About Batteries


Once you have purchased a 12 Volt DC powered light trap, the next item you purchase will be a 12 volt lead acid battery to operate the light trap. Light trap owners are very battery dependent. The vast majority of light trap owners purchase lead acid lawn tractor batteries because they are small and rather light weight and can be easily packed great distances into the field. These batteries can provide adequate output, however, they must be kept in excellent condition. Even with excellent care, lead acid lawn tractor batteries seldom survive a season, or two. The frustration rises when you have hauled the battery and trap into the field and upon returning for the trap the following morning only to discover that the trap contains very few specimens due to battery failure after only a few hours of use.

As the cost of replacing lawn tractor batteries rises every year, eventually, the user graduates to heavier automotive batteries and eventually to even heavier and more costly deep cycle batteries. These larger and heavier batteries have a better survival rate, but three seasons or even four season these batteries succumb to the discharge - recharge cycle. Some larger deep cycle batteries may survive the five year life expectancy of any lead acid battery. A deep-cycle design stands up to repeated heavy discharge-recharge usage much better than an ordinary automotive battery. An automotive battery is designed to deliver very large  bursts of current for short periods when starting an engine and then is immediately recharged by the vehicles' alternator. However, these heavy lead acid batteries can be a true burden to haul into the field to set out with a light trap.

An automotive battery will lose a significant percentage of its full storage capacity after being heavily discharged just one time. It will typically lose half of its capacity after 50 discharge-recharge cycles. A heavy discharge is one that can remove all but 20% of the battery’s original full charge.

By contrast, even the lightest-duty deep-cycle battery will typically tolerate 200 to 300 such discharge-recharge cycles before reaching a similar state;  some of the heavier deep-cycle designs can exceed  10,000 such cycles. In short, no matter how "heavy duty" a battery is claimed to be, if it isn't a deep-cycle design it won't last very long in most light trap applications. It has been said that only battery a light trapper needs that is not of the deep-cycle design is the one that starts his or hers vehicle engine.

The true cause of battery failure is sulphation. When a battery becomes too old and weak to sustain a usable charge, sulphation is the most frequent culprit. Every time a battery is discharged, its sulfuric-acid solution is gradually broken down, leaving deposits on the battery's lead plates. If the battery is promptly recharged, most of this sulphation is driven back into solution, leaving  the plates in an essentially unchanged state. Leaving the battery in a discharged state for extended periods, however, allows the sulphation to harden into a form that permanently embeds itself within the plates.

Sulphation deposits permanently reduce the battery's storage capacity. Continual undercharging or excessive discharge also leads to plate shedding, in which some of the active solid-plate material flakes off and accumulates in the bottom of the battery. This accumulation eventually shorts out the plates, resulting in a dead cell. Consequently, if full storage capacity over a long service life is to be realized, it is important to fully recharge a battery promptly and to avoid over-discharge. To help extend the life of your battery, proper maintenance is required. Failure to maintain your battery will only cost you money. Anyone who has traveled with me on a collecting trip knows that maintaining the batteries is done first before you look into the trap to check the catch.

Gelled-electrolyte ("gel-cell") batteries have become more readily available and affordable. Gel-cells offer very good performance with virtually zero maintenance. Where ordinary "wet-cell" batteries require monthly checks of electrolyte levels, the gel-cells are sealed, using an electrolyte that is jellied with nothing to replenish. They also offer higher charging efficiency than ordinary batteries and provide slightly higher output voltage down to complete discharge. Expected life is three to four years, although some models may better this estimate by a great margin.

Do not confuse gel-cell batteries with the "maintenance-free" lead acid (wet-electrolyte) automotive/ marine batteries being sold in some department stores under brand names such as Delco Voyager and Sears Die-Hard. Unlike the true gel-cells, these batteries are basically sealed automotive/marine batteries with slightly altered plate chemistries that reduce battery gassing and, consequently, water loss. The positive side of sealed batteries is rather simple, there is no battery acid to spill. A plus no matter which type of battery you use.

Batteries should be recharged at 2.5 amps or less. Recharging lead acid batteries at 10 amps causes the battery to heat up and damaging both the plates and the acid solution of the battery. Gel-cell batteries must be recharged at 2.5 amps. Recharging gel-cells at more than the recommended rate will severely damage the structure of the battery.

I am a Lepidopterists by avocation and I use my own products extensively. When I state that my products are field tested, that is an absolutely true statement. When it comes to batteries, I think I have experience every problem. Lead acid, gel-cell, deep cycle etc., I have tried them all and have experienced the negatives that come with each one of them. I have burned holes in carpeting in the floors of vehicles, my clothes, my skin, I have removed the paint finish from  my vehicles, spilled acid on floors (Does wonders to linoleum), sneakers, and furniture. I could go on and on. The most discouraging of events occurs when you travel long hours to set a trap out in a particular spot for a particular bug only to have the battery fail to perform. In the spring of 2005 I explored a new store that sold only batteries, BatteriesPlus + in Lexington, Kentucky. I spoke with the store manager and he recommended Werker SLA gel-cell or a Werker SLA AGM sealed lead acid battery. I purchased one of each. They were slightly larger than a lawn tractor battery and weighed about 20% more (24 lbs vs 31 lbs). A handle was included and was attached to the top of the battery. I could pack two of these batteries rather easily into my back pack and carry a light trap in each hand which reduced the time required to set out the traps. After extensive use and over a 170 recharges, both batteries still contain 98% of their capacity. I have been extremely satisfied with these batteries. They are the best that I have encountered in over 25 years of light trapping.

AGM (Sealed Lead Acid)

Gel Cell Battery

When buying a battery, look for similar date codes stamped on each battery. If the batteries have been sitting on the stores shelf for more than a three months, use a hydrometer or voltmeter to ensure that the state of charge has been maintained. Don't buy old or partially discharged batteries. When in doubt, ask the dealer about the date of manufacture and product rotation of the batteries.

For additional information on Werker Batteries, click on the link to BatteriesPlus + below.


Every season I will make a trip out west to collect moths. These trips typically last 10 to 14 days. I will usually take four light traps and eight batteries, two for each trap. I have a two compartment wooden box with lids. Each compartment will hold up to five (5) batteries and four (4) 2 amp battery chargers. I use a 300 WATT inverter which I plug into my vehicles power port. A six plug power strip is plugged into the inverter to power the battery chargers. This will allow for the recharging of four batteries at one time as I drive about and still have four recharged batteries for that nights light trapping. Also, there is a full charge indicator light on the 2 amp battery chargers when the maximum sustained voltage of the battery is achieved.

Maintain the fluid levels of lead acid batteries with distilled water. Test the acid solution regularly. When I used lead acid batteries I carried a small amount of battery acid on my trips to increase the acid concentration levels when required. Use wet wipes which contain alcohol to wipe acid solution from the batteries.

It is advisable to wear rubber gloves whenever you are working with battery acids and/or performing battery maintenance  functions. Wash your hands with soap and water after working with your battery. When in the field, use wet wipes to clean your hands and equipment that may have come in contact with battery acid.

Lead acid batteries will off gas. The gas is flammable. Always connect your battery cable clamps to the battery first. Then insert the plug on the ballast or photoelectric switch to the battery cable. This process will prevent sparks which could cause a battery fire.

Keep the battery terminals free of corrosion. Use a battery terminal coating which is available at most automotive parts stores. This coating will help maintain a clean surface and provide a good connection for alligator clamps on the battery connection cable with the posts of the battery.

I hard mount a female end of battery cable adapter to the battery with stainless steel bolts, nuts and washer. The male adapter on the ballast enclosure will simply plug into the female end of the battery cable and eliminate the alligator clamps.

Female battery cable adaptor hard-mounted to a yard tractor battery

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