Voltage Regulators and Lithium Batteries
Grand HDF Member
Joined: Sep 2022
Posts: 4,411
Likes: 3,813
From: Florida
So new to me torn down built up 93 fxsts. (Replaced my 90 fxsts)
Put in a 640 CCA antigravity like was in the 90 this one the battery is going dead in one day, battery is hot to the touch. I DID FIND A LOSE MAIN BATTERY CABLE GROUND WIRE. Cleaned and tightened but testing further to be sure its fixed.
I tested the stator as far as no ground. Charged the battery and it shows 13.2. Start the bike, dips maybe 12.99 raises to 13.2 but no higher. Kept the throttle at 2500 for 7 seconds. Still no higher than 13.2
thoughts?
Put in a 640 CCA antigravity like was in the 90 this one the battery is going dead in one day, battery is hot to the touch. I DID FIND A LOSE MAIN BATTERY CABLE GROUND WIRE. Cleaned and tightened but testing further to be sure its fixed.
I tested the stator as far as no ground. Charged the battery and it shows 13.2. Start the bike, dips maybe 12.99 raises to 13.2 but no higher. Kept the throttle at 2500 for 7 seconds. Still no higher than 13.2
thoughts?
Last edited by Rains2much; Oct 26, 2023 at 02:33 PM.
Grand HDF Member
Joined: Apr 2007
Posts: 3,724
Likes: 3,068
From: Brighton, MI
Kind of lost as the thread is getting long.
What charging system components are new, what is not, what brand stator, what brand regulator, how old are the #4/#6 battery cables and ground wires? Should be getting higher running volts.
What charging system components are new, what is not, what brand stator, what brand regulator, how old are the #4/#6 battery cables and ground wires? Should be getting higher running volts.
Grand HDF Member
Joined: Sep 2022
Posts: 4,411
Likes: 3,813
From: Florida
On charger it will charge to 14.26. On stator seems to cap at 13.2
Last edited by Rains2much; Oct 26, 2023 at 04:11 PM.
Grand HDF Member
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From: Florida
As typed above.
Grand HDF Member
Joined: Apr 2007
Posts: 3,724
Likes: 3,068
From: Brighton, MI
AC VOLTAGE (not dc voltage).
Also when measuring AC VOLTAGE (not DC voltage) it is measured at the connector at the engine block.
Disconnect the connector that the regulator plugs into at the engine block. Set your meter for AC VOLTS, start the bike, touch one probe to one of the female pins (actually a socket) and the other probe to the other female. Does not matter which probe goes to which pin, just don't short the pins with the probes (don't touch them together while running). A safer method is to make a couple pig tails using some insulated wire inserted into the small brass sockets and connect the pigtails to your meter probes.
You are measuring the AC voltage that the stator creates before any voltage gets to the regulator/rectifier. If your AC VOLTS is in spec, then the next step is to check the regulator, but start with the stator first by measuring the AC volts. It is easy to do and AC volts should increase with engine RPM.
Follow the Dr. Hess instructions posted here and you will find the problem:
https://www.hdforums.com/forum/evo/8...ng-system.html
"Set meter to AC Volts, 100V scale. Attach each meter lead to a stator pin. You may need to rig up some type of temporary plug. It is important that nothing can short to ground or to each other accidentally, or you will blow the stator if it wasn't blown before. An old plug off of your last regulator is a good way to do it, but, get creative and be careful. I can do it holding the leads on the pins once the bike is running, but I don't like to. Start bike. Voltage should vary with engine speed. Specs are in your shop manual, but 35V at a couple thousand RPM is probably about right. My book says 19-26 V / 1K RPM."
Also when measuring AC VOLTAGE (not DC voltage) it is measured at the connector at the engine block.
Disconnect the connector that the regulator plugs into at the engine block. Set your meter for AC VOLTS, start the bike, touch one probe to one of the female pins (actually a socket) and the other probe to the other female. Does not matter which probe goes to which pin, just don't short the pins with the probes (don't touch them together while running). A safer method is to make a couple pig tails using some insulated wire inserted into the small brass sockets and connect the pigtails to your meter probes.
You are measuring the AC voltage that the stator creates before any voltage gets to the regulator/rectifier. If your AC VOLTS is in spec, then the next step is to check the regulator, but start with the stator first by measuring the AC volts. It is easy to do and AC volts should increase with engine RPM.
Follow the Dr. Hess instructions posted here and you will find the problem:
https://www.hdforums.com/forum/evo/8...ng-system.html
"Set meter to AC Volts, 100V scale. Attach each meter lead to a stator pin. You may need to rig up some type of temporary plug. It is important that nothing can short to ground or to each other accidentally, or you will blow the stator if it wasn't blown before. An old plug off of your last regulator is a good way to do it, but, get creative and be careful. I can do it holding the leads on the pins once the bike is running, but I don't like to. Start bike. Voltage should vary with engine speed. Specs are in your shop manual, but 35V at a couple thousand RPM is probably about right. My book says 19-26 V / 1K RPM."
Last edited by Yankee Dog; Oct 26, 2023 at 06:41 PM.
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