Battery/Charging Problems

[BowlingSS]

It seems to be running OK now after re-synching the carbs. Now my problem is the battery and/or charging. How can you test for a bad cell? One cell has white/milky stuff in it. After charging all night it started right up this morning. After I took it for a 5-10 mile test drive and let it set for A COUPLE OF HOURS THE BATTERY SEEMS TO BE DOWN AGAIN. I use to have a electrode tester long time ago. Do they still use them to check for bad cells? I want to make sure my battery is good first before I do any debugging.

Thanks everyone. I am getting closer to getting this girl running.

Bill

[BowlingSS]

They still make the ball tester but I would have to order it. I bought one from Auto Parts but the line is too big to go into the battery holes.

Bill

[3Phase]

Bill,

It's not as reliable as a hydrometer and an ammeter but charge the battery and check the voltage, then remove the Negative wire from the battery to isolate it. Let the battery sit for a while and go do something else, then come back and check the voltage again.

If the voltage is low, the battery is bad.

If the voltage is good, put the Negative wire back on the battery and try to start the engine.

If the voltage drops below 11 Volts when you press the Start button, it's the battery and/or the starter.

If the voltage is good and stays good when you press the Start button, there's a short somewhere in the wiring that's draining the battery when the Ignition is off.

.

[BowlingSS]

What should the starting voltage be after charging? Mine is 12.85 and had a drop after setting all night to 12.75. Not much drop after setting all night. I did have the battery on the bench and not in the bike.

Bill

[BowlingSS]

Put the battery in and noticed the voltage dropped to 11+ but the bike started. Revving up to 2 to 3K the voltage went to 14+.

What does everyone think?

Bill

[bikerphil]

Sounds normal.

[Jeffintampa]

Make sure

Make sure you check your grounds take them off the frame and shine em up. I think the battery is going bad spec if the bike is charging it.

[BowlingSS]

The bike had a new regulator/rectifier installed before I received the bike. I noticed after the bike was running and got hot the voltage at the battery dropped to about 13. I performed a connector test on the box just what the book I have said. One problem was the voltage regular only had two leads-Brown and Green. I figured the black was ground. Between the black(GRD) and green the reading was 1.1v which should be good. I started the engine up with the black and green. My v should have gone up to 9-11 but stayed at the 1.1v.
I connected the brown + and black - and the voltage was only 13.3. The manual says it should be 14.2 to 14.8.
I rechecked the voltage at the battery and the voltage now only went to 13+. It was not as high as it was when the engine was cold.

Question- Does this regulator have a black connector in the socket?

I have a Clymer Service manual. Could the manual be wrong on testing this or do I have a bad regulator?

Thanks everyone.

Bill

[3Phase]

Bill,

Bring the engine up to 2000RPM and hold it there.

What is the voltage at the Positive battery terminal?

What is the voltage at the Brown wire at the three-pole Voltage Regulator?

If there is more than half a volt difference between the two, there is a dirty/corroded connector somewhere between the battery and the Voltage Regulator.

It could be the battery terminals, the frame or engine grounds, the 30A Main fuse holder, the Ignition Switch connector, the Ignition Switch itself or a delightful combination of all of the above.


The voltages you measured aren't too bad but if you believe the alternator output is low after the engine gets hot, you can test the alternator output by grounding the Green wire. Grounding the Green wire totally bypasses the Voltage Regulator and full-fields the alternator.

For the three-pole Voltage Regulator connector, Yamaha quit using the Black wire. The harness side still has a Black wire and, yes, it is a Ground. It runs into the harness and then right back around to the large Phillips head frame ground screw that's less than an inch or two away from it at the Voltage Regulator/Rectifier mount.

Here's a color schematic for your bike. It shows a Black wire for the Voltage Regulator but don't worry about it, just click to download it:-


.

[BowlingSS]

Bill,

Bring the engine up to 2000RPM and hold it there.

What is the voltage at the Positive battery terminal?

What is the voltage at the Brown wire at the three-pole Voltage Regulator?

If there is more than half a volt difference between the two, there is a dirty/corroded connector somewhere between the battery and the Voltage Regulator.

It could be the battery terminals, the frame or engine grounds, the 30A Main fuse holder, the Ignition Switch connector, the Ignition Switch itself or a delightful combination of all of the above.


The voltages you measured aren't too bad but if you believe the alternator output is low after the engine gets hot, you can test the alternator output by grounding the Green wire. Grounding the Green wire totally bypasses the Voltage Regulator and full-fields the alternator.

For the three-pole Voltage Regulator connector, Yamaha quit using the Black wire. The harness side still has a Black wire and, yes, it is a Ground. It runs into the harness and then right back around to the large Phillips head frame ground screw that's less than an inch or two away from it at the Voltage Regulator/Rectifier mount.

Here's a color schematic for your bike. It shows a Black wire for the Voltage Regulator but don't worry about it, just click to download it:-


.

Thanks for the schematic. I have a number of checks to make.

Bill

[BowlingSS]

Still having problems. I cleaned a number of connectors/grounds. I just installed the new fuse holder. I put my meter on the battery. Had about 12.2 v on the battery. When I started it and kept it at 2K the voltage slowly went up to 14+. It did take a long time to get the voltage up to 14. I read a thread about some else having the same problem. Anyone rem?

Thanks guys.
Bill

[bikerphil]

One cell has white/milky stuff in it

I'd get a new battery, $55 at Walmart.

[somesuch]

from the voltage numbers, it looks like you are missing one phase.

[BowlingSS]

from the voltage numbers, it looks like you are missing one phase.

Are you talking alternator? I have not checked that yet. Is the 79 special the same as a 80SG? I have a donor 79 that I have been using parts off of.

Thanks.

Bill

[BowlingSS]

I took the reg/rect off my 79 donor and after cleaning it up got it installed. The volts seems to get to 14 pretty fast now. The one I took off was just replaced by the earlier owner. It looked new but was not the stock one. It had a 2012 date on it.

Thanks everyone.
Bill