On my ride home from work, my voltage dropped from 14+ to around 11.5 and stayed that way for the hour ride home. This happened twice in the past 3 months but both times only lasted less than a minute. (I have a new cycle electric voltage regulator sitting in my garage just in case)

I know I have to test the charging system (battery, stator, regulator) but was wondering what danger is it running the bike at lower voltage? Is the battery not charging? Anything else? I noticed this morning that my battery tender is flashing green (+80% charged) when it usually is solid green (100%) which leads me to believe my battery was draining during that 1 hour ride home.

Thanks!

 

If your gage is right, you're correct in that it is not charging. My guess is it's the obvious battery connection since this stuff (stator, regulator) is quite reliable. Mine works loose quite often. When it's random, it's usually a connection.

Just some info 101 electrical if you like to read.

Rev. 091615

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 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.
12.8 = full 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 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. 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.

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. 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 an 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.

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. The older stators with two wires are a two phase AC system. Lot of people call it a single phase but it is two phase. The AC voltage you see appears single since you check it AC across the two wires since there is no earth ground. If you were to check one wire to an earth ground, it would show one half the voltage that you would see when you check the two wires together on the bike. Same with the other. Together they double and are two phase. The newer three-wire system is a 3-phase AC system for the higher amperage output.

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.

 

Just FYI the regulator knocks out the stator about 90% of the time. Can't tell ya the number of people I've heard of that change out the stator only to have it go South because they didn't replace the regulator.

Just saying.....

8~\o

 

I'd question that.

the components of the charging system are inter-related and a bad component may damage other components.

just "replacing parts" is a guess and may or may not solve a problem but will lighten your wallet.

diagnosis is the key, adn for that a real voltmeter needs to be used to confirm any observations at the in dash gauge.
which can be affected by other loads on the system...turn signals, spot lights horn etc

mike

 

I had a sim problem on an 04 Touring bike,it was just a bad connection undervoltage reg where it plugs into stator.I cleaned conn and used Diaelectric grease and that took care of it. Was told by a mech that is a common problem.

 

Take the seat off, start the bike, and measure voltage on the terminals of the battery with an accurate VOM. Of course you will want to do this when your in-faring voltage meter is reading at the 11.5 v value.

If the battery is reading 13.5 and north to a little over 14 vdc with the bike running, then your charging system and battery is likely in good shape. It may simply be a case of loose connections here or there. Ensure your battery cables are clean and tight, and that the connectors on the rear of the voltage gauge are clean and that the spade terminals are snugly attached. You will of course have to remove the faring to accomplish inspecting the rear of the meter. Remember that the voltage meter is NOT a precision instrument and can be relied on only as a "relative" voltage indicator. A little smear of dielectric grease on the meter terminals before pushing on the spade connectors is always a good preventative of moisture contamination and corrosion.

If you get a low voltage reading, then you really have to start diagnosing where the voltage deficiency is originating...and that means measuring voltage from the stator to the regulator, them from the regulator to the battery. The service manual will walk you through the procedure. Your battery may be fine, but with a bad charging system, it may not be getting the consistent charge it needs to maintain operating voltage and current delivery. If there is a charging/regulation issue, I don't recommend operating the bike at all until what time the problem is correctly diagnosed and the defective parts replaced.