Battery chargers

Model Airplane News, Oct 2001 by Hunt, Tom

14 of our Favorites and why we like them

A good battery charger is one of the most valuable pieces of equipment you can purchase for your RC hobby. For the batteries that power our radios and drive our electric models to operate reliably and predictably, we need to take care of them properly.

We asked Model Airplane News contributors and editors which are their favorite chargers and why. This article highlights some of these chargers and offers advice on purchasing your next battery charger.

Several types of chargers are available, ranging from the very simple and inexpensive to the high-tech, multi-function type. First, you have to decide which type of battery packs you need to charge. Will you charge only your radio's battery packs, or will you charge high-- capacity drive battery packs? Perhaps you want a charger capable of doing both. Do you want a field charger, or one you can use in the workshop? Some can be used both indoors and out.

The simplest and least expensive charger is the fixed-rate timer-- type. Though economical, it has limited use, and you risk overcharging and damaging your batteries if you charge them too long. You must constantly check your pack to be Sure it doesn't overheat.

The most popular charger is the "peak, detection" type that can determine when the battery pack has reached full capacity; it then automatically shuts off the fast-charge rate.

AC OR DC?

Basically, chargers are available with two input-voltage requirements AC (alternating current; normal household 110 voltage) and DC (direct current; 12 volts supplied by a high-capacity automotive battery). AC chargers simply plug into a wall socket, and they contain a rectifier that converts the AC input current into DC output current. DC chargers have two alligator clips that you attach to the automotive battery's terminals to power the charger. Some chargers also come with a power-adapter plug that can be inserted into a car's cigarette lighter socket.

CHARGE AMPERAGE

CHARGE AMPERAGE

Amperage is the measurement of the output current supplied by the charger. The greater the amperage, the more quickly your pack will be charged. The type and size of the cells in your pack determine what the amperage should be, and you will have to adjust your charger's output accordingly. Chargers are available in fixed, selectable and adjustable amperage output.

* Fixed output chargers usually have a timer that sets the length of time you charge your battery pack. The timer counts down and then turns off the output current.

* Selectable output chargers have two, three, or more amperage settings that you select before you attach your batteries; the charger quick-charges the pack, and when the battery is fully charged, it switches to a trickle-charge rate.

* Adjustable output chargers work like selectable chargers but allow you to precisely adjust the output current with a dial, knob, or button. Typically, the output range is from 0.5 to 5 amps. Again, after the fast charge is complete, the charger switches to a trickle rate.

CHARGE RATES

The three basic rates for charging battery packs are: "fast (or quick),"overnight" and "trickle." The fast/quick rate is typically used at the flying field and will usually recharge your battery pack to full capacity in about half an hour. Depending on the type of battery you charge, the fast rate is about two times (2C) or threee times (3C) the battery's capacity in milliamp hours (mAh). For example: for a 1000mAh (one amp hour) pack, the charge rate would be 2 or 3 amps.

The overnight charge (or "slow" rate) takes about 10 to 24 hours to fully charge a battery pack using roughly 1/10 (C/10) of the battery's capacity as the charge rate, e.g., 50mA for a 500mAh pack.

Thr trickle rate is a low-level charge that should be about 1/50 (C/50) of the battery capacity (20mA for a 1000mAh pack.) Your battery pack can be left on trickle charge indefinitely without harming the cells.

For the health and well-being of your battery packs, it is very importantly to property match the charge rate-duration to the size and type of cell you charge.

Ace Hobby Distributors, 116 W 19th St., Higginsville, MO 64037-- 0472; (800) 322-7121; (660) 584-7121; fax (660) 584-7766; acehobby@ctcis.net; www.acehobby.com

AstroFlight Inc., 13311 Beach Ave., Marina del Rey, CA 90292; (310) 821-6242; fax (310) 822-6637; www.astroflight.com.

Batteries America, aka E. H. Yost & Co., 2211 D Parview Rd., Middleton, WI 53562; (608) 831-3443; ehyost@midplains.net; www.batteriesamerica.com.

Bob Selman Designs, 9054 Bum Rd., Carthage, MO 64836; bselman@janics.com; bsd.domnainvalet.com.

Dymond Modelsport USA Ltd., 683 N. Main St., Oshkosh, WI 54901; (888) 4FUN FLY; (920) 303-1100; fax (920) 303-2021; www.rc-dymond.com.

FMA Direct, 9607 Dr. Perry Rd., Unit 109, Ijamsville, MD 21754; (800) 343-2934; fax (301) 831-8987; www.fmadirect.com.

Great Planes Model Distributors Co., PO. Box 9021, Champaign, IL 61826-9021; (800) 682-8948; fax (217) 398-0008; www.greatplanes.com.

Hitec RCD Inc., 12115 Paine St., Poway, CA 92064; (858) 748-6948; fax (858) 748-1767; www.hitecrcd.com.