Fort Worth Motorcycle Riders

It was sitting at 12.7 volts when I unplugged the charger. I already exchanged it, twice. It's a Batteries Plus branded battery. I think I will stay away from their crap going forward.

I was able to get it started and charged enough for the the trickle charger to charge it. I disconnected everything except the digital volt meter. I'll let it charge up to full overnight, then unplug the charger and see what happens.

If it was disconnected and went from 12.7v to 6v in three days, there is something wrong with it.

I just let it sit with just the volt meter connected and it dropped from 12.7 to 12.5 volts. Then I realized the screws weren't tight. I just tightened everything up and will let it sit overnight connected to the charger. I'll restart the test in the morning.

I unplugged the charger from the battery at 9 AM Thursday morning. Volts were reading 12.7. I checked it periodically throughout the day and by 9 PM it was down to 12.5 volts. I left it overnight and at 11:30 AM this morning it was still reading 12.5 volts. I'll let it sit overnight again and see what it reads tomorrow morning. If it hasn't dropped much I will hook the motorcycle connections back up and see if it will start the bike. If it does then I will recharge it to full again and let it sit with just the bike connected to it. See if the bike itself is drawing it down.

AGM sucks.

Agree, but to go from 12 to 6 volts in 3 days something is drawing it down. Just need to figure out what it is. I checked it about an hour ago and it was at 12.4. Slowly dropping, but not fast enough to go from 12 to 6 on it's own.

Chart of the battery voltage in our four bikes. I've kept the bikes anonymous to preserve objectivity.
Vertical Axis on the left is static EMF measured in the traditional "Volts"
Horizontal Axis on the bottom is time in units of "days." Note: multiple measurements per day.
So, span from first to latest measurement just under 2 full days.
Bike 1 Battery is 6 month old AGM from Batteries +. Battery charged in bike and left to sit for about 1 week
Bike 2 Battery is 4 years, 9 months old OEM AGM. Battery charged fully just before starting to record data
Bike 3 Battery is 9 month old AGM from Batteries +. Battery charged in bike and left to sit for more than 1 week
Bike 4 Battery is 8 month old OEM AGM. Bike ridden just before starting to record data, and ridden again just before last measurement. This bike has low parasitic draw due to accessories.
I will continue to gather data for at least a few more days.

I didn't do anything with mine yesterday. This morning the voltage was down to 12.1 volts. I plugged the charger back in. At this point I'm considering the battery weak, but not junk yet. The battery dropped from 12.7 volts to 12.1 volts in 4 days with nothing attached to it, except the volt meter. But that should not be drawing that much voltage.

I think the battery will work as long as it is kept charged. I'll buy a new one next year. I still need to check for parasitic draw, but I need a good battery for that.