I have a 2019 FLHTP ElectraGlide. In my recovery, I was not riding as often. I have the bike on the battery charger now. But have not had good luck once a battery gets drained that low. Battery is only 15 months old. Still under warranty.

I do not have a radio. No devices were left charging on the bike. I do not have a security system. But I do have two USB charging devices always on the bike. I know they do draw power, but did not think it was that much power.

It has been chilly here for an April in Piedmont NC. But no sustained temps much lower than 35.

I was surprised at this. The 5 amp charger brought the battery back to 11.5 volts in under 90 minutes. I will leave it on the charger overnight, and ride it tomorrow for about 100 miles before shutting down. The run local errands. It has been chilly here for an April in Piedmont NC. But no sustained temps much lower than 35.

Is this usual?

 

Mine is stock OE battery in my ‘24 FLHP. 22,000 miles. It does have security. I usually keep it on a tender if I don’t plan to ride for more than 3-4 days. I rode about 60 miles a few days ago, did not put it on the tender, then pulled the seat off the next day. The multi-meter said 12.8 volts which is fully charged.

I would check voltage again tomorrow before taking the bike out. If it’s not 12.5 or better I don’t know if I’d trust it.

 

IMHO, a good battery should not be depleted in a week as you describe above. I suspect a bad battery or an unknown (possible new) parasitic draw.

You don't mention how low the battery voltage got..... or for how long it was stored in that depleted condition.

In any case, a battery stored in a drained condition can (will) negatively affect the battery. While the amount of time will be contingent on a several factors, storing a battery at low voltage can kill a previously good battery.

I'd start by load testing the battery...

 

Before my surgery, I rarely let the bike sit for more than 3 days. My RAM 3500 Diesel will sit for 3-4 weeks at times. Solo I'm on the bike. With wife, we are in the minivan.

 

This above.^^^^^^
Charge it overnight, then load test.

 

In addition to this I use a digital tester that takes into consideration the CCA of the battery and gives the percentage of charge and resistance.
It’s proved useful a couple of times for information to give the guy at my local Interstate Battery store before I go there. But he also uses his own tester when I bring a battery in. Kind of a double check.

 

Battery tester on Amazon. I have one. They’ve sold 8,000 of them with good reviews.

Twenty bucks

 

I have a digital and a carbon pile load tester. The carbon pile tester is more accurate as it actually draws a load on the battery that you set it for. The electronic one makes some calculations on smaller draws from the battery.

 

How much power do they each draw? Should be listed on the unit itself or available on line in the instructions/technical specifications of the USB devices.

Maybe list them here so we can see what they are. Any draw on a battery without a recovery phase will bring it down fairly quickly.

 

As stated I use both a load test and the electronic.