lithium battery questions

[up2nogood]

I wouldn’t worry about the 85% rule unless your specific trolling motor manufacturer says it’s required. Most modern trolling motors that are lithium-compatible can run normally on LiFePO4 without you constantly watching the speed setting. The BMS is usually built into the lithium battery, so you don’t normally need to buy one separately. It handles overcharging, over-discharging, overcurrent, and temperature protection. For a small 9-ft pontoon, I’d choose LiFePO4 if your motor is rated for it. Otherwise, sticking with lead-acid or upgrading to a lithium-compatible motor is the safer route.

I ran lithium on a 50 thrust MinnKota in pontoon boat before I knew about the 85% rule . The motor was not brushless . I ran it as much as I wanted at 100% to get somewhere , not knowing I shouldn't . The motor was not a 5 speed ,it was the variable speed with the digital maximizer , but it was older than before they came out with the brushless , I believe that was 2023 . I got away with it , but apparently it's not advisable .

I now a 24 volt 80 MinnKota Terrova in a fishing boat ,and that motor is not brushless . I don't run lithium with it yet , but I will when the two lead acid batteries give up . I will switch to lithium , two 100 amp. I will also have to switch my onboard charger to a Noco or similar that will support charging lithium . My existing onboard charger does not . But I will follow the 85% rule with the Terrova . That motor I never run it any harder than 5-6 , most of the time its down around 4 trolling . Even less on spot lock .

But , Doublebluff I wouldn't be afraid to run Lithium with whatever motor you have , but some of the newer Minnkota's do come brushless , some don't . Regardless with a little caution , I would definitely go lithium , if anything the weight .

 

[SurfnFish]

Use a 20 hp to run then switch to a transom MK50. During my usual terrestrial flinging shoreline jaunts I'm running the MK 2 to 3 of hours a day, using it to hold position against wind as I control the 'slide' 10 yards off the shoreline, and then run it full throttle upwind to set up another pass.
With about 30 hours mol of MK run time on it, just put the 100 amp Weize LiPo on the charger yesterday afternoon when back from the lake, battery was at about 25%.
Once switching to lithium the only question that arises is 'why the hell did I wait so long?'

 

[up2nogood]

Use a 20 hp to run then switch to a transom MK50. During my usual terrestrial flinging shoreline jaunts I'm running the MK 2 to 3 of hours a day, using it to hold position against wind as I control the 'slide' 10 yards off the shoreline, and then run it full throttle upwind to set up another pass.
With about 30 hours mol of MK run time on it, just put the 100 amp Weize LiPo on the charger yesterday afternoon when back from the lake, battery was at about 25%.
Once switching to lithium the only question that arises is 'why the hell did I wait so long?'

With my 80 Terrova 24 volt I can go 5-6 hours trolling 1-1.4 mph. provided it's not fighting a lot of wind ,if so I will go 4 hours ,switch to my 9.9 kicker to finish the day . This is with lead acid batteries , I suspect I will get at least a couple days out of lithium once I go to them. But I'm going to use up these two lead acid before I switch ,as said I will have to change out my onboard charger also .

 

[Chucker]

I have read this...

"Lithium Batteries maintain higher voltages for longer. Motors engineered to make the most of flooded lead acid batteries can be damaged by the higher power output. To prevent this damage when using Lithium batteries you should not run your motor at its highest speeds, staying at 85%/Speed 8.5 or lower."

So this doesn’t actually make any sense to me. A fully charged lead acid “12v” battery could put out 14.5v or more. If that won’t damage the motor, how could it be damaged by using a lithium battery with a BMS that never puts out more than 13v.

I have never heard any sort of reasonable explanation of why using a lithium ion battery would damage a trolling motor during normal use, it’s probably just scaremongering.

 

[up2nogood]

So this doesn’t actually make any sense to me. A fully charged lead acid “12v” battery could put out 14.5v or more. If that won’t damage the motor, how could it be damaged by using a lithium battery with a BMS that never puts out more than 13v.

I have never heard any sort of reasonable explanation of why using a lithium ion battery would damage a trolling motor during normal use, it’s probably just scaremongering.

The reason is a lithium battery runs flat , no drop in voltage under load , it will run 13.2- 13.4 until almost dead . So those motors are getting more voltage at full throttle than when a lead acid battery under load will be producing which is 11 -12 volts . It's the sustained high voltage that gets the motor when at full throttle ,whereas the voltage drop in lead acid is not harmful to the motor . Anyway thats explanation from what I read . Makes sense .