Sears 200.71211 - 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
RECOMMENED.
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
discharged batteries.
BATTERYSIZE/RATINGI
CHARGE RATE/CHAF GING 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 - 27e
315-550 CCA 60 - 85 RC 14-18 27a - 374
550-1000 CCA 85-190RC 18-35 374 - 7
MARINE/DEEP CYCLE
80 RC 18 372
140 RC 27 572
160 RC 30 6
180RC 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
GRAVITY
PERCENT
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 = Reserve Capacity + 16
2
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.
Example:
Amp Hour Rating X charge needed x 1.25 = hours
Cha rg er Setting of
charge
100 (AH Ratinal x .50 (charge needed) x 1.25 = 6.25
10 (Charger Setting) hours
100 X. 50 = 5 X 1.25 = 6.25
10
You would need to charge your 100-Ampere Hour Bat­
tery for approximately 6V4 hours at the 10-Amp charge
rate using the above example.