I bought an ‘06 FatBoy with just shy of 20k miles in February. I’ve been having some issues with the battery since the first week of October. On 10/5, I switched the bike on - it was totally dead. I charged the battery on 10/7 and threw it back in the bike the next day, the bike started but with some hesitation. Basically, the motor turned over once, paused, then spun again and fired up. I rode for a couple of hours on 10/8 and 10/9 and experienced the same thing when I started the bike the first time on each day. Over the next two weeks, I rode to work a few times. The bike started hard each day, and before my ride home from work. The battery was tested on 10/21 and it checked out - volts were a bit low (12.10), but it had plenty of amps (330). I reinstalled the battery and went for a 4 hour ride with a few stops. There were no hard starts except the very first time the bike started that day. After one last ride to work on 10/27 and a 6 hour run on 10/31, I tried to start the bike on 11/3 - totally dead again. I installed a replacement battery that I’d bought; it started hard and I ran it for about 10 mins. I restarted the bike and it fired up without hesitation. Then, on 11/8 I tried to start it at night to warm it up and check the oil level. It hesitated as before, then made a clicking sound after a second or two. It was about 32 degrees; I was in an unheated garage.

So, I have a few questions:

 

[QUOTE=mh06fatboy;16816682]I bought an ‘06 FatBoy with just shy of 20k miles in February. I’ve been having some issues with the battery since the first week of October. On 10/5, I switched the bike on - it was totally dead. I charged the battery on 10/7 and threw it back in the bike the next day, the bike started but with some hesitation. Basically, the motor turned over once, paused, then spun again and fired up. I rode for a couple of hours on 10/8 and 10/9 and experienced the same thing when I started the bike the first time on each day. Over the next two weeks, I rode to work a few times. The bike started hard each day, and before my ride home from work. The battery was tested on 10/21 and it checked out - volts were a bit low (12.10), but it had plenty of amps (330). I reinstalled the battery and went for a 4 hour ride with a few stops. There were no hard starts except the very first time the bike started that day. After one last ride to work on 10/27 and a 6 hour run on 10/31, I tried to start the bike on 11/3 - totally dead again. I installed a replacement battery that I’d bought; it started hard and I ran it for about 10 mins. I restarted the bike and it fired up without hesitation. Then, on 11/8 I tried to start it at night to warm it up and check the oil level. It hesitated as before, then made a clicking sound after a second or two. It was about 32 degrees; I was in an unheated garage.

So, I have a few questions:
1)why might the OEM battery keep dying when the bike sits for a while?
2)what might be causing the hard starting? Keep in mind that the bike was ridden from April until October without this problem.

A few other facts:
1) There is a USB cable running off the battery tender lead that I use to charge my phone when it’s mounted to the handle bars.
2) when installing both the new battery and the HD OEM battery, the negative terminal sparks until the loop connector is tight against the terminal. When this happens there’s also a buzzing noise coming from the dashboard on top of the gas tank.

 

You should do a charging system test.

 

if you have security, it will draw current.
if you insert a meter in series with the battery + with all fuses pulled and insert one at a time till you have a reading, that circuit is of concern, check all. if that circuit feeds a security , then it maybe normal. if you disconnect security and still have a reading, that circuit might have an issue.
if all passes, move on to charge system.

 

Thanks! I’ll give that a try. There’s no security system in this bike. Also, I pulled the new battery out of the bike today. It had juice, but I didn’t try to start the bike. After disconnecting the USB cable, I backed off the bolt on the negative terminal. I saw the sparks I mentioned before. Also noticed that every time there was a spark, the speedo needle jumped a bit; that buzzing sound happened too. I noticed that these two things also happen when the switch is flipped to “ignition” with the battery connected. Is is possible that instruments in the dashboard draw some power even when the switch is off?

 

UPDATE: I performed a current draw test per my Haynes manual yesterday. The manual says that the ECM and voltage regular should draw 3 milliamps of current when the bike is switched off. To test if any more current is been drawn when the bike if powered down, I placed my multimeter in series with the negative side of the battery. I got a reading of 45 milliamps! So, still not sure what’s causing the problem, but I’m now confident that some kind of parasitic current draw has been killing my batteries and causing the hard starting issue. I’m going to have the dealer fix it under the extended warranty.

 

probably in the regulator.

 

Thanks! How can you check to see if the voltage regulator is drawing the extra current? Also, what about the voltage regulator might change or fail to cause it to draw the extra current?

 

Update: I took the bike to the dealership to have the electrical issue sorted out. After just over a week, the dealership claimed that they had tested everything and couldn’t detect any issue. They also weren’t able to duplicate the current draw I noticed; they but their meter in series with the battery and measured 2.4 milliamps. They claimed that you can’t do the current draw test until you let the bike sit awhile (there are relays that need to discharge they claimed). The bike also started right up with out incident (same when I picked it up).

I feel like I should get a second opinion. Thoughts?

 

How's it starting now?