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Why my charging system does not deliver enough volts?

proride

proride

Member
Hi there my overseas Harley friends. Since we do not have a H-D dealer here in Bosnia, I need your help.

My bike is 2001 Road King Classic FLHRCI and my bike's charging system does not fully charge my battery. For example, at regular ride, at about 2000 – 2500 rpm I can get only 11.50 VDC up to maybe 12 VDC, only at really high rpm I can get 13 or more volts. The result is that my battery drains and after the ride I can read about 12.20 VDC. I can only dream about 12.9 VDC, which is full battery.

I do have certain technical skills, experience and proper equipment, so I did several tests:

- brought my 2 years old AGM OEM H-D battery to professional, he says battery is very strong and just perfect. Also, when I start the bike, voltage does not drop below 10 VDC, meaning – good and strong battery.

- tested voltage regulator and additionally mounted and tested another replacement voltage regulator, the both of them give about 13.9 to 14.5 VDC

- tested alternator, H-D manual says AC output needs to be 19-26 VAC per 1000 rpm. My bike delivers that, and when I roll the throttle I can get even up to 29 VAC

- checked and cleaned both ground leads, the one connected to the starter and the second on the fuse under the seat, close to the battery

- checked and cleaned alternator cables connected to the voltage regulator, and voltage regulator cables connected to the battery and the ground. Also checked cable connections under the frame/right footrest

So, taking into account all above written information and tests, I'd like to ask for your help to learn what could be the problem, why my charging system does not deliver enough volts to charge my battery?

Thanks in advance.
 
How about your gauge, are you sure it's reading correctly? Have you checked voltage with an alternative meter?

Testing the charging system.


Step 1. First things first, load test the battery. Most places like Auto Zone will do it for free. Even if it measures over 12.5 vdc it can still be bad under a load. Battery is typically rated at 19 amp hours and 270 Cold Cranking Amps (CCA).

Start the engine and measure DC Volts across the battery terminals, the regulator should be putting out 14.3 - 14.7 vdc at 3600 rpm and 75 degrees F.


Step 2. To check the regulator unplug it from the stator. Take a test light and clip it to the negative terminal of the battery and then touch first one pin and then the other on the plug that goes to the regulator. If you get even the slightest amount of light from the test light the regulator is toast.

To do this with a meter which is more accurate: black lead to battery ground, red lead to each pin on the plug, start with the voltage scale higher than 12vdc and move voltage scale down in steps for each pin. Any voltage is a bad regulator.
You may get battery voltage on all three pins on the newer 3 phase regulators.
The no voltage is for older type regulators with diode indicating the diode is bad and the regulator needs replacing.


Step 3. On the other part of the disconnected regulator plug. Set the multimeter for Ohms x1 scale and measure for resistance across the pins of the stator. You should read something around 0.1 to 0.2 ohms for the TC88 32 amp system.


Step 4. Then check for continuity between each pin on the plug and frame/engine ground. The meter needle should not move (infinite resistance)(digitals will show infinite resistance) if the meter needle does move (indicating continuity)(digitals will show some resistance), recheck very carefully. If the meter still shows continuity to ground the stator is shorted (bad).


Step 5. Set the meter to read A/C volts higher than 30 volts (the scale setting for voltage should always be higher than the highest voltage you expect or you may fry the meter). Start the bike, and measure from one pin to the other on the plug (DO NOT cross the multimeter probes! - touch them to each other). You should read roughly 16-20 vac per 1,000 rpm.


Step 6. If the battery was good under load test, if the stator is NOT shorted to ground, and the stator is putting out A/C voltage, then the regulator is bad (most likely even if if passed step 2).


Generally the following is true:
Check your owners/service manual for the system amp output for your bike.
22 amp system produces about 19-26 vac per 1,000 rpm, stator resistance is about 0.2 to 0.4 ohms.
32 amp system produces about 16-20 vac per 1,000 rpm, stator resistance is about 0.1 to 0.2 ohms.
45 amp system produces about 19-26 vac per 1,000 rpm, stator resistance is about 0.1 to 0.2 ohms.

(Disclaimer) I may not always be right but at least I tried. 05 Ultra Classic 95 ci.
 
Welcome from Spokane Wa.
After reading this my question is, what is the cold cranking amp rating of your battery and what does it test at.
A battery can have good voltage but be low on amps. And make the changing look poor, can you use a different battery and recheck?
A 2 yr old battery with low cca will cause slow cranking and not gain voltage.
 
