Altenator question...

I've just gotten this 82 750 Twin M1. I want to light up the front end so hopefully more people will see me. How do I find out the output of my altenator so I can figure out how to not overload it with lights?

It would seem that regular car driving lights wouldn't work on a bike. Is that a safe assumption?

Post edited by: torr10, at: 2007/03/20 14:53

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20 amp output is what the alternator is rated at.

you connect a Ammeter in series at the negative side of the battery.

do not electric start the bike with the meter hooked up. it will burn the meter.

the trick is to get the biike started and then disconnect the neg cable and insert the meter without loosing the connection.

I believe the output will be 7-13 dc ampres.

a good 80/100watt halogen is going to use most of the current so periodic charging will be necessary

however a couple H-3 55 watt driving lights will do very nice

Do what Trippivot says if you want to measure the current the battery is getting.

If you want to measure the alternator's output, it's not simple. The alternator's output is split between the battery, the bike, and the regulator. You can measure what the bike and the battery are using because you can put an ammeter on the reg/rec's output. Measuring the current that the regulator is sinking (to shunt the excess output in order to regulate the voltage) is a little more difficult. This is because the shunt current is only at about 2 volts, so the current is higher than if it was to be applied to the bike or battery at 12~14 volts.

A true test would have to be RPM specified, and would require a variable load to use all of the alternator's current at at 14 volts such that the regulator shunts none of the current.

Since the regulator converts excess current into heat, you could measure the temp rise over ambient, then convert that into amps at measured volts.

The easy answer is the manual, and it states 280 watts at 14 volts, and that equals 20 amps.

Um... I meant... just look in the manual.... yeah that's it.

steell wrote:

Since the regulator converts excess current into heat, you could measure the temp rise over ambient, then convert that into amps at measured volts.

The easy answer is the manual, and it states 280 watts at 14 volts, and that equals 20 amps.

That seems to be the standard. So the bigger question is how much do you have left over... So measuring the amp draw as stated in the above answers will tell you what you are using now. If you are already drawing 13 amps with the bike running, headlight on then you dont have much left to play with. I'd test it with the turn signal and brake light on as well. Then if you get a halogen headlight you can test the amp draw of that using the same methods to see if you have enough power, in theory, to use it without draining the battery while driving. I'm doing similar things myself but I have not gotten around to testing due to my multiple other problems right now. I got the H-4 headlight from JC-whitney and changed all my turn signals and brake light to LED's (you need different flashers too). Something to think about.

Ron

Some have reported that two 55w halogens ends up being too much on top of the regular lighting system. Another issue is if you are running an aftermarket ignition. Something like a DYna-s uses twice as much current as the stock system.

I got dizzy reading all the electrical theory. A couple of 35W spots (70W total) will add about 6 Amps. I suspect your bike will have 6 Amps to give to the lights. To do this safely, you need to understand that in general the smaller fused circuits on a Kaw are 10A rated and if you have a couple, they won't have the 6 Amps for you to use. What I suggest is you buy a switch, the spots and a relay. Trigger the relay just as you would if you were doing the COIL REPOWERING mod. You can see it written up on our website at www.wgcarbs.com under the wg's Tech Stuff Index. Anyway, instead of powering coils, you will power spots. Use the switch between the power OUT of the relay to the spots and shut them off in town or when not needed. Keep in mind that when you bike is running under 4K rpm, it doesn't produce all the voltage that it does over 4K rpm and so lots owners would do well to turn the spots off if trolling from stoplight to stoplight. Use the wire recommended in the writeup and you should be OK. The 10A circuits on an old Kaw really shouldn't be stressed as the connectors and wire is old and tend to want to melt more than when they were new.

I've been sitting around waiting on emails to tell me someone responded. Now I see a bunch of responses. I guess I forgot to check that box when I posted.

I'm sorry I haven't checked sooner.

Thank you for all the responses. I think I'm going to try to find an altenator/regulator combo with a higher output capability.

But before I address that...I gotta find some clutch parts that aren't ridiculously high priced....gotta love these older bikes!!!!
Thanks again...