no modification and retains OEM look. It’s worth something that you don’t have to mess with the wiring harness or even drill extra holes in your machines.

This is why I, too, would attempt to modify the bulb assembly itself instead of just installing an aux work light on a lawnmower that already has the headlight. My recently purchased mower has none, so N/A and will not be participating in this endeavour but just installing a cheapo LED aux light - which is a viable alternative in case you need more lumens and/or won’t be satisfied with the miniature bulb performance.

Even in a car this is probably the controversial lighting upgrade that causes least harm to others. It’s nothing like amateur drivers blasting their front fog lights goin 100 km/h in darkness when it rains, or DIY HID kits or fubar’d halogen bulbs someone decided to cram in 15 tilted degrees. :rage:

Making an actually usable 100% duty cycle modification is a respectable project. :+1:

What I used was this style, but I have no idea if this is similar. Probably not useful for a headlight even if if could take the abuse of running continuously. www.gearbest.com/led-bi-pin-lights/pp_009171013619.html

My guess is that it is running off the battery and the stator is just charging the battery. But for the LED to actually fall off the MCPCB should be due to heat and possibly vibration.

I think you’re right. This lawnmower does not have a light switch, so it’s always on when I’m mowing. It takes me about 45 minutes to mow my yard. We’ll see if my mod helps. I’ll certainly report back if it fails again. And if it does, I already have another mod in mind. :slight_smile:

Seems like it must be getting too much power at the light. Have you measured it yet?

My zero turn didn’t come with any lights. I mounted a 20 inch led light bar on the front of it so I can finish mowing.

No, I haven’t taken any measurements.

I mowed the lawn today and it still works. :+1: Probably the last time until next year.

I thought about possibly reducing the power at the driver. Maybe by changing the R16 resistor?

that led looks cooked.
you might want to replace it with an xm-l series and see if your heatsinking improvement makes it hold up longer.
it will be underdriven and more efficient.
meaning less heat.

I’m sure that several of you are anxiously awaiting an update on my lawnmower headlight mod :wink: , and I’m happy to report that it’s still working 2 years later!

It appears poor heat sinking was the cause for the LED failure and the addition of the washer resolved it. I’m also glad my first reflow continues to be successful.

And in case you’re wondering, I don’t mow my lawn at night. The headlight just automatically turns on when the lawnmower is running.

Wow, it survived for 2 years already. I wonder what’s happening with it atm. Unfortunately, I personally have a bad experience with lawnmowers. I had only 3 in my life and all of them broke very fast. I don’t know the reason, but I don’t think that the exploitation of them was wrong. Not my fault, lol. Fortunately, my dad has his own lawnmower which works perfectly. But I also prefer handy tools like wed pullers to work on the lawn. My dad shared with me an article at Choosing the Best Weed Puller Is Easy with Our Top 5 Reviews! that describes the best options on the market. I think I’m gonna get one of these because sometimes a lawnmower isn’t enough.

if I ever have a lawn, I will do this mod. cool idea.

Can you switch off power to the light when you’re starting up the gasoline engine?

I know there’s long been a caution for automobiles to switch off LEDs when starting the vehicle because the electrical system voltages can go through some incredible peak excursions right at startup, which can destroy semiconductors.