How many watts / amps for LED light bar?

[Timmer92]

Hi all,

I take delivery of my Kubota L3901 next week. I have a project I want to tackle immediately, and would like to have all the parts here ready to go. I want to add a 12-20" light bar to my ROPS. I am aware there is a prewired worklight connection. Based on my research, that is connected to a 10 amp fuse. I can find LED lights in the 75-125w range, which by my calculation would be up to 10 amps, and therefore would work on that connection. At the same time, there are many units out there in the 150-350w range. I am guessing if I'm going to go through the trouble of adding a light, I don't want one that is under powered. I obviously can go with a bigger one and connect it directly to the battery with the appropriate fuse. Given that very few have specs for lumens, watts is pretty much the only measure I have. Any advice on whether I should go with a bigger wattage unit?

Thanks!

 

[Sodark]

https://videos.cctvcamerapros.com/voltage-to-watts-conversion

https://www.google.com/search?sxsrf...5i304i39j0i13j0i13i30j30i10j33i10.Um8btyTVKXM

Look into changing out the factory incandescent bulbs for LED bulbs while you're at it. Makes a surprising difference on it's own.

 

[200mph]

You're going to find the advertised wattage claims are overstated. Typically they are based on the max output of the individual LED, but typically not driven at this level.

I've tested a number of smaller wattage lights (36 watts and under) and they only pulled about 50% of the claimed wattage. Even the 18 watt units put out more light than stock, so your light bar will be very bright.

Of course the particular unit you're looking at could be different and actually pull the rated current.

Regardless of actual vs claimed wattage, the light output will be overkill. The reduced wattage can also simply wiring and wire size if desired.

Perhaps you can measure the actual amps and post when they are received.

Just remember to use a good DC rated switch.

 

[Timmer92]

https://videos.cctvcamerapros.com/voltage-to-watts-conversion

https://www.google.com/search?sxsrf...5i304i39j0i13j0i13i30j30i10j33i10.Um8btyTVKXM

Thanks Sodark. I can calculate amps, that is how I came up with the 125w max. My question is if it pays to go bigger or if a lower watt unit will suffice.

 

[GreensvilleJay]

Actually you need to look at the Lumens ( light output) numbers. You can have 2 LED bars , both 120 Watts but A produces 4,000 lumens, B makes 12,000.
Obviously 'B' will be brighter.....
The other number is Kelvins , that's the colour of the light....

 

[RCW]

Oh boy, math used to be my thing, but I'm an electrical idiot.

Watts/Volts=Amps

Conversely, Amps x Volts=Watts

So.....125w/12v= 10.4A

Many like to have a lights forward an backward. If you double that...20.8A

You can get beyond the 10A by setting up a separate circuit fed directly from the battery, with a relay triggered by the Keyed start circuit and dedicated fuse for that circuit.

Some guys have done some great WL installs, and documented them here.

I wouldn't use the 10A worklight circuit for anything >10A.

As an aside - - if you didn't see it Kenny at www.boltonhooks.com has GREAT looking ROPS clamps just for your purpose. I don't have them, but looked at them online from here the other day.

PS - also to Jay's point above - you NEED to look at lumens. Wattage means almost nothing anymore, except when you're trying to make it work with the tractor....

For what it's worth, I have 4 little LED's 2 forward/2 back. I get plenty of light for snowblowing in the dark. Don't recall wattage or lumens anymore, but they've gotten much better and cheaper in last 5-6 years.

 

[ccoon520]

If I remember correctly they don't put the actual wattage for the LED lights on their listing. They instead put the wattage from the comparable traditional incandescent bulbs. I'd be surprised if it pulled much more than 5 amps.

 

[RCW]

If I remember correctly they don't put the actual wattage for the LED lights on their listing. They instead put the wattage from the comparable traditional incandescent bulbs. I'd be surprised if it pulled much more than 5 amps.

That's correct for 120v home lightbulbs....they'll say in the finer print "100w replacement, but only uses 13w"

For the 12 volt light bars, they list the actual wattage.

 

[Timmer92]

Thanks all, I'll take any and all advice.

As noted, I'm not finding lumens in nearly any of the specs. I know that's ideal, but not really a decision point if they don't have the rating. They are all staying watts. I think just to be safe I'll probably get a kit with wiring and fuse.

 

[Sodark]

If you're going to feed it off the rear factory supply, you'll probably want a switch somewhere in the circuit. That supply is always-on, any time the tractor is on your lights will be as well.

 

[Dvan]

I added 2 forward facing, and a rear facing 18” bar. I wanted them switched separately so I added a sub fuse panel and a 4 bank switch panel that also has a usb plug and 12 volt plug in it. More than enough light, my driveway is 400 ft long and it lights it up clear to the bottom.

 

[Timmer92]

Thanks all for the advice.

