Could my coil drain my battery, why?

[mike in idaho]

With that kind of a draw, there should be some wires smoking somewhere. Sure sounds like a battery problem, has it been load tested? I know, it's new, but sometimes that doesn't mean much.

 

[Jan_P]

With that kind of a draw, there should be some wires smoking somewhere. Sure sounds like a battery problem, has it been load tested? I know, it's new, but sometimes that doesn't mean much.

Yes to that On the box says no charging required .. but I would do it now Especially if the charging in bike is low
it can be down now.. No changes after charging take it somewhere for a load test

 

[Jim]

lso, when I disconnect the ignition system, spark plug wires and all -just the charging system wired, with the key on the voltage drops to 6v.

So I am beginning to think, while I am having a voltage drop through the points wire, I am also, with the ignition completely disconnected, getting the same voltage drop with just the charging system connected.

I have yet to pull the left side cover away to dig, poke and prod, but I believe my charging system may be shorting to the engine/frame and thus, when I connect the ignition system and give power to the points it is somehow drawing power from the battery as well. Again, I am an idiot so any input is greatly, monumentally appreciated.

Now we're gettin' somewhere.

The alternator rotor will gradually lose resistance as the copper windings insulation breaks down with age. It's not unusual for one to drop to between 1 and 2Ω. I'll bet that's what you'll find.

Ring to ring on the rotor should read about 5Ω.

 

[Jim]

If the rotor resistance is down to say 1Ω, then the current draw will be about 12 amps.... that's enough to pull your battery down like you're seeing.

And then you need to look at a recent thread here on generic blade fuses not blowing when the current's high... like yours is doing.

 

[Rook32432]

If the rotor resistance is down to say 1Ω, then the current draw will be about 12 amps.... that's enough to pull your battery down like you're seeing.

And then you need to look at a recent thread here on generic blade fuses not blowing when the current's high... like yours is doing.

I guess then my next question is, with the charging system disconnected from the battery, would the rotor still be able to draw from the battery through the connection of the points to the engine?

 

[Jim]

I guess then my next question is, with the charging system disconnected from the battery, would the rotor still be able to draw from the battery through the connection of the points to the engine?

Don't know what year your bike is, so I can't pin down wire colors, but the two wires (or just one) for the rotor run through the engine disconnect.... the one big wire harness that comes from the engine.

 

[Rook32432]

Don't know what year your bike is, so I can't pin down wire colors, but the two wires (or just one) for the rotor run through the engine disconnect.... the one big wire harness that comes from the engine.

The bike was TCI ignition stock a 1981. The pickup and black box removed and points installed. Combo reg rec.

With the harness to the stator housing completely disconnected, housing and all plug in the wind. would the rotor alone still installed be capable of drawing current from the battery through the engine with the help of a potentially damaged coil and/or a short at the points?

I will test the rings on the rotor and get back.

 

[Jim]

With the harness to the stator housing completely disconnected, housing and all plug in the wind. would the rotor alone still installed be capable of drawing current from the battery through the engine with the help of a potentially damaged coil and/or a short at the points?

Nope. Power to the rotor runs through that plug.

 

[Rook32432]

I will charge the battery, get a proper 4-5 ohm coil ordered, test the rotor and follow up. But with the rotor being the only connected part of the charging system, there is still a large draw from the battery to the ignition system. I’m not sure how, if the coil is testing good, it could make such a draw even with it being 3ohm. The battery perhaps. Time will tell.

 

[Bruno_c]

I will charge the battery, get a proper 4-5 ohm coil ordered, test the rotor and follow up. But with the rotor being the only connected part of the charging system, there is still a large draw from the battery to the ignition system. I’m not sure how, if the coil is testing good, it could make such a draw even with it being 3ohm. The battery perhaps. Time will tell.

If the battery is almost discharged, even a small draw will cause a big voltage drop.
So in my opinion, the first thing to do is to have the battery fully charged.

 

[Wingedwheel]

Unplugging the wire from the ignition to the fuse plate then key on, the battery held its voltage steadily increasing from the drained amount. Plugged the ignition wire back into the fuse plate then keyed on and the voltage immediately dropped to roughly 6v.

Removed the charging wiring only, and still with ignition wired up and key on the voltage came back down to roughly 6v.

I may be reading this wrong but could there be a problem with the fuse plate? Just throwin that out there.

 

[Rook32432]

I may be reading this wrong but could there be a problem with the fuse plate? Just throwin that out there.

