DieHard 200.71991 Operator's Manual page 16

13.2 The hydrometer or Electronic Method
To find the time needed to fully charge your battery, determine the bat-
tery'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
1.265
1.225
1.155
1.120
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
NOTE: The Reserve Capacity can be obtained from the battery specifica-
tion sheet or the owner's manual.
To calculate time needed for a charge:
• Find the percent 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, 15, or 60 amps).
• Multiply the results by 1.25 and you will have the total 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
Charger Setting
100 (AH Rating) x .50 (charge needed) x
20 (Charger Setting)
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.
PERCENT Of ChARGE
100%
75%
25%
0%
2
13
• •
PERCENT Of ChARGE
x 1.25
1.25
NEEdEd
0%
25%
75%
100%
= hours of
charge
= 3.125
hours