Battery loses charge

timleslie1957 · January 16, 2018, 03:39:22 PM

.... bike dies after running about 20 minutes. Charge up. Same thing. I would like to know how to troubleshoot in the easiest of explanations and terms please. I measured at the alternator side of the two wire brown and red wire connector and got no voltage reading from either wire when I grounded probe at battery. Is this the correct way to check? I am at a point as to I will take cover off and verify wiring for no opens to plug and redo plug and wires. I have also purchased an external adjustable rectifier and am ready to install per mods procedures found on this web site. I prefer an external rectifier to get it away from the heat and such of the engine and will install at rear of seat compartment.

I checked the battery when running and revved it to about 5 grand, voltage remained the same. I have replaced the ignition switch as it always did have a quirky little dead spot in it time to time, acting as a no start time to time.

Any further recommendations? How do I isolate for sure if it is a rectifier or the alternator itself? I know - I guess the install of the new remote rectifier will determine that. Thanks for any input.

red · January 16, 2018, 09:03:13 PM

Quote from: timleslie1957 on January 16, 2018, 03:39:22 PM
.... bike dies after running about 20 minutes. Charge up. Same thing. I would like to know how to troubleshoot in the easiest of explanations and terms please. I measured at the alternator side of the two wire brown and red wire connector and got no voltage reading from either wire when I grounded probe at battery. Is this the correct way to check? Any further recommendations? How do I isolate for sure if it is a rectifier or the alternator itself? I know - I guess the install of the new remote rectifier will determine that. Thanks for any input.

Timleslie,

A voltmeter may give deceptive readings if you try to measure voltages with the wrong setting. A test light (taillight bulb, maybe in a socket) with wires attached will not care whether it gets AC or DC voltage. If the alternator makes voltage when running, that's good. If the rectifier gets power in and sends power out, that's good. If the battery voltage does not change with higher RPM, one of those two gadgets will probably be bad. There is one little kicker: the alternator needs some battery power (even just a little) to start working. One wire to the alternator (the FIELD wire) must have voltage coming in, for that gadget to work. An open wire there (no voltage) means the alternator will produce no electricity, even if the alternator is good. If the FIELD wire has voltage on it (as it should), then the problem is elsewhere. If you connect a jumper wire (12Vdc) to the FIELD terminal, and the alternator starts working, just find and fix the wiring (or switch, or relay) that is not feeding voltage to the FIELD terminal.

Happy hunting.

Bezmozek · January 16, 2018, 10:50:35 PM

Where did you tried to measure?
Cranks fast enough? Isn't battery old/weak?
Is there a difference in lights brightness while engine running vs battery operated?

1. Clean a tighten battery connection. While engine running, there should be readings about 14,5V DC
FJ is known for boiling battery - overvoltage. More rev, more volts on battery terminals.
If not..

2. Unplug alternator, / do not start the engine /.
I am not familiar with 1200 wiring harness, on 1100 it is red/white connector with 3 wires under your seat on left side by airbox.
Between each two wires there should be approx same reading of resistance, those are alternator phases.
As these connectors sometimes melts due to heat, one of phases can be burnt, I had this issue on FJ600.
(even with readings above 14V, only two phases were working, with lights on, 20min/20km range - no lights, no problem)
If OK, clean and reassemble.

While running, is regulator hot?
Have spare regulator rectifier to try?

Pat Conlon · January 17, 2018, 12:17:48 AM

Beware the dreaded RED PLUG

Looks fine....right?

