recommends the use of a high end battery charger for charging
your matched battery packs. The charger should be identified
as safe for NiMh batteries and include adjustable Delta V
settings should be set to 5 amps with the lowest delta peak
setting available on the charger (3-5mV per cell). Higher
charge rates can be used to gain increased voltage into and
out of the battery but care is to be taken that the
temperature of the battery does not increase past 125-130º.
If the battery is over heated due to the settings of charge
rate or delta peak setting being set to high risk of permanent
damage or explosion of the cell can occur. Batteries should
NEVER be left unattended while charging. Also monitor the
temperature of the battery during the first few cycles to make
sure the charger settings are not overheating the cells.
Slingshot does not recommend charging battery packs over 6
amps for racing applications.
The most valuable tool you can
have to maintain top performance of your battery packs is a
good discharging tray to equalize your battery packs. There
are many good discharge trays on the market to day but we
recommend the Novak Smart Tray. It will cut off each
individual cell when it is discharged to a specified voltage.
Discharge/equalizing trays are important since the discharge
the individual cells in the battery pack. When charging and
discharging a battery pack one or more cells will hold more of
a charge then the others which over time will reduce overall
performance of the battery pack. This will happen regardless
of how well the cells of the battery are “matched”. To
ensure the best lasting performance of the battery pack a
discharge/equalizing tray is invaluable.
How to use the tray. Most
discharge equalizing trays on the market do not discharge at a
very high amp rate. This results in a more accurate voltage
cutoff but takes longer to drain todays high mah batteries
down to a .9V cutoff. It is recommended after the battery pack
has been run in the car to discharge the battery using a bulb
discharger or if you charger has a discharge function to use
that to bring the voltage down on the entire battery pack.
Once the battery has been brought down as a whole and allowed
to cool, then place the battery pack on the discharge tray to
equalize the cells. This method of discharging has been proven
to help maintain the low internal resistance and high voltage
of you new Slingshot battery pack.
If you run your batteries on a
regular basis (every one to two weeks) then it is recommended
that you store the batteries after being equalized on a
battery tray. Before the first charge of the day it is a good
idea to re-equalize the batteries on the tray before charging
as the battery will have regenerated voltage during it’s
rest time. This equalize just before the charge will help the
battery take a better full charge.
If you plan on not running the
batteries for more then two weeks it is recommended that you
put at least 10-15 minutes of charge on the pack prior to
storage. Over a long period of time (a month or so) the
battery will actually discharge itself. This is a normal for
these types of batteries but if being stored for an extended
period of time it is recommended to store them with a some
charge in the pack. Prior to use the next time after long term
storage you will want to discharge and equalize the battery
pack prior to charging. The first run of the battery pack may
feel a little flat after prolonged storage but the battery
should regain previous top performance after one full cycle.