the reason for my asking this has nothing to do with any of my trucks "but it could".... at the moment it pertains to a tractor electrical system. (still 12V neg ground)

story problem.... (remember those?) I have 2 headlites on my tractor, rated at 12 volts and 35 WATTS each. I have 2 here collecting dust that I would like to use, (mostly because it would help in clearing snow with said tractor) that are rated at 12V and 100 WATTS each.

knowing that this tractor has a 15 AMP charging system, and the PTO clutch draws 5-6 AMPS, will I run out of charging capacity and start discharging the battery while running, if I run the 100 watters in place of the 35s? no other changes. tractor has no other lites, no radio, etc.... but is a 12v battery ignition system that need a little bit of juice to operate the ignition coil much like an old points system on a car or truck....

reason PTO clutch is a consideration, is that it needs to run to power the snow blower that will be mounted to said tractor.

Sorry I could of helped you with that but, I haven't been on the laptop in a few days because my Daughter has hijacked it for collage scholarships and such. You did the right thing by going to LED.

next question.. (along the same lines) Why are house generators rated in WATTS when my house circuit breaker box is all about AMPS?

AMP's is dependent on which voltage is used "100v vs 220v" on a home Generator, you get Amp's by dividing Voltage into Watt's.

For Example:

For DC lets say your Generator puts out 330 Watts and your using all 330 of those Watts at 110 Volts that would equal 30 Amps. Or "I = 3300W / 110V = 30A"

I know cars don't put out 110 volts this just makes the math easier

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Then you have AC Single Phase Watts into Amps conversion which is a lot more complicated where you would have to know Power Factor...

Example:

The phase current I in amps (A) is equal to the real power P in watts (W), divided by the power factor PF times the RMS voltage V in volts (V):

I(A) = P(W) / (PF × V(V) )

So amps are equal to watts divided by power factor times volts.

amps = watts / (PF × volts)

or

A = W / (PF × V)

By using the same figures as above it would come out to 3.75 Amps but still at 330 Watts.

The there is 110 Volt 3 phase which I wont get into

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So there is 2 reasons Home Generators are listed in Watts...

1. The Generator Manufactures have really no way of trusting "liability" the public to do the math to try and figure what AMPS each appliance will draw and Power Factor. Plus AMPS can't be determined until there are Watts used at a certain Voltage.

2. The second reason is advertising, Watts is a bigger number. It makes people feel better lol