However, unplug it and peek inside:

Not so good after all:

Photos courtesy of FJ Monkey

timleslie1957 · January 17, 2018, 02:49:12 PM

Quote from: red on January 16, 2018, 09:03:13 PM
Quote from: timleslie1957 on January 16, 2018, 03:39:22 PM
.... bike dies after running about 20 minutes. Charge up. Same thing. I would like to know how to troubleshoot in the easiest of explanations and terms please. I measured at the alternator side of the two wire brown and red wire connector and got no voltage reading from either wire when I grounded probe at battery. Is this the correct way to check? Any further recommendations? How do I isolate for sure if it is a rectifier or the alternator itself? I know - I guess the install of the new remote rectifier will determine that. Thanks for any input.
Timleslie,

A voltmeter may give deceptive readings if you try to measure voltages with the wrong setting. A test light (taillight bulb, maybe in a socket) with wires attached will not care whether it gets AC or DC voltage. If the alternator makes voltage when running, that's good. If the rectifier gets power in and sends power out, that's good. If the battery voltage does not change with higher RPM, one of those two gadgets will probably be bad. There is one little kicker: the alternator needs some battery power (even just a little) to start working. One wire to the alternator (the FIELD wire) must have voltage coming in, for that gadget to work. An open wire there (no voltage) means the alternator will produce no electricity, even if the alternator is good. If the FIELD wire has voltage on it (as it should), then the problem is elsewhere. If you connect a jumper wire (12Vdc) to the FIELD terminal, and the alternator starts working, just find and fix the wiring (or switch, or relay) that is not feeding voltage to the FIELD terminal.

Happy hunting.

Red ... is the field wire in this case the brown wire?

red · January 17, 2018, 03:19:55 PM

Quote from: timleslie1957 on January 17, 2018, 02:49:12 PMRed ... is the field wire in this case the brown wire?

Timleslie,

I do not have the wiring diagrams. For anybody who does, it would help if you told them what year/model FJ that you have.
You can put that information into your signature line, or with your avatar.

FJmonkey · January 17, 2018, 04:15:24 PM

Try this
http://www.fjowners.com/index.php?topic=9216.0

FJ_Hooligan · January 17, 2018, 04:41:57 PM

I believe the brown wire is the field wire. The red takes the alternator output and goes directly to the battery for charging it. The red wire should always show the battery voltage even when the key is turned off.

The brown wire is what powers everything else. It should only show voltage when the ignition is on.

racerrad8 · January 17, 2018, 05:23:34 PM

The red wire should be 12V power all of the time. It is also a fused wire.

The brown wire is 12V keyed power.

Both must be 12V or the alternator will not energize.

Randy - RPM

Pat Conlon · January 17, 2018, 05:24:02 PM

Tim, if you follow the link in my signature line, you can down load (for free) the Owner's Handbook for your '89. In the back of every Owners Handbook is a wiring diagram specific to your model.

timleslie1957 · January 17, 2018, 05:52:44 PM

Now I get it. The brown is common to my ignition switch brown and powered up with it. Red goes to battery for battery voltage. I think I will just put the rectifier in and rewire the thing. If that does not do it, I will get an alternator.

timleslie1957 · January 18, 2018, 07:24:03 AM

Thanks Pat

Yamahahammer1300 · January 26, 2018, 05:56:04 PM

What if a plug is bad, dreaded red plug or not? I have an 89, I throw it on a trickle charger every weekend. Even if I did ride, it needs charging a week later. There is a half melted plug, was zip tied when I got the bike. Think it's white. Never gave it a thought, but lithium ferrous batteries are expensive.

Pat Conlon · January 26, 2018, 06:31:53 PM

Change the plug.
Download a free Owners Handbook for your '89.
Look at the color of the wires on your melted plug.
Look up on the wiring diagram were these wires go and what they serve.

That will get you in the ballpark.

racerrad8 · January 26, 2018, 09:58:36 PM

Quote from: Yamahahammer1300 on January 26, 2018, 05:56:04 PM
What if a plug is bad, dreaded red plug or not? I have an 89, I throw it on a trickle charger every weekend. Even if I did ride, it needs charging a week later. There is a half melted plug, was zip tied when I got the bike. Think it's white. Never gave it a thought, but lithium ferrous batteries are expensive.

Correct, your XJR1300 alternator has a white plug. They addressed the issue by increasing the spade size. Not sure how the installer wired it, but based on the other work that comes out if that shop, you need to tear into it and see what they did.

Randy - RPM

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Battery loses charge