Schumacher Automatic PWI70300A User Manual

Page 9

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Using the Battery Voltage Tester
Overview

This battery charger has a built-in voltmeter to test your battery’s state of charge. The

charger does not have a built in load tester. As such, a recently charged battery could

have a temporarily high voltage due to what is known as “surface charge”. The voltage

of such a battery will gradually drop during the period immediately after the charging

system is disengaged. Consequently, the tester could display inconsistent values for

such a battery. For a more accurate reading, the surface charge should be removed

by temporarily creating a load on the battery, such as by turning on lights or other

accessories for a couple of minutes before you read the display. Read it a couple of

minutes after you have shut the headlights off.
Testing Sequence: There are four basic steps required to test the battery state of charge:

1. With the charger unplugged from the AC outlet, connect the charger to the battery

following the instructions given in Sections 5 and 6.

2. Set the charge rate switch and the timer to the OFF position.
3. Plug the charger AC power cord into the AC outlet, following the instructions given in

Section 7.

4. Read the voltage on the voltmeter.

General Charging Notes
Fan: The charger is designed to control its cooling fan for efficient operation. It is normal

for the fan to start and stop when maintaining a fully charged battery. Keep the area

near the charger clear of obstructions to allow the fan to operate efficiently.
Voltage: The voltage displayed during charging is the charging voltage and is usually

higher than the battery’s resting voltage.

12. CALCULATING CHARGE TIME

Use the following table to determine the time it will take to bring a battery to full charge.

First, identify where your battery fits into the chart.
NR means that the charger setting is NOT RECOMMENDED.
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% charge prior to recharging.

Add more time for severely discharged batteries.

BATTERY SIZE/RATING

CHARGE RATE/CHARGING TIME

4 AMP

20 AMP

40 AMP

70 AMP

SMALL

BATTERIES

Motorcycle,

garden,

tractor, etc.

6 - 12 AH

1 - 2 hrs

12 - 32 AH

2 - 5 hrs

CARS/

TRUCKS

200 - 315 CCA

40 - 60 RC 5½ - 7¼ hrs

1 - 1½ hrs

½ - ¾ hr

20 - 30 min

315 - 550 CCA

60 - 85 RC 7¼ - 9¼ hrs

1½ - 2 hrs

¾ - 1 hr

30 - 40 min

550 - 1000 CCA 80 - 190 RC

9¼ - 17½

hrs

2 - 3½ hrs

1 - 1¾ hrs

40 min - 1 hr

MARINE/DEEP-CYCLE

80 RC

8¾ hrs

1¾ hrs

140 RC

13½ hrs

2¾ hrs

160 RC

15 hrs

3 hrs

180 RC

16½ hrs

3½ hrs