Electrical issues. HELP!
Road Warrior
Joined: Jun 2009
Posts: 1,943
Likes: 3
From: NYC
take the battery out of the bike and fully charge it. once fully charge....let it sit for 12 hrs....then ...using a ditigal multimeter...measure your static voltage...find that voltage on the below chart....you will get your batter state of charge. the older the battery...low lower the state of charge will be...replace the battery if you get less than 12.36 volts.
State of Charge (SOC) Chart:
% of Charge - - - - Charging - - - At Rest - - - Discharging
100 - - - - - - - - - - - - 14.75 - - - - - - - - 12.70 - - - - - - 12.50
90 - - - - - - - - - - - - - 13.75 - - - - - - - - 12.58 - - - - - - 12.40
80 - - - - - - - - - - - - - 13.45 - - - - - - - - 12.46 - - - - - - 12.30
70 - - - - - - - - - - - - - 13.30 - - - - - - - - 12.36 - - - - - - 12.25
60 - - - - - - - - - - - - - 13.20 - - - - - - - - 12.28 - - - - - - 12.15
50 - - - - - - - - - - - - - 13.10 - - - - - - - - 12.20 - - - - - - 12.00
40 - - - - - - - - - - - - - 12.95 - - - - - - - - 12.12 - - - - - - 11.90
30 - - - - - - - - - - - - - 12.75 - - - - - - - - 12.02 - - - - - - 11.70
20 - - - - - - - - - - - - - 12.55 - - - - - - - - 11.88 - - - - - - 11.50
10 - - - - - - - - - - - - - 12.25 - - - - - - - - 11.72 - - - - - - 11.25
State of Charge (SOC) Chart:
% of Charge - - - - Charging - - - At Rest - - - Discharging
100 - - - - - - - - - - - - 14.75 - - - - - - - - 12.70 - - - - - - 12.50
90 - - - - - - - - - - - - - 13.75 - - - - - - - - 12.58 - - - - - - 12.40
80 - - - - - - - - - - - - - 13.45 - - - - - - - - 12.46 - - - - - - 12.30
70 - - - - - - - - - - - - - 13.30 - - - - - - - - 12.36 - - - - - - 12.25
60 - - - - - - - - - - - - - 13.20 - - - - - - - - 12.28 - - - - - - 12.15
50 - - - - - - - - - - - - - 13.10 - - - - - - - - 12.20 - - - - - - 12.00
40 - - - - - - - - - - - - - 12.95 - - - - - - - - 12.12 - - - - - - 11.90
30 - - - - - - - - - - - - - 12.75 - - - - - - - - 12.02 - - - - - - 11.70
20 - - - - - - - - - - - - - 12.55 - - - - - - - - 11.88 - - - - - - 11.50
10 - - - - - - - - - - - - - 12.25 - - - - - - - - 11.72 - - - - - - 11.25
Ultimate HDF Member
Joined: Jun 2009
Posts: 6,932
Likes: 4
From: 46th State, USA
When it comes to battery issues, I've always found it best to have it load tested.
Road Warrior
Joined: Apr 2011
Posts: 1,905
Likes: 66
From: Hartford, AL
2 basic suggestions. Check the voltage at the battery with a multi-meter and compare with the gage. Check the battery connections and make sure they are tight along with the ground-to-frame connections.
Stellar HDF Member
Joined: Feb 2010
Posts: 3,403
Likes: 268
From: Southern California
Like Chunker suggested; Put a voltmeter on the battery and with your headlights "On" compare the Voltmeter reading at the Battery to the one on the bike. You may have a wiring problem somewhere (not a short, more likely a dirty connection or a wire that is nearly cut through), or maybe a bad voltage regulator, but it's also quite possible that you have a voltmeter on the bike that has bad connections to the wiring.
Road Captain
Joined: Sep 2010
Posts: 574
Likes: 3
From: AB Canada
Bills90,
You may or may not have a problem. You say your bike starts no problem, that is the function of the battery, once the bike is running the charging system takes over. If your bike failed to start due to a discharged battery and you suspect the charging system is at fault, have it 'tested', this involves a means of putting a load on the 'system' ( the battery, by means of a load tester ) this will evaluate the ability of the charging system to reach it's maximum current output. Without the load, you will be unable to determine the max currrent capability. The second vital peice of equipment needed is an 'amp clamp', capable of measuring more than the 10 amps a multimeter can measure. Without that, you are guessing at the amperage the charging system is producing.
You'll also need to determine the current draw of your bike, the current draw needs to be lower than the current output by at least 3 amps. Also note, if you are under 1200 rpms or so, you will most likely be in a 'no charge' situation...you need to ride the bike. All these tests are clearly identified in any HD service manaul and mentioned several times on this site. I hope I've helped somewhat.
You may or may not have a problem. You say your bike starts no problem, that is the function of the battery, once the bike is running the charging system takes over. If your bike failed to start due to a discharged battery and you suspect the charging system is at fault, have it 'tested', this involves a means of putting a load on the 'system' ( the battery, by means of a load tester ) this will evaluate the ability of the charging system to reach it's maximum current output. Without the load, you will be unable to determine the max currrent capability. The second vital peice of equipment needed is an 'amp clamp', capable of measuring more than the 10 amps a multimeter can measure. Without that, you are guessing at the amperage the charging system is producing.
You'll also need to determine the current draw of your bike, the current draw needs to be lower than the current output by at least 3 amps. Also note, if you are under 1200 rpms or so, you will most likely be in a 'no charge' situation...you need to ride the bike. All these tests are clearly identified in any HD service manaul and mentioned several times on this site. I hope I've helped somewhat.
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