Forget excessive draining. Why does my battery drain to zero? Why do I have to keep a trickle charger on it all the time?

 

Hi from the UK and welcome to HDF. There are several things that may be wrong, from the battery, to alternator, to rectifier, etc. What is your bike and give us some more info, so we can help diagnose things for you.

 

My '86 FLHTC has the same issue.
I had it checked by the local dealer 2 weeks ago, and everything checked out. At idle, 12.7 Volts, 13.8v @ 3000 rpm. Battery 366CCA, 10.8 Volts at start.

If I just run short local runs >5 miles at a time, the battery will not start the bike.

If I let it sit for 2 days, battery is dead. My bike sits on the charger when not in use.

Battery is good etc.

The mechanic did suggest disconnecting the radio as there may be a fault in the radio that causes an intermittent high drain. When I checked the battery drain, it was only 0.01 amp.

I have a new 3 phase 32 amp charging system, and have just accepted it now as a gremlin in the 25 yr old wiring.

Interestingly enough, if I ride 100 miles or so, no problem with the battery.

Like to "hear" from anyone else their experiences.

 

Bought more than one defective battery over the years would definitely eliminate that problem before looking elsewhere ..