replaced regulator, still overcharging,

[ken65]

gday, as above, when i turn the lights on it goes up over 15v, with the lights off about 14.7v, at around 4000rpm, im thinking do i need to go thru the connections and make sure there all good, maybe start at the light switch perhaps, i know very little about electrics, thanks in advance ken

[movenon]

Good Morning 
                                   What condition is your battery in? If it is low it will demand more charging from the alt.. As just a good thing to do on and older bike is go through all the ground connects. Battery, where the cable bolt to the engine block, alt. connectors etc.. Hope this gives you some idea's.  Its all fixable and most likely a simple problem. Keep us posted as we all learn.
George

[Pat Conlon]

Hey Ken, there is a red wire that goes to the alternator that supplies the field voltage...check this wire and all connections as Jon discusses below:

Another thing you can do to extend battery life is to check the voltage at the alternator. Over charging a battery will harm it quickly. The smaller red wire that goes to the alternator supplies the field voltage. If this voltage reads low (it will because it passes through the main switch, and several connections) you will need to clean the switch contacts and connectors. The other fix is to use a relay to supply full battery voltage to the alternator and use the original circut to activate the relay.  My 89 was overcharging it's battery all the time because the reg/rec was always seeing a false low voltage. I have installed a nice Bosh 30 amp relay, a 15 amp blade fuse and some 10 gauge wire and it now works fine.

[ken65]

thanks for the replies fellas,  the battery is brand new and fully charged so can rule that out, onto the red wire at the alternator, what would be considered low?to test this with a voltmeter would i just use the red probe on the red wire and ground out the black probe, ? thanks again ken

[Pat Conlon]

Check for voltage drop thru the harness. If the battery gives you ~12 volts, measured from terminal to terminal and measuring the red field wire at the alternator terminal to the negative side (-) of the battery gives you less than 11 volts, I would check this red wire circuit for a burned or loose connector.
To experiment, Why not run a temporary wire from the battery(+) to the alternator and see if the charging voltage changes?

I got 10 volts to my headlight before I did my relay mod.
Lesson learned: The dc voltage drop thru the oem wiring harness, switches and connectors could be significant.

If the red field wire is giving a low voltage reading to the alternator, your alternator thinks that your battery needs charging when it really does not.

Cheers.  Report back.

[ken65]

thanks pat, well I'm off to buy a can of contact cleaner and will check these things out , do a bit of cleaning and report back, only guessing but the bike is very low milage and looks good but i reckon its sat for long periods of time on occasions and i don't think it was owned by an enthusiast,  ken

[movenon]

I had a new battery that failed in a week. They sent me a new one and all was well after that. After the battery is fully charged and with the cable's disconnected the "resting voltage " in a few hours ( 4- 6hours) should be around 12.7 volts. That's out of memory, I will try to locate that information. When trouble shooting make no assumptions.. You mentioned that you changed the regulator. What motivated you to do so ? Did you have the problem before the change ? When regulator conversion did you use ? Sorry for all the questions just trying to fill in the blanks. Here to help, not "pester" 
George

[ken65]

gday, ok so far, checked the negative terminal, and it was only just connected so recrimped,soldered at both ends, all the connectors i could get at from under the tank and around battery  i disconnected and sprayed with contact cleaner, a couple had a bit of green so i sanded it off, pulled the right hand switch aPART and sprayed, looked nice and clean, anyway at 4000 rpm its reading 14.5-14.8v and around 15.3 with lights on (high beam). the reason i changed the regulator was i thought that was the problem, i switched it over to 1 of those R025 things with the black and red cables attached,testing the red cable at the alternator and the negative on the battery it read not quite a volt lower than the + and -  termanals at the battery  a couple of  questions, ?, i would think as the lights are drawing power it would be normal to go up wouldnt it ?, when you all test for the charging do you turn the lights on at all?, thanks again ken

[Pat Conlon]

Yes, lights on. On the USA models the lights are on full time....Yes, lights on will draw more output from the alternator. OK the field wire checks out, good you checked.
IIRC 14.5-15 volts, you are within the normal charging range specified in the shop manual... However....
Traditional Lead acid batteries can tolerate higher charging voltages, the wet cells just boil off electrolyte and you refill them with distilled water, no harm, no foul (LA Lakers term)
Sealed AGM's on the other hand, do not tolerate overcharging. 14.2 volts max. That's why I went with the Transpo adjustable voltage regulator. (See the Files)  I can dial down the charging voltage to 14volts, which is much more friendly to my AGM.
You may want to consider that mod.

Cheers

[ken65]

thanks again pat, that would be right, i replaced my lead acid battery with a AGM only last week.lol, ok worst case scenario i stuff up my new battery over a period of time and go back to the acid ones, or can i wreck other things aswell, ? i have learnt a fair bit this last day or so,thanks to everyone who helped, cheers ken