Battery Performance; Charging Procedure - DeWalt DW937 Instruction Manual

• Disconnect the charger from the outlet before attempting any
cleaning. This will reduce the risk of electric shock. Removing
the battery pack will not reduce this risk.
• NEVER attempt to connect 2 chargers together.
• The charger is designed to operate on standard household
electrical power (120 Volts). Do not attempt to use it on any
other voltage. This does not apply to the vehicular charger.

Battery Performance

Some chargers have a Tune-Up™ feature that optimizes battery pack
performance. Your charger may provide automatic Tune-Up™ mode
or manual (i.e., push button) Tune-Up™ mode. For information on
this feature, please see the appropriate section below. Because bat-
teries slowly lose their charge when they are not on the charger, the
best place to keep your battery pack is on the charger at all times.
USING AUTOMATIC TUNE-UP™ MODE
The automatic Tune-Up™ Mode equalizes or balances the individual
cells in the battery pack allowing it to function at peak capacity.
Battery packs should be tuned up weekly or after 10 charge/dis-
charge cycles or whenever the pack no longer delivers the same
amount of work. To use the automatic Tune-Up™, place the battery
pack in the charger and leave it for at least 8 hours. The charger will
cycle through the following modes.
1. The red light will blink continuously indicating that the 1-hour
charge cycle has started.
2. When the 1-hour charge cycle is complete, the light will stay on
continuously and will no longer blink. This indicates that the pack
is fully charged and can be used at this time.
3. Whenever the pack is left in the charger after the initial 1-hour
charge, the charger will begin the automatic Tune-Up™ Mode.
This mode continues up to 8 hours or until the individual cells in
the battery pack are equalized. The battery pack is ready for use
and can be removed at any time during the Tune-Up™ Mode.
4. Once the automatic Tune-Up™ Mode is complete the charger will
transition to a maintenance charge; the indicator light shuts off
when the automatic Tune-Up™ Mode is complete.
USING THE MANUAL TUNE-UP™ MODE
The manual Tune-Up™ mode equalizes or balances the individual
cells in the battery pack allowing it to function at peak capacity. This
mode takes up to 8 hours to complete. Battery packs should be tuned
up weekly or after 10 charge/discharge cycles or whenever the pack
no longer delivers the same amount of work.
1. To tune up your battery pack, place the battery in the charger as
usual. The red light will blink continuously indicating that the
charge cycle has started.
2. Press the Tune-Up™ Mode button any time after the charge cycle
has started. The red light will stop blinking momentarily, blink
quickly 3 times, and then resume blinking continuously. The
charger is now tuning up the cells in your battery.
3. When the Tune-Up™ mode cycle is complete, the light will stay on
continuously. The pack is fully charged and may be used at this
time or left in the charger.
4. If you select Tune-Up™ Mode and then change your mind,
remove the battery from the charger. After 5 seconds, insert the
battery into the charger. The normal charge cycle will begin.
SAVE THESE INSTRUCTIONS
FOR FUTURE USE

Charging Procedure

1. Plug the charger into an appropriate outlet as shown in Figure 1.
2. Insert the battery pack into the charger. The red (charging) light
will blink continuously indicating that the charging process has
started.
3. The completion of charge will be indicated by the red light remain-
ing ON continuously. The pack is fully charged and may be used
at this time or left in the charger.
5