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Old 06-01-2007, 05:05 PM
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PerryC PerryC is offline
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Thumbs up Re: Bait tank pump & battery life

Steve,
In theory, you're correct about current getting reduced to about half with everything else being the same. I originally used a flow restrictor with a 12 volt battery in the beginning, but have since switched to using a 6volt battery because if something happened to one power source, I would still have the other one to use. But, using one 12 volt power source means one battery and set of connections to maintain, instead of two which is easier. With current draw, I dunno if this will help or muddy the water, but it's part of the page we have here on gel-cell batteries.

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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 considered fully 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.
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Hope this helps in some way,
Perry
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