02 Ultra classic check engine light came on battery gauge dropped to 10, installed new battery about a week ago, after reading post sounds like the regulator?

 

You can assume that and start throwing parts at it. Or you can so a good diagnostic check and be sure.
Low voltage can be either the stator or the regulator or poor wiring connections at a number of places.
There's a troubleshooting sticky in the Electrical section.

 

Fixed mine by unplugging the plug between stator and vr,cleaned and oiled contacts.

 

Need to do it at high idle or best at 2000 rpm but sounds like the AC from the stator is way low.

Rev. 03-29-17
Some electrical 101 and a little more..

Remember, the best made brand new battery that has been on a maintenance charger for 3 days that has a loose or bad connection is no better then a boat anchor with a loose rope. The connection can get loose after one ride if the battery is not anchored and the wires are short and get tugged in a direction that can unscrew the bolts.

After a good 24+ hour maintenance low amperage (never over 2 amp) charge, with the charge light in the solid green and the battery has set about 24 hours off charge, voltage should be about 12.8 volts.
You can speed up this process by turning on the ignition key (headlight comes on) for ~3 seconds and then switch it back off. This is enough of a load to bleed off the excess residual charge from the charger and then you can measure the battery voltage.

12.8 = fully charged
12.6 = 75% charged
12.3 = 50% charged (Lot of new modern cars with system protection will not even click at this point but will have good headlight beams showing)
12.0 =25% charged

Always check both the terminals at the battery lead and also at the terminal on the wire. That helps to verify connection. With a DC volt meter (one that has a feature to lock high and low reading is best) hooked across the battery terminals and reading 12.8 or so, crank motor and while its cranking it should not drop below about 9.6 volts and as soon as it starts and throttled up to 2000 rpm, voltage should read around 14.8 volts. The 2000 rpm is the bench mark standard. Ignore idle output. Ignore output above 2000rpm unless it exceeds 14.9 volts. That is a sure indication that regulator is bad.

The crank check shows a rough check of the reserve amperage capacity of the battery while cranking with a 150-200 amp load on it. The 14.8 shows a good alternator and if you leave it on a while as the regulatory will drop the voltage a little showing itself working. However, with the lights and stuff always on, it will never drop back much. If you have a lot of options, most modern bikes will not show 14.8 charging volts at idle but stock newer bikes will be close. Older bikes with lower amperage output not so much. However, 2000 rpm is the bench mark for the standard 14.8 volts.

If the voltage is only about 13 volt DC at 2000 RPM, the AC volts stator may be shorted or bad. Unlike the regulator, this is an easy check with an AC meter. Check that the two or three legs do not go to frame ground and that the ohm resistance across all combinations of checks are within an ohm of what is called out in the service manual. Also check the AC volts coming from them at 2000 rpm.
Be cautious here since you can kill yourself with this much AC volts. You need a service manual or look you spec up on line for your unique bike. I have seen about 3 verations over the last 20 years of Harleys due to ever increasing output.

If you think battery is good and something is draining it sitting, now would be a good time to check for drain problems. Go to Harbor Freight and get you a AC/DC meter for under $25 or so. http://www.harborfreight.com/ac-dc-d...ter-37772.html Make sure it has DC amps draw, DC voltage, resistance and AC voltage. Key off. Remove the negative cable off the battery. Set meter on DC amps. Hook the meter lead to cable and the other to battery. !!Key off.do not turn on!! Ignore that first draw as the alarm trims back and stuff charges for 1 minute. Now, how many milliamps (mA) is it drawing? It should be no more then 6 mA which is the ECM (1), speedometer (1), tac, TSSM (1), HFSM (1) and voltage regulator (1)


When a battery wears out, a good charge will show fairly good voltage, but the battery can still have very low amperage capacity which will show in the crude crank test above, but it really should be checked after a good charge by removing it from bike and getting a free check at a place like AutoZone that has a fancy load meter check that gives you a print out of the battery health. Battery MUST BE CHARGED to check it. Be sure they set their meter to correct cold cranking amperage stated on the battery. Never charge the AGM absorbed glass mat battery with a regular car battery charger unless it is a newer one that says safe with this type of battery. Also, by taking battery out you now know you have good connections. Vibration tends to loosen the connections or a little corrosion will prevent charging or cause starting problems. Be forwarned, these checks quite often are incorrect due to the low amperage of these small batteries and junk checking equipment. If bike is charging, no load on battery when key is off and you are still having problems…REPLACE THE BATTERY. If battery is more then 3-4 years old.. REPLACE THE BATTERY.

