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post #11 of 32 (permalink) Old 12-05-2012, 12:59 PM
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Have you checked to see if there's a current drain from the battery with the ignition switched off?

There could be a high resistance short circuit somewhere.

Sam Murray

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post #12 of 32 (permalink) Old 12-05-2012, 05:44 PM Thread Starter
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Sounds like I have several more tests to do before replacing the rectifier.
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post #13 of 32 (permalink) Old 12-05-2012, 08:09 PM
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Originally Posted by johngreco View Post
Are my short trips around town not enough to keep the battery properly charged? Any advice is appreciated.
Just my .02,
I swapped out my stock stator for a wassell high output and that ended my battery problem. Someone told me bumbling around town under 2000 rpm's would not keep a charge up,epically for the ei.
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post #14 of 32 (permalink) Old 12-05-2012, 09:11 PM Thread Starter
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One more thing I probably should have mentioned (and thought of). I installed a Cebie halogen headlamp a while back. Probably around the time I noticed the charging system wasn't up to snuff. I installed a relay with the headlamp, but is that enough with an electronic ignition and 43 year old stock rectifier? Maybe my real issue is I'm drawing too much juice and not providing enough to satisfy the demand. At this point I feel like I've upgraded a bunch of electrical components without upgrading the equipment that needs to supply them.
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post #15 of 32 (permalink) Old 12-06-2012, 09:22 AM
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Well make some measurements first and let us know what you find.

The relay won't take much extra and nor will the Cibie unless you changed the bulb for a higher output one?


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post #16 of 32 (permalink) Old 12-07-2012, 06:43 PM
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No1 I'd say is (assuming the multimeter is reliable) you should have greater than 12.5volt on a decent charged battery (I mean after having disconnected the charger for an hour).
If it's lower, battery is well past its best.

Zener diodes are hard to judge without test equipment, in basic multimeter tests they can say ok, but if they have started to fail in that they allow current to flow at slightly lower voltage, you won't pick up unless you've got the gear.

What will happen in that case, is that a steadily worsening case of undercharging of the battery will occur, which has a dramatic impact on battery useful life.

I have also known the other end of the scale, where the zener has gone open circuit, which caused far greater damage to other components as well.

I can't see any reason to use zeners anymore, or an old rectifier, a podtronics, boyer powerbox and others do a better job, they take the pressure off the alternator having to run at full output all the time as well.

The advantage of going to a 3-phase alternator (with appropriate powerbox) is that the amps build in a quicker curve with revs, so chugging with lights on is less of a problem.

While on the subject, I laugh at all those ammeters we have on british bikes, needle flapping from one side to the other, only true reading you get is when you switch on before starting!
Put a digital voltmeter on it, tells everything you need to know (I know that's not good for all, I am a triton owner! with freedom)
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post #17 of 32 (permalink) Old 12-07-2012, 07:54 PM Thread Starter
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Thanks for everyoneís input. Iíve been out of town all week so havenít been able to perform additional tests until today. I checked the battery fresh off the charger with no load and it read 13.07. After an hour there was no change. Obviously I havenít been able to test it after a few days sitting.

I took a voltage reading with the bike running at about 3000 RPMs (I donít have a tachometer so I ran it in top gear at 45 MPH per the manual) with the headlight on (Iím running a 60/55W H4 bulb with relay) and my volt meter was only reading about 10 volts. Even with the headlight off I wasnít getting up to 14 volts. Keep in mind I only ride this bike around a metropolitan area and rarely get up to 45 MPH and itís brief when I do. And Iím also using an electronic ignition.
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post #18 of 32 (permalink) Old 12-08-2012, 01:40 AM
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10 volts isn't near enough. you Headlight draws considerably more than stock, but it shouldn't be that high of a draw. Check the output at 3000 with the lamp off and see what you get. Be willing to bet it still won't be above 12v.

You need to determine if the zenner has bit it, teh stator, or the regulator. Meter your 2 stator leads for A/C voltage where they plug into the harness. Should see upwards of around 9 volts A/C when running loaded at around 2500-3000RPM on each leg (white/green and green yellow wires if memory serves). If one is low, swap the leads where they plug into the harness and test again. If the low leg still reads low plugged into the different connector you either have a problem with the connection or the stator itself. If the voltage drops on the previously normal stator leg, then you have a problem with the harness or rectifier.

If you check solid on both leads, then you need to check the output going to the zener, after the rectifier before the zener. You will be checking D/C voltage at this point. If the zener is bad and shedding to ground too soon, you will read low period. In essence, you need to disconnect the output from the rectifier to the zener and check raw output through your meter to ground. There are several ways to get it done, but not sure I can acurately describe how to do so, and do not want to risk spiking your Boyer Box (bad news if ti happens). Maybe someone else can step in and describe this step. If not, I will make the attempt, but will reccomend extreme caution doing so to ensure unregulated voltage doesn't reach the Boyer.

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post #19 of 32 (permalink) Old 12-08-2012, 09:19 AM
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It might be useful John to spend a few minutes checking over your charging system connections, from the alternator to the battery. Disconnect each one at a time if you can and make sure each one is good. What you are looking for is a weak connection, weak as in it's just about to break.

Charge your battery.

To test if it's the zener, disconnect it. Start your bike and measure the battery voltage. If it's now 14-16v then the zener is duff.

To check your alternator disconnect it and measure the resistance between any two leads. It should be very low, about 0.5ohm. If the resistance is very high then it is broken.

To confirm it is OK start you bike and measure the alternator voltage, still disconnected, between any two leads at 3000 RPM. Make sure your meter is switched to AC for this measurement. It should be high, 30v AC or over.

If this is OK then it looks like you have a broken rectifier.


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post #20 of 32 (permalink) Old 12-08-2012, 09:25 AM
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It might even be the same problem i had.The rotor had lost nearly all its magnetism.Looked at that last of course after the rectifier,battery etc.I connected a lamp across the two alternator wires and it barely glowed.I also read up on DerryUk s alternator info which was very useful
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