wheel chair v. deep cycle

[oneboatman]

has anyone heard of using wheel chair batteries instead of deep cycle batteries for trolling motors. i have a friend that says that wheel chair batteries are better and are alot lighter. any thoughts?
mack

[messabout]

Some wheel chair batteries have 6 volt batteries therefore a series circuit of 2 or more batteries will be needed for a trolling motor. The wheel chair batteries ought to be better because they cost much more per pound than a standard deep cycle type. It is not likely that they are any better. A reasonable rule is that the capacity of the battery is directly related to the amount of lead in them. More lead equals more weight. A standard 100 amp deep cycle weighs 50+ pounds. A smaller battery will have less ampacity. Batteries for an electric fork lift are huge and very heavy. That is because the fork lift needs plenty of power and long running time. Thus it uses more amperes than lesser vehicles. Gotta have a collossal battery for that kind of use.

If you have a very small boat, say a canoe or similar,you will not need a lot of power. In that case you can get by with smaller batteries if they are the right voltage.

A small trolling motor like say a 30 pound thrust type will use about 20 amps at full power. Multiply voltage times amperage and you get watts. O.K. the 20 amp drain times 12 volts = 240 watts. The 100 amp battery at 12 volts has a potential of 1200 watts. Divide 1200 by 240 and you have a theoretical (1200/240=5) running time of 5 hours. It wont work quite that way because while the battery drains, voltage decreases too. Figure on only about 60% discharge and you'll be safe. So 60% of 5 is 3 hours of realistic running time. If you use a battery with a capacity of 35 amps then your real running time is diminished to just over an hour. Investigate the ampacity of the battery that you intend to buy and you'll have an estimate of how long you can run. Use this simple arithmetic. If you are interested, 746 electrical watts is theoretically equal to one horsepower. Your 240 watt motor is making about 0.32 HP.

There is a difference between common automobile batteries and deep cycle types. The difference is in the way the lead plates are configured. Car batteries must furnish a lot of short term power for starting the engine. You will see the car battery that has 500 cold cranking amps or something like that. That definitely does not mean that it will deliver 500 amps for a long period of time, so dont be fooled by those numbers.

[stonebreaker]

Wheelchair batteries are AGM - absorption glass mat. They outperform gel batteries because they use fiberglass mat instead of silica gel to immobilize the battery acid. But they don't outperform regular old sealed lead acid wet cell batteries. They're SAFER, 'cause they don't spill and they don't leak as much as a regular battery if it cracks, but a plain old deep cycle lead acid battery actually works as well as anything.

[gonzo]

Is there a difference in charging rates?

[lazeyjack]

gonzo. yes, there is, on a smartcharger you get the option, lead acid is higher in Bulk charge
for a really good lowdown on charging maybe visit Trace , or one of the big american batt cos. like Dyno, MESSABOUT good post)
you cant SAVE money on batts, you do get what you pay for

[lazeyjack]

here ya go mate
http://www.trojanbattery.com/Tech-Su.../Charging.aspx