Using front and rear 24v motors at same time...

[Box]

I don't recall seeing this question before, so sorry if it is a repeat. I did search... anyway...

We have 24v AP motor up front, and there is also a 24v plug going to the same batteries in the rear of the boat. We are thinking of getting a Vantage for the rear, due to cost difference and our trolling usage compared to gas kicker. (Next boat will most likely have one, unless the Vantage does the trick for us.)

My question is, would it hurt the batteries or either motor if we used both motors at the same time?
Not to get more power, but simply to steer the boat with the front motor but power it from the vantage. I'm not saying we'd do this often, but am wondering about it.

Of course, most the time we would be using the Vantage as it is intended, with the excellent steering it has, but for some long straight trolling runs... and I also understand that the drag from the front motor would be there. More a theoretical question.. Or would a better option be to steer with the main motor if we wanted a temporary "hands-off" steering?

Thanks for any input.
-Box

[Goose]

I have a Vantage 50lbs and a Minkota 50lbs (both 12 volts) on the front. I have used them at the same time and actual like it a lot. I was expecting to distroy the battery very quick but have done so thus far. I was very suprise to see that I did not drain it very much. I was expecting to drain it quickly but that was not the case.

Goose

[REW]

Think about this:
A "typical" maximum draw on a trolling motor runs about 40 amps - this is very generally true - irrespective of the voltage. If you have a higher voltage battery i..e 24, or 36 volts rather than 12- you are still drawing about 40 amps at max power - you are simply developing a lot more thrust for your boat.

So, in your case - you have the potential of having to source about 80 amps - in a worst case load situation.

With the power of both of your motors - i.e. over 50 lbs each - this means that you would be able to get your boat to about 10 mph with this much power.

Now, having said that - with a group 105 battery - this means that you basically have 105 minutes at a 25 amp discharge rate. Or, if you were running both of your motors at maximum current and had a pair of 105 rated batteries, you would be able to run for about 15-25 minuts.

Most folks that are using the heavier trolling mtor batteries in the group 29 or 30 - are typically running a 150 minute rated battery. So, if this were true for you - you would be getting 45 minutes to 1 hour at maximum power.

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The beauty of your system however, is that under the vast majority of conditions, you will not be using your motors at power settings much past a 3 -- if you have power ratings running from 0 - 10.

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So, for calculation purposes, lets suppose that if both motors are running at a max power setting of 10 - on an arbitrary scale - and they pull a combined total of 80 amps ---- then power both motors back to a sett of 3 - or 3/10 of 90 or 24 amps.

This would mean - that at this setting - you would be getting about 2 hours out of a group 29 battery.

Now, consider that in most fishing situations, you are either turning the power off and on, or at the very least - turning the power down at times - it is quite likely that this 2 hour time - under most conditions will be closer to 4-6 hours of actual motor use.

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Summary - with a pair of group 29 or better yet - group 30 batteries; a person in a typical 17 foot boat should be able to fish for a day using both front and back trolling motors on an intermittent basis - (normal fishing day) with out any problems.

Take care
REW

[Box]

Thanks Goose and REW!

I appreciate it!

And yes, I wouldn't use them on high settings, or to go fast, as we would use the big outboard for that. But I can see using them for special purposes together at times.

I think this seals the deal that we will try the Vantage on our current boat. We don't do much "big water trolling" but rather contour type where we fish. Next boat will probably have a T8 or Merc 9.9, but for now I think a Vantage is probably better for us.

I sure wish our MK AutoPilot feature worked... darn thing just keeps breaking, even after warranty and pay service repairs. We love it, but it sure ain't dependable! MK 824 AP.

Thanks!
-Box

[Sparky]

Too bad about your MK AP 824 not being reliable. I bought mine in '92 right after my boat was delivered. The only problem I've had was self induced. I sort of forgot about the autopilot being out and the old 175 merc popped right up on plane. I sent it in and they repaired it. I also sent it in one more time to have the brushes replaced. The motor was working OK, it was winter and the only boat maintenance thing I could think of at the time. I haven't used it a lot since adding a HT 9.9 yammie and TR-1 in 1998. I tried it again last summer and it still works.

[Box]

Yeah Sparky, we love the AP, and our last 812 worked great with only one repair needed in about 5 years or so. Then we got the 824, and it worked great until just inside the warranty, and we had it fixed. Then it worked great until just outside the warranty, and we paid to get it fixed. Then it worked great for a while, then we just got outside that 6 month service warranty and it broke.

Basically, the auto pilot will start turning to the left wilding until you hit the pedal. We just can't trust it. Tried different pedal, and still does it. The batteries were two different sets we tried, so should not be it. It is just frustrating. So now we use it as non-AP... it stinks, but we aren't going to pay more for it to break again. We sure wish it did work though, cuase its great when working !!! :(

-Box