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  Running Motor During Heavy Battery Drain

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Author Topic:   Running Motor During Heavy Battery Drain
JMARTIN posted 05-10-2006 07:38 PM ET (US)   Profile for JMARTIN   Send Email to JMARTIN  
My new pot puller draws 11-amps and runs for about four minutes to pick up a pot; I have 3 pots. So I am drawing 11-amps for at least 12 minutes. Does it do any good to start up the motor so the battery is getting some poop to it while I am using the pot puller? One of the pots must wheigh in at 100 pounds when you consider the 400' of weighted line attatched to it. The puller seems to be straining, but pulls the same regardless to wether the motor is on or off. I have 2 batteries with a switch and the motor is a 1992 Evinrude E200TXENE. John
Chuck Tribolet posted 05-10-2006 08:14 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
11 amps * 4/60 hours * 3 pots = 2.2 Amp-Hours. Your battery
will yawn at that.

You might try heavier cables. Can you jury rig something
with a set of jumper cables to see if it helps? If it does,
they get approporate heavy-gauge marine-grade cable.

And a question: How many feet of wire is there between the pot
puller and the battery?


Chuck

JMARTIN posted 05-11-2006 12:30 PM ET (US)     Profile for JMARTIN  Send Email to JMARTIN     
The puller plugs into my Scotty downrigger plug in. They have 10 guage wire with an inline 30 amp fuse. Of course I was using the one farthest away from the battery, Duhh. I will use the one that only has about a 4 foot run this weekend. The puller mounts on my new swivel bases that I purchased from the TWC Ballard store. I can get the correct angle on the puller by using the swivel base. Thanks Chuck, you always seem to help with my electrical questions.

Shrimping was good, two-license limit from a one hour drop, 3 pots. John

jimh posted 05-14-2006 10:48 AM ET (US)     Profile for jimh  Send Email to jimh     
quote:
Does it do any good to start up the motor so the battery is getting some poop to it while I am using the pot puller?

Yes--It is absolutely a good idea to have the motor running while you are operating heavy loads like the the pot puller. This will allow the motor to furnish the current for the pot puller instead of the battery.

A battery is rated for a limited number of discharge and recharge cycles. If you discharge the battery to operate the pot puller, you will have to recharge it later. By operating the engine to supply the current to the pot puller, you will avoid discharging the battery. This will improve the battery life.

Of course, on the other hand, running the motor will put more operating time on the motor, and that will decrease its life. So you must weigh the trade off: replace a $75 battery a bit sooner, or replace a $7,500 motor a bit sooner.

Another consideration is the ability of the motor to provide charging current at idle speeds while you are pulling the pot. This depends on the motor. Some motors, such as the Mercury OptiMax, have very little surplus current available at idle speeds, and it would not make much sense to run the motor while pulling the pot. The motor would not be able to supply much current anyway, and the battery would be discharged. In fact, at really low idle speeds some motors are net consumers of current from the battery, so running a motor like that would make the situation worse.

Other motors, such at the Evinrude E-TEC, can supply more charging current at idle. If you have a motor like that, then the current to pull the pot will come mainly from the running engine and not from the battery. A 90-HP E-TEC can supply about 10-amperes of charging current at a 600-RPM idle. If you have a motor like that, it will be supplying the current to the pot puller, not your battery.

Enjoy those fresh shrimp.

JMARTIN posted 05-16-2006 05:43 PM ET (US)     Profile for JMARTIN  Send Email to JMARTIN     
Update on the puller. It makes no difference if the motor is running or not on the "speed" of the puller wheel. It makes no difference if the puller power is on a 25' run of wire from the battery or a 4' run. It pulls about 100' per minute and it just sounds like it is straining.

I checked my batteries before leaving the dock with the Navman. Batt 1 was 12.4, batt 2 was 12.6. I used batt 1 on the way out to the shrimping grounds, 5 minutes at 1100 rpm, 5 minutes at 3600 rpm. We did 6 pulls without running the motor, we used the kicker to move around. The battery was also powering the sonar/gps and the radio for 3 hours. We ran the 10 minutes back in on battery 1 and the Navman said it was at 12.6 when we got to the dock. I should have checked it after the 6 pulls.

The weather was absolutely perfect, and we limited on spot shrimp/prawns, what ever you want to call them. I call them San Juan lobster. If I can figure out the new camera, I will post some pictures of the shrimping Whaler. F. Gump

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