(Long info ahead) So recently my Sportster has been acting whack: On Christmas Eve it just randomly had a dead battery and I had to push start it, but on my way back home it just completely died and wouldn't start back up so I had to push it home. So I eventually charged the battery and everything was fine. BUT just yesterday the same thing happened, battery died on the road and had to get the damn thing towed this time. So my friend gave me a (like new) battery. I charged it up and it sounded like it was having trouble starting but it did start. Eventually it stopped starting up and now it just makes this clicking noise, but the weird thing is the neutral light and headlight aren't dim like they usual are when the battery is dead. So WTF is the problem here? I tried tightening the + and - cables but it doesn't seem to do anything. Can someone please she's some light on this

Could be a lot of things, but don't overlook that you don't really know the quality of your replacement battery. It would be a shame to screw around with everything else and end up back at the battery.

A load test on the battery tells you reserve cranking capacity, a static voltage check isn't sufficient to determine that.

Beyond the battery, a bad connection, ground or otherwise, bad stator coil, or bad rectifier/voltage regulator is what you might end up dealing with. A weak magnet which spins inside the stator is an unlikely last resort.

I suspect your battery, those bikes use a lot of current to be electric started, and don't have high amperage batteries to

start with.

A dead battery can still have enough power to illuminate a couple of light bulbs.

But it won't have enough power to spin the starter motor.

Little bulbs can be lit with a AAA battery.

After charging a dead battery, it will have enough strength to run the electrics.

But without the charging system charging the battery, the battery is going to drain down to zero volts (dead).

Check the charging system.

They go bad on all bikes.

I had an old Honda that did the same thing. I bought a new battery but that only fixed the problem temporarily. I went to the library and copied the diagnostic section of the manual. I went home with my multi-meter and within an hour I found a dead voltage regulator. A good manual is a great investment, and HD sets the standard for them.

Timbo has the correct next step - the charging voltage should be > battery voltage and < 15 V. Check idle and about 3000rpms if it drops off at the higher RPM to battery voltage you have a problem - if it never charges above battery voltage you have a problem, if it only charges above battery voltage at idle you have a problem.

The spare battery you got may have a dead cell, so the voltage is too low for the starter to engage properly.

Get the battery tested or just buy a new one.

Check alternator output as it may not be charging the battery.

Your stator is bad .