Battery or Charging system?

[User9053]

OK so the one thing that's never given me grief has been the charging system.. Until now.

I took the bike out for a long ride approx 1hr down the hwy doing 120 km/h the whole time. Get the bike home have a rest and then took it out again. First I noticed my turn signals on the dash dim and not flashing, then a lower idle rpm when sitting still. Pulled over and the bike wanted to die so I let it. After that the bike wouldn't start, doing the typical clicking sound when you have a dead batt. Bump started it and got it home although it hesitated quite a bit on hills so I removed the headlight fuse to give it some more juce to get home.

My question is could it just be a dead battery as I know these bikes cannot run without one. Or is it much worse and my stator is dead. Picking up a multimeter this afternoon to check voltage.

If the charging system is working fine but battery is dead would the bike still run bad or should it be good once started? Thanks

 

[HoughMade]

It could be the battery, but usually if you are charging well, the bike won't die while running. Think of it this way, is you have a bucket that is leaking a gallon a minute, but you are pouring in a gallon a minute, the leaking bucket will stay full until you stop pouring water in.

That being said, sometime batteries can do strange things. If you have the ability, put the battery on a charger to fully charged, then disconnect the charger. Is it reading 12+ volts? How about 8 hours later? It should hold a charge for longer than that.

As to the charging issues, it could be bad wires coming from the alternator. It could be a bad voltage regulator or rectifier, which are easier to deal with than the stator, but it may also be the stator. Just follow the testing instructions in the manual and don't start parts-changing willy-nilly.

Good luck!

 

[User9053]

Yeah I don't think its the battery as it had more juice in it this morning. If it was dead it would have nothing... Damn

 

[HoughMade]

When you get the multimeter, first check the voltage at the battery at about 2-3,000 rpm. It should be around 14.5v. If it is, it may be loose connections somewhere or a bad ground...if you're lucky. I had to replace my fuse box a few years ago.

 

[User9053]

OK so got a charger and a multimeter and charged the batt as it was dead. Bike stated right up idled fine but when I revved it the voltage went uplike crazy. 3-6k was about 15-17v anything above 7k was up to 19v. So that's pretty high. Regulator problem?

 

[arfstrom]

Well with out testing out each component, It could be rectifier or the VR. The VR is sampling the amount of energy 300 to 500 times a minute (I dont' remember actual number) with that said, when the juice is lower than 12 volts, it send power to the field coil to pump up the electicity. with the electricity pumped up, its suppose to be filtered by the recitifier to keep it about 12 to 14 volts. If the juice is less than a certain amount it comes from 2 or 3 parts of the recitfier. if the juice is more, the rectifier will only use the available from one of the 3 white stator wires. With that much juice coming out, it may be worth while to ohm out the 3 white wires. typically there is one spot that will fry all three wires. makes the wire brittle, in a 2 inch area. Do the multimeter checks first, with the manual open, so you have the right info next to you. Good luck
Tobie

 

[User9053]

Aren't they the same thing? The VR and the rectifier? I have an 83 DOHC. If that makes any difference. I'm probably wrong

 

[arfstrom]

There are combo units out there. 3 white wires is your rectifier unit. the red, is for the field coil (I think) black is common/ground. your bike is a newer generation than mine, at the time i think they were still separate.

 

[User9053]

OK, well I solved the problem! Turns out it was my regulator/rectifier. Purchased a second hand one off eBay and bam solid 14.8v above 2k. Just a side note, if you search eBay for xs400/maxim 400 regulator rectifiers they are not cheap $30+ for a 30 year old part.. no thanks! Noticed the new ones from China advertised they worked on an XJ650. Searched eBay for XJ650 regulators and bam loads of them dirt cheap. Got one for $10 + shipping. Seems XJ650s are much more common and parts are cheap. Took a guess and it played off.

Basically I boiled my battery overcharging it with the bad rectifier. Totally not what I thought happened at first, normally after a long ride your battery is better. You learn something new everyday!