Sears 200.71232 - Manual (Page 13)

11
Calculating charge times
• Marine, or deep-cycle batteries are usually rated in
Reserve Capacity (RC).
• NR means that the charger setting is NOT RECOM-
MENDED.
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.
CHARGE RATE/CHARGING TIME - HOURS
6 - 12 AH
12 - 32 AH
40 - 60 RC
60 - 85 RC
85 -190 RC
80 RC
140 RC
160 RC
180 RC
BATTERY SIZE/RATING
SMALL
BATTERIES
CAR/TRUCKS
MARINE/DEEP CYCLE
200 - 315 CCA
315 - 550 CCA
550 - 1000 CCA
Motorcycle, garden
tractor, etc.
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 = 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, 20 or 60
amps).
• Multiply the result by 1.25 and you’ll have the 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 % of charge needed x 1.25 = hours
Charger Setting of
charge
100 (AH Rating) x .50 (charge needed) x 1.25 = 3.125
20 (Charger Setting) hours
100 x .50 = 2.5 x 1.25 = 3.125
20
You would need to charge your 100-Ampere Hour
Battery for a little more than 3 hours at the 20-Amp
charge rate using the above example.
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, 12, 32 AH etc.
• Batteries in cars and smaller trucks are usually rated
in Reserve Capacity (RC), Cold-Cranking Amps
(CCA), or both.
20 AMP
NR
NR
1 - 1½
1½ - 2
2 - 3½
1 ¾
2 ¾
3
3½
2 AMP
2 - 4
4 - 10
11 - 14
14 - 18
18 - 35
18
27
30
33
60 AMP
NR
NR
3 /
8
- ½
½ - 5 /
8
5 /
8
- 1
NR
NR
NR
NR