Adding lights, How many extra amps draw is ok?

Hi,

How many extra amps of load can a stock charging system handle reliably?

My wife rides an '81 KZ440LTD. We would like to add some running/fog/spotlights to you her bike to increase her visibility and other driver's ability to see her and hopefully prevent cars from pulling out in front of her, etc. We're thinking two extra lights, just offset from the headlight on either side of the headlight.

It seems like there are plenty of options for lights. I'm trying to decide between halogen and LED. Halogen would be much brighter, cheaper, and there are far more choices available. But, I'm guessing from experience with other Japanese bikes of this age that the charging system has just enough capacity to handle the factory loads and nothing extra. 60W seems to be a common choice for halogen lights. A pair would be 120W, or 10A. Is that too much extra load? There are some 20W halogen bulb options too - a pair of these lights would still be over 3A. Is 3A extra too much?

I guess the alternative is LED. I'm assuming the draw on these is a negligible extra load, but there are fewer choices, I don't think they'd be as bright and they seem to cost more. Has anyone added some LED lights like this? Happy with the results?

Thanks,

The amount of extra amps it can handle depends on how you ride it. At idle there are almost no extra amps. If you spend a lot of time in traffic then definitely don't add a 100 watt light. If you are mostly doing highway riding, you may get an extra 55 to 75 watts pretty reliably.

These are very round numbers and assume the charging sytem is fully functional, obviously.

But if you are looking for visibility, and not trying to light up a dark road, then LED all the way. Make sure they cover a large surface area and are not super-directional. Also, they will be seen by more people if they have a diffuser lens.

Bightness, alone doesn't get you seen. Fog lights or other focused lights don't get you seen during the day. The only people who see them are far away or in direct line of the beam. Up close the fog lights look dark if you are not in the beam. (I use two driving lights as head lights, and the problem with that is there is not a big lighted surface on the fron of the bike to be seen from many directions. But I drive mostly in lighted areas.)

The key is a large visible surface area of light with the light scattered in many directions. Plain LEDs are too directional. They need a diffuser which makes them weak, so it helps if there are more LEDs pointed in different directions with a reflective surface on the inside of the light fixture. This is what catches other people's eyes.

You can easily buy yourself some "headroom" by changing your tail light and turn signals from the 18W power hog standard 1157/1034 incandescent lamps to 3W Luxeon LEDs. You can get the LEDs at superbrightleds.com.

There are some loads like the horn that eat about 2A you don't use often.

My guess is that a stock systme might have 40 - 50W of extra but that's just a guess.

I have gone threw a quite a few KZ1300 stators by adding fog lights. I would not add any extra lights on ANYTHING before 1982 that you KNOW has a 20A alternator. Unless you choose to install a new high output alternator.

I have 2 extra driving lights on my '78 650.
Can't recall the wattage off hand, but if I ride slow in 1st & 2nd the battery does loose power, fast.
I do most of my riding in the country now adays so the RPMs stay above 5000 most of the time.
I have a volt meter on the dash that I use to moniter the battery's power. When the battery's power gets what I think is too low, I'll switch off the driving lights for a while and let the battery build up some power again. It dosen't take long and I turn on the extra lights for a while.

to increase her visibility and other driver's ability to see her and hopefully prevent cars from pulling out in front of her, etc.

I also put reflective tape on the front of my bike for this reason. Saw it done in a magazine. The tape looks black in the day, but reflects light white.
I've got some on the backs of the mirrors, a stripe on the bottom edge of the windshield, and more on the fork tubes and side frame tubes:

SUPER BRIGHT LEDS

As already mentioned, has LED bulbs that are intensely bright, and can be used to replace all the stock lighting, permitting you to add several extra lights and things.

A standard 100W bulb puts out around 1700 Lumens, some of thier LED's put out over 8000 Lumens, and have a much improved light dispersion over previous versions.

GL!

Maybe these would work:
www.jpcycles.com/Search/ProductDetail?sk...Ne=0&Ntk=All&Ntt=LED light&Ns=&results=10&No=&v=B

Thanks for the advice. It seems like there are a lot of good ideas here.

Does anybody know where to find a 50/35W 5-3/4" sealed beam halogen bulb that is made to fit an '81 kz440ltd?

It would be nice to change the headlight to a halogen headlight of the same wattage. That way it's brighter, but doesn't add any extra load for the charging system. We'd prefer not to mess with changing the mounting or wiring for the headlight (or the look of the bike), but just buy a sealed beam halogen headlight that would mate with the back side of the factory headlight. Unfortunately we haven't been able to find this.

I like the idea of replacing some of the bulbs on the bike with LED's to gain some extra capacity. I actually happened to have an extra LED bulb that I bought for another project but didn't end up using. It happened to be the same size as the tail light. The old bulb would draw .56A with the taillight on, and about 2.7A with taillight and brakelight on. The LED seems to draw 10% of that. That's about 6 Watts of load that was continuously on before. The LED seems a little brighter too. I attached some before and after pictures here.


I could see using some of the LED strip lights as side markers. We were also thinking of converting the turn signals to LED's. The factory ones are normally OFF and then blink ON when you signal a turn. We were thinking of changing them to LED and wiring them so they're normally ON and then blink OFF when you signal a turn - so they'll serve as running/marker lights. We could use a bulb similar to what we used for the taillight - but this wouldn't be normally ON without changing the wiring. There are a lot of "silver bullet" type LED turnsignals that are designed to do this but they are pretty spendy. I've seen some kits w/ an LED board and plug meant to go in the factory bulb socket - so you can convert your existing turnsignal housing to LED. They're sold to fit specific Harley models, not the for a kz, but they look about the right size for the kz. Might have to guess and modify if we go that route.

Sorry,

I meant to add these pictures in the post above. Hopefully this works this time.

Taillight with standard bulb:
(can't seem to get the other file to load here)

Taillight with LED bulb:

If you have a shop manual, it should list the amount of wattage the charging system will support.

You'll have to calculate the total wattage for all the bulbs and additional electrical demands like the ignition system.

www.electrosport.com makes alternator stators that have a higher output at idle.

Some more alternator related websites:
www.rmstator.com
www.customrewind.com
www.regulatorrectifier.com
www.ricksmotorsportselectrics.com

A KZ440 takes an oddball 6 3/8" headlamp. A halogen replacement is available from www.candlepowerinc.com
I have one and it is great! No problems with the charging system.
Part #802212, around $50 complete with replaceable 60/55w H4 bulb which are available most anywhere.

Bill Frazier
1982 KZ440LTD
Original owner