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Posts: 27
| How many hours of power should I expect out of a 12 - 24 volt Motor Guide 56lb trolling motor on an average outing? I have a 19' fiberglass Astro with a 200hp outboard. Its a 97 that's not made anymore - People always ask if its a ranger, if that helps to know what kind of boat I'm refering too.
This past weekend my batteries where very low after about 6 hours of moderate use. Mostly used it to control the boat on wind drifts. It seems I should be getting more hours than 6.
Any opinions?
Thanks
Edited by dlman 5/20/2008 12:36 PM
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Posts: 2754
Location: Mauston, Wisconsin | I assume you mean 56lb-> 56hp would be one very healthy trolling motor. How old are the batteries? Batteries are just like us human's, i.e., we don't last forever. Maybe it's time to change out the batteries. The more abuse the shorter the life! I lost a few days at the PMC. (thanks to my fishing partner) 
Al
Edited by ESOX Maniac 5/20/2008 12:26 PM
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Posts: 27
| Thanks - I corrected it to lbs! So I should be getting more hours. I was thinking they should last for a 14-16 hour day. |
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Posts: 2754
Location: Mauston, Wisconsin | Marine batteries are rated by "reserve capacity". This is usually defined as a discharge at a 25A rate to 10.5VDC. So if the battery is rated at 120 minutes reserve capacity, when fully charged it will last for ~ 120 minutes at 25A discharge rate. Now the trick! Battery discharge rates and capacity are not linear. If I double the discharge rate (50A), I will get 1/3 of the runtime (40 minutes) from the same battery. If I cut the discharge rate to half (12.5A), I will get ~ 3 x the runtime (360 minutes). Most trolling motors go up to 40-50A depending on the actual power setting. The lesson here is: What you expect. may not be what you get.
Al |
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Posts: 468
Location: Not where I wanna be! | you should be getting more life out of your batteries than what you mentioned.
I run a 24V system on a 65 lbs Minn Kota, it pushes a 16' alluminum boat around fast enough to pull a skiier....  But i can use it in a windy day to fish banks and adjust to the wind.... for two full days..... now that doesnt mean i run the trolling motor at full tilt the whole time, but it should last at least a full day before needing charged.
Judging on your post, id say its time for a new battery system.... also, if you run on 24V/two battery system, id recommend getting an On-Board charger that will equally charge both batts at the same time. using uneven batteries in Tandem will decrease their life significantly. |
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Posts: 742
Location: Grand Rapids MN | I have a 52lb 12V on my 17' Targa WT with 2 Group-27 AGM batteries (in parallel of course) and if it's fairly windy out I get about 6-8 hours of decent power and then it starts to tapper off. That's at mid to higher power most of the time. Mine is kind of a small TM for the size of the boat so any wind I have to run it harder.
So I don't think you are to far off with how long they will last.
Hope this helps....
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Posts: 5874
| Last weekend, I just ran my 80 lb Terrova AP US for 8 hours straight, between the 4 and 6 setting, and still had plenty left in my batteries. This is on a Tuffy 1890. We were pulling harnesses for walleyes in a tourney all day. The only time the TM was not on, was on the way out, and the 2-3 minute runs to start a new run.
I would think your batteries are showing there age. |
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Posts: 2687
Location: Hayward, WI | While your batteries may be showing their age, you might need to check into a bigger trolling motor. That's a pretty good sized boat to be pulling around with a 56 pound motor. I'm guessing you have to use at least 50% of the motor's power on most days, and probably close to, or the max power when it gets windy.
I run a 70 pound motor on a 16 foot aluminum boat that ways 800 some pounds (hull only), and would not want much less. On a 19 foot glass boat, I would go no less than 80 pounds.
Even though it's a bigger motor, due to lower efficiency running at high speeds, a 80 pound motor will run longer at 20% than a 56 pounder will run at 50% or more.
Either way, you should get a lot more life out of your batteries. I usually fish two whole days before charging my batteries, and a few times I have fished three without charging, and my batteries have never been run down enough for me to notice. And, I'm not a drifter, I head my boat into the wind pretty much all day long, so I am constantly on the trolling motor.
Might not be a bad idea to try new batteries to start with. If you still have issues, you might need to get a bigger trolling motor. OK, I'm done rambling now!
curleytail |
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Posts: 742
Location: Grand Rapids MN | I haven't had this rig to long and it's my first so I never knew what to expect from it.... I've thought about new batteries but was told by a few locals that is about what I should expect because of running such a small TM. I've put off trying new batteries because of the expense but with some of your recommendations seen here I might have to break down and get some. The wife will just love this one!! |
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Posts: 27
| Thanks for all the input. I think I might be looking at the batteries showing some age and the trolling motor is too small. Curlytail nailed it ..... I do have to run in half power most of the time and full power when its windy. I'm going get knew batteries and if that doesn't work time to drop some cash on a new TM. |
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Posts: 5874
| dlman - 5/20/2008 12:06 PM
How many hours of power should I expect out of a 12 - 24 volt Motor Guide 56lb trolling motor on an average outing? I have a 19' fiberglass Astro with a 200hp outboard. Its a 97 that's not made anymore - People always ask if its a ranger, if that helps to know what kind of boat I'm refering too.
