So I have an 89 softail custom. My battery always dies. It can usually turn over for a short period, but then I will get clicking. I just replaced the starter last winter. I assumed it was the battery all summer but stuck it out since it was almost winter. I installed a brand new battery yesterday and it instantly clicked, without even truning over. The battery was around 12.5V before trying it. I charged it for 5 or so hours. The battery sat at 12.77V now. It turned over for about 5 seconds then I got clicking. Sometimes (not lately) I will see a tiny bit of smokes puff off of the neg terminal on the battery.

I got to thinking, I do have a lot of stuff running off the battery right now: normal bike lights, I just added a sidecar with a Harley headlight, and running lights, and I also just installed an audio system (which I am adding a switch on so its not run off the ignition anymore). I never run this stuff with the motor off though. I check the battery and it was 12.77V, and then I turned the key and it went down to 12.10V (without turning the motor over). This is a brand new battery mind you. It was happening with my old battery before the audio system, and I believe before the sidecar. HELP! THANKS!

 

First thing I did when I got my new then 1986 FXSTC home, was run a jumper so my lights weren't running when I started it.
The European versions had it default. Ignition and lighting positions.

Do you have a shop manual to trouble shoot the electrical system?

 

so you changed the ignition wiring so that a half turned key could start the bike, then once its running you turn it the rest of the way to turn the lights on?

i do have a manual but i only want to mess with all that if its the sure cause. if it is the sure cause, why isnt it happening to everybody else...

(just trying to induce convo about it, not doubt your idea)

 

Yes I changed the wiring so the lights only came on by switching to the second position.
The console markings show ignition/start and a second for lights. Both had the lights on in either position stock.

 

Check your ground wire. Sounds like it is loose to me!!

 

ya thats weird how they did that. i will plan to do that either way but am going to rule out the obvious first. were there any tricks i should know before doing it?

same here, but i just installed the battery and its definitely on tight.... the ground leaves there and goes to the frame..

 

Here's what I know of the charging system/battery system. HD's run off the battery. The altenator is designed to provide enough amps and the voltage regulator/rectifier is designed to limit the amount of volts going to the battery. Now if you are drawing too many amps off the battery that the altenator can't keep up then you are running on a defecit. Have you done a voltage check to the battery with the bike running and a amp check. 12.8v is 100% charged, 12.6 is 75% charged. My 02 Dyna cranks out 13.1v at idle, 14.2v at 2000 rpm.

 

Ever replace the cables from ground and positive to the bike? Sometimes corrosion gets in them and they don't conduct like they should. I replaced them on my '88 and it made a big difference. BIke starts after the first RPM. I also cleaned off all the bike electrical contacts and applied some dielectric grease to keep them corrosion free. It took some time but well worth it. Lights are flicker free and bright. I have zero battery or electrical problems.

 

Bingee- i did a new starter last winter and the positive wire going between it and the battery looked brand new (i know it could still be corroded inside, but this bike is mint, stuck in rain probably under 5 times since 89. always garage kept and covered. The ground is short, going from battery to frame with about 6 inches of wire. that also looks mint. maybe the frame connection could be better. i will add a pic of it soon.

seniorsuperglideE8-yes the alternators working. i had issues with it last year and hunted forever and got towed once all to find out the rectifier was unplugged from the alternator! But then i tested and its charges. i get around 13.xx while running. i think i remember it hitting 14 with a rev. i will have to do an amp test. one guy did this for me last year while i cranked the start and it maxed the meter out. he said that meant i needed a new starter. i dont think i did, but its on there now.

 

Yes and no.

Your bike runs off the charging system, which is supposed to supply enough to run the bike and charge the battery. If this was not true, then your battery would never charge because you would always be running at a deficit.