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Q&A: Battery Chargers

Written by William C. Shumay Jr. for Arcon Equipment Inc., published in the Material Handling Wholesaler
copyright © William C. Shumay Jr.
For more articles, please visit http://www.arconequipment.com

Let’s take a look at some common questions electric lift truck owners and dealers ask about the battery charger:

1. "I have an older charger that makes a very loud buzzing sound. Is this easy to fix?"

If the sound comes from the A.C. contactor, the repair can be as simple as either cleaning the dirt and dust off its armature surfaces, or replacing the contactor entirely. If the sound emanates from a transformer, this is much more serious, and should be inspected by a charger expert.

Sometimes, a loose panel on the charger cabinet can pick up a 60hz hum from the transformer field and vibrate loudly. Tighten up all of the sheet metal fasteners to eliminate this.

2. "My charger shows no readings on the meter, but I hear a slight hum. Is it charging the battery?"

If a working panel meter shows zero, the battery is not receiving a charge. Check the cable and battery connectors to ensure that they are undamaged and properly mated. If the meter needle moves as you move the cable or connector, you have a bad connection that must be fixed promptly.

Check the polarity of the connector to make sure that it has not been put on the charger cables backwards. If this is the case, it is also likely that the D.C. fuse inside the charger is blown.

3. "Why does the charger meter read low on some batteries and high on others?"

Battery chargers will charge at lower rates on batteries that already have some charge in them. In fact, most properly adjusted chargers will drop down to approximately 20 percent of their starting rates during the last three hours of the charge cycle. If a discharged battery will not take a full starting rate charge, a bad cell or internal battery problem (sulfation) may be the cause. If a sulfated battery will take any current at all, extended charging may bring the battery back to operational condition.

4. "My charger meter reads substantially lower than the nameplate maximum, no matter which battery I plug it into. Is there a simple troubleshooting procedure? "

First, make certain that the battery you are hooking up is in good condition (not sulfated due to long-term uncharged storage) and in a discharged condition (2.00 V per cell open voltage or less). A discharged battery will begin its charge at approximately 18 amps per 100 ampere-hour of battery capacity.

If the charger indicates a starting current substantially less than that recommended, check all meter connections (with power off) and make certain that fuses for all three phases are good. Many three phase chargers will still operate with one phase out, but at reduced current output. If low output persists, a capacitor or diode may be faulty and you should contact an experienced service person.

5. "When I turn the charger timer knob on, it doesn»t move even after I check it a couple hours later. Why? "

You may have a charger with an 80 percent relay that doesn»t activate the timer until the last 3 hours of the charging cycle. If the charger does shut off after an eight hour charge, your timer is okay. If the charger does not shut off at all, then you either have a faulty timer, a faulty or improperly adjusted relay, or a battery that will not reach sufficient voltage (2.35 volts/cell) to activate the relay. A battery in this condition will also get hot on charge and cannot be placed into normal service.

Charger relays can be tricky to adjust, and this should be done by qualified service people only. It is now a common practice to replace unreliable timers and relays with an automatic electronic control, that starts when the battery is plugged in, and stops as soon as the battery is properly charged. If an algorithmic microprocessor charger control is selected, even older batteries will receive a proper charge without overheating. This type of control is self contained in a small box with indicator lights, and is installed by hooking up four wires.

6. "I have a 36-volt golf cart battery charger. Can I use this to charge my big lift truck battery? "

Your golf cart charger»s maximum output may barely be the finish rate needed by your big battery. As the battery charges, this low rate will drop even further and be far too low to properly mix the battery’s electrolyte.

An undersize charger can take a very long time to completely charge a battery, and it will eventually harm the battery’s performance because of its abnormally low finish rate.

All chargers should be periodically inspected for proper operation. The start/finish rates and 80 percent relay should be checked for proper calibration on a yearly basis. Battery life can be considerably reduced if the charger is out of adjustment.

Pay attention to the cooling needs of your charger. Dust and dirt should be blown out periodically to allow heat sinks and transformers to shed heat properly. And always make sure that the charger’s ventilation openings are clear of obstruction.

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

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