Battery packs

There are 3 basic types of battery chargers:

Pulse chargers are designed to mix a discharge pulse (negative charge) with a charge pulse (positive charge) 1 negative to 5 positive, this breaks up the crystals to be dissolved.

Linear Chargers supply the battery with a constant uninterrupted supply of positive charge usually controlled by a timer.

Auto Peak Chargers shut off by detecting the voltage rise and drop during the charge cycle, when a battery reaches full capacity, the voltage peaks and then begins to drop off; the charger detects the drop and shuts off.

There is a large verity of manufacturers that make a model with one or all three features listed above.
Other variations include adjustable amp output AC/DC input options and number of cells of which the most common are 6 cell and 7 cell, some can go as high as 24.

For example purpose I am showing some DuraTrax models with specs below.
Some other good brands are Tekin, Piranha ( Duratrax), Novak and MRC

Personally I use the DuraTrax IntelliPeak AC/DC Pulse Charger and the Novak digi peak plus battery charger, on average it takes 15 minutes to charge a 6 cell battery, 20 minutes to charge a 7 cell battery and on a typical race day I usually have 8 packs fully charged, that is why I also have several linear chargers (pretty cheap on eBay), I use these to charge other batteries when my main chargers are in use, then top them off with the peak chargers, I also use them as a trickle charge to keep the batteries up just before a race and as a discharger after.

DuraTrax IntelliPeak AC/DC Pulse Charger for Charging/Discharging Nickel Cadmium (NiCd) and Nickel Metal Hydride (NiMH) Battery Packs. Output: 4-7 cells on DC, 4-8 cells on AC. Adjustable fast Pulsed charge current of 0.5-4.0Amp AC, 0.5-6.5Amp DC. (Note: 3A maximum charge rate recommended with NiMH packs.) 100mA TRICKLE charge. 1A fixed discharge rate. Fixed 2.60V discharge cutoff voltage- Cycle functions: Select a single discharge/charge cycle for periodic pack conditioning, or continuous "auto-repeat" cycles for reviving batteries that have developed a memory, or breaking in a new pack.

DuraTrax IntelliPeak DC Only Mini Pulse Charger for Charging/Discharging Nickel Cadmium (NiCd) and Nickel Metal Hydride (NiMH) Battery Packs. This model can use AC input power with the DuraTrax Compact Switching Power Supply purchased separately. Specs are same as AC/DC model

Deluxe Pulse Charger: Adds to the Mini Pulse Charger's features with DC input, detachable AC power supply. 2 and 10 amp discharge rate (faster discharge ability). Negative Delta V (for NiCds) and Zero Delta V (for NiMHs) peak technologies, auto-selects. High rate charging for high-capacity NiMH packs. Two built-in cooling fans.
Typical Linear Charger
Hobbico #900 AC/DC Auto-Charger used for charging 6-7 Cell Sub-C size Battery Packs w/Kyosho Adapter 15 minutes timer shuts off, TRICKLE Charge starts w/LED indicator light, TRICKLE Charge Light DC Input Wire w/Alligator Clips and 5-1/2' AC Input Cord. SPECS: Pack Rating Charge Time in Minutes: 1300 to 1500mAh: 15 - 23 minutes 1700 to 2000mAh: 28 - 33 minutes approx. Fastcharge Rate: 2.5 Amps TRICKLE Charge Rate: 100mA Power Source: 12V DC or 110V AC US Standard
False peak is when a fluctuation occurs for any reason from the power source or connections to the battery. Trickle charging is a low charge rate that keeps the battery from self discharging, thus maintaining a full capacity charge, NiCad cells lose power naturally at a rate of about 1% to 5% a day. Charging rates are a personal preference on adjustable chargers, some have ranges of 1 to 10 amps or higher, some give charts relating to the type of your cell and power source (AC or DC) personally I never exceed 5 amps. Most non-adjustable chargers operate at 3 amps quick charge and approx. 1 amp trickle. NiCad's will develop a memory, if a battery is not fully discharged when charged again; a false capacity will develop giving a shorter run time. Discharging a NiCad the voltage should not go below .5 volts per cell (3 volts for a 6 cell pack) if voltage drops below .5 volts per cell, this can cause "Cell Reversal" and can cause permanent damage to the cell. Most auto chargers are programmed to stop at this voltage. If you feel a battery has developed a memory, you will need to perform a series of charge/discharge cycles (Cycling the battery).