Sizing Up a Battery Charger

The battery charger is often the most neglected component of an electric lift truck system. Operators and equipment dealers alike tend to ignore the fact that the battery charger can be the source of short and long term problems unless it is properly sized, adjusted and operated.

The consequences of improper charger operation can be either over or under charging of the battery – either is harmful to truck performance. Overcharging results in overheating and will shorten battery life. An older battery is more susceptible to rapid damage in this way. Undercharging of the battery will make it more likely that the truck will be operating at lower than optimum voltage. Burned contactor tips, overloaded electronic controls and overheated motors result from such low-voltage, high current operation. Also be aware that an undersized charger, even in light duty applications, will not charge that battery sufficiently to properly mix the electrolyte.

In general, here are some guidelines for battery charger troubleshooting:

  1. Make sure battery charger rating matches both voltage and ampere-hour capacity rating of the battery.

  2. Verify that the charger output current is correct. It should be close to the nameplate D.C. current rating when a fully discharged battery is connected (typically, 18 amperes for every ampere-hour of battery rating).

  3. Watch for proper finish behavior. Most chargers settle into a low rate (approx. 4 amperes per 100 ampere–hour of battery rating) three quarters of the way through the charging cycle. If the output current never drops this low, you have charger and battery problems. Adjustment of finish rate onset is critical. If the rate drops to finish rate at the wrong time in the cycle, the battery may be either over-charged or starved.

  4. Check cable and connector integrity. Damaged cable insulation and loose connectors are safety hazards and a repair priority.

  5. Verify that the timer (and relay, if present) is working properly to shut off the charger within designated time limits (usually eight hours). Relay adjustments must be done carefully by a knowledgeable serviceperson. Problems with timers and relays can be eliminated by installing a microprocessor (computerized auto-start) control kit. Older batteries benefit greatly from the precise charging provided by a microprocessor control.

As you can see, it is important to pay attention to the condition of the battery charger. Start by establishing a working relationship with a knowledgeable charger serviceperson. A good charger shop can keep you out of trouble and should be able to offer you a wide selection of used battery chargers to complete any electric truck package you may have. If the charger you have now does not match the rating of the battery, trade it in for a fully tested, adjusted and properly matched charger. It’s worth the effort.

For more information, contact Arcon Equipment Inc. (440) 232-1422.