how long does trolling motor last per charge?

[Boatnut]

I have a 24volt AP65 autopilot trolling motor. I bought two new, Trojan scs 225 trolling batteries today. On the label it states "7.1 hr run time at 15 amps". According to my manual, the trolling motor draws 28 amps at top speed.
Now, I'm no electrical genius, but since the batteries are wired to give me 24 volts, does this still mean I'd get 7.1 hrs at 15 amps when wired as 24 volts??? or......would i get twice that??
Also, anyone have any idea what those motors draw at lets' say, 1/2 speed??
thanks,

[PJM]

Boatnut


I have the same batteries and motor and On a clam day I have ran it from 8:00am to 8:00pm in the Summer on like 3 or 4 on the foot control with no problem. Those are great batteries.

[REW]

In response to your question about the label on the battery.
This label simply means this battery will supply 15 amps at 12 volts for 7.1 hours.
If you tie two of these same batteries together, it simply means that they (together) will supply 15 amps at 24 volts for 7.1 hours.

A rough rule of thumb for many trolling motor batteries, is that they will draw 20-30 amps at full throttle.
This seems to be somewhat independt of voltage. If you have a 24 volt motor, as opposed to a 12 volt motor, it still will draw the same 20-30 amps at full current, it will simply supply more thrust at the higher voltage.

Conversely, as you slow the throttle, the current draw tends to go down exponentially. i.e. If you go to 2/3's throttle, the battery tends to draw about 1/2 the current as at full throttle.

At 1/2 throttle, the motor draws about 1/3 the current as it does at full throttle.

So, with your batteries, at full throttle, you will be getting a fairly typical 4-6 hours of run time.

At 1/4 throttle, you will be getting several days.

Take care
REW

[Dutchman]

Mike, I run the same set up, as far as batteries and bowmount are concerned. I have nothing but good things to say about the SCS 225 Trojans, They get better the more you use them. I usually run them down to dead daily. The Autopilot steers boat while the kicker pushes pulling cranks in a stiff wind, usually it takes 8 hours and that's running the bowmount hard with the autopilot on(turn off the autopilot and they last alot longer) On a day that your not so hard on them they'll take it twice as long. Great choice....



"Fishing is the pursuit of what is elusive but attainable, a perpetual series of occasions for hope"

[Boatnut]

Thanks for all your help. Looks like i made good decision to go with the Trojan's.

REW, I was really just testin' ya. I already know about Home's Law, Pie R round and measure once/cut twice. :) ;)

[REW]

You know the adage about measuring twice and cutting once, only works if you make the cuts where the measurements tell you.
It seems that sometimes when we are in the midst of doing something, we "measure twice" and still cut it too short - becuase we make the first cut on the wrong side of the line - so to speak>

Take care
REW