Topic: How long will a fully charged battery last with headlights disconnected

[jhood41591]

I have a charging issue. The Rotor burned out, had the rotor rebuilt still not charging, seems it has blown the regulator. I have a regulator ordered but how long will the battery last if I disconnect the headlights and the alternator?

Thanks anyone

[tlbranth]

Different bike but 2 years ago My wife and I rode our 1999 Goldwing to Alaska. On the way back the alternator died. I disconnected everything that was tungsten. Luckily I had recetly converted most lights to LED. Our travel partner swapped batteries with us about every 200 miles - so maybe 4 hours.

Once on my CB750, I was about 50 miles from home and I accidentally killed the engine. Wouldn't turn over the starter - battery was dead-ish. Turned off the lights, kick-started it and made it home easily on the battery. Problem was the rectifier.

I've run cars (old cars) for hundreds of miles on what appeared to be a dead battery.

[jhood41591]

Thanks for the reply. I have installed a voltmeter so I will know how it is doing, just don't know how low I can let it go.

[curemode2002]

On my leg of the relay this year I figure I got about 120 miles on the 650 with no charging and headlight on. I could easily do the 40 miles round trip to work and back without having to push start it, as long as I threw it on the charger at home every night.

[singedebile]

my rectifier was blown for a while but it was still "charging" at about 11v... I kept ridding the bike putting it on a tender every night after work until i figured out what was wrong (I had brought the bike to a 'mechanic' in philly that had diagnosed it as the stator but I was suspicious.. and it turned out I was right). My round trip was maybe 30 miles of mostly highway and I never had a problem even with the light on at night and the running lights on all the time for a week or two.

[jhood41591]

I have another question and am going to try and ask it within this thread.
How low can the battery voltage go and still have enough  power to power the ignition system?

[TwoTired]

I have another question and am going to try and ask it within this thread.
How low can the battery voltage go and still have enough  power to power the ignition system?

Wouldn't it be nice to deal in absolutes.

It's not just voltage, it is voltage with current that does the work.  When batteries deplete, they lose not only some voltage while static, but much more voltage when asked to deliver currents.

The chart below shows the voltage of depleted, but otherwise good battery as 11.9 V.  This voltage will drop significantly when a load is placed upon it.  The more load, the farther the voltage will drop.

So, my question to you is :  How low do you want the voltage to go?  And which ignition system are you referring to?

Some have reported 6V as still "working" with unspecified load, battery health, test conditions, and test method. 

I believe the practical limit is about 9v under load conditions for a stock, well tuned, SOHC4, while still expecting the engine to start.

Cheers,

[phil71]

ignition should still make a serviceable spark down around 8v.. any lower than that and it'll run bad till it eventually doesn't

[jhood41591]

This is a 1981 cb650 custom, I do not know what kind of ignition it is. I rode the bike this afternoon without any charging system. The voltage was at 12.4 volts after starting. I rode about 5 miles the voltage went to 12.3 volts. So if I let it go to 11 volts parked it on a hill and rolled it off it should still run ok. Does'nt have a kick start. Is this correct? When I was having the problem with the rotor I rode it about 2 miles, stopped it and it would not start back. I think the bad rotor was causing it to pull more power from the battery than it should have , it blew the regulator.

[kpier883]

Different bike - '80 CBX, I lost alternator on the wAy to Nashville, about 1/2 way on a 180 mile trip.  It was night time and I tried to get there with lights on.  Stopped running about 20 miles short. I pulled all fuses that weren't necessary for the bike to run, push / bump started and drove the remaining distance by following a van. 

I bought a Battery Tender at Batteries plus and charged it till the day I was heading back home.  I hooked up the brake light and whatever is on the same circuit and headed home.  About 160 miles in it got dark and I pulled over and plugged in the fuse for the headlight because of the traffic, and made the last 20 miles with the light on - no problem. 

I think 250 miles with no headlight would have been doable.  It uses three coils instead of two and igniters rather than points.  I don't have any idea if that pulls more power than a SOHC4.

FWIW...

Kirk

[TwoTired]

I think the bad rotor was causing it to pull more power from the battery than it should have , it blew the regulator.

Quite possible.  But, the system can be measured and the reg. output tested to confirm fault.

How did you confirm the brushes were working correctly?

[jhood41591]

I checked the voltage at the field terminals with ignition on 0 volts dc, checked output voltage from stator 5000 rpm (yellow wires) 0 volts ac. I then applied battery voltage to the field and checked voltage from stator, 54 volts ac from stator. I had already put new brushes in alternator, before I had the rotor rebuilt.

[trueblue]

Sounds like the reg/rec unit is at fault, FYI the ones off the DOHC 750's work on the 650's, you may need to change the plug though

[jhood41591]

Thanks Trueblue,
 You had helped me get to this point on the charging system, on another thread. I have an RR ordered just trying to determined if I could ride the bike without it charging and how long the battery would last on a full charge.

[trueblue]

No worries mate, you can ride it without it charging, but for how far I wouldn't hazard a guess.  One thing to keep in mind is the batteries used in bikes don't like to be deep cycled.  Basically, if you heavily discharge them, the next time you recharge it, it won't be as strong as it was before. You may be able to do it 100 times before you start to notice it, but every time it is run down you are weakening it. 

