Lithium battery with Ulterra

[70diesel]

I'm looking to replace my 3 group 31 AGM batteries that are used to power my 36v Minn Kota Ulterra with Lithium batteries. I was looking at Amped Outdoors and they mention that lithiums shut off at a certain point when they are low. From what I've read, the meter on the Ulterra remote doesn't accurately tell you how much power lithium batteries have. The Ulterra has an auto stow/deploy feature and you can not manually stow the motor easily (must be serviced after manual stow also). What happens is your using lithium batteries and they shut off and the Ulterra is in the water? You're kinda in a jam so how can this be avoided? Is anyone using lithiums with the Ulterra? Should you use lithium batteries with an Ulterra?

[TOXIC]

Interesting question.  It would be worth a call to Minnkota to get your answer.  I know lots of guys with lithiums and none of them have ever drained them while fishing but I’m sure it’s possible.  They also only run Ultrex and Ghost trolling motors. The only negative I ever heard was that a lithium runs at full output until drained and that some were burning up trolling motors because they weren’t designed to run at maximum output for long distances.  There was also an issue with using a lithium as a cranking battery but that has been rectified.  Also the PowerPole Charge battery charger didn’t like the ecm controller in some lithiums. 

[Craig P]

You could install a Bluetooth shunt to see the power level of the lithiums or purchase a brand that includes Bluetooth connection that shows voltage via your phone.  If you’re the type to charge after every outing, I doubt you would ever run into an issue if you’ve correctly sized your batteries.

[Tennessee Boy]

I have one lithium battery that I run my electronics on.   It cuts off at 10.6 volts.   That’s pretty low.   It would take some serious trolling to drain 3 good lithium batteries.   It’s often said that lithium batteries don’t lose voltage as they are discharged.  That is not true.   They start at a higher voltage and the voltage drops slower as it’s discharged.   I can see how that would throw off your remote.  My charger tells me what the voltage is when I start charging and how many amp hours it took to charge the battery.   I can predict pretty closely how much charge the battery will need based on the starting voltage.  If you’re remote tells you the voltage of the battery pack then you should know when it’s close to shutting off.  If not you could check the voltage after 16 hours of fishing to see what state the batteries are in.

 

Also,  MinnKota says the following on their web site.

 

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.

[Deleted account]

1 hour ago, Craig P said:

You could install a Bluetooth shunt to see the power level of the lithiums or purchase a brand that includes Bluetooth connection that shows voltage via your phone.  If you’re the type to charge after every outing, I doubt you would ever run into an issue if you’ve correctly sized your batteries.

Or hardwire a gauge on the console like we used to do in the last century...

[Bankc]

You can buy an amp/hour meter, sometimes called a watt-hour meter, and hook it up to your battery.  That'll tell you how much power has been drained, and give you an idea for how much is left.  Normal voltage readings won't work, as lithium batteries tend to drop in voltage pretty fast, then level off, then drop really fast again just as they go dead.  Their discharge curve is mostly flat.  So you need a way to measure the current draw over time to really know the level.  

 

For instance, fully charged is about 13.6v.  At 99%, it drops to 13.4v.  At 13.2v your down to 70%.  At 13v, you're at 30% and so on.  So at tiny 0.2v intervals, you have 100, 99, 70, 30, 17, 15, and 13%.  Since those aren't very well spaced out, making voltage readings alone pretty much useless.  

 

Having said all of that, I'd just hook up your trolling motor to your starting battery if it ever runs dead to get it back up, so you don't have to do it manually.  

 

1 hour ago, Tennessee Boy said:

Also,  MinnKota says the following on their web site.

 

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.

That was written for Lithium Ion batteries.  They run at a much higher voltage than Lithium Iron Phosphate (LiFePo4) chemistries (3.7 vs. 3.4 volts per cell).  Lithium Ions are smaller, lighter and more powerful than LiFePo4 batteries, but you'll rarely find them in boats, RV's, or off-grid power storage devices as Lithium Ion batteries are much more expensive, much more likely to explode, and don't handle the heat and cold nearly as well as LiFePo4.  A "12V" Lithium Ion would run at 14.8volts fully charged, whereas a "12v" LiFePo4 would only run at about 13.6v fully charged.  A "12v" gel battery will run at 12.8+ volts fully charged, for comparison.  

