New battery dead next day.

I have a 1985 XJ700N, and had a bad battery, I thought, so I purchased a new one and followed the manufactures instructions for prep and installation. Great I thought. New battery, good to go. Not! The next morning got on the bike to go to work and NOTHING! Needless to say, I was a little upset that I had to walk to work. So I get home from work and pull the battery and charge it again. Great. Go for a ride and all works good. But I noticed that when I put the key in and went to the on position, the headlight was on. Now I don't remember if the head light is supposed to be on before start or after. All I have read is that the headlight doesn't come on until the motor starts. Could this be the issue for the dead battery? It is the original wiring harness. Should I replace the the harness due to age or something else. I love this bike and the now that summer is here, and I can't ride her, I feel left out. Help

 

Which XJ do you have? The headlight behaves differently on different models.

Is it possible that you may have turned he key past the off position and to the park position? A worn key can be removed when the ignition is in park, and that will leave the taillight (and some other lights, depending on model) on.

 

I have 700N. I looked at the factory wiring manual, and it doesn't show a headlight relay. So I don't know what the problem could be. I charged the battery and I am going to try it again in the morning. I just don't know what would cause the battery to discharge

 

The headlight is controlled by the starter switch. When you turn the key on the headlight should come on. When you push the start button you open a set of normally closed contacts for the headlight and it goes out as long as the start button is depressed.

Check the charging system with the bike running. Measure the voltage at the battery terminals and rev the motor. 2K and up the voltage should measure 14.5 +/-.3.

Since the battery drained overnight after charging lets hope you did leave the key in the park position as k-moe suggested. However, that said a defective Rect/Reg assembly is a likely culprit for draining the battery. When you hook up the battery with the key set to "OFF" look for small sparks indicating a flow of current; there should be no sparks.

 

When I hook up the battery, I don't see any arching or sparks. I did check the voltage at the battery when running and it showed 14.4 v. I do have a spare regulator, but I don't know if it any good. I need to test it.

 

Looks like you don't need to if you are getting 14.4V. Did you actually measure the voltage on the battery after it discharged overnight? Just thinking of other things like a poor connection at the terminals (battery or engine ground) or at the main fuse, particularly since you mentioned you pulled the battery to charge it.

 

With motor off and key off, use the current setting of your meter between battery positive and cable positive. If current is flowing with key off you have leakage (short) or something drawing power somewhere.

 

Voltage is good in the battery, 12.6v, and it was draining a little at a time, around .1 per sec. So I disconnected the reg/rec and the voltage stopped draining. The voltage today in the battery read 12.66 volts. I have another reg/r c with the plug cut off that I checked the diodes with a diode checking meter and they read .528 a .536. According to everything I have read is that the diodes should read between .5 a .8. The diodes meter in that range. So I am assuming that it is good. The only problem I have is since the plug has been cut off, it came that any with a bunch of parts in a box when I got the bike years ago, I don't know what white wire goes to which white wire on the plug. Anybody have a picture or diagram that shows which is which.

 

All the white wires are the same. Hook them to whichever mate is convienient.

 

Well I swapped the reg/rec and started the bike. Checked the voltage at idle, 13.34, and at 2000, 14.60. Ran for Alittleupsea biota tilde . Shut the bike off and checked voltage drop. It was at 13.75. Funny thing is, that as I read the voltage, the voltage started rising. It rose about .2 volts with the key off and removed. So I guess it is good now. Now let's see if it drains the battery overnight!

 

Well, I just checked the voltage again and it is holding at 12.67v. Starts just fine. Haven't taken it for a ride yet. So I will take it out here in a little bit. And then see what it does overnight. Hope it doesn't drop any voltage. Good news this time of year. Nice and sunny.