Sears 200.7121 - 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
Resen/e 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 g iven 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.
BATTERY SIZE/RATING
CHARGE RATE/CHÀRGINGTIME - H( DURS
2 AMP 10AMP
SMALL
BATTERIES
Motorcycle, garden
tractor, etc.
6 -12 AH 2-4 NR
12 -32 AH 4- 10 NR
CARДRUCKS
200-315 CCA 40 - 60 RC 11-14 2 - 27e
315-550 CCA 60 - 85 RC 14-18 27в-3^/4
550 -1000 CCA 85-190RC 1 8 - 3 5 З У A - 7
MARINE/DEEP CYCLE
80 RC 18 З У г
140 RC 27 5 У г
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
GRAVITY
PERCENT
OFCHARGE
PERCENT OF
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 -t- 16
2
To calculate time needed f o r 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 hourfor a deep-cycle battery.
Example:
Amp Hour Rating x charge needed x 1.25 = hours
Charger Setting of
charge
100 fAH Rating! x .50 fcharoe 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.