Buying tips—industrial battery chargers

What should you consider when buying an industrial battery charger?

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

Know the type you need.
Each of the three types of battery chargers—magnetic-amplifier, ferroresonance and SCR-bridge—has benefits and drawbacks. Study your needs carefully to make an informed choice.

Price is only one part of the equation.
Do not buy based on price alone. Over the long run, a higher efficiency rating should yield significant energy savings.

Match the charger to the battery.
Mismatched batteries and chargers can lead to chronic over- or undercharging and shorten battery life.

Amperage matters.
A charger’s size (in Amperes) usually dictates how quickly it can charge a battery. Rapid charge speeds are not always best, however. Too-fast charging can damage battery components. Choose a charger whose charging current (in Amperes) is between 15 and 25 percent of the capacity of the battery (in Ampere-hours, AH).

How many stages do you need?
Chargers with one, two or three stages exhibit very different characteristics and should be used in specific applications only.

  • One-stage chargers are least expensive and charge slowly. Monitor carefully, however: they can cause premature battery failure.
  • Two-stage chargers provide a constant current until the battery reaches capacity. The unit then drops current to a level required only to maintain battery voltage. These units are ideally suited to recharging batteries under load.
  • A three-stage charger is similar to a two-stage charger, but allows a slight overvoltage while the charging current drops off to enable a quicker recharge. Three-stage chargers should be used only in batteries that are not under loads.

Smooth out any ripples.
In battery charger vernacular, the term “ripple” refers to the quality of the current and voltage passing through a battery. High ripple can overheat a battery and shorten its life.

Three-stage chargers typically exhibit lower ripple than one-stage models, but are more expensive to buy.

Keep ergonomics in mind.
Ask yourself whether a battery charger is too heavy to be easily moved. Can it be easily connected and disconnected? Does it protect against damage from reversed connections? Can the unit prevent against overcharging? Will it lose power when the AC input power is shut off? Such considerations can help to prolong a charger’s life.