[Tennessee Boy]

52 minutes ago, Bankc said:

That was written for Lithium Ion batteries.  They run at a much higher voltage than Lithium Iron Phosphate (LiFePo4) chemistries (3.7 vs. 3.4 volts per cell).  Lithium Ions are smaller, lighter and more powerful than LiFePo4 batteries, but you'll rarely find them in boats, RV's, or off-grid power storage devices as Lithium Ion batteries are much more expensive, much more likely to explode, and don't handle the heat and cold nearly as well as LiFePo4.  A "12V" Lithium Ion would run at 14.8volts fully charged, whereas a "12v" LiFePo4 would only run at about 13.6v fully charged.  A "12v" gel battery will run at 12.8+ volts fully charged, for comparison.  

I thought I read the same thing once but that’s not what is says here.  I think you’re right and the wording on the website is very confusing.

 

https://minnkota-help.johnsonoutdoors.com/hc/en-us/articles/4413535309207-Battery-Selection

[Siebert Outdoors]

If you go lithium get a lithium with a BMS(Battery Management System.  You can Bluetooth to it. It will show you exactly what the batteries have. I'm not close to my batteries but this is what it looks like.  Also,  The lithium will last a lot longer than any of your other batteries before you would hit that point your talking about.  I run 3 50amp Ionics and a ghost.  I have only got them down to 77%.  That was on a longer day with a lot of trolling into the wind.

 

If you got 3 100ah Ionics I dont know if you could wear them out unless your fishing a river or hold the pedal down on high for most of the day.

 

You can also calculate the run time if you know the AH that motor runs at and the speed you normally run. 

[Kirtley Howe]

3 hours ago, 70diesel said:

I'm looking to replace my 3 group 31 AGM batteries that are used to power my 36v Minn Kota Ulterra with Lithium batteries. I was looking at Amped Outdoors and they mention that lithiums shut off at a certain point when they are low. From what I've read, the meter on the Ulterra remote doesn't accurately tell you how much power lithium batteries have. The Ulterra has an auto stow/deploy feature and you can not manually stow the motor easily (must be serviced after manual stow also). What happens is your using lithium batteries and they shut off and the Ulterra is in the water? You're kinda in a jam so how can this be avoided? Is anyone using lithiums with the Ulterra? Should you use lithium batteries with an Ulterra?

Just thinking out loud here.....What voltage does it take to actually stow the trolling motor? It may be that you could disconnect your lithium batteries from the trolling motor, and jump off your 12v starting battery to stow the motor. Just wonder if that is possible?

[70diesel]

Thanks for all of the advice. Amped Outdoors also mentioned the SmartShunt BT monitor and I like the idea of Ionic batteries having BT capability built in.

 

I'm not sure if you can stow a 36v Ulterra by using the 12v starting battery. I've contacted MinnKota for that one.

 

I doubt that I'd ever run the motor so much to drain the batteries into shut off mode but then again I don't want to find out the hard way. I go to a couple electric only lakes and the Susquehanna river which has a lot of current and I've run my AGM batteries low a few times where I could tell the Ulterra struggled to stow itself. This has been recent though and I think my batteries aren't lasting as long as when I first bought them 3 years ago.

[Woody B]

(I have skimmed, but not read all of the replies.  This may have been mentioned and I missed it)

 

The voltage doesn't drop as much when a lithium battery discharges.   That's why the gauge will always show fully charged on your Ulterra.    Like Siebert Outdoors I have an Ionic battery for my (12 volt) Terrova.    My only lithium experience is with this battery.  I'd get batteries with bluetooth regardless of brand.   

 

4 to 6 hours in the wind would render my old 88 amp hour lead acid battery pretty much useless.   I've fished multiple days, at least 12 hours in the wind with my 125 amp hour lithium battery and never had it under 50%.   I've only had it since March, but so far I'm very pleased.   It $tung when I bought it, but I would have spent that money on something else by now anyway.   

 

I'd recommend picking a manufacturer you like, then call and talk to them about your expectations, ect.   Ionic said a 100 amp hour would be more than sufficient for me.  I went with the 125 because I wanted overkill.   

[GaryH]

4 hours ago, 70diesel said:

Thanks for all of the advice. Amped Outdoors also mentioned the SmartShunt BT monitor and I like the idea of Ionic batteries having BT capability built in.

 

I'm not sure if you can stow a 36v Ulterra by using the 12v starting battery. I've contacted MinnKota for that one.

 

I doubt that I'd ever run the motor so much to drain the batteries into shut off mode but then again I don't want to find out the hard way. I go to a couple electric only lakes and the Susquehanna river which has a lot of current and I've run my AGM batteries low a few times where I could tell the Ulterra struggled to stow itself. This has been recent though and I think my batteries aren't lasting as long as when I first bought them 3 years ago.

You won’t be disappointed with the Ionic batteries. 

[looking45]

If your batteries die, you can still manually lift the Ulterra out of the water. You have to remove a couple of pins, but you need to carry tools to do it