Hi guys, thanks a lot for your inputs. Well, I do use 4 (four) voltmeters for the purpose of accuracy and I use 'em directly on the battery. My battery is OEM AGM H-D battery 28Ah, 400 cca (part number 66010-97). And yes, I shall go through all these steps that Jeff suggested. I am also surprised since the battery has low voltage/poor charging and still very good cranking power!
 
proride said:
Hi guys, thanks a lot for your inputs. Well, I do use 4 (four) voltmeters for the purpose of accuracy and I use 'em directly on the battery. My battery is OEM AGM H-D battery 28Ah, 400 cca (part number 66010-97). And yes, I shall go through all these steps that Jeff suggested. I am also surprised since the battery has low voltage/poor charging and still very good cranking power!
Click to expand...

It may have good cranking for a short period of time before it drops off dramatically. I'd start with another load test with a fully charged battery before you move onto the other outlined steps. It may save you time and aggravation.
 
I fully agree Jeff and that is what I'm gonna do tomorrow: full load test for about extended period of time....even though they said my battery was good, I do not trust this battery too much....I shall know more tomorrow.....but...still....when the engine is running, I can not get/measure full 13,9 volts....until I roll the throttle more than let's say 3500 rpm....I measure about 12, more or less, volts....and ...as I said, alternator delivers more than 26 VAC, and TWO voltage regulators - the old one and the new one delivers identical voltage........
 
Your on the right track, process of elimination when it comes to electrical. Eliminate the battery first, if that test fine move onto the other tests outlined in my post.
 
Jeff, I got very, very strange result with the both of my two voltage regulators( the old one and the new one).

Test 1:
OLD VOLTAGE REGULATOR
Positive lead (voltmeter) to AC output 1, negative lead to battery charge lead - reading: infinity (must be 0,5 V) - did not pass the test
Positive lead (voltmeter) to AC output 2, negative lead to battery charge lead - reading: infinity (must be 0,5 V) - did not pass the test

NEW VOLTAGE REGULATOR
Positive lead (voltmeter) to AC output 1, negative lead to battery charge lead - reading: 0,2 V (must be 0,5 V) - did not pass the test
Positive lead (voltmeter) to AC output 2, negative lead to battery charge lead - reading: 0,2 V (must be 0,5 V) - did not pass the test


Test 2:
OLD VOLTAGE REGULATOR
Positive lead (voltmeter) to AC output 1, negative lead to ground - reading: 0,2 V (must be infinity) - did not pass the test
Positive lead (voltmeter) to AC output 2, negative lead to ground - reading: 0,2 V (must be infinity) - did not pass the test

NEW VOLTAGE REGULATOR
Positive lead (voltmeter) to AC output 1, negative lead to ground - reading: 0,2 V (must be infinity) - did not pass the test
Positive lead (voltmeter) to AC output 2, negative lead to ground - reading: 0,2 V (must be infinity) - did not pass the test


Test 3
OLD VOLTAGE REGULATOR
Positive lead (voltmeter) to battery charge lead, negative lead to AC output 1 - reading: infinity - test OK
Positive lead (voltmeter) to battery charge lead, negative lead to AC output 2 - reading: infinity - test OK

NEW VOLTAGE REGULATOR
Positive lead (voltmeter) to battery charge lead, negative lead to AC output 1 - reading: infinity - test OK
Positive lead (voltmeter) to battery charge lead, negative lead to AC output 2 - reading: infinity - test OK

Test 4.
OLD VOLTAGE REGULATOR
Positive lead (voltmeter) to ground, negative lead to AC output 1 - reading: 0,5 V - test OK
Positive lead (voltmeter) to ground, negative lead to AC output 2 - reading: 0,5 V - test OK

NEW VOLTAGE REGULATOR
Positive lead (voltmeter) to ground, negative lead to AC output 1 - reading: 0,5 V - test OK
Positive lead (voltmeter) to ground, negative lead to AC output 2 - reading: 0,5 V - test OK


It makes no sense that the both voltage regulators are damaged and I am quite sure that I did not make mistakes during my measurements...to that end, I did complete tests four times....

Tomorrow I shall do the other things that you suggested.....
 
We have seen , in the automotive side ,
That an internally shorted battery can make the charging system look like it's the problem.
If you can use a different known good battery and recheck the charging output you could if nothing else, eliminate the battery as the cause.
Also the voltage regulator on these older bikes went thru many updates.
So check the part number of the new regulator to see it's not new - old stock.
The other recommendation is to always cover the regulator to protect it from oil when changing the oil filter.
Over time the oil can wick into the wire harness leading to charging problems.
 
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