Lithium battery - worth the expense?

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About 15 years ago I worked on a medical device powered by lithium batteries, so I had to deep dive into the technology as part of product design and regulatory approval. The charging information of different cells was, as Ray Clark says, all over the place, but storage at full charge was never desirable. Storing for long periods at full charge will damage the cells. If you have a newer phone, computer or other device, you may notice they don't fully charge right away if you plug them in over night. They'll charge to 75-85% and then stop, giving a final boost to full charge around the time you normally start using them in the morning. The laptop I'm writing this on is almost always plugged in and as such holds its charge at 80%. If I need a full charge for a day or two off the charger, I have to tell it to fully charge. Likewise, if I wake up at 3AM my phone won't be fully charged, even if I dropped it on the charger many hours ago. But at 5AM when I normally pick it up it's charged to full. Whether 30%, 50%, or 85%, anything below full charge is better. As CRS says, the voltage check for lithium isn't reliable without highly sophisticated circuitry, so the MinnKota press to check feature is pretty worthless. That's a feature of the discharge curve, which for lithium is very flat (compared to lead acid which has a steady and easily monitored decline.) Monitoring Ah used is the far superior way, thus something like a SmartShunt or similar battery monitor (I mention SmartShunt only because I use one and can vouch for it--I'm sure others are good.) If I fish a few hours twice a week, I leave the batteries in whatever state of charge they were in after fishing, unless they're below about 40%. Then I plug in the night before I head out.
Another thing to watch is charge rate. Generally, lower charge rates are better, but of course that sucks if you've used 50Ah and want to charge overnight with a 3A charger. 1/20th to 1/10th C is a good range, but don't worry about anything under 1/2C (That's a ratio of charge rate over total capacity, so a 5A charger on a 100Ah battery is 1/20C. A 10A charger on a 20Ah battery is 1/2C, and so on.)
With good quality modern batteries, the degradation from "abuse" is not fast. Don't get overly concerned if you charge to full today expecting to go out tomorrow and then work or weather keeps you off the water for a week. But it is worth worrying about when storing a battery over the winter, or even if you're a Saturday fisherman and always charge to full after use. Charging the night before use would be better.
Unlike a cell phone, you probably aren't charging every day, 365 days a year. So if you abuse the snot out of your trolling battery and only get 600 cycles out of it instead of 1000, that's still decades of use for a weekend fisherman in Minnesota getting out 20 times a year, but it cuts my cell phone from about 3 years to 2 years. So it's relative. You don't have to be overly concerned. If you're the kinda person that geeks out about this stuff, a good battery monitor is helpful. I you don't care, do the best you can and the battery will still likely outlive your boat ownership until you sell it for something better or something cheaper, depending on your needs.
 
Chargers designed for handling lithium batteries are a must. Finagling a lead acid charger to charge a lithium battery is where the fires come from.
 
About 15 years ago I worked on a medical device powered by lithium batteries, so I had to deep dive into the technology as part of product design and regulatory approval. The charging information of different cells was, as Ray Clark says, all over the place, but storage at full charge was never desirable. Storing for long periods at full charge will damage the cells. If you have a newer phone, computer or other device, you may notice they don't fully charge right away if you plug them in over night. They'll charge to 75-85% and then stop, giving a final boost to full charge around the time you normally start using them in the morning. The laptop I'm writing this on is almost always plugged in and as such holds its charge at 80%. If I need a full charge for a day or two off the charger, I have to tell it to fully charge. Likewise, if I wake up at 3AM my phone won't be fully charged, even if I dropped it on the charger many hours ago. But at 5AM when I normally pick it up it's charged to full. Whether 30%, 50%, or 85%, anything below full charge is better. As CRS says, the voltage check for lithium isn't reliable without highly sophisticated circuitry, so the MinnKota press to check feature is pretty worthless. That's a feature of the discharge curve, which for lithium is very flat (compared to lead acid which has a steady and easily monitored decline.) Monitoring Ah used is the far superior way, thus something like a SmartShunt or similar battery monitor (I mention SmartShunt only because I use one and can vouch for it--I'm sure others are good.) If I fish a few hours twice a week, I leave the batteries in whatever state of charge they were in after fishing, unless they're below about 40%. Then I plug in the night before I head out.
Another thing to watch is charge rate. Generally, lower charge rates are better, but of course that sucks if you've used 50Ah and want to charge overnight with a 3A charger. 1/20th to 1/10th C is a good range, but don't worry about anything under 1/2C (That's a ratio of charge rate over total capacity, so a 5A charger on a 100Ah battery is 1/20C. A 10A charger on a 20Ah battery is 1/2C, and so on.)
With good quality modern batteries, the degradation from "abuse" is not fast. Don't get overly concerned if you charge to full today expecting to go out tomorrow and then work or weather keeps you off the water for a week. But it is worth worrying about when storing a battery over the winter, or even if you're a Saturday fisherman and always charge to full after use. Charging the night before use would be better.
Unlike a cell phone, you probably aren't charging every day, 365 days a year. So if you abuse the snot out of your trolling battery and only get 600 cycles out of it instead of 1000, that's still decades of use for a weekend fisherman in Minnesota getting out 20 times a year, but it cuts my cell phone from about 3 years to 2 years. So it's relative. You don't have to be overly concerned. If you're the kinda person that geeks out about this stuff, a good battery monitor is helpful. I you don't care, do the best you can and the battery will still likely outlive your boat ownership until you sell it for something better or something cheaper, depending on your needs.