- Yuasa Battery, Inc. Automobile Battery Charger User Manual

Let’s see what happens as the two work together to
discharge a battery:
The battery, starting out 100% charged, has a 30mA
discharge rate from electrical accessories on the
motorcycle.
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 dou-
ble 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.
Does the surface the vehicle’s parked on, or a battery’s
sitting on, contribute to how well it holds a charge?
You sometimes hear “experts” say parking on concrete
will accelerate discharge. Bet them it’s not so. Then
collect. Concrete, macadam, wood, dirt, stones, sand
– makes no difference. A battery discharges at the
same rate, no matter what surface it’s on.
And here’s a hint: if a battery suddenly dies and there’s
no apparent reason for it, check the electrical system
before you buy a new battery. One of life’s little let-
downs is to shell out dollars for a new battery when
you didn’t need to – and then still have the problem.
POINTS TO REMEMBER
❐ Conventional lead-antimony batteries discharge @ 1/100 volt per day.
❐
Lead-calcium batteries discharge more slowly @ 1/300 volt per day.
❐ Higher temperatures mean faster discharge.
❐ Temperatures over 130°F kill batteries.
❐ Self-discharge and short trips cause drain.
❐ The more electrical accessories you add to a bike, the greater the
current drain.
15
3
SECTION
Inspecting, Testing
and Charging
Current Drain
12 Days x 0.030 Amps x 24 Hours = 8.64 AH
8.64 AH
÷ 20 AH (Y50-N18L-A) = 43.0% Available Capacity
PLUS (+)
Self-discharge
1 2 Days ÷ 200 Days to 100% Loss = 6.0% Available Capacity
Total Loss
Current Drain 43.0% Available Capacity
Self-discharge + 6.0% Available Capacity
Loss in 12 Days 49.0% Available Capacity