Which lasts longer?

[richg99]

Let's assume we have a well functioning 12 V trolling motor system. It pulls ( or pushes ) the boat around just fine. But, it starts to run out of juice ( with a BRAND NEW battery) about Noon each day of fishing. If I want to continue fishing the same area, but for an extra few hours each day...which, of the following two scenarios makes more ELECTRICAL sense? What WORKS best, and is most cost efficient, please?.<br /><br />Option 1 Add another battery and hook it up in parallel. ( same voltage..more amperage).<br />Option 2 Buy a 24 V system and run it on two batteries, because no one sells a 24 V battery.

 

[JB]

Re: Which lasts longer?

Assuming that the batteries are of the same power storage capacity and the motor is of the same efficiency the 24V system will probably last a bit longer due to lower currents in the wiring/cabling.<br /><br />Batteries should be high capacity deep cycle and the motor should be of the pulse modulated, electronic control type. Power deploy and power steering or autopilot will all use power and shorten the operating time compared to expertly operated mechanical steering. If you are as clumsy as JB on the foot pedal the autopilot will probably save power.<br /><br />Either system should "work" well, but the 12V system would probably cost less.<br /><br />Good luck.

 

[Yepblaze]

Re: Which lasts longer?

You didn't mention the motor(s) thrust ratings. As the thrust goes up the current draw does too.<br /><br />So to say you replace the motor with a 24v system along with batteries, you may find the addition thrust ratings of the 24v motors, even with 2 12v batteries in series may not double your fun.<br /><br />Now about ganging up a couple of 12v batteries in parallel, You may run into an issue down the road where if you do not disconnect and charge separately the charger may mistake when they are fully charged. Especially if one battery is of marginal capacity. <br /><br />At which point, after making these changes you end up replacing batteries more often or just have to deal with the frustration of what might transpire. (this is not a definite only my overview of connecting two 12v batteries parallel).<br /><br />My suggestion would be, get another 12 deep cycle battery like you already have and change the connections mid day.<br /><br />I think it's also important to get the batteries charged right back up when I get home. So if it were me I might also want to add another charger too. That way, they both go on the charger right away.<br /><br />And by having two batteries and two chargers, it will make it easier to figure out what happened when one battery just don't go as far as the other anymore.

 

[richg99]

Re: Which lasts longer?

Ah hah!!! What a great answer!.....<br />....from YepBlaze...."My suggestion would be, get another 12v deep cycle battery like you already have and change the connections mid-day." <br /><br />I've read a zillion prior responses to "my battery doesn't last long enough" The usual response is almost always "get a bigger 24v system"....I've alway wondered why I would buy another trolling motor when my present one works just fine. I don't need MORE THRUST... I just need more staying power later in the day. <br /><br />I've always believed that another battery ( in parallel) was the answer. Yepblze gives me yet another very good alternative. Just carry two batteries, fully charged, and switch them over. You could even work a battery switch in the circuit to make the battery swap easy. It would facilitate re-charging too!<br /><br />Please note..the problem is NOT ( .."it isn't powerful enough to move by boat."..or ("the river current is too strong ") <br /><br />The stated problem is simply that the TM doesn't LAST as long as the boater would like.<br /><br />Thanks to all who responded<br />regard, RichG TX

 

[Drowned Rat]

Re: Which lasts longer?

richg99. You forgot what JB told you. A motor drawing less current will last longer. You will get about 30% more run time from 2 12V batteries hooked up in parallel than you would from 2 12V batteries discharged one after the other. Batteries release their energy more efficiently at lower amperage draws. A 50 lb. motor will pull about 45 amps off one 12V battery at full power. But, the same motor will pull only 20 to 22 amps off two batteries in parallel. Lower amperage means more efficiency. In the order of about 30%! It also means longer battery life. If you were getting say 3 hours of run time on one battery, you would get 6 hours if you ran them one after the other, but if you hook them up in parallel you would get about 8 hours. Amazing how that works. <br /><br />As for charging batteries in parallel, It should at least be done that way occasionally. It's called equalizing the batteries and it ensures that one battery or the other isn't taking too much of the load. Batteries used in parallel should be the same size and model and ideally bought at the same time. Good luck.

 

[richg99]

Re: Which lasts longer?

OK .. now then, either ...usng two batteries connected in parallel,.....or... using two batteries discharged one at a time... I'm still back to only adding a single battery (assuming both batteies are in top notch shape....... instead of buying a whole new 24v rig to solve a problem that doesn't exist ( lack of thrust..heck, I've got plenty of thrust). <br /><br />Thanks, RichG

 

[jlinder]

Re: Which lasts longer?

