Yuasa manual states a 10ma load will discarge the bat to 50% in 42 days
From the Yuasa manual
The battery, starting out 100% charged, has a 30mA
discharge rate from electrical accessories on the
At an average outdoor temperature of 77°F a lead antimony
battery loses about half its capacity in only
12 days due to the combination of self-discharge and
current drain. In another 12 days, it’s completely
dead. In other words, it doesn’t take long for the double
whammy of self-discharge/accessory drain to
knock out a battery for good.
If current drain is measurable when the motorcycle is
turned off, you can do one of two things: disconnect
the battery when the vehicle is in storage, or charge the
battery every two weeks to a full charge. However,
cycling – or continually recharging the battery – will
shorten its life. Check the battery’s condition with
either a hydrometer or voltmeter (or a multimeter). The
section on Testing a Battery has details.
Short Trips: What if you use the vehicle now and then –
a couple of times a week for errands, or even daily for
a short trip to work?
You can’t assume that occasional use or
short trips (under 15 or 20 miles) will keep
the battery charged. In fact, they’re probably going
to add to drain, because the bike’s charging system
doesn’t have enough time to make up for losses from
normal starting and self-discharge. You’re going to
have to charge the battery more often. Maybe every
month or so, depending on temperature.