When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So this morning (45°F) my sportster wouldn't start and presented symptoms of a weak battery. It seems to do this on every cold morning.
This afternoon, I tried to start it again, and it started first shot no problem. (65°F) This battery is a month old.
Now what I noticed, on the speedometer, the arrow doesn't seem to be settling even when I pull the battery fuse. It drops when I shut the engine off, then goes back up. Can this indicate a loose draw somewhere? I'm honestly completely stumped. Electrics are my weakness, so any guidence on what to do next would be amazing.
1st Remove the battery and bench charge it, then take it and get it load tested to ensure it has the appropriate Cold Cranking Amps (CCA). Even new batteries can be faulty. Once tested and if okay follow the procedures to test for power drain.
I would not worry about other stuff until I was sure the battery is good.
About 120 or so milliamp draw. If you have an alarm, close to 40 more as attach battery in line with it set or wire leads positioned for amp draw.
That trims off in about 30 seconds to 120 as the alarm goes to sleep mode.
A new battery really needs charged when brand new on a bike unless you run it 4 hours or so.
A good battery will start a bike a few months without running. Never jump a bike except in an emergency.
Take that volt/amp/OHM meter and just hook it to your maintenance leads on DC volts. Crank it. If it drops below 9.7, battery is dead or bad. 12.7 is full charge. 12.3 is dead battery.
..
You have a 2008 Nightster of unknown mileage, unknown ownership history, unknown modifications from stock and unknown condition.
It is unknown if motor has been altered in any way.
We know that bike has a 1 month old AGM battery of unknown brand.
Is it the correct battery? Same cranking amps as stock?
Have battery cable connections been reviewed? all FOUR ends?
For example: Some batteries require a provided spacer at terminals in order for battery cable to sit correctly at posts.
Sometimes the other ends of battery cables are loose. Check the FOUR ends.
Has battery been removed and taken to a shop for a load test?
Just because a battery is new does not mean that it is not defective.
Have you tested charging system with a simple digital voltage meter connected to battery post? voltage at rest, Key ON, Cranking, at idle and above idle?
If all this tests out then a simple parasitic drain test can be performed with a cheap digital voltage meter.
Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Slideshow: A standard cruiser becomes an intricate metal canvas in the hands of a Swiss custom house known for pushing Harley-Davidson platforms far beyond their factory brief.
Slideshow: Harley-Davidson's challenges aren't abstract; they show up in dropping shipments, shrinking dealer traffic, and strategic decisions that aren't yet translating into growth.
Electric Draw?
