It’s important to distinguish between full-fledged battery chargers and products designed to maintain batteries that have already been charged.
Battery chargers by any other name might be different
Trickle chargers, battery maintainers, float chargers and smart chargers are confusing terms you’ll find when shopping for a way to keep batteries charged while tractors, combines, motorcycles and boats are in storage this winter.
Choose your power wisely. Battery trickle chargers provide a constant flow of low-amperage current. Trickle charger capacities range from 500 milli- amps to 10 or 20 amps. A trickle charger can slowly bring a discharged battery to full charge, but its output must match the size of the battery.
"If you put a 500-milliamp trickle charger designed for a motorcycle battery on a big tractor battery, the self-discharge rate of the tractor battery, along with parasitical loads from
onboard computers, clocks and other electronics, might exceed the charging rate of the trickle charger. The battery would eventually become discharged even if it was plugged into the trickle charger all winter," explains Jim O’Hara of Clore Automotive. "If you put a 10-amp trickle charger on a little motorcycle battery, you would probably overcharge and damage it."
Not only must trickle chargers be sized to match batteries, they are "dumb" and need to be managed. A charger provides its designated 1, 2 or 10 amps of charge whether the battery needs it or not. Trickle chargers should not be left attached to batteries for extended periods of time.
"The user has to monitor the battery’s condition and manually connect or disconnect the trickle charger as needed," O’Hara says.
Maintain the charge. Technically, battery maintainers and float chargers aren’t full-fledged battery chargers. They are designed to maintain batteries that were fully charged before being put into storage. Designs vary, but most battery maintainers and float chargers have a built-in monitoring system. It turns the unit on when battery voltage goes below a specified value and turns the unit off when battery voltage exceeds a specified value.
Battery maintainers and float chargers can often be connected to batteries throughout storage. Users must read instructions on the label of battery maintainers and float chargers to ensure the units have charge rates and cycle times that are appropriate to the batteries to which they are connected.
Smart chargers use built-in technology to not only keep batteries charged during storage but also to optimize battery longevity.
"Our smart chargers are designed to be left connected to a battery, bring it to full charge, then shut off and monitor its charge," O’Hara says. "When the battery’s charge falls below a certain value, the smart charger brings it back to full charge. We’ve found it’s better to let batteries that aren’t being used regularly discharge slightly before bringing them back to full charge."
Because of many different designs, buyers must carefully decipher exactly what manufacturers mean by "smart."
"True smart chargers alter the charging regime based on feedback from the battery," says Luke Case, executive sales director for NOCO. "The char-ger automatically alters the charge current and voltage based on the battery’s needs. Our NOCO-brand smart chargers, and a few others on the market, use switched-mode technology [also called pulse technology] to safely charge and maintain batteries."
Case notes that smart chargers require adjustments before being left on batteries in storage.
"Smart chargers usually have different settings for flooded cell, AGM [absorbed glass mat] or gel-type batteries," Case says. "Each type of battery requires unique voltage and charging cycles. Charging an AGM battery with the charger set for a flooded-cell lead-acid battery can damage the battery.
"Owners need to know what type of battery is in their vehicle and make certain a smart charger is set for that type of battery," Case says.
Battery 'Mold' Explained—and Prevented
The whitish-yellowish corrosion that erodes battery terminal clamps and the black film that reduces conductivity between battery terminals and battery terminal clamps are caused by acids that leak from batteries.
The whitish-yellowish slime and powder that builds on battery terminal clamps is due to chemical reactions within the battery that can create acidic vapors and hydrogen gas. The vapors escape from the vents of a flooded-cell lead-acid battery and attack bare, ferrous metal surfaces inside battery boxes—most notoriously, battery cable clamp bolts and battery hold-down bolts.
To minimize corrosion, keep metal surfaces within battery boxes painted so no bare metal is exposed to the corrosive vapors.
Ventilating battery boxes reduces buildup of corrosive vapors and explosive hydrogen gas. However, dust and field debris can build on top of batteries and mix with the acidic vapor or liquid to create a conductive path between the positive and negative terminals, which can cause the self-discharge of batteries during storage. Any vents in battery boxes should be filtered or baffled to allow air movement but minimize dust infiltration.
Another factor that contributes to corrosion on battery terminals is acidic liquid, which can wick up the sides of battery posts. The tops of new batteries are tightly sealed around battery posts, but mechanical vibration in farm equipment and tugging or prying during installation or when tightening battery terminal clamps can disrupt the post-to-battery case seal.
When acidic liquid wicks up the sides of the posts and insinuates itself between the posts and the terminal clamps, it creates a thin, black, nonconductive layer of corrosion that must be scraped from the outsides of battery terminals and the insides of battery clamps to regain full electrical conductivity.
"The little treated fiber washers you slip over battery terminals before you install the battery terminal clamps can reduce corrosion buildup on battery posts," says Roy Hellmund, technical services specialist with Interstate Batteries. "The specialized battery terminal treatments you wipe or spray onto terminals work, too. But plain old high-temperature grease is a great alternative. You get the same sealing effect, which prevents the acid from attacking the terminal clamps."
- January 2012