Sears 200.71221 - Manual (Page 9)

Calculating charge time
The Chart Method
Use the following table to more accurately determine
the time it will take to bring a battery to full charge.
First, identify where your battery fits into the chart.
• Small batteries — motorcycles, garden tractors,
etc. — are usually rated in Ampere Hours (AH).
For example: 6 to 12 AH, or 12 to 32 AH.
• Batteries in cars and smaller trucks are usually
rated in Reserve Capacity (RC), Cold-Cranking
Amps (CCA), or both.
• Marine or deep-cycle batteries are usually rated in
Reserve Capacity (RC).
• NR means that the charger setting is NOT REC­
OMMENDED.
Find your battery's rating on the chart below and note
the charge time given for each charger setting. The
times given are for batteries with a 50-percent charge
prior to recharging. Add more time for severely dis­
charged batteries.
BATTERY SiZE/RATJNG
CHARGE RATE/CHARGING TIME - HOURS
2 AMP 10 AMP
SMALL
BATTERIES
Motorcycle, garden
tractor, etc.
6-12 AH 2-4 NR
12-32 AH 4-10 NR
CAR/TRUCKS
200-315 CCA 40-60 RC 11 -14 2 - 2Ve
315-550 CCA 60 - 85 RC 14-18 2Ve - 3®/4
550-1000 CCA 85 -190 RC 18-35 3Y4 - 7
MARINE/DEEP CYCLE
80 RC 18 3V2
140 RC 27 5V2
160 RC 30 6
180 RC 33 7
The Hydrometer or Electronic Method
To find the time needed to fully charge your battery,
determine the battery’s charge level with a hydrometer
or electronic Percent-of-Charge Tester. The following
table will help you convert hydrometer readings to
percent of charge values.
SPECIFIC PERCENT PERCENT OF
GRAVITY OF CHARGE CHARGE NEEDED
1.265 100% 0%
1.225 75% 25%
1.155 25% 75%
1.120 0% 100%
When you know the percent of charge and the Amp
Hour (AH) rating of your battery, you can calculate the
approximate time needed to bring your battery to a full
charge.
To convert Reserve Capacity to Amp Hours, divide
Reserve Capacity by 2, and add 16:
Amp Hours = Resen/e Capacity + 16
To calculate time needed for a charge:
• Find the percent of charge needed. (A battery at
50 percent charge that will be charged to 100
percent needs another 50 percent (.50).
• Multiply the Amp Hour rating by the charge needed
(.50) and divide by the charger setting
(2 or 10 amps).
• Multiply the result by 1.25 and you’ll have the
approximate time needed, in hours, to bring the
battery to full charge.
• Add one additional hour for a deep-cycle battery.
ExampI«:
Amo Hour Rating x charge needed x 1.25 =
hours
Charger Setting of charge
100 (AH Rating) x ,50 (charge needed) x 1.25 =
6.25
10 (Charger Setting) hours
IOOX.50 = 5 X 1.25 = 6.25
10
You would need to charge your 100-Ampere Hour
Battery for approximately 614 hours at the 10-Amp
charge rate using the above example.