Charging

Slingshot 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.

Charger 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.

Discharging

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.

Battery Storage

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.