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Hi I was thinking of installing an LED light to a craftsman 8.5 hp blower but I'm not sure if it is AC or DC coming out on the wire. The engine is Briggs & Stratton model 15A114-0342-E1 and I searched online and see that some sites mention that it is DC. Does that mean that I can wire up a light directly? Or do I still need to do the bridge rectifier?
 

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Led lights will work on it but it may need rectifier for pulsing. Some pulse some dont


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Noma 10/29
Cub cadet 5/26 conv to 8/26
Toro 8/24
Husqvarna st230p
 

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Sorry got the name of the thing wrong, There are posts on here about what u need to upgrade to 12v led (when it pulses) there’s a great stickie all about it. Connect it first if it doesn’t pulse your good to go. Check the wattage of the orig bulb and don’t get a bigger wattage led light more wattage then that, or combination of multiple lights


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Noma 10/29
Cub cadet 5/26 conv to 8/26
Toro 8/24
Husqvarna st230p
 

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Ahh, you'd add a suitable capacitor if you're getting pulsing. A rectifier converts AC to DC. A capacitor will smooth out ripples in the DC voltage.
 

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You can buy a replacement LED bulb on Amazon that will solve all your problems. This had been previously posted on here.
 

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a couple of these and be good to go


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Noma 10/29
Cub cadet 5/26 conv to 8/26
Toro 8/24
Husqvarna st230p
 

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At 72W, that's almost guaranteed to be a higher power draw than the alternator could support. Apparently 18W, or thereabouts, is a fairly common alternator output, at least if it's just meant to power a light. If also running handwarmers, it might be higher power.

An LED light that's more like 10-15W is probably more reasonable. And that output from an LED should still be pretty significant, vs from an incandescent.
 

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Sorry bad example.. I used these, they operate from 12-24v



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Noma 10/29
Cub cadet 5/26 conv to 8/26
Toro 8/24
Husqvarna st230p
 

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Typically, wattage should only be used to describe actual power consumption. If they are trying to describe brightness, they should use lumens, candlepower, etc.

I would assume that light actually draws 72W, unless proven otherwise.
 

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Discussion Starter #14
thanks for the replies. I have seen the sticky thread about LED lights. I will give it a go and post my results here.
 

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OK, my 2 cents, since I just added a light to my Toro PS 824, and did a more elaborate lighting to my TB 2410 last year.


The newer Briggs engines seem to have a 60 watt stator. My older Tecumseh engine has an 18 watt. You really want to keep the power requirements low, if you have only 18 watts to deal with. I would plan on getting a light that only needed about 1/2 of the rated power, otherwise you'll be making a strobe light, not a headlight. :)


The output is probably going to be AC, not DC . . . unless the manufacturer has put the diode in their wiring harness (connector). You can use a volt meter to see if you get a better reading with an AC setting or a DC setting to try to verify. Keep in mind that 'DC' in this case really means recitifed AC, in that the 'negative' portion of the AC wave has been cut off by the diode. I have an oscilloscope, so I can see exactly what the output looks like, etc. (I know, that's cheating :) )



In order to take away the 'pulsing' that you may get, a large capacitor can be put across the DC voltage. On my TB 2410 I used a 2200 uf capacitor. It pulses at low RPM. On my Toro, I used a 4700 uf and the thing is pretty solid even at low RPM.
 

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@tpenfield has pretty much, darn well answered this thread. Maybe I can add some further insight - I'm not a small engine tech or factory guy, this is just my personal observations and experience.

As tpenfield says, the output of various alternators seems to run from 18 watts to around 60 watts. But some of the larger engines are even more.
From what I could dig-up from factory specs is that it seems alternator output is loosely tied to both engine horsepower and how the original machine was optioned. A machine without these options, and/or, with smaller hp engines might have no alternator at all.
Regardless, if your machine has a factory-optioned incandescent light then the factory must have supplied an alternator of sufficient wattage for that light which could then be rectified and used for LED lights (25 watts of LED's is a lot of light!).
For example, if your snowblower came optioned with heated grips (~6 ohms / 20-30 watts) and 1156-type incandescent bulb (27 watts) then it probably has a 50 or 60 watt alternator.
By the way, neither the heated grips nor the 1156 bulb need dc to operate; they'll both work just fine on ac because they're both purely resistive.

On machines with alternators there should be at least one ac output lead -usually yellow colored (but not always)- but there could also be a dc output -usually red (but not always). The dc lead is used on battery-equipped models for battery charging. Such battery-equipped models may or may not have a voltage regulator in order to maintain a constant battery voltage. But some of those with batteries and starters are not regulated, and, instead, just let the battery voltage rise unregulated.
The ac output, once rectified, could further be tied common with the dc lead, if you wanted to do that, if there is one. This would have an additive effect on available voltage and current. However, when wired this way the dc voltage can rise well over 30 vdc, even with a load. So you'd probably want to use some type of regulation, maybe a buck-boost converter, something like that.

Another thing to understand is these alternators produce rated output only at "full" engine speed, usually 3300-3600 rpm. If the engine is idling in the 1500 rpm range you won't get the power needed for 12 v LED's.
For example, my 11 hp Tecumseh gives me 8 watts at idle, about 15 watts at 2200 rpm, and well over 40 watts at 3000 and above. These are not fancy inverter technology, they're simple alternators; the faster they spin the more they make.

As for the rest of the LED conversion I think enough has been written here (thanks tpenfield) and much more detail elsewhere on this forum. The only thing I guess I would add is you don't specifically need a full wave rectifier for the dc - a single diode of appropriate rate will do. But, you will need a lot of filtering for smoothing voltage variations and for negating residual ac ripple.
 

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Update: So I got some lights from amazon and mocked one up. It does not flicker at all, it is steady light and I just wired it up directly from the wire coming from the engine. I'm going to add the other light to the other side next and also wire in a fuse. I bought an AC to DC convertor but i don't think i am going to use it. might try to return it.



video:


link to the lights: https://www.amazon.com/gp/product/B00IY3YLCI/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
 

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Cool! That single light seems very effective. Hopefully the alternator can run 2 of them together. But even if not, that single one seems to be putting out much more light than the incandescent headlight on my machine.
 

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They have other lights that look like that but have “side shooter” lights good for more of a flood effect. I have them as reverse light on my vehicle


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Noma 10/29
Cub cadet 5/26 conv to 8/26
Toro 8/24
Husqvarna st230p
 

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Discussion Starter #20
Update: I got out the multimeter and i measured that the machine puts out 24 volts of AC so I wired in the AC to DC convertor which yielded 12 volts of DC. The one light is plenty bright so I think i'll just leave it as is.
 

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