Lithium Charging Question

I'd like to get a lithium battery for my Minn Kota Traxxis 55 to be used on my Stealth 2000.

Not being an electrical genius, here is my question. I was talking with my son about getting the lithium battery, and he told me that I have to discharge the battery as close to 100% as I can.

He told me that you don't use those batteries fishing for a day and then go home and charge them up for the next day. Something about these batteries developing a memory and that short use and constant recharging is not good for the battery. Okay fine.

So here is my question. For talking purposes, let's suppose I go out fishing for 7 hours today trolling on a lake. I take my battery home and DO NOT charge it. All along not knowing how much my 7 hour day of fishing has depleted my battery.

I go out fishing the next day and I can only fish for 2 hours because my battery is drained!

Now my question is, is there a meter or some way to test the battery after the first day to see how much juice I have left for the next day of fishing? Maybe I should have charged the battery after the first day of 7 hours of fishing?

So what I'm hearing is that lithium batteries like to be fully discharged before charging again. How then do you determine when the battery has reached that discharged point?
Many thanks for the answer.

He is misinformed. Sounds like he may be trying to keep you from purchasing it for some reason.

You can discharge them to whatever level you wish and they DO NOT get a memory, that is what is great about them. Its best to leave them sitting at 70-80% charge for long times, but it is not necessary by any means.

You will need a battery charger that has a lithium or AGM mode on it, make sure you use the correct charger.

So to be clear, there is no discharge point and no required level for discharge. You can use it for 3 hours and be down to 95% charge and then recharge when you get home if you want.

Sounds like he may have confused it with the Nicad power tool batteries of years ago.

Read this entire posting on a lithium battery gauge. Lithium battery gauge

Right now,,I charge my lithiums up to use now that it’s time to fish. If the batteries still have 75%-80% charge from last time out fishing…I may not charge to 100% and just go ahead and use them and I try never to take them down to 20-25% or any lower. If storing for wintertime,,I store them at 50-60% with a charge. Some people store them with 100% charge. Best advice will come from the battery manufacturer on the brand you buy so check them out. I use Ionic Lithium Batteries and they have a blue tooth built in them for monitoring the batteries with a phone app so don’t need a gauge for my batteries. The phone app gives me all kinds of info on each of my lithium batteries.

Here is a description for maintaining Ionic lithium batteries from Ionic Batteries.

For the IONICs, and im only speaking for IONICs, the engineers charging specs differ just a little from what others may say, but for the most part they are very flexible, during fishing season if you choose to plug in every time and they are at 80% do it, you will not shorten the life of this battery and if you are running 50ah I highly recommend charging every time unless you know you are only fishing short days, its ok to drain the battery dead every now and then but for the best battery life you want to keep them above 20% and its easier to do that if you start out at 100%, The IONIC will use partial cycles so you can charge 5 times from 80% and only use one cycle, but if you use down to 40% they will equal a cycle, with the 100ah you can go 2 or 3 trips if you like but dont not leave them sitting for a long time below 50%,
when you do charge you can plug in and leave it with the proper charger or charge and unplug it really wont matter because the charger will never come back on any way for months unless the power goes off and comes back on and restarts the charging cycle , there is no maintenance mode on lithium, they charge then the float., Find a routine that works best for you and use the app, when it comes to lithium's dont every rely on the lights on the charger no mater what charger you have. I usually charge a day or 2 after fishing and unplug, if its been a coupe weeks I may plug in the charger the day before to top off.

IONIC LITHIUM BATTERIES FOR BASS BOATS - Drewcraft LLC

Call Andy. He will go over exactly what you need and will answer any questions you have. Ionics batteries have an app that will tell you everything you need to know about your batteries.

I also have Ionics and 100% would recommend. I ordered from drewcraft as well.

I have 4 Ionics and recharge my starting/electronics battery everytime I use it. I have gone out 4 times long lining and trolling motor batteries are at 60% and I will recharge them the next time i go out. My boat is in the water year round. Really like the ionics. I am using minn Kota battery chargers set foe AGM.

I have been looking at lithium batteries to change locations and reduce some weight. It certainly is tempting