I have a 2004 FatBoy. I allowed the battery to discharge. I hooked up my trickle charger for a couple of days and when I turned on the ignition key the headlight was very dim and it would not even try to crank. I hooked up my regular battery charger to it and left it overnight, the next day when I turned on the ignition, the light was brighter but the speedo background light started blinking and the engine would not crank. I checked the battery condition with my tester and it read 13v, with my battery charger hooked up it read 15v. I left it charging overnight again, but the next day I had the same results. I did notice that my battery charger was showing that the battery was not accepting any current? I am at a loss as to what is happening here. Any thoughts?

 

When you read 13 volts, how long was it after you disconnected charger? Need to let surface charge go away before taking a voltage reading. Is this the original battery? If so probably due for a new one. Would not hurt to check all connections just to be on safe side.

A battery can get to the point where it will no longer take a charge. You may be at this point with a 5 year old battery.

 

New battery.

 

Hook up a meter to the battery then try to crank it,bet it goes to allmost nothing,these batteries dont like to be completely discharged they allmost allways need replacing...

 

5 Year Battery? wow, It took my first one less than 2 years to do what yours is doing. Time for a new one....