Charging system voltage - Printable Version

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Charging system voltage - Jim Penner - 11-03-2015

I just installed a new battery in my 84 interstate as the old battery would not start the bike if left for a couple of weeks. Also installed new 25 watt LED headlight. I have a venco voltage meter on the bike which I know reads a bit low in the 11 to 12 range even with the new battery. Bike has lots of juice in starting, but I notice a pulsing in the headlight beam plus when I apply the brake there is a definite dimming in the headlight output. I have all standard stuff on the bike and no accessories to consume power. I would have thought with the LED headlight there would be plenty of wattage left to not see this noticeable drop in headlight output. Any thoughts or words of wisdom? Perhaps poor voltage regulator performance?Huh

RE: Charging system voltage - roscoepc - 11-03-2015

With the battery fully charged, check the voltage at the battery with it idling and at about 2500rpm. If your not getting at least 13.5vdc, preferably 14-14.5vdc, you got problems in the charging system somewhere. Start by checking the three yellow stator wires connector located beside the left side of the battery. If that connector appears to be burnt, I'd advise checking the stator to see if that is good and we can walk you through what to do next. The remaining connectors that'll give you problems are the regulator connector, at the regulator under the fake tank fairing, and the connector on top of the starter solenoid. The 2 red-red/white wires there feed into the main 30amp "Dogbone" fuse located under the cover on the solenoid. When you get you charging problem sorted out you might want to replace that with an inline fuse holder!

Let us know what you find and good luck!!

RE: Charging system voltage - Jim Penner - 11-04-2015

I did the hardwire trick to the yellow stator wires a number of years ago. I will check into the other connections and also monitor the battery voltage. It is a brand new battery but the pulsing bothers me.

RE: Charging system voltage - bs175dths - 11-04-2015

.....also check the negative cable at the engine block for cleanliness.
Electrons do not like resistance!
Running a second red wire (of proper gauge) from the regulator to the battery through a 30A fuse can help.
Clean terminal ends in the plastic plugs of the charging system. Clean out that oxidation and coat with a dielectric.
Make sure your battery has the same CCA and aH as the original factory unit.
Test the output of the stator as described at this site.
The only way to test the reg./rect. is with a known good unit. Sad

With a little luck, the fix will be easy (read, cheap) and you can get more happy (s)miles down the road.

Check the entire charging system as the fault may be a combination of many things.

Good Luck

-Ride On

RE: Charging system voltage - roscoepc - 11-05-2015

I'm glad you took care of the stator connector. BUT.... The same problem will eventually affect other connections in the charging circuit! In other words, you repair one area and the problem moves to the next weakest link! As I said check the voltage and then the connectors for getting hot and we'll go from there!

BTW, if the regulator proves to be the problem you can get the OEM Shindengen model at for 1/2 the price that Mother Honda wants for one!!

RE: Charging system voltage - Jim Penner - 07-13-2016

I did go with new regulator. Turns out the solenoid connector finally went into meltdown mode. Replaced dogbone fuse with sir Trickys recommendations and now have good 13.2 to 14.5 voltage readings. Perhaps former voltage regulator was still good.
Word of advice! if you haven't done the dogbone changeover, do it sooner than later. It will save many headaches down the road.
Oh, And the pulsing headlight seems to have been corrected too.Smile

RE: Charging system voltage - SIR tricky - 07-13-2016

Continue checking that the fuse does not loosen up even in the auto fuse holder they can loosen.

RE: Charging system voltage - Rigid - 08-06-2019

This is an old thread but I have a question along these lines, The plug on the three yellow wires fried, which I guess is common, after hooking everything back up, I am getting 15.3-15.5 volts at 3000-4000 RPMs, I know the shop manual states 14-15v, but I tried two different regulators, and both were over 15V, are they both bad ? do I need a new regulator?

Thanks for any help

RE: Charging system voltage - glhonda - 08-11-2019

Probably not, if two regulators act the same. Check the voltage at the black wire on the regulator. It should be the same or close to the actual battery reading. You might find it's a volt or so less. The regulator could have a corrupted signal, causing it to over charge.