Using the maintenance charger can get more years from a battery but be careful here. You do not want the last start 5 miles from home. If it still grunts when you first hit starter or kicks back with a bang, replace it. After a few years, charge and pull battery and have it checked for cold cranking amperage ever spring. Even then, if it grunts most ever start, I would replace it. Most battery checkers at AutoZone and places like that do not do really well on the low amperage setting on small batteries. Not sure why but they tend to say they are OK when they are weak. If they have one that fits your bike, Wal-Mart's AGM absorbed glass mat battery is just as good as any for one third to half the money of a Harley Battery. My last 4 years befor it started grunting. And out it came. Do not put an old fashion one with vent tubes on a modern TC Harley. Do not jump, push start or run bike with a half dead battery except in a real emergency. If a bike battery is down and you jump it, throwing all that amps to it from a big car battery especially one that is running can wreck a bike regulator or charging system. Charging a worn out battery can kill alternator stator or the voltage regulator or both. Probably ending in a big dollar repair in parts alone.

It is also a good idea to always check your battery at 2000 RPM with your meter set to AC. If by chance, the regulator goes bad, sometimes it will let AC come thru. That is a sure sign of a bad regulator. Older 2 wire stators have a single-phase output while the newer stators with 3 wires have a 3 phase output. The 3 phase system provides a more consistent and higher current output to the voltage regulator. The voltage regulator takes the AC from the alternator, rectifies it to DC and limits the voltage level to the battery depending on the voltage reading it gets back from the battery.

Also remember, when starting a Harley, hit the starter and hold it in till it is firing on both cylinders and running before letting up. If you let up before it’s running, quiet often, it actually take an FI motor longer to start. There is a fraction of a second more for a long stroke Harley then a multi-cylinder car for it to get going. If you do not do this, it will kick back with a bang, sneeze thru the intake or crank a lot longer the second time or shame on you the third time. Also, if you have a habit of doing this, the starter solenoid switch contact will only have half the life it could. You cannot hurt the starter. The starter gear has a sprag clutch. There are drive pins in it that as the gas motor catches and run, it outruns the starter motor drive and disengages it from the electric motor. If you hold it in a little too long and listen carefully, you will hear the sprag clutch run up the ramps and slip. Makes a sizzle hum. This will show you your starter sprag clutch is OK.

My batteries:
11-05-03 Originial Harley 3 years
08-07-06 Harley 6.5 years (nursed way too long and was grunting and banging often)
04-29-13 Walmart Ever Start 4 years (grunting)
03-25-17 AutoZone Duralast Gold

 

Years ago, same symptoms. Very happy with my Cycle Electric VR. Looks a little different but works beautifully.

 

02 Ultra classic check engine light came on battery gauge dropped to 10, installed new battery about a week ago, after reading post sounds like the regulator?

Thank you for the input. Went out and started her up and the check engine came out and went out and battery gauge starting reading over 14, so now this is an intermittent issue.

 

ran all the test on the charging system and all checked good, did diagnostic check and every one was clear. Took bike out for a ride and battery gauge was fluctuating between 12 - 14 volts at acceleration and deceleration coming to a stop at idle dropped to just above 12 volts. I have my old voltage regulator and will replace the newer one that was installed in 2013.

 

I have had the stator replaced 2 times on this bike.

 

You need to replace the battery gauge.

 

My brother has a 03 Harley trike he has a bad battery terminal connection. his bike died. I told him that he needs to fix terminal connection. hes stubborn and says that the bike should run with battery disconnected. Im trying to tell him its not like a car and the battery needs to be connected or the bike will stall. Please help me confirm this for his stubborn ***.....