: I've done that on an inflatable boat. Car batteries (particularly the
: well-used ones which are readily available for such games) don't have a
: very long life when used to drive trolling motors. They are great for high
: current for the few seconds needed when starting a car, but they just
: aren't meant for really deep discharge and heavy use.

: Fortunately, batteries designed for deep-discharge are just as easily
: available at Wal-marts and Sears stores. Look for liquid filled batteries
: designed for golf carts (roughly the same size and pretty close in price
: to a car battery) or gel-filled batteries for electric wheel chairs. These
: cost more but won't leak if they get turned on their side.

: My 17-pound thrust trolling motor drained a (not too perfect) car battery
: after about 2 hours of use. The voltage dropped down to the point where it
: was not doing much. I would expect double that performance, or better,
: from a new deep-cycle battery. This design has a 36 pound thrust trolling
: battery. That is about a one horsepower motor. One horsepower is just
: under 750 watts, so this should draw about 60 to 70 amps from the battery
: each hour at top speed. A battery rated at 210 amp hours would last about
: 3 hours at that draw. at half speed you might get 5 to 7 hours of use from
: the thing. They sell in the $60 range most of the year, but come on sale
: occasionally. Want more use--buy a bigger battery, or put in two.

: a 36 pound thrust motor may be oversized for this application. The motors
: used on electric bicycles and scooters are in the range of 150 to 200
: watts. You could probably get maximum hull speed froma much smaller motor
: which would drain the battery less.

: I noticed the device comes with a wall charger. I can see where it would need
: one. Those solar panels look like the 5 watt panels sold by Harbor
: Freight. (part number 41144) I can't tell if they have two or three of
: those panels mounted. But let us suppose that you'll buy 4 of these,
: 'cause right now they are on sale for $40 instead of the usual $50. In
: full sun you'd get 20 watts going back into the battery for every hour you
: had good daylight.

: For every hour of full-bore use (750 watts) you'd need to charge the battery
: for 37 1/2 hours. That is about 3 days of charging for each hour at
: maximum speed. If a slower speed only used 100 watts, you'd need 5 hours
: of charging for each hour under power.

: Put more money into the solar panels (at maybe $6 a watt) (look at
: http://www.wholesalesolar.com/index.html for instance) and you could
: easily get larger, and more economical panels. Lets say you bought a panel
: which produced 100 watts every hour, and used an efficient trolling motor.
: You could probably propel a kayak continuously with such a setup.

: And on the overcast days you could put up a sail.

: PGJ

Hi Paul,

A new car battery, relatively cheap, works fine for this, done it with a couple different boats. Most deep cell batteries that are designed for this are much heavier and larger.

With a small sailboat I used to own, also fairly easy to drive, I could go several miles on a charged car battery with no sign of discharge. Sure a car battery isn't the ideal, it still works. That boat was 5' beam, much harder to drive than a 2' wide kayak.

Bill H.