High-G FJR Junkie!
Join Date: Jan 2013
Location: Millgrove, ON, CA
Lots of confusing info about batteries, even urban myths.... educate yourself on the real deal from credible sources....
Using Yuasa's Technical Guide, we have AGM/VRLA batteries, when fully charged and resting voltage checked, should be 12.9-13V. Yuasa says not to discharge below 12.5V (50% charge) as degradation starts and not to discharge it below that multiple times.
That may be the ideal state, but if you have a voltmeter installed direct or plug in a Battery Tender voltmeter into your Battery Tender harness, you can see the voltage before you turn the key on. The FJR has a natural parasitic draw to keep clock/trip meters/ECU memory, and you can monitor how many days it takes to discharge to 12.5V. In theory with that ideal state, time to plug in your Battery Tender if you're not a regular user of one.
Add to this any accessory you may have that is unswitched, such as USB chargers, or GPS left on with a wired direct cradle, and the discharge rate will be even higher.... best have those on an aux. fuse box or on a circuit that is switched on only with ignition. I prefer a voltmeter constantly powered but with a switch I can use to shut it down for storage... again, I'm looking for the voltage before I turn the ignition on.
So, I recommend everyone have a voltmeter, educate yourself, and pick a number where you'd plug in your Battery Tender.
Some just plug in to the Battery Tender when they return from a ride if the bike is going to be sitting for a week, it does keep it up there at 13-13.2. I haven't had an issue with that and most of my batteries last the expected 5 years. OEM's even longer. But that depends where you live..... Arizona and Texas heat will eat a battery in half that.... heat is the enemy.
Keep yer stick on the ice....
2014 FJR1300A - Root Beer (sold)
2009 CBF1000A - Sienna Red
1999 VFR800Fi - Pearl Shining Yellow