This past weekend my batteries where very low after about 6 hours of moderate use. Mostly used it to control the boat on wind drifts. It seems I should be getting more hours than 6.
Any opinions?
Thanks
This is a 12/24 volt motor? You are running in 24 V mode? If you have the power way up to full, then I might suggest a new TM. You might try connecting the batteries in Parallel, and running the TM at 12V. That might get you a bit more run time, but probably not much more. The problem is running at full power. That will drain the batteries right quick. |
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Posts: 27
| Shep,
Its is a 12/24 volt. Most of the time I run it sporatically to control a drift in the 12v setting at level 4 or 5 (out of 5) unless its really windy then I bump it up to 24 once in a while. I would estimate after 3-4 hours on 12v it gets weak so I'll bump it up to the 24 and get a few more hours at the same power output of the 12 setting. |
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Posts: 2754
Location: Mauston, Wisconsin | I also have a 12/24V on my boat. Having been involved in UPS/battery industry and use of batteries for deep cycle applications for the past 25 years, I'd suggest using the trolling motor at the higher voltage (24V) and lower power setting (1-3) versus using the lower voltage (12V) and a higher setting (4-5) for the majority of your usage.
The problem with the 12V setting is that you are seriously depleting one battery because of the higher current draw. Then when you switch to the 24V mode you already have used one half of your battery power in that 12V setting. If you use the 24V mode you will see significantly better performance from your batteries because of the lower current draw. FYI- I only use 12V when I really want to sneak around in shallow water.
OK, I'll say this one more time here on MF for those whom are not familar with lead-acid batteries and their design/discharge characteristics. Many folks think about an individual battery (jar) as the equivalent to a tank of gas, i.e., there is a linear relationship between capacity and consumption rate.
This is an absolutely false assumption for a battery, F. ex. if I have a 5 gal gas tank and consume the gas at 1 gallon per/hour, I would expect the tank should last ~5 hours. Likewise, if I consume the gas at 2 gallon per/hour the tank should last ~ 2.5 hrs.
The problem with lead-acid batteries is the capacity versus consumption rate is nonlinear. If I have a marine battery rated at 180min reserve capacity at 25A discharge rate. That battery will last for ~ 180 minutes @25A (~3 hours@ ~300W). Now if I change the discharge rate to 50A (600W), most folks would expect that battery to last for 90 minutes (1.5 hrs). That's false, that same battery will only last ~ 60 minutes (~1 hour) @ 600W. Likewise, if I drop the discharge rate to 12.5A (150W) that same battery will now last ~ 540 minutes (~9 hours).
Now lets look at a 12/24V system with two (2) 180 min reserve marine batteries in series. The math would seem to say that 180+180 = 360 miinutes @ 25A. Let's assume I deplete one battery using the 12V mode @ 25A discharge (300W) setting. So I get ~ 180 minutes(3 hours) @ 300W from battery number one. Now I switch to 24V mode to get more juice at the same power level/thrust (300W). What happens? Well first, battery number one is empty, that leaves just battery number two to supply the total power. The trolling motor is now demanding the same power (~300W) from both batteries. But only battery number two can supply the power so I get another 180 minutes (3 hours) or a total of six hours.
If I had simply operated the trolling motor at the same power level/thrust (300W)using the 24V @12.5A setting I would get ~ 9 hours.
The rule of three's for lead-acid batteries- "Cut the load in half you get ~ 3 times the runtime. Double the load you get ~ 1/3 the runtime."
When it comes to batteries- don't expect miracles! You have to take care of them and they will perform (much like a wife). However, just like a wife, they won't live forever!
Al
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Posts: 27
| Wow! Thanks for sharing your knowledge with that explaination. That really make sense to run on 24v on a lower setting! I'll give that a try. I'm sure it will make a difference. |
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Posts: 7
Location: Rockford Il | If your charger has a refurbish or refresh button follow directions on doing that it has worked for me a few times |
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| Just thought I would add my 2 cents.
I had a similar problem with battery life. My 24v Motor guide 70# thrust on a 19' boat lasted me two days. I mainly use to 1 & 2 of 5 settings. On 5 it may pull a skier. Currently I can only get about 6 hrs.
I deep charged both batteries and at the end of the day I checked them with a multimeter and I found that one of the batteries went bad. one battery was 2/3 charged and the other reads as dead.
Good post by the way. Lots of good information. Any one have a recommendation on replacement batteries. Mine are Interstate SRM-27 (160 min RC) but I am thinking of switch to an Autozone brand that has more reserve for significantly less money but I am not sure.
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Posts: 2
| I have two trolling motors - one forward, one aft
both rated at 12 v, 55 lb thrust for a small pontoon
(15 x 5.5 feet). If I hook two deep cycle batteries
to each motor, how much time should I expect to get
out of them?? |
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