[TwoTired]

I checked the voltage at the field terminals with ignition on 0 volts dc, checked output voltage from stator 5000 rpm (yellow wires) 0 volts ac. I then applied battery voltage to the field and checked voltage from stator, 54 volts ac from stator. I had already put new brushes in alternator, before I had the rotor rebuilt.

Yes, the reg has given up.  Seems common with the 650.  When the rotor fails, it draws more current than the regulator can handle.  Then it also fails.  A replacement rotor AND regulator are then indicated.

Cheers,

[jhood41591]

I also Feel trhe regulator has to be bad. What I do not understand, using the fault finding diagram and checking the regulator on the diode  setting all measurements are perfect. Is this possible?

[TwoTired]

I also Feel trhe regulator has to be bad. What I do not understand, using the fault finding diagram and checking the regulator on the diode  setting all measurements are perfect. Is this possible?

Kinda depends on what is inside the box being tested and test technique.  I don't know how you tested and to what parameters.

[trueblue]

The 650's have a combined unit.  It is quite common for the transistors in the regulator part of it to get damaged and the diodes test fine

[jhood41591]

Following is how I tested:

With Fluke Multimeter Set ON Diode Check

Red meter lead to white/red on 4 prong connector-----Black meter lead to each of the yellow wires from the 6 prong connector:
1st yellow wire --OL(OVER LOAD)
2nd yellow wire-- OL
3rd yellow wire-- OL

Black meter lead to white/red on 4 prong connector--------- Red meter lead to each of the yellow wires on the 6 prong connector:
1st yellow wire-- .497 volts
2nd yellow wire-- .475 volts
3rd yellow wire-- .501 volts

Black meter lead to green on 4 prong connector-----Red meter lead to each of the yellow wires on 6 prong connector:
1st yellow wire-- OL
2nd yellow wire-- OL
3rd yellow wire-- OL

Red meter lead to green on 4 prong connector---- Black meter lead to each of the yellow wires on 6 prong connector:
1st yellow wire-- .476 volts
2nd yellow wire-- .491 volts
3rd yellow wire-- .479 volts

These readings were by using the (FAULT-FINDING-DIAGRAM) found on this site.

I do not know if this is revelant or not but somewhere on this site I have read that the black wire on the regulator (4 prong connector) was ground. Looking at the wireing diagram the black wire from the ignition switch comes into the blach wire on the 6 prong connector. THE BLACK WIRE ON THE 6 PRONG CONNECTOR IS DIRECTLY CONNECTED TO THE BLACK WIRE ON THE 4 PRONG CONNECTOR INTERNALY (ZERO ohms between the two black wires) IN THE REGULATOR THEN GOES FROM THE 4 PRONG CONNECTOR TO ONE SIDE OF THE FIELD (POSITIVE VOLTAGE). I do not know if thes BLACK wires should be connected internaly or not, but if so then the regulator should pass a NEGATIVE voltage to the White wire (going to the other side of the field) on the 6 prong connector. This is not happening. I can remove the white wire from the 6 prong connector and ground it and I have approximately 54 volts AC between each of the yellow wires (at 5000 RPM)

It seems everything checks out using the FAULT-FINDING-DIAGRAM  as it should, but I do not have negative voltage (GROUND) to the field (ROTOR).
Anyone know of any other test?

I have a regulator/rectifer ordered but just curious. This is really BUGGING me.

Thanks

[TwoTired]

As trueblue said, the unit on the Cb650 is a combined regulator/rectifier.
You have measured the Rectifier portion as being good.

The B and F terminals apply power to the alternator field in reaction to its sense of the battery voltage.  No Doubt B is black (or Battery) and the F is Field current drive, most likely the White wire.  TR3 and TR2 are a Darlington pair and control current flow through the field Coil/rotor.  The Darlington pair is only capable of limited current capacity.  If the field coil resistance drops too low via internal wire shorting, the current capacity for TR3 or TR2 is likely exceeded and one or more transistor junctions open, preventing further current flow.  In theory, the circuit component(s) could be replaced and the unit restored to operation.  I don't know if it is practical to open the unit to gain access.

If the voltage is measure during operation, you should find the B terminal measured as battery voltage and the F terminal should vary between battery voltage and ground, depending on battery voltage state.  When battery is in a low state the F voltage will be about 1.5V, which will drive the alternator to full output.  When the battery reaches above 14.5V the F terminal will also have 14.5V on it, which indicates no current flow in the alternator field.   In operation it will reach an equilibrium between those two extremes depending on equipment load, battery state, and engine or alternator RPM, which all vary during operation.

[jhood41591]

Two Tired from one old timer to another THANKS a million. This is the first time I have gotten an explanation as to how the RR actually works, and THANKS for the schematic I have hunted everywhere for it.
I will now just wait on the RR to arrive.

Thanks Again,
 Jhood

[lucky]

The Clymers manual has all of the wiring diagrams.

[jhood41591]

My clymers does not have the internal wiring of the RECTIFIER/REGULATOR.