High performance battery chargers with a minimum charge rate of 4 to 5 amps are required to completely charge some of today's high-capacity (3000 - 5000 mah) NiCad and NiMH batteries in one cycle. Most inexpensive manual timer chargers that are available (non-peak chargers) have a 15 to 30-minute timer and a preset charge rate of 4-amps or less. These types of chargers can usually charge a battery pack with 1500 mAh or less in one 30-minute cycle, but they may not be able to charge a high-capacity battery pack without subsequent recharges.
When charged properly, the battery pack should be slightly warm after the charge cycle. If the battery is not warm to the touch, recharge it for another five minutes. If the battery is not warm after the 5-minute re-charge then charge the pack for an additional 2 1/2 minutes. You may have to recharge the pack a couple more times if you're charging a hi-capacity battery pack on a charger with a charge rate that's less than 4 amps. It is important, that you do not leave the battery pack unmonitored during the recharge process. Constantly check the temperature of the pack. The moment the pack becomes warm, disconnect it from the charger to prevent damage from over charging. (Note: It is recommended to charge all NiMH cells with a battery charger made specifically for charging NiMH cells. NiMH cells are more susceptible to damage from over-charging than NiCad cells are. Using a good peak charger designed to charge NiMH cells will prevent damage to the cells from over-charging.)
Peak chargers are very popular because they feature special peak detecting circuitry that senses the moment the battery pack is fully charged and then shuts down to prevent over charging. They usually also feature adjustable charge current ability for use with the smaller 6v rechargeable batteries used inside nitro vehicles. These types of chargers are recommended for high capacity battery packs and onboard 5 cell receiver packs because they usually feature higher, and adjustable amp rates than manual timer chargers and can quick charge a high-capacity pack automatically in 50-minutes or less. A full "peak charge" is required to properly operate Traxxas electric vehicles as well as to allow proper use of the Traxxas EZ-Start equipped nitro vehicles.
If your battery pack is not warm to the touch after one full charge cycle on a peak charger, press the start button to re-peak the battery pack. If the battery is still not warm after the second cycle, either your charger is malfunctioning, or it's time to replace the battery pack. You may want to test your charger with another battery pack that is known to be in good shape. If the other battery pack charges up OK, you've narrowed down the problem to the first battery pack. If the good pack will not accept a charge either, then the charger could be bad. Follow the manufacturer's recommendations for sending in your charger for service.