Battery Doesn't Want to Hold a Charge

[dgore]

I have a 1978 XS11 that will not start. I rode the bike to work this am(1hr) with no issues, then after my 8hr shift she did not want to start-had to kickstart her. Then on my way out of town, she just shut down. I love her very much but I said bad things to her at this time-things I am not proud of right now. So...I purchased a new battery at the local hardware store and she kicked into life(electric start a no go). Rode for 20 miles with power, then shut down again-all lights dim then out. A bike friendly passerby gave me a quick jump and she roared back into life-then 2 miles later....goodnight sweet girl. My wife came to me in our Yukon to see if we could jump the bike again but instead of getting the bike going...our Yukon shut down, looks like probably the alternator. I'd sure be grateful for any advice ya'll might have. I can deal with a broke yukon-but my girl really needs me...

[b.walker5]

Charge your battery and start your bike. Measure the voltage at the battery at idle, should be around 13 or so volts, rising to around 14.5 volts as the revs climb. If it voltage doesnt climb then your charging system isnt working. Best clue for this is the rev counter, if it's working then alternator is working if it's not then you have no output. Check all your plugs and then test between the alternator leads with an ohmmeter, can't remember what it should be (1.5 Ohm's or something) but readings should all be the same across all three phases. If that checks out then check your regulator, do a search thru the threads for this, but theres a known issue around soldered joints in the regulatotr breaking down. It's repairable and someone on this forum does it for a few bucks. Check the tech tips for lots of info on the charging system. These beasties have a woefully inadequate charging system so problem arent uncommon. Too much extra load, lights and such, can burn your alternator out. I fried mine a few years ago with a set of heated handgrips. (it's gets cold here in the winter) Any electric motor rewinder can rewind one if they have the right info on turns and resistance, you can even get a few extra turns put on by reducing the wire size slightly to increase the output a little.

[DGXSER]

Yep, seems like your alternator is not charging, these bikes actually pull juice from the battery even when running. The alternator just replaces it as you use it. This is why your sucking it down and it is dieing.

Start by pulling the right side cover off, then pulling off the panel that holds the fuse block. Behind there is the main alternator connectors. It would not be uncommon to find one melted . I would clean those REALLY good. Also check the regulator as Brian suggested.

I do not think the regulator can be repaired. I know member Randy repairs the TCI known issue of bad solder joints though. However, another member, Geezer, sells a much improved regulator.

HTH

[b.walker5]

oops..

I stand corrected. DGXSER is correct, the regulator is sealed and not repairable. It's the TCI with the solder issue and not likely to be your problem.

[Geezer]

There's a bunch of things to check before suspecting the reg/rec unit. I'd start with checking all the connections then move on to doing resistance tests on the stator and field coil.

Geezer

[foreda]

Battery

I read in your post that you purchased a battery from a "Hardware Store" ? You did buy a replacement in kind and not a lawn mower battery?? Just trying to get all the facts.

[skids]

Assuming the new battery is not defective (only a load test will tell for sure):
1. turn on the key and see if you have a magnetic field at the right side alternator cover with a steel feeler gage. It should be strong pull. If not, your field coil, its connections, or sending current is suspect. Sending current comes from the volt regulator unit but depends on good connections.
2. If the field coil is OK, but the alternator shows significantly less than say 14.5 volts @ 3500 rpms, I would check the connector clip beneath the fuse panel. Those connectors are for the 3 white wires and one yellow from the alternator and are high volts (30 volts?) which will make them arc if the connectors are corroded. This arcing causes high temperatures and can melt the connector. This is fairly common. If the connections are good, then clean the contact surface under the volt regulator. This is where the volt regulator makes ground with the frame. It is good to scrape off the paint there to make good contact and apply dielectric grease to maintain ground. If there is still trouble, look at the grounding strap for good contact from the frame to the battery.
3. If you do all of the above, I would start checking the volt regulator. The tachnometer can quit working if the alternator is not charging the battery, because it gets its pulsating current from one of the phases (white? Yellow?) wire from the regulator.

Hope this helps...

[Crazcnuk]

No one has mentioned the fuse block yet? That is the first thing I would look at.

[b.walker5]

Okay, i'm going to plead ignorance here, but which fuse kills the charging system? As i understand the problem the lights dimmed before the bike stopped, giving a clue that the power supply, i.e. battery, drained rather than instantly failed as would be result of a fuse failure, or bad connection. But i,m by no means an expert and happy to be enlightened.

[DiverRay]

dielectric grease to maintain ground.

DO NOT DO THIS!!! Apply Anti-seize to the bolts and ground lugs. Dielectric grease is an insulator, anti-seize is a conductor. You want to conduct as much voltage and amps as possible through the ground wires into the frame.(sorry skids)

[Crazcnuk]

Thre is a main fuse, on the left side, under the sidecover that controls everything.

The rest may or may not have anything to do with the charging system, but if the connections in the fuseblock are melted, loose and otherwise compromised you can get all kinds of wierd stuff happening, not the least of which is a bike that just up and quits whenever it feels like it.

[DiverRay]

The '78 does NOT have the "main fuse". That was 1980 and later. ALL the fuses for the '78 are in the fuse panel, as are the '79 models.

[Geezer]

There's no replacement for diagnostics. You will need to get a meter and do some tests or you will never know what's going on. Without a meter you won't be able to know exactly when it's working right.

Geezer

[oldnortonrider]

The '78 does NOT have the "main fuse". That was 1980 and later. ALL the fuses for the '78 are in the fuse panel, as are the '79 models.

Doesn't that 30 amp fuse that's with '78s and 79's, located in fuse panel with all the other fuses, still act as "main fuse"? Red wire(s) on both sides of fuse going same place(s)?..........for same purpose(s)? Just different location of fuse, from '80s and '81s?

[b.walker5]

Thre is a main fuse, on the left side, under the sidecover that controls everything.

The rest may or may not have anything to do with the charging system, but if the connections in the fuseblock are melted, loose and otherwise compromised you can get all kinds of wierd stuff happening, not the least of which is a bike that just up and quits whenever it feels like it.

Okay, granted, but... The main fuse does control everything, at least on my 80 it does but if it fails everything does, which leads to instant stop, not dimming of the lights first before stopping. That points to something discharging and running out of power, which in this case would have to be the battery. The main fuse interrupts the circuit from the battery to the rest of the bike, so if it blew or had a bad connection the failure would be instant. Least thats the way I read the wiring diagram. Not sure about Ray's comment of the 78 not having a main fuse, I havent got a 78 wiring diagram. I accept your point about bad connections causing all sorts of grief and stopping the bike, but the fault seems to be the result of running out of battery power and the alternator connector block is much more likely to be the cause of that. I think.