I like the idea of 2 batteries on a switch. <br /><br />Barring that, how about what they do on golf carts - 6 volt batteries in series? You get to keep the same trolling motor and accessories, but get a lot more power.<br /><br />I think the optima (yellow top) is rated for 70 minutes at 25 amp. I found a 6 volt batteries and found one made by Interstate (model U2200) that is 6 volt and is rated at 447 minutes at 25 amps. $88.95 on the web.<br /><br />You'v e got about $180 of batteries invested, but a heck of a lot more capacity.<br /><br />Just a thought. Anyone out there taking this approach who could share real life experience?

 

[Boatist]

Re: Which lasts longer?

What is the output of your Main Motor alternator??<br /><br />One thing to keep in mind is all trolling motor are not alike. Some will produce the same power with a lot less current draw from the battery.<br /><br />Most brands their top Line has a power saving to do the same work. In general a motor with higher thrust run at a lower thrust will last much longer than a smaller motor run at the same thrust but near it max thrust. <br /><br />Put another way most of the better motor have a pluse type system that saves power. If the motor is turned all the way up it saves very little power. If your motor is big enough to run your boat at 50 percent power then it saves a lot of power.<br />Example:<br />Motor 1 25 pounds of thrust run on the highest setting might last 3 hours.<br /><br />Motor 2 50 pounds of thrust but run at the 50 percent setting of 25 pounds of thrust might run for 6 hours on the same battery.<br /><br />This is why a bigger troling motor can be the answer.

 

[richg99]

Re: Which lasts longer?

The main motor alternator is NOT connected to my trolling motor batteries. So, it is a non-factor.<br /><br />I rarely use my present trolling motor at anywhere near high speed. If and when I might do that, it would be for a few seconds to get me away from a reef; dock, etc.<br /><br />Even at medium speed, it moves my 16 ft. boat along quite nicely. It will last much of the day for my general purposes. I often do not have to re-charge the batttery for three or four trips. MY trips tend to be only a few hours, except on special occasions.<br /><br />My main reason to post here was to clarify the usual "buy a 24v Trolling Motor" answers and issues. I still don't believe that a bigger motor ( however efficient it is ) which requires the purchase of two batteries ANYHOW...is the logical, or cost-wise, best solution to simply extending the running time a few extra hours. <br /><br />Small boat, small needs. <br />regards, RichG TX

 

[18rabbit]

Re: Which lasts longer?

Jack L brings up a good point. 6v GC batteries will cough up more deep-cycle power per pound than a 12v will…and it will do it longer. Also, the high-end batteries have a longer deep-cycling life. But I don’t think there is a lot of value in a high-end battery for only occasional use. If you regularly use that trolling motor to yank those batteries down, some L16’s would not be a bad way to go when it comes time to replace batteries.<br /><br />Boatist is on to something, too. A motor is optimal at a certain point (rpm). Below that rpm or above that rpm they are not as efficient. Don’t know where that point is.

 

[Boatist]

Re: Which lasts longer?

Richg<br />I understand may not make since for you. Your batteries will last longer if you always charge them as soon as possilbe. When you first get home charge all your batteries all the way up with a good automatic charger.<br /><br />Main advantage of 24 volt motors is you lose less power in the cable. Where the motor is up front and the batteries are in the back a 24 volt motor will draw half as much current. This means you loose a lot less power due to heating in the power cable so the motor can use it all. Many trolling motor can be wired for 12 volts or 24 volts.<br /><br />For me when we fun fish we use one group 27 battery but when we fish a Tournament use two Group 27 batteries and switch at first sign of weakness.

 

[jlinder]

Re: Which lasts longer?

Just curious - <br />1. Do you know how many amps your motor is drawing? If not, what is the rating?<br /><br />2. What is the distance between the batteries and the motor (lenght of the wire)?<br /><br />3. What gauge of wire do you have installed?

 

[18rabbit]

Re: Which lasts longer?

Originally posted by Boatist:<br /> ... when we fish a Tournament use two Group 27 batteries and switch at first sign of weakness.

You mean if you're not catching anything you change batteries? <br />Sorry...still working on my fist cup of coffee.

 

[richg99]

Re: Which lasts longer?

To Jack L<br />1. No I do not know the amp draw of the 42 lb 12 v Minn-Kota Powerglide ( and their site seems to be "flashing" but not revealing anything helpful today).<br />2. two feet ( I moved the battery up front)<br />3. 6 gauge

 

[jlinder]

Re: Which lasts longer?

Well it sounds like the wire is not a problem. <br /><br />I asked because I have seen people put the batteries on one end and the trolling motor on the other end, then run some pretty light wiring. This causes power to be lost in the wires, low voltage at the motor, and then the motor draws an even higher amperage.<br /><br />It was worth checking into

 

[richg99]

Re: Which lasts longer?

Jack L I appreciate the double check. I actually have very little problem with this issue. <br /><br />I've always seen the "buy a 24v TM and two batteries") solution to every comment about "the trolling motor doesn't last long enough" queries.<br /><br />I never thought that answer was the most effective ( cost and realistic ) solution. So, I posted here trying to elict some responses. That has happened. Thanks for your help <br />regards, RichG TX