I thought about this so I tried testing that out by touching the wire to the ignition coil direct to battery and the drop still remains. Going to take the battery to be load tested today. If it does fail that will make 2 batteries within a 2 month span to fail.

 

[Rook32432]

so I am revisiting my charging system wiring. I’m assuming I’ll need to replace my rotor at the very least since it tested at 3 ohms and not 5.
But I have gone over some other wiring diagrams on the forum for the harness leaving the stator. Many show a black wire that appears to need grounding. I found no such wire on my harness. Only a blue wire, that I believed to be the blue wire that needed capping along with the yellow.

 

[Rook32432]

I also charged my battery and took it to be load tested which it supposedly passed.

 

[Jim]

What year engine do you have? pre '80 bikes used the regulator to power the rotor with the other brush going to ground. A green wire is power to one brush and a black ground wire on the other brush.

'80 and up bikes had power from the battery (switched) going to one brush on a brown wire and the ground is supplied by a green wire going back to the regulator.


Btw, I rewind rotors. Have a look here...

https://www.xs650.com/threads/rewound-alternator-rotor.54276/

 

[Rook32432]

What year engine do you have? pre '80 bikes used the regulator to power the rotor with the other brush going to ground. A green wire is power to one brush and a black ground wire on the other brush.

'80 and up bikes had power from the battery (switched) going to one brush on a brown wire and the ground is supplied by a green wire going back to the regulator.


Btw, I rewind rotors. Have a look here...

https://www.xs650.com/threads/rewound-alternator-rotor.54276/

It’s an 80s model. And I’m definitely going to keep the rewind in mind. However I would hate to spend the money rewinding or replacing only to have my supposedly “good” battery fry it or any of the other components for that matter. I’ll continue with my testing and try to rule out as many variables then pull the trigger. Currently the only things wired are the ignition and charging system, both still sucking my battery in ways I only dream about.

 

[Rook32432]

JFI sake and some clarity.

When you changed back to points did you change the stater, (from the 80-83 type for a 70-79 type), or the wiring at the brushes and associated wiring from the Factory Reg/rect.

Did you change the factory Reg/rect to an aftermarket 70-79 points SS Reg/Rect, (if yes where was it purchased from), or to an Automotive Regulator with bridge Rectifier.

The stator and rotor are 80s. The reg/rec is the solid state type and I assume stock but honestly don’t know how to verify that other than looking at pictures. The reg/rec has only one plug coming from it. Wires are red green black brown three white-ish.

 

[Jim]

It’s an 80s model. And I’m definitely going to keep the rewind in mind. However I would hate to spend the money rewinding or replacing only to have my supposedly “good” battery fry it or any of the other components for that matter. I’ll continue with my testing and try to rule out as many variables then pull the trigger. Currently the only things wired are the ignition and charging system, both still sucking my battery in ways I only dream about.

The stator and rotor are 80s. The reg/rec is the solid state type and I assume stock but honestly don’t know how to verify that other than looking at pictures. The reg/rec has only one plug coming from it. Wires are red green black brown three white-ish.

3 components: Rotor, stator and reg/rec
Rotor I can rebuild
Stator is about as bullet proof as you'll ever see for an electrical part. Hardly ever breaks
Reg/rec. You can build your own. It's the best and cheapest you'll find.

https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/

 

[Jan_P]

Not read through all -- But lets keep this simple

The schematic below
The battery is now checked and charged GOOD

Please

Remove the 10 Amp Fuse under the battery at the Picture
Measure Voltage across battery Before and after power Switch on please report here if Voltage drops

then

Remove the 10 A fuse also to the right of the fuse plate leaving the first removed 10 A out
Both these fuses out -Thus disconnecting the charging .and Switch on
Measure Voltage across battery Before and after power on please report here here if drops
if Voltage drops the fault lies in the ignition loop.

We reevaluate on that

 

[Rook32432]

Not read through all -- But lets keep this simple

The schematic below
The battery is now checked and charged GOOD

Please

Remove the 10 Amp Fuse under the battery at the Picture
Measure Voltage across battery Before and after power Switch on please report here if Voltage drops

then

Remove the 10 A fuse also to the right of the fuse plate leaving the first removed 10 A out
Both these fuses out -Thus disconnecting the charging .and Switch on
Measure Voltage across battery Before and after power on please report here here if drops
if Voltage drops the fault lies in the ignition loop.

We reevaluate on that


View attachment 248320

Yes the voltage drop remains. I am looking around for a replacement coil.