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New trolling motor decision

7512 Views 40 Replies 20 Participants Last post by  MariettaMike
I am considering adding a TM to my Maverick 17 HPX-V. After speaking with several very reputable installers, most suggest the 24v system which I agree is the safe way to go but to keep all batteries in console I would need to reduce the Reserve min to 80-90 [email protected] Amps for the battery sizes to work.
A 12v system would be the easiest install and I have not ruled that out as I could install one grp 29 battery and get 210 RC min’s
Here’s where I could use help.
Different conditions require different amounts of thrust so to provide a simple comparison, the 55# MK draws 50 amps at max which will burn through a RC 120 battery in one hour. If I go 24v, the MK 80# using 55 lbs of thrust uses 38.5 amps based on 56 max amp draw x 69% of max thrust. In other words, if my math is good, the 80# motor requires roughly 75% of the amps to achieve the same thrust as the 55# motor. I am using terrova numbers here.
When I read comments like “if you fish in wind and current then go 24v” doesn’t that simply translate to more thrust for longer?
It would be great if anyone with my skiff would respond and/or anyone who would set me straight on what I am missing in my analysis.
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I opted for a 12V Riptide PowerDrive 55 with i-Pilot for my Dragonfly Emerger 16'.

I'm using a VMAX XTR34-75 12Volts 75AH Deep Cycle, XTREME AGM Battery.

So far very pleased with the setup. I generally fish during the tidal bite, about a 2-3 hour window. The battery generally has ~65% remaining when I get home. I use a Schmacher 15A smart charger. I don't want the weight of an onboard battery charger. I'm trying to stay as shallow draft as possible.

I try not to discharge below 50% even though deep cycle AGMs can tolerate an 80% discharge on a limited basis.
I have some strong currents to deal with in the Cape Romain Wildlife Refuge and Bulls Bay area of SC. I don't have any issue with currents and my 12v 55# Riptide on my Emerger. Even against the strongest current, 4 MPH, troller speed 3 1/2 moves me along at fishing speed.

Exactly...not all Li batteries are the same.

If I had the coin, I would have installed the Battle Born 100Ah 12V LiFePO4 Deep Cycle Battery for the Riptide. At $949 each (and on sale) I couldn't justify the expense for the boat. But, I have two Battle Born batteries in my Four Wheel Camper, Hawk model which has a solar charging system. They are absolutely superb batteries and are used for trollers as well.
Just be careful what you read. If you take the lithium to 50% DOC you will kill the battery very quickly. Talking ~200 50% DOC cycles vs ~2000 to 85%. Lithium has an incredible power density but has to be managed very well. A good quality charger is also a must. Constant amps that switches to constant volts to prevent over charge.
There are many types of Lithium batteries on the market. And many Li batteries are not suitable for marine use or >50% depth of discharge.

However, LiFePO4 batteries are not as intolerant to depth of discharge. Yet, like all batteries, regardless of type, depth of discharge and temperature will ultimately determine how long your batteries last. LiFePO4 is more tolerant of deep discharges and a longer battery life than most other energy storage solutions.

It is absolutely imperative a LiFePO4 battery be maintained with a smart charger with a Li battery charge mode selector.

Here's an all inclusive list with descriptions of all lithium battery types. And if interested, be sure to read the comments below the list. During my research for Li "house" batteries for my camper, I found the material in the list to be accurate. I also discovered, LiFePO4 batteries were being used for trolling motors.
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I'm confused on what you are speaking of. Are you saying it is better to run the battery down more?
the Chart below is for Relion Lithium 60AH battery. It shows a DOD chart which show that even with 100% Depth of Discharge, you will still have 80% battery capacity after 2000 cycles. that is 38 years if you recharge once a week.

Relion is another excellent LiFePO4 battery. I opted for Battle Born's 100Ah LiFePo4.

Most folks are only familiar with the general Li term and unfamiliar with the many different types of Li batteries on the market today for various applications.

In the chart you offered, note that the temperature was 77F for the analysis. As temperature decreases, expect the cycles associated with "Remaining Capacity" to slide to the left.

I would expect 77F to be a good median temperature for making yearly assumptions on life cycles for a LiFePO4 battery in south FLA.

All batteries experience reduced life cycles if taken into a deep (>50%) discharge. LiFePO4 batteries will have the highest number of life cycles if take below 50% remaining capacity than most any other battery. LiFePO4 is the only marine suitable battery (based on my limited research and knowledge after contacting LiFePO4 manufacturers) capable of more than 1000 taken to a depth of discharger >80%.

Even AGM life cycles will be greatly reduced if taken below 50% and some AGMs can tolerate limited DoD cycles to 80%. But you can't expect more than a couple of years of service out of an AGM constantly drained by a troller greater then 50%.

As mentioned in a previous post, I opted for a VMAX XTR AGM for my 12V troller. I'm operating my Riptide PowerDrive 55 for 3 hours max on any one outing at no more than speed 3 1/2 and seeing about 35% discharge.

What is 50% depth of discharge (DoD)? That varies from battery type to battery type, but a good rule of thumb is 12.2V is about 50% remaining capacity for most batteries. To know exactly what the SoC (state of charge) is for a battery, you need to test for specific gravity. But, we can't test SG on a sealed battery. If you're using a flooded battery you can test for specific gravity; 50% is a specific gravity of 1.190.

11.98V is 20% remaining capacity; 80% discharge.
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