After scouring youtube, I think this set up matches one I had in my mind almost perfectly. I was going to mount 2 for reverse as well, with forward lights and reverse lights on their own switch. https://www.youtube.com/watch?v=lXfj3ZLKpkU

And I was thinking I would get a kit, regardless of whether I used the supplied fuse or cut the wire ahead of the fuse and connected to the existing Worklight wire (and therefore fuse) already on the tractor:

https://www.amazon.com/dp/B071XJ4HF8/?coliid=IERJGPCYT0W53&colid=24PIC4H54X764&psc=1&ref_=lv_ov_lig_dp_it


or something potentially beefier:

https://www.amazon.com/dp/B06XQGQTXQ/?coliid=I2O926OHSH22HT&colid=24PIC4H54X764&psc=1&ref_=lv_ov_lig_dp_it


https://www.amazon.com/dp/B00WE47RP6/?coliid=I2VJM3C9OAQXXJ&colid=24PIC4H54X764&psc=1&ref_=lv_ov_lig_dp_it Have to buy a wiring harness separately.

As far as cost, we are talking $3-$15 difference no matter what I choose.

 

[Timmer92]

I added 2 forward facing, and a rear facing 18” bar. I wanted them switched separately so I added a sub fuse panel and a 4 bank switch panel that also has a usb plug and 12 volt plug in it. More than enough light, my driveway is 400 ft long and it lights it up clear to the bottom.

Nice! Can you share the specs of your lights as a point of reference?

 

[Dvan]

Nice! Can you share the specs of your lights as a point of reference?

My 2 forward facing lights are 12 inchers @ 108 watts each, both on a 10a fuse together
My rear facing light is an 18 inch @ 180 watts also on another 10a fuse

 

[200mph]

My 2 forward facing lights are 12***8221; @ 108 watts each, both on a 10a fuse together
My rear facing light is an 18***8221; @ 180 watts also on another 10a fuse

I'll say it again... These lights do not pull the amps stated on the packaging and the above illustrates this point

Two forward lights at 108 watts each would be 216 watts total for a current draw of 17 Amps. If they truly pulled the stated amps the 10A fuse would blow every time.

Running both forward and Rearward lights simultaneously would also tax the alternator output significantly at the published loads. (396 Watts or approximately 31 Amps!)

 

[GreensvilleJay]

There's two issues with 'power specs' for LEDs.
1st one is you need to know what voltage they were tested/rated at. A '12 volt' battery isn't 12 volt. A nominal full charge lead wet battery(aka old skool car battery') should be 13.2 V. New type batteries aren't 12 volt either and of course it also depends if alternator is running or not...

2nd issue, is really HOW they are powered. LEDs are current driven devices NOT voltage. You should feed them from a constant current source, varying the current will vary the intensity.Yes, it costs marginally more BUT the LEDS will last longer and give better overall performance. Cost ? I can do it for about $3 per light bar and that includes dimming ability.

seems like LED bars are rated by the same clowns that sell 100W PC speakers powered from a USB port.
Jay

 

[SDT]

Hi all,

I take delivery of my Kubota L3901 next week. I have a project I want to tackle immediately, and would like to have all the parts here ready to go. I want to add a 12-20" light bar to my ROPS. I am aware there is a prewired worklight connection. Based on my research, that is connected to a 10 amp fuse. I can find LED lights in the 75-125w range, which by my calculation would be up to 10 amps, and therefore would work on that connection. At the same time, there are many units out there in the 150-350w range. I am guessing if I'm going to go through the trouble of adding a light, I don't want one that is under powered. I obviously can go with a bigger one and connect it directly to the battery with the appropriate fuse. Given that very few have specs for lumens, watts is pretty much the only measure I have. Any advice on whether I should go with a bigger wattage unit?

Thanks!

Forgive me for not reading the previous posts.

FWIW: I installed a 22" HF LED light bar onto the ROPS of my B3350 and powered it from the unused rear harness connector. I checked the owners manual, wiring harness schematic, and fuse panel and learned that the connecter is fused with a 10A fuse.

Though my 3350 also has the OEM rear work light, I've had no power issues.

10 A at 12 V is quite a lot of power vis a vis LED lamps.

SDT

 

[BX23S-1]

Forgive me for not reading the previous posts.

FWIW: I installed a 22" HF LED light bar onto the ROPS of my B3350 and powered it from the unused rear harness connector. I checked the owners manual, wiring harness schematic, and fuse panel and learned that the connecter is fused with a 10A fuse.

Though my 3350 also has the OEM rear work light, I've had no power issues.

10 A at 12 V is quite a lot of power vis a vis LED lamps.

SDT

Just because you haven`t had any power issues yet,(famous last words) dosen`t mean you won`t.
I would wire the light bar up directly to the battery. Use the the key switch to power your relay on/off.

 

[RCW]

200 and Jay - if you had to guess, what do they draw versus stated load, i.e., 50%, 20%?


Sent from my iPhone using Tapatalk

 

[GreensvilleJay]

I won't guess, too many 'variables' involved... always best to test on bench and measure BOTH volts and amps.
Without seeing what's inside it's a crap shoot....just be sure you CAN return if NOT satisfied or as stated.
I returned $200 worth of '100Watt' LEDS when I showed them pictures of volts/amps readings on my test bench.