Sears 200.71201 Calculating charge timeCalculating charge time, Calculating charge timeCalculating charge time Calculating charge time

Sears 201- Sch 506 1/9/98

Calculating charge timeCalculating charge timeCalculating charge timeCalculating charge timeCalculating charge time

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

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 rate

(1.5 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

Charger Setting of

charge

20 (AH Rating) x .50 (charge needed) x 1.25 = 8.33

1.5 (Charger Setting) hours

20 x .5 = 6.66 x 1.25 = 8.33

1.5

You would need to charge your 20-Ampere Hour Bat-

tery for approximately 8 hours at the 1.5-Amp charge

rate using the above example.