Batteries Not Included

How much battery life can you afford?

Outdoor Life Online Editor

You could probably power your trolling motor on a potato battery if you could find a potato big enough, and maybe make home fries when the battery wore out. But technology has pretty much left spuds behind when it comes to direct current. With at least two dedicated deep-cycle batteries for your troller, electrical power is a costly part of any rig, but careful shopping can keep your circuits humming at a reasonable price.

Basically, you want to get the most "amp-hours" possible per dollar, and this may mean spending a little more up front. A size 27 battery, the one most familiar to all of us, weighs 55 to 65 pounds and typically puts out between 85 and 105 amp-hours. The amp-hour measurement indicates the sustained amount of energy a battery can put out over a 20-hour period.

**Cheap Electricity **
The "standard" deep-cycle battery with a liquid sulfuric acid electrolyte costs $70 to $90 in size 27 at discount stores. Their obvious advantage is low price, plus they're less sensitive to overcharging than some more exotic batteries are. However, you have to regularly add water, you have to recharge them soon after use and you have to make sure they don't spill that dangerous acid. They typically survive 200 to 300 cycles of discharging and recharging.

Gel-type batteries, which employ a thick acid gel rather than a liquid, are a step up. They're sealed, never need water and are more resistant to vibration than flooded-cell batteries. The size 27 gel-type costs around $150 to $160 and will survive approximately 500 cycles of discharge and recharge.

The Best Buy
Absorbed Glass Mat (AGM) batteries are packed with absorbent fiberglass matting between the lead plates; this mat then absorbs the acid electrolyte. AGM batteries are sealed, require no addition of water and are much more resistant to the pounding in a fast bass boat than standard batteries. They're also said to last considerably longer than gel-cells. As is the case with a gel-cell, overcharging can be a major threat to longevity. You should be sure to use a charger with an automatic shutoff. The price for a size 27 AGM battery is $170 to $190.

Are these latter two batteries worth two or three times more than standard deep-cycles? Based on the math, you bet. You get more life out of one of them than you would out of two or three conventional flooded-cell batteries, plus you have fewer headaches in servicing them.