Here's the skinny on modern Harley motorcycle batteries. They are not lead acid batteries, they are AGM, Absorbed Glass Mat. They do not develop a "memory" from charging. Neither do lead acid batteries for that matter. If they did, then the memory would be about 10 seconds from the charge they get after starting the bike.

Battery Tenders do not charge the battery all the time. When the battery is recognized as charged the charger stops charging. You can kill a battery with a regular charger if it continues to charge but it won't happen with a Battery Tender product.

The trouble with internet forums is that you will sometimes get information that sounds correct but is actually in error. Or in laymans terms, the people who know what they're talking about are in the same isle as the dumb MFers who think they know everything. You can listen to those that will tell you that plugging a battery tender into your battery after every ride will cause it to develop a memory or you can listen to the truth.

You have a charging problem by the way. I'd start with basic stuff like the battery connections (make sure they aren't corroded or loose) and then use a multi meter to determine charging output and battery voltage.

That's my take on it and its worth what ya paid for it

 

My year old battery goes to green in about 15 seconds no matter the length of the ride. BTW, a battery TENDER is NOT the same as a battery CHARGER.

 

I keep my bike on the tender at all times unless I'm riding it, of course. Same as my Cobra.

As others have said, there is no memory issues to worry about and a tender (Deltran Battery Tender and Battery Tender Jr. is what I use) only charges until it reaches 100% and then just "floats" and keeps it there until you pull it off. You probably do have some type of charging/electrical issue on your bike if you are needing hours for your tender to get your bike back to "float" mode after riding it.

I would start by checking the voltage, while the bike is running.

 

I use the HD Tender after every ride. I got 6yrs out of the OEM and suggest you use it. Just my op but it works for me. If your battery is under 1yr old I would take it back for a replacement after checking what other posters have said.

 

I forget to put the tender on, so it is my memory that needs tending. Should battery tender be hot the touch?

 

Definitely sounds like a battery or bike charging system problem. Start with simple - have the battery load tested.

G/f took the battery from her Fatboy to HD couple of weeks ago - they said all was fine. Then the bike wouldn't start - had it towed in, thinking it had to be the starter (bi*ch to change on a softail) since the battery was fine. They found a loose ground wire and said all was good. Next time we tried to ride, no go.

I swapped batteries with my Fatboy and her's fired right up, without the initial "catch/hesitation" it normally gives. Bought a new battery and all is great now. Don't necessarily trust the guys at HD.

Correct, provided the OP is actually using a Battery Tender and not just applying the term generically to any old trickle charger. I use Deltran Battery Tenders on all my bikes and have never had a problem. I only started doing that when I acquired multiple rides - it's year-round here so no winter storage but with 5 bikes in the garage and 2 riders they don't each get ridden as often as they should.

 

The term AGM does not mean the battery has no acid. I does have acid but the acid is absorbed by the glass mat, making it 'non-spillable'.
I just went through this: I bought a new batt for my '03. It was 'dry' and the acid came with its own installation 'system'. I followed the acid installation instructions, waited 1 hour for the acid to be absorbed by the glass-mat and then charged it with my BT+. That 'initial' charge took 40hr to attain 100% charge....13.87v
The 'new' battery I replaced in Jan '12, even though it was on the BT+, would show 13.07v. Within 10hrs of being Off the BT+, (0 Ma load) that 13.07v dropped to 11.3v. (No start). I was blaming the BT+, since it was a brand-new battery. The new battery (Jan '12) was faulty.
The battery I installed last Tuesday(13.87v) is showing 12.83v right now after having sat 7 days, Not on the BT+.
There is a lot of useful info in the FAQs at the Battery Tender website. I used the 2nd to last FAQ to learn about the 'initial' charge using a BT+.

 

Are you having a laugh.

 

What's the difference between the battery being charged by a a battery charger, or on the bike?

 

An AGM battery is not the same as a lead acid battery. While they both have acid in them, the AGMs do better in applications that are prone to vibration. As you found out, they have different charging requirements as well.

So, as I said before. Modern Harleys do not have lead acid batteries and neither lead acid or AGM batteries develop "memories" from short duty charging.

Poor guy won't ever come here for an answer again;-)