# 2007 8.5hp MTD gold lighting coil rating



## drmerdp (Feb 9, 2014)

Hey, my Mtd has a LH318SA-156554G Tecumseh. I'm going to add led lights, but I need to figure out how many watts the lighting coil is rated for. I haven't found any cut and dry numbers so far. 

The common number is an 18watt system but I haven't found anything specific to this engine.

Anyone know?


----------



## JayzAuto1 (Jul 25, 2016)

GAfternoon dr, your correct on the wattage of that coil, as it appears to be the only alternator supplied with that engine. So, figure at 12v that would have 1.5a available. How many and what size lights do you plan to add? Is that going to be in addition to the light on there now?? Or replacements?? Thanx, Jay


----------



## Vermont007 (Mar 29, 2015)

I think I have that same engine, and probably the same Alternator Coil #611104, which I am also told is 18 Watts Total.

If so, then you should have both a Red and a Yellow lead exiting the engine.

The *Red is 3Amp DC* for the Heated Hand Grips, and the *Yellow should be 5Amp AC* for the Light circuit.

I've changed my Headlight to a Multi LEDs (27) plus four sticks of Blue Running Lights for safety (about 150 LEDs total); but I have no idea how many watts I've consumes, or how many thousands of Lumens it's producing.


----------



## drmerdp (Feb 9, 2014)

It looks like my options are pretty limited. I though this Tecumseh had a bigger lighting coil. Bummer.

I found Tecumseh literature specing the 18watt coil at 6v 2000rpm and 10v 3600rpm. I haven't seen an led bulb or fixture rated for less then 10volts. I'll have to measure tomorrow and chime back in. The worst case the bulb won't last its full 50,000 hours.

I built a bridge rectifier, capacitor setup rated for 10+ amps. I might save this one for my tractor and build a new smaller setup for MTD.


----------



## Vermont007 (Mar 29, 2015)

I looked up my Engine, and it's an *LH318SA-156568H* . . . . close but no cigar !

Still, before concluding that your Alternator is inadequate, I'd put an Multi-Meter on the leads and measure the output from each of your leads.

Do you have BOTH the YELLOW (Lights) and RED (Hand Grips) leads coming out of your engine ?


----------



## drmerdp (Feb 9, 2014)

Just a yellow for lights.


----------



## drmerdp (Feb 9, 2014)

I had a chance to measure the voltage from my lighting coil on this MTD. And the disappointing results are.

5 volts at idle
7 volts at 3600rpm

Im thinking I have 3 options.

-Stick with the stock incandescent bulb
-Pop in an led bulb and see how long it lasts.
-Add a step up converter after the bridge rectifier and before the LED bulb. This is turning into a sizable investment for a little more light...On my spare snowblower. LoL

I have 30 bucks in my bridge rectifier box. Add 10 bucks for a pair of bulbs from Amazon. And another 15 bucks for a step up converter on Amazon also.

Might just scrap idea for this season. I'll wrap up my LED light project on my HSS928 and see how I feel about the lowly MTD. 

Thank you for the Input from you guys.

Here's my bridge rectifier concoction. Not a bad prototype, I'd make it more compact, and size the components more specifically next time. Good learning experience though.


----------



## JayzAuto1 (Jul 25, 2016)

That's quite a box you made there dr. How bright is the stock light while it's running? Does it go to full brightness at 3600 rpm and dim accordingly with rpm drop?? I would think that @7v at 3600 rpm's, that the original light is pretty dim. Are you measuring AC volts? Or DC volts at that rpm? It may be worthwhile to toss an alternator in it if it's truly that low. I have some used units that I'd be willing to send your way for the cost of shipping if need be. LMK, Jay


----------



## drmerdp (Feb 9, 2014)

The light does illuminate fully at 3600 rpm, and dim as RPMs drop. And my voltage numbers are in AC.

I've seen base Tecumseh light coils being referred to as 3amp alternators, Which would make sense... 3 amps at +/- 6-7 volts is +/- 18watts.

Thank you for your offer jayzauto, but I have a feeling that the alternator is functioning properly.

I'll likely revisit this machine and do something with it eventually.


----------



## JayzAuto1 (Jul 25, 2016)

I just check a Tecumseh 9hp that I finished up this morning. It shows 6 [email protected] 1.1 amps at idle and at 3550rpm, it's showing 10.1 vac @ 1.8 amps, similar to yours i'd imagine. Most automotive style LED's run on 3 vdc and packaged generally with a board that will knock 12/14 vdc down to the required operating voltage. You already have the parts, why not just lay all the wiring on the floor, connect it up and wait for the smoke to come out of the wires? Sorry, I meant, see how it works with that fancy box and take some volt & amp measurements?? If the smoke comes out of the lights, send them back as defects. GLuck, J


----------



## JayzAuto1 (Jul 25, 2016)

drmerdp, do you have a wiring schematic for that b circuit board you built?? That is a beauty!!! Thanx, J


----------



## drmerdp (Feb 9, 2014)

I kinda winged it. 

Fuse is before the bridge rectifier and the capacitors are in parallel tied into the DC output using the oddball spade connectors. Nothing crazy. 

Nothing is glued into place. I can take a more detailed picture of the guts if you'd like.


----------



## JayzAuto1 (Jul 25, 2016)

GEvening dr, Yes, a diagram would be awesome!!! I first found this forum, months ago, while looking for info on LED's in general. I found this forum, read ALL the LED upgrade posts, and thought: 1) What a great place for ideas 2) I didn't realize that LED's posed so many problems for soooo many people. So, 1) I joined this forum....great place to share ideas 2) in my spare time. wanted to make up a box, similar to what you made, to make adding LED's 'Plug-N-Play', including different connectors to plug into various alternators. BUT the logistics of making all those combinations makes it very time consuming. Not to mention the various light designs...... Considering I haven't had the time to design even ONE of those boxes for myself, I gave up. Now it looks like we are FINALLY getting snow!!!! Soon it'll be tractor season, so designing it now is fruitless.

But on a side note, I stumbled across a website, of a "Serious Tinkerer" that was really into the lighting thing. It appears that what he really does is waaaaayyy above my pay grade, but he researched the Tecumseh Alternator and Flywheel part numbers. I thought I'd pass it on, as it looks interesting. He does a lot of intersting things. It's worth a look.

George Stone: Adding Alternator to Snowblower with Tecumseh Engine

GLuck, J


----------



## Mikethefinisher (Jan 4, 2019)

I have a 611104 stator one yellow one red wire and i hooked a bridge rectifier to the one yellow and the other a/c side to ground on block and a capacitor on pos and neg d/c out of rectifier and it powers a 72 watt led light it cranks out more than you think idk why it works but it does not at idle only mid and full throttle at mid it blinks a little bright at full though im going to hook my heated hand grips to to the red wire maybe direct or maybe through a battery so i can turn grips on 20 min b4 i start it so they are nice and warm. I've read articles that people that have heated hand grips by the time they're done with their driveway is when the grips of warming up so I think with a battery I can start them early without having the engine running


----------

