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More Battery Charger Questions and Answers

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

Q: My auto control charger will not turn on if I plug in my completely dead battery. Why?

A: The charger is looking for a battery voltage that tells it that the right battery is plugged in. As a safety feature, most auto controls will not, for example, allow a 36-volt charger to start if you plug in a 24-volt battery. If you plug in a battery that is extremely deeply discharged, the charger may not see the voltage it needs to OK a startup. You will need to find a charger with a manual "on" switch to get things on the right footing. After an hour or so of charging on the manually controlled unit, you may be able to return the battery to the auto control charger for its normal charge.

If your dead battery has been sitting in that condition for months, then sulfation of the battery becomes a factor. The auto control may see strange voltages immediately upon start-up (if it does start) and may just as quickly shut down again with a "full charge" light showing. As with the dead battery example above, the answer is to plug into an old-fashioned timer-controlled charger, one with a knob you can manually turn to activate it. After some extended charging (could be a day or two), a sulfated battery may begin to accept normal currents, but don’t expect much for many hours.

Q: The light on my charger’s auto control panel flashes at the end of a charge. Does this mean the charger is the problem?

A: If the light is flashing a "fault"signal (see your control’s instructions), the computer control may have determined that your battery did not attain proper voltage during the normal charging time. Since many computerized charging controls do not make a distinction between problems caused by the battery or by the charger, the fault signal could be the result of a battery problem caused by one or more cells failing, but it might be caused by low or absent charging current due to failure of a charger component, an interruption in the AC power source (fuse blown, breaker switched off, etc.), or a poor or intermittent connection to the battery.

As a battery ages, it may no longer be able to attain a voltage that the auto control recognizes as appropriate to a fully charged battery, even though the old battery may be at its maximum charge point when it is removed from the charger in the morning. In such a circumstance, the fault light code will usually flash after the charge cycle is completed, but this does not necessarily mean the charger was prematurely shut down.

Many 3-phase chargers will still charge at a reduced rate with a single AC fuse blown, but this will result in insufficient battery charging current– a condition that could trigger a fault signal. Check the AC fuses (or overload breakers) inside the charger cabinet as well as those in the wall box. If the charger has just been installed, be sure that it is not wired to a breaker that is routinely shut off at closing time.

Always remember to check those internal fuses whenever charger output is absent or reduced. An auto control panel may light up and go through the motions even though no AC power is being fed to the charger– many auto control circuits are powered by battery voltage alone– but no current will flow, and the auto control will ultimately signal with a fault code.

Q: I’ve heard that cleaning connector tips by sanding or filing is not a good idea, but what if they are corroded?

A: Battery and charger connector tips, as well as lift truck contactor tips, are typically coated with a layer of silver. Silver provides an ideal contact surface because of its very high electrical conductivity and a special property: corroded (oxidized or tarnished) silver surfaces also conduct electricity well. This is certainly not true for the other metal conductors used in battery construction– copper and lead oxides are very poor electrical conductors.

Sanding or filing of tarnished silver-plated tips to brighten them is completely unnecessary, and this tends to remove the valuable silver layer. There is also the danger of distorting or roughening the mating surfaces of these high-amperage contacts and severely reducing their current-carrying capability. Tar, varnish, grease, or other contaminants can be removed by wiping with an appropriate solvent.

Remember, connectors that have been operating with poor contact may have been heating. This will aggravate the connection problem by weakening the contact tip springs in the housing and softening and distorting the thermoplastic housing itself. If the tips have been crimped in place on the ends of the cables, oxidation (due to extended heating) on copper surfaces within the crimped area can compromise current carrying capability. When in doubt, replace all parts, and cut the cable back several inches to an area of bright, unoxidized copper for a crimping surface.

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

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