I’m interested in reducing the weight on my boat so I’m considering going to Lithium batteries for my trolling motors. I use an Ulterra on the bow and a Vantage on the transom. My current batteries are group 27 deep cycle. What size Lithium batteries do I need? Thanks for your help.
Hey Duchman, I actually have good knowledge of lithium batteries because i sell them to the RV industry. Currently we are not selling into the Marine market, but the technology is the same.
Your average Group 27 deep cycle battery has approximately 80 amp hour of power. One of the biggest differences between Lithium and wet batteries is the useable power in them. an 80 amp hour wet cell battery will give you about 35 amp hours of useable power. An 80 amp hour lithium will give you 75 amp hours of useable power. If you have 2 group 27 wet cell deep cycle batteries currently, and want similar performance, you should shoot for something over 70 amp hours in lithium. Personally, i would try to get something over 100 AH and improve your situation. You will also need a new charger with a lithium setting. Noco makes a great lithium charger in their Genius Genpro.
^That is the clearest answer I’ve heard thus far about lithium upgrades. Thank you!
I just went with 125 amp hr for my boat. Although weight wasn’t the driving issue, it will be nice to drop 100 lbs, especially if I find that I need a 5th house battery for the new locators I am having installed. Honestly probably would have been fine with 100’s but the cost diff wasn’t that much.
You will be very happy with 125 AH. Once you go lithium you will never go back. Make sure you understand how to manage your lithium system and it will consistently outperform all other other types of batteries.
I am considering going lithium as well. I want to go with a 24 volt single battery in the bow for the trolling motor and free up the second battery in the stern for an exclusive electronics battery and leave the starting battery for just that. Anyone have it set up that way and any reason not to do it?
Thanks for the help! Sound like I need 100+.
I have considered a single 24 volt battery. I’m interested in hearing the pros and cons.
It’s all about the AMP hour ratings. If you get one 24v instead of two 12 volts in series the size of the battery may not work well in your boat. it just depends on what kind of space you can create in your battery compartment. Most boats are configured to accept two group 31 batteries. For instance, my Lund has one battery under each council. For me to put just one 24-volt lithium in there I don’t have enough space for a 24v 100-AH hours battery under one side. There are companies that make a 24v 60 AH that has the footprint of a group 31, however i do not believe 1 60 AH battery is enough power for most boats. Therefore 2 12-volt lithium batteries seems to be the best option in most cases.
If you never want to worry about running out of battery power use two 12v 100 AH batteries in series. It is simply amazing!
I guess I had not considered how big the battery was, I only have room for a 31 size battery in the compartment, so I will do some research but had hoped I could get a 100 AH to fit in there, it could be a bit taller and still work in mine.
I am also considering Lithiums for 36V Trolling motor, 3x 100Ah. My biggest deciding factor is to go with a cheaper $350 or $800 battery. There are many good tear downs on batteries at this link and if you go over to BBC there are dozens of discussions on Lithium batteries.
https://www.youtube.com/@LithiumSolar/videos
https://www.bbcboards.net/search.php?searchid=27398788
Depending on your current charger, you may be able to have it reprogrammed versus replacing. For my Dual Pro 4x15A, the cost to reprogram is about $180 plus shipping.
If you have a switch in your boat to allow for switching over to one of the trolling motor batteries from starting battery, when going to lithium this is probably going to be a problem as most lithiums can’t be used for cranking.
I just switched to lithium batteries for my trolling motor. I went with Amped. I had three 31 series batteries for my 36 volt Ulterra. I was told I should go with two 36 volt 60AH batteries wired in parallel to replace the three lead acid. I installed Amped’s 36volt 10amp single bank charger. I was concerned it would take too long to charge the two batteries. Lithium batteries can not be shipped with a charge of more than 30%. When I looked at the app that shows battery power the batteries were at 25% and 27%. I plugged the charger in at 10:30PM and at 6AM the next mornimg they were fully charged, so I think that will not be an issue. I haven’t used them yet. I will report back once I get a real life report. I did ask about charging below 32F, and asked if I should get a battery heater blanket. I was told they will charge down to 17F. I will still get a blanket just in case and I will use it if needed. Now I just need the ice off of Green Bay. 
Mojo, I am looking forward to your results.
How much weight savings did you acheive and do you think the (2) 60 amp batteries will produce more run time than (3) 31 series AGM batteries?
The lead acid weigh about 70lbs per battery and the 36volt lithium weigh about 45lbs so I save about 120lbs. I talked to three different guys about it. I asked if I should go with three 12volt 100Ah batteries, and then I could have used my existing precision battery charger, or the two 36volt 60Ah batteries, and they all three said no question go with the two 36volt lithium’s. They also said that the two 36volt batteries wired parallel should last at least 2x’s longer, but probably closer to 3x’s longer than the lead acid setup runtime. I sure hope they are right. They weren’t cheap, but come with a 5 year warranty. The sport show price included the 2 batteries, and two chargers. I only used the one charger for $1890.00
I am considering going lithium as well. I want to go with a 24 volt single battery in the bow for the trolling motor and free up the second battery in the stern for an exclusive electronics battery and leave the starting battery for just that. Anyone have it set up that way and any reason not to do it?
I have a single 24v and never ran out of power. Using PP Charge keeps 24v good.I have no room for 3 batteries and got tired of 12v trolling motors-mostly gutless for spot lock in currents.
One can now get a 24v single 100ah that is a 31 series size.
I just got back from 4 days of fishing on Green Bay using my new lithium batteries for my trolling motor. AMPED lithium batteries (2) 36volt 60ah batteries wired parallel. The first day consisted of 11 hours of fishing with low winds and slowly moving. Trolling motor is a 36 volt ulterra settings of 1.5-2 for the day. End of the day it used 2%. The next two days were breezy/windy with similar 11 hours of fishing, mostly spot lock and moving from place to place. Power wise spot locked it was fluctuating between 20-60% on the motor. I also trolled for about 30 minutes one day. I think one day it used 6% and the other 8%. The last day was very windy. 16mph sustained with gusts to 25mph. on the lake I think they were higher than on land. I trolled for 2 hours, spot lock the rest of the time, and power wise spot locked it was between 4-8 on the trolling motor, and that day 10 hours of use it used 20% of the battery power. I would say I am very impressed with the lithium batteries after the first trip. Hopefully they end up lasting 6-8 years and that would be phenomenal.
Also impressed with my Amped 24V 50ah. Ran my Terrova for 8 hrs in current, only used 10%.
A buddy did mention that the battery reader may be off as some don’t accurately read the high discharge on LiFePo4’s. Should I trust that readout? I saw that Amped makes a power reader but not inclined to purchase that, yet.
I did buy the Amped bluetooth reader you use with their app. I think it was $64. I hope that it is accurate.
Also impressed with my Amped 24V 50ah. Ran my Terrova for 8 hrs in current, only used 10%.
A buddy did mention that the battery reader may be off as some don’t accurately read the high discharge on LiFePo4’s. Should I trust that readout? I saw that Amped makes a power reader but not inclined to purchase that, yet.
Resized_Screenshot_20230410_143632_Amped_Outdoors_Battery_Monitor.jpeg
Also impressed with my Amped 24V 50ah. Ran my Terrova for 8 hrs in current, only used 10%
Curious what size is that 50ah is, a 27?
Edit..
Googled it and see its at 24 size. Do you feel you are getting as much run time as you got out of 2 12 volts?
I’ve had good luck w my ionic lithium battery. 125 ah for starting and electronics. 10 year warranty and a free app to track battery info
Screenshot_20230413-150552_Ionic-Blue-Batteries.jpg
Screenshot_20230413-150615_Ionic-Blue-Batteries.jpg
Just order 3x 100ah PowerUrus at $400 each with BT to power Ulterra.
I did a lot of research on batteries and for a budget battery, the tear downs were pretty impressive.
Just order 3x 100ah PowerUrus at $400 each with BT to power Ulterra.
I did a lot of research on batteries and for a budget battery, the tear downs were pretty impressive.
Please report back. I may go this route.
I’m in the same boat where I may consider a switch.
My trolling motor batteries(31 group) are fairly new so I don’t plan to make a switch on them until they’re dying.
I need to crank a 115hp Optimax on the fishing boat and have a Helix 9 wired to the same battery. What is my best option? I’m not sure how dual purpose batteries work with regards to lithium. I’d love the weight savings, along with the overall higher capacity of the lithium battery. My on-board battery is only a 2 bank setup charging the trolling motor batteries, so that would not be an issue to change yet.
Bucky, look at the Ionic 125 Amp starter/troller battery. 31 size and you could run 2 or 3 locators all day and still have power to start. Also has the protection circuts built in, plus Bluetooth for monitoring. About $790
Bucky, look at the Ionic 125 Amp starter/troller battery. 31 size and you could run 2 or 3 locators all day and still have power to start. Also has the protection circuts built in, plus Bluetooth for monitoring. About $790
I have the same battery and I have been impressed as well!
<div class=”d4p-bbt-quote-title”>ganderpike wrote:</div>
Also impressed with my Amped 24V 50ah. Ran my Terrova for 8 hrs in current, only used 10%Curious what size is that 50ah is, a 27?
Edit..
Googled it and see its at 24 size. Do you feel you are getting as much run time as you got out of 2 12 volts?
Hey John, if my battery indicator is accurate I am getting much more battery life than the 12V’s I ran previously, albeit on a MotorguideXi5. I made the switch mainly for weight, and I am happy I did. Spent 8 hrs in Sippi current and barely used 20%.
Where is the best place to buy these Ionic batteries?
Lithiumhub.com
I’m interested in reducing the weight on my boat so I’m considering going to Lithium batteries for my trolling motors. I use an Ulterra on the bow and a Vantage on the transom. My current batteries are group 27 deep cycle. What size Lithium batteries do I need? Thanks for your help.
Dutchman, if you are looking to upgrade to a lithium battery setup for your trolling motors you should check out Norsk Lithium. They have 80AH & 100AH capacity batteries that are the same size as Group 27 but will give you a much longer runtime and are half the weight of lead-acid. Overall lifetime expectancy of those batteries is 4k charging cycles and 15-20 years. Worth looking into if you are in the market.
Also, most on-board chargers are equipped with an AGM setting so if you go with 12V batteries you already have a charger that can take care of the lithiums. No need to purchase a new one.
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