Chargers

Deciphering the Specifications

A common cause of confusion when shopping for a charger is the specifications. There's quite a few of them, and the information presented to you can get quite complex. Not all chargers will contain all of the features below, so you'll have to decide what's important for you and fits within your budget.

AC/DC Power Supply

Some chargers have the capability of using both an AC electrical outlet, and a DC power supply such as a car battery to power them. This can be a big deciding factor for some people, especially those who may run at a public park or track where an electrical outlet can be non-existent or hard to find. You can still run a AC charger on a car battery, it will just require you to purchase an external AC to DC power supply.

Auto Start Timer

This feature allows you to start charging at a specified time instead of immediately. That way your battery pack has just been peaked when you pull it off of the charger instead of having peaked some time before.

Battery Capacity

The maximum Mah battery pack a charger is recommended to be used with.

Cell Count

A charger is designed to only charge a certain number of cells. If you go above or below the manufacturer's rating you could wind up with a pack that is undercharged or possibly even damaged due to overcharging. Usually this specification is actually a range of cells that it can charge.

Charger Current

The amp rates at which the charger can charge the battery pack.

Cycling

Many of the higher end chargers offer something called cycling or conditioning. This is a mode where the charger discharges and charges the batteries under controlled conditions to keep the batteries in optimum shape and capacity. This is a way to eliminate the memory function that can occur in both NiCad's and NiMH packs. While most people only think NiCad's are subject to memory, NiMH batteries can suffer from this problem as well. It's just not as common as it is with NiCad's. At any rate if you're in the market for a higher-end charger, it's a nice feature to have.

Delta Peak Voltage

This is the threshold that determines the peak voltage indicating a charged condition. Since NiCad batteries and NiMH batteries have different peak detection voltages, many chargers allow you to tailor this setting within a certain range to help better charge your packs without overcharging them.

Delay Time After Charge/Discharge

Some chargers will allow you to tailor the time between step of a charge/discharge cycle to allow the pack time to cool.

Discharge Current

Many chargers can also act as a discharger. This specification explains the rates at which the battery can be discharged.

Flex Charging

This method of charging starts out at a fixed rate but at several points during the charge, it's interrupted with short bursts of discharging. This is often used to revive older batteries and restore much of their usefulness. This is used on NiCad packs, and usually isn't recommended on NiMH packs.

Internal Cooling Fan

Charger produce a lot of heat when they charge a battery pack. Many chargers have an internal fan to help keep the electronics in the charger cool.

LCD Display

Some chargers actually provide a LCD display, much like a calculator, showing you your setup menus and charger status. Some chargers will also have a backlit LCD display, so that you can easily read the display in darker surroundings. Basic chargers will just have LED indicator lights.

Linear Charging

This type of charging charges a pack at a fixed rate until the battery has reached it's capacity. This is commonly used with NiMH battery packs.

NiCad/NiMH Compatibility

When purchasing a charger you will also have to make a decision of whether you need NiMH compatibility. Right now NiCad's are more commonly used, but advances in NiMH technology are trying to put them on a level playing field with NiCad's for about the same amount of money. For more information about NiCad's and NiMH, and their differences, see my section entitled Batteries.

If you plan on using NiMH, the charger has to be capable of charging at a rate that will not harm NiMH cells. Unless the charger states that it can charge NiMH packs, it cannot safely do so. Ignoring the compatibility issue will damage your NiMH packs, eventually forcing you to replace them prematurely.

Overload and Reverse Polarity Protection

This is a feature to help prevent damage in the event you set the charger up incorrectly. It's not a substitute for reading the directions however.

Trickle Charging

Trickle charging uses a very low rate to charge the battery pack. Often trickle charging is used as the first charge on a new pack. Also many chargers revert to trickle charging once they've reached their peak threshold.

Trickle Current

The rates at which the charger will charge while in trickle, or slow charge, mode.

Part One:	Introduction to Chargers
Part Two:	Deciphering the Specifications
Part Three:	Recommended and Popular Chargers
Part Four:	Charger Comparision
Part Five:	Using a Timed Charger