How much wattage/amps in lights can I add with this set up?

[Freelancer]

Hey guys,

Just as the title asks,"How much wattage/amps in lights can I add with this set up?".

'91 K100rs 4v
Has stock 460 watt/33 amp alternator
ABS has been removed
Has oem heated grips
Running the large 28amp/hr Odyssey gel cell batterry(wanted good reserve power for weekend campouts where I keep my wife's phone charged)

That's it.

So, to how many watts of driving/fog lights am I limited?
Am I limited to a single 55w lamp or is there enough to run 2 of them?
I know that at some point I'll move up to the 50-amp alternator but am curious as to what the limits are when the ABS is gone.

Look forward to y'alls replies,
Freelancer

[552255]

IMHO, if you installed them with relay switches, good wiring, and wired to shed the load upon start-up, it would be fine...i have (4)-55+wattage driving/fog lights installed(2-sets)....but, have the higher powered alternator found on the K1100.

[frankenduck]

The battery doesn't matter.  Either you're sucking more amps than the alternator can provide or you're not.  A larger battery will take longer to drain, that's all.

The ABS drain is minimal since all it does most of the time is power the control unit.

Based on my experience with my K1100LT I could run a pair of 35W aux lights (w/ or w/o heated grips) but when I upgraded to a pair of 55W lights (with heated grips off) it drained the battery.

Based on my experience, my guesstimate is that a stock bike with a 32A alternator has about 100 "spare" watts.

[Freelancer]

Thanks Duck,

Now for a silly question prefaced with an explanation.

 I am not sure as to which alternator is on the bike. I can't find any numbers on the darn thing and I haven't yet needed to tear into the bike far enough to pull the thing. I got the bike with 60K almost 20 months ago. Its now @ 70K and I'm getting ready to do a major service on it.

Now the question-

Is there a way to check to see whether it is a 33A or a 50A  Alternator without/before tearing into the bike?

I ask because I like to have all of the parts on hand before I open the girl up.

Thanks for your time and knowledge,
Freelancer

[frankenduck]

Very easy to tell. The 32A alt is metal in the back.  The 50A alternator has a black plastic cap on the rear of it and, if it hasn't worn off, has "50" and some other stuff printed on the black plastic.

[Freelancer]

Duck,

Your are a gentleman and a scholar. :2thumbup:

Thank you for the info. Turns out that mine is original. Now I gotta decide on whether to get the 1100 altenator or just run a small set of 30 watt lights???

Hmmm, I have a pair of 55w hellas laying around that would require the alternator upgrade. Or, I could try out the tiny cateyes or that 30w 10"x4" light bar. (I would've jumped on the 35w ones you just sold but I saw that someone else had already got there first. Too bad, they would have fit perfectly under the front of the fairing.) Oh well. ....sorry to ramble.

Again, thank you.
Freelancer

[JimBlalock]

Have you considered LEDs?  They only use a few watts and are getting better every year. 

I upgraded the Motolights on my GS (yes, my other BMW is a K100) and reduced their load from 100W to 7W.  I think my gas mileage went up.

[frankenduck]

FL:

What kind of lights are you looking for? Conspicuity or something that lights up the road at night?  You really can't have both because anything that puts out enough light and high enough to provide good highway lighting at night just makes you an asinine nuisance during the day.  (Unless you go with an LED vendor that includes a dimmer with their lights which is a good trade-off if watts are an issue.)

Also, if you want to be SEEN in the daytime, then run orange/amber lights so you'll stick out from the crowd more given the number of cars that have DRLs or run their low beams in the daytime.

If you want some kickass night lighting then you could probably run these on a 32A alternator: http://www.motobrick.com/index.php?topic=3498.0

Jm 02....

[Inge K.]

Could just add to this thread that I've used 2 x 55W additional long range lamps
and the OEM heated handles together with the 32A alternator in 25 years w/o any problems.

Inge K.

[frankenduck]

Could just add to this thread that I've used 2 x 55W additional long range lamps
and the OEM heated handles together with the 32A alternator in 25 years w/o any problems.

Inge K.

Hmm... interesting.  That's why I always qualify my posts with expressions like "based on my experience" as I've never actually measured the current draw.  All I know is that after going from 35W lights to 55W lights on my K1100LT that my ABS faulted and then a short while later the bike died after a couple hours of errand running.  Luckily, I was on a long downhill when it died so I was able to make it home by turning off the lights and compression starting the bike.

And then there's the issue of what vendors claim the draw of aux lights is vs. what it really is.  As stated, I'v'e never actually measured the current draw and have just gone with the nominal claims made by the manufacturer.

[Freelancer]

FL:

What kind of lights are you looking for? Conspicuity or something that lights up the road at night? 
*snip*
If you want some kickass night lighting then you could probably run these on a 32A alternator: http://www.motobrick.com/index.php?topic=3498.0

Jm 02....

Hey Duck,

I'm looking for long range driving lights. Texas has more road than road crews and the abundant wildlife has made us the unofficial "roadkill state". This slogan was actually one of the final 10 contenders for our license plates 20 some years back. Had a dead upside down armadillo that seperated the first 3 digits from the back 3-4.  :laugh

Thanks for the link and the help. :2thumbup:

I'll post what I go with when I decide upon which route I'm gonna take.

Later,
Freelancer

[wmax351]

FL:

What kind of lights are you looking for? Conspicuity or something that lights up the road at night? 
*snip*
If you want some kickass night lighting then you could probably run these on a 32A alternator: http://www.motobrick.com/index.php?topic=3498.0

Jm 02....

Hey Duck,

I'm looking for long range driving lights. Texas has more road than road crews and the abundant wildlife has made us the unofficial "roadkill state". This slogan was actually one of the final 10 contenders for our license plates 20 some years back. Had a dead upside down armadillo that seperated the first 3 digits from the back 3-4.  :laugh

Thanks for the link and the help. :2thumbup:

I'll post what I go with when I decide upon which route I'm gonna take.

Later,
Freelancer

My uncle used to live near Bastrop, after moving away from Houston. He asked me: How many Texans does it take to eat an armadillo? 2, someone has to watch for cars.  :drool:

Long range driving lights sound like a good plan. I remember all the roadkill on the side driving down there. One thing I do on my bike is have 2 projector type fog lights for the short range and side vision, and a 100/130 watt H4 bulb for longer distance vision, as the H4 has a good cutoff so you don't blind people, and I have it in selective yellow (like old french cars) which reduces glare significantly for other drivers.

I used that setup riding along rte 50 last summer through Nevada and Utah. Similar issue with wildlife.

I have the 50 amp alt, so it handles that with ease, even with both filaments of the H4 running, for almost 350 watts of lighting.

You could install a voltmeter, and use that to monitor the status of the battery. One of the issues is that errand running doesn't generate the needed power. The RPM is lower, and frequent starter usage drains the battery.