Low Crank Voltage
Thread Starter
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6th Gear
Joined: May 2018
Posts: 13
Likes: 1
From: Queens
Low Crank Voltage
Hey guys and gals. Brand new to the forum.
So I had a battery die, charged it, died again. So I started to trace the charging system with a meter. Got 35v ac from the strator/rotor at idol (check), and got bad diode reading from the r/r. I tested voltage from the tender once the bike was running to see the volts. It was 12.5 v which means it was purely reading the battery and that the battery wasn't getting any juice. I replaced the battery with a Motobatt and the r/r with a Twin Power.
Now the bike charges, the battery sits at 12.65 and climbs to ~14.1 volts running. All good there!
The only thing now... when I start the bike volts drop low (~7) and it s chugs on. If I let it sit for a couple seconds, turn it off and turn it right back on, volts only drop to 10.5 and it cracks instantly.
What else could this be?
BTW the grounds seems good throughout. I could always investigate more.
So I had a battery die, charged it, died again. So I started to trace the charging system with a meter. Got 35v ac from the strator/rotor at idol (check), and got bad diode reading from the r/r. I tested voltage from the tender once the bike was running to see the volts. It was 12.5 v which means it was purely reading the battery and that the battery wasn't getting any juice. I replaced the battery with a Motobatt and the r/r with a Twin Power.
Now the bike charges, the battery sits at 12.65 and climbs to ~14.1 volts running. All good there!
The only thing now... when I start the bike volts drop low (~7) and it s chugs on. If I let it sit for a couple seconds, turn it off and turn it right back on, volts only drop to 10.5 and it cracks instantly.
What else could this be?
BTW the grounds seems good throughout. I could always investigate more.
Banned
Joined: Jul 2009
Posts: 7,406
Likes: 834
From: Straight Jacket Memories and Sedative Highs
What year bike and battery? Battery should be around 12.7 when not running .
Connections tight? Battery should not drop 10 something just from sitting for a little bit. Should take few months.
Connections tight? Battery should not drop 10 something just from sitting for a little bit. Should take few months.
Thread Starter
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6th Gear
Joined: May 2018
Posts: 13
Likes: 1
From: Queens
Bike:
- 2010 1200cc Nightster
- MotoBatt MBYZ16HD
- AH 16.5
- CCA 240
- Twin Power 498255
Road Master
Joined: Jan 2017
Posts: 1,129
Likes: 505
From: Illinois
Check the starter to battery cable for resistance. It looks like you have too much resistance on the cable from corrosion between the cable and the crimped-on end, acid sulfarization inside the cable, or brittleness on the cable. Replacing the cable with a lower gauge (thicker) cable should help.
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6th Gear
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From: Queens
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Thread Starter
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6th Gear
Joined: May 2018
Posts: 13
Likes: 1
From: Queens
- 1- Battery Terminals - The positive terminals are all rusted. I didn't check yet as to whether the rust stops at the terminal or has gone down to the wire.
- 2- Power from Battery. The boot isn't completely on... got to check for rust there.
- 3- I'm guessing this is another power line... am I right?
- 4- Primary Cover Ground - corroded as hell. Need to trace it to see where it goes. Could/Would this effect the starter turning over?
- 5- ? Is this the signal from the switch?
