I’m setting up a boat for a friend and he has purchased a 36 volt min kota. He has very limited space due to the boat size and he is contemplating a single 36 volt lithium battery. Does anyone have a good recommendation on brand or a trusted dealer?

The Ionic batteries I have have been flawless.

I have the Epoch 100amp/hr, pretty much the same size and weight of a group 31 agm. I can get several days of fishing out of it before needing to recharge.

Running my 36v with my three Epoch 50amp can last all day long. Usually I am around 80% after a day of fishing.

NOW, I have two Epoch 50amp run in parallel which make it 100amp and I might can get 6 hours on them and they are just running my graphs and live scope.as the day go on, I check my power and start cutting off graphs to save enough power for 1graph to run my Lakemaster map to get back to the ramp.

For my particular setup, my single 36v has been amazing.

How many amps do you run?

The pro guide salesman at the expo told me a 36v 50amp would run an ultrex all day long …. but I know nothing about batteries so he could’ve been pulling my leg.

60Ah @ 36v. That's a little more usable energy than 3 brand new deep cycle 12v Lead Acid batteries...

I'm sure it would run it for a full day on your trolling motor, if you are not running it between 8-10 and your foot is not on it pretty much all day. I run mine when just trolling down a bank at around 5 and I do not have my foot on it all day long. 50 amps is 50 amps no matter what the voltage is. With lithium's you can get pretty much everything out of them whereas a wet cell you keep losing power as you go down in power, then you have to compensate by turning the trolling motor up higher which eats away at your amperage.
I know some friends that run a solar panel to keep their lithium's charged up all day because they keep their foot on the trolling motor.
Hooking up and alternator charge to your batteries will only charge them when the main engine is running. Mine does not run all that much. I have had my boat now for 4 years and have around 110 hours on the main engine. I probably have 5 times or more on my trolling motor.

I wouldn't listen to that. If you are gonna go lithium why cut it close.

I went with three 12V lithiums so one could be used as a backup for the main battery if necessary.

I'm running 2 each 36v 40AH Impulse litiums. I have them on a battery switch and only run 1 at a time. That way, if I have a battery go down, or have an issue, I always have a fully charged battery on back-up. I can usually fish 2-3 days on 1 battery. (Disclaimer: I fish slowly and methodically) I've never had to switch to the backup durring the day.