trolling motors

[jeff]

Have a 98 Mirrocraft striker looking at either a pd ap model should i go with a 12 volt 55 or 24 volt 65 is 54 inch shaft enough orshould i go with 60 inch. Can you have to much shaft ie for deploying and stowing sure could use some help don't want to buy the wrong one.

[stevefellegy]

Hey Jeff,

The 24 volt system is surely the way to go. The trust rating is not relative if you don't have power left to engage the optimum output of the motor. 55 pound trust is plenty IF the power supply is there. You will never run the 24volt system down in a day. Can't say that about the 12volt system. Remember, the PD's use power to steer as well as propell the boat.
If mounted right, the shaft length shouldn't cause problems involving storage. Go with the longest you can. 54" should work on that rig but longer is never too long. Good luck!

[striker]

Thanks Steve for the info.

[punch1]

Jeff,

I used to have a 17' MirroCraft that came rigged with a 12V PD50 MinnKota. The shaft was 48" and worked just fine for this boat (1730 Holiday) in most situations as far as the shaft length goes. The 12V is another story. Definately go with the 24V as mentioned above. If you troll bigger waters like Winnebago, Sturgeon Bay, Litttle/Big Bay de Noc, than you may want to go bigger on the shaft. I would think the 54" would be a great all around size. I currently run the 54" Minn Kota AP65 on a 17' Crestliner Sportfish. It's a good fit. Good luck!

[Chris]

Hey guys, What is the advantage of a 24 volt system? Isn't that when you run two batteries in series or parallel? I can never remember. I just have a small 14ft Lund. What would be the advantage over using a 12 volt motor with two batteries if the thrust is similar? Sorry to sound so clueless!!
Chris

[REW]

Basically, it boils down to power.
With the typical DC motor - power is determined by the torque of pushing current through the motor armature.

If you run higher voltage - you develop more push or thrust. Of course your motor has to be designed to handle the extra votage.

That is why - you can run a 24 volt motor on 12 volts at about 1/2 power. But, if you try to run a 12 volt motor on 24 volts, the wiring size is such that the motor will quickly fail.

The 24 volt system, as we use it in our boats, are typically nothing more than 2-12 volt batteries connected in series.

Thus, if you have a 12 volt motor - you can use a single 12 volt battery and get a specified amount of use with a given specified amount of power setting. Then, if you connect a 2nd 12 volt battery in parallel - you will still get 12 volts at the motor terminals - and thus not harm the motor, you will get no more power from the motor - but the power that you do get - will be there for twice the time.

Thus a parallel connection doubles the trolling time - so to speak.

A Series connection - if the motor is cabable of handling the voltage - leaves the duration of trolling time the same, but doubles the available power.

Take care and - keep the sparks from flying.

REW

[Chris]

Hey thanks REW!
If anyone happens to check back, I was wondering if there are any considerations when running a line back to the batteries for connecting a bow mount motor(wire gauge etc.)

Am I right in thinking I'd be better off running two 12 volt motors from two batteries connected in parallel, versus a separate battery for each, considering I'll never run them together, and one may get more use than the other from day to day? This is probably stuff I should know, but the info and advice is very highly appreciated!!
Chris

[REW]

Mayby, or mayby not.
The problem in running two batteries in parallel - is that it is sometimes tough to get matched batteries.
If you buy two batteries at the same time, the same brand, and the same manufacture date - it is likely that they will be fairly closely matched. However, any other combination, likely leads to a mismatch on the batteries.

The mismatch results in uneven charge and discharge. What I mean by this - is that with a parallel combination - the weak battery always sucks down the stronger battery. Or as the Red haired british MC says on TV - this is the Weakest link.

The opposite happens, when it comes time to charge the batteries -- the weaker battery tends to hog all of the chrging current - and because it is weak - it really never gets to full charge - and again because of the parallel connection - never lets the other battery get to full charge.

Having said that - if you do get "matched batteries" and keep them matched -- i.e. if you ever replace one - you replace the other one with an identical battery - you can go years and years with successful operation - in running a parallel battery. This is evidenced by the fact that many of the Diesel pickups have used parallel 12 volt batteries for many many different vehicles and many years of successful operation.

If you want to run in parallel - run matched batteries. If you happen to have different sized batteries - or different age, or different brand - it is likely that you are better off - running, and charging them by them selves.

Take care
REW