If you've been around the kayak fishing community, you hear certain "Buzz" words. Undoubtedly, gel cell batteries has been one of them. If you want the low-down on these gel cell batteries, read on. They are very easy to understand when you break them down into individual parts.

surf ski fishing in South Africa

Technically they are "Sealed Lead Acid" batteries, but they are made slightly different which makes them a Gel Cell type of battery. The cases are made from a non-conductive material usually consisting of ABS plastic, styrene or polypropylene. A gel battery design is typically a modification of the standard lead acid automotive or marine battery. A gelling agent (often silica) is added to the electrolyte to reduce movement inside the battery case. Gel Cell batteries are considered non-spillable, and can usually be used in any position except upside-down. They usually have a one-way valve acting as a vent for excess gases to escape. A gel cell must be charged at a lower voltage to prevent excess gas from damaging the battery. Fast charging batteries on a conventional automotive charger may permanently damage a Gel Cell Battery. Connection points for power are usually push on spade type of connectors on the lower amperage batteries, or screw and nut type of connection points for higher amperage batteries.

Capacity, expressed in ampere-hours(AH) is the total amount of energy available from fully charged batteries over a 20 hour period.

Discharge Rate is expressed in milliamps(mA) provides the constant current discharge for a 20 hour period. For example, a gel cell battery with a rating of 7.0AH will deliver 350 mA for 20 hours. For a typical example, lets use a fish finder. My Humminbird draws about 250mA. So a battery with a 5.0AH rating would discharge at a rate of 250mA for a period of 20 hours. More than enough for a few days of fishing. When is a battery considered discharged? It depends on a batteries rated voltage, which for our uses is usually 12volts.

Batteries are made up of what are called "Cells". A cell is consideredfully charged when it's voltage is a little over 2.0volts. Therefore, a 6volt battery would have 3 cells, and a 12volt battery would have 6 cells. When the voltage of a individual cell drops from a fully-charged state of 2.0volts to 1.75volts, the cell is considered discharged. Therefore, when the voltage of a 6volt battery drops to approx. 5.25 volts (3 cells X 1.75volts=5.25volts), it is considered discharged. For a 12volt battery, a discharged battery would measure about 10.5volts or less. What is the useful life for a Gel Cell? There's alot of variables, but a few of the manufacturers say somewhere of 200+ charges/discharges.

This is largely dependent on how deep the battery was discharged and the charging methods used. What is the "Battery Memory" I hear about? What this means is that if a battery is repeatedly only partially discharged before recharging, the battery "forgets" that it has the capacity to further discharge all the way down. Lead Acid batteries DO NOT develop any type of memory. What type of chargers do you use? Chargers made for charging Gel-Cell batteries. Chargers for these operate at a lower voltage and current as stated above.

Charging these batteries at too high a voltage/current can cause premature drying of the electrolyte and greatly shorten battery life. Most chargers operate in the 200-800mA range. Some of the better ones automatically switch from Fast/Full Charge to Float Mode where the battery is safe from being over-charged.

Hope this helps... PerryC