Battery draining when headlight on

[CJF]

I had this problem over the summer on my GT500 and have yet to figure out the culprit. I ended up swapping out the boyer powerbox setup I had and hooked up a battery and oregon elec. regulator/rectifier. The battery stays charged fine at 13.0-13.5 as long as I don't turn on the headlight when riding. Once I turn it on, the battery drains to the point that the headlight starts to dim on a long ride. Is it possible that the headlight isn't grounded properly and that may be causing the battery to drain? How do i check for this? Any other ideas on what might cause this problem?

[tz375]

Hopefully someone that knows about electrics will be along soon. On the face of it, the electrical system is drawing more power than the alternator is producing.

It's possible that the headlight is too high a wattage and is drawing too much current or that there are bad connections in the system. It's also possible that the problem lies elsewhere and either output is too low or there's too much current draw in the rest of the system. In other words, if the system is generating just slightly more than it needs with no headlamp and you turn the light on, it now draws too much in total.

I'd start with simple stuff such as checking all the connections and grounds and then I'd probably get an ammeter and measure the output under different conditions.

What ignition system do you have? DYNA S and DYNA coils make fat sparks and draws a lot of power.

[jabcb]

T500/GT500 wiring diagrams are listed under category electrical - sticky topic wiring diagrams.
viewtopic.php?f=29&t=4743

Which Oregon regulator/rectifier did you use?

The T500 & GT500 alternators have separate charging coils & lighting coils. The lighting coil is switched on only which the lights are on.

Did you wire up both coils similar to what's shown in this thread?
viewtopic.php?f=2&t=4858&hilit=t500+regulator&start=15

[H2RICK]

jabcb +1.

You have to make absolutely certain that the lighting coil is hooked into the charging circuit when the headlight/taillight is turned on.
As well, the T/GT500 charging system is marginal even when everything is operating correctly so it doesn't take much of a partial short to ground somewhere to screw things up.
One other little thing to be aware of: a brake light switch stuck in the "ON" position WILL drain your battery even if the lighting coil IS hooked into the system. Make sure that your brake light switch(es) is/are operating correctly and consistently. Repair or replace as necessary.

[Suzukidave]

Sounds like the 500 could really use a switch over to LED bulbs to save power ?

[CJF]

I'm running the stock generator setup for the GT500. The oregon electric regulator/rectifier is the VRRPM2 model. My headlight is a 34/45 watt. My front turn signals are not set as running lights, so are only on when turning. The tail light has integrated turn signals and is LED. I was following that other thread over the summer trying to figure out my own problem and I have hooked it up per the diagram in the thread.

There is one thing that I think may be the problem. The green wire from the light coil was brittle and broke when I was installing it on the motor. I guess there is a chance this connection wasn't repaired fully, so i should probably start there. Is there a way to test the wires coming off the lighting coil to see if they are testing out correctly? Not sure what the spec is that I would look for with the meter when testing the wires.

[tz375]

Chris, what voltage do you see on that wire going to the lighting switch when the bike is running? It sounds as if that may be the problem.

[jabcb]

The G/W wire is for the lighting coil.
The problem is likely to be the lighting coil, the G/W wire or the light switch.

Check the charging/lighting coil resistances:
Y/G to R/G: 1 ohm
Y/G to G/W: 1 ohm
Y/G to ground: infinite / no reading

You repaired the G/W wire. As you suggested the repair might need additional work. There also could be an additional problem that you haven't identified.

[CJF]

I'll check those ohm settings. Does it matter what setting I use on the meter? I have ohm settings at 200, 2000, 20k,...?

[jabcb]

Use the lowest range setting that doesn't cause the meter to max out. This will give you the most accurate reading your meter can produce.

Use 200 ohm range for 1 ohm testing.

Best approach for infinite / no reading depends on how your meter works.
Try 200 ohm range, then try progressively larger ranges.

Also, do these tests with the alternator disconnected from the regulator/rectifier. Otherwise you'll be measuring the resistance of the regulator/rectifier too.

[CJF]

I checked the settings and here is what i found:
y/g to r/g = 1.1ohm
y/g to g/w = .9ohm
y/g to ground = no reading

What do you think? The y/g to g/w reading isn't 1ohm, but is real close. Does it have to be at least 1ohm or more to me good?

[jabcb]

Those numbers look good.

Disconnect the regulator/rectifier.
With the bike running check the AC voltages at the connectors for the regulator/rectifier. Check:
Y/G to R/G
Y/G to G/W

Check the connectors for the Y/G, R/G & G/W wires. (The G/W wire has connectors in the headlight shell.) Are they clean? Are some of the wire strands broken at the connector?

Take a look at the wiring. Are there any spots where the wiring looks damaged or abraded? Make sure to check in the headlight shell & near the battery box. For example, look at the pic of the installed Tympanium regulator/rectifier. Some wiring near the battery box had some damage so I covered the wiring in a plastic conduit.
viewtopic.php?f=2&t=4858&p=109480&hilit ... um#p109480

[CJF]

I checked the ac settings with the engine running and the stator wires unplugged from the regulator/rectifier.

y/g to r/g = range from 14.9-17.0
y/g to g/w = 9.9-11.00

Did I just find the problem with the y/g to g/w reading? Does this mean the lighting coil is bad?

[jabcb]

Looks like you've figured out the problem. You need to replace the lighting coil. Fortunately its still available from Suzuki & the price isn't too bad.

I was expecting much higher open circuit voltages than you got.

Stator output voltage varies with the current. Its highest with an open circuit and no current. A short inside a coil that is between the windings allows current to flow inside the coil, so you get reduced voltage without have any load.

[CJF]

Thanks for the help. I'll post back after I replace the coil with results.