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Industrial Battery Chargers

Purchasing Tips

  1. Be familiar with the three main types of battery chargers in use: Magnetic-amplifier, Ferroresonance, SCR-bridge.
  2. Know the benefits and tradeoffs of the different types.
  3. Assess your needs and current usage carefully.


Efficiency has little effect on charger prices. Capacity (in Ampere-hours), whether it is a one-phase or three-phase device, and optional features lead to great variations in price.

Manufacturers' prices for small-capacity chargers (less than 100A) for forklifts, golf carts and other motive applications range from approximately $80 to $3000. Large capacity chargers are typically customized and cost from $1500 to $30,000. The full-load efficiency of small capacity chargers is typically about 70 percent to 85 percent. Large capacity chargers have a full-load efficiency of about 80 percent to 90 percent.

Consider ergonomics

  1. Is the charger too large or heavy for easy positioning and access?
  2. Can it be easily connected and disconnected?
  3. Will it prevent potential damage from reversed battery connection?
  4. Does it have electronics that will prevent overcharging the battery if left unattended?
  5. Will it drain the battery if AC input power is shut off?

Consider charger operation

Battery chargers have optimal charging characteristics. Match chargers and batteries carefully, as a mismatch can lead to overcharging or undercharging. Consult the manufacturer to make sure their product is suitable for your application and that the charger will help preserve optimal battery capacity and life. Pay special attention to the safety instructions provided by the manufacturer.

Consider Amperage

The size (in Amperes) of a charger gives a general indication of how quickly a battery may be charged. It is generally better to charge a battery slowly. Rapid charging may damage internal battery components. Typical industry sizing guidelines recommend that the charging current (in Amperes) should be 15-25 percent of the capacity of the battery (in Ampere-hours, AH). A 100A charger, for example, would be a good match for 500AH batteries.

Consider stages

The number of stages does not affect electrical conversion efficiency, but it does have an effect on overall aspects of performance.

One-stage chargers are the least expensive but they charge slowly. Without monitoring, they can cause premature battery failure from overvoltage and water loss.

Two-stage chargers provide a constant current until the battery reaches its rated capacity, after which the current drops off to the level required to maintain the battery voltage. Two-stage chargers can recharge batteries that are under load.

Three-stage chargers are similar to two-stage chargers, except that they allow a slight overvoltage while the charging current drops off, leading to a quicker recharge. Three-stage chargers should only be used when the battery is not under load.

Consider electrical input

Three-phase chargers are typically more efficient and exhibit lower ripple than one-phase chargers, but are more expensive. 'Ripple' refers to the quality of the current and the voltage passing through the battery. High ripple can overheat a battery and shorten its life.

Consider life

Industrial battery chargers are expected to last from 10 to 30 years.

Next: Operation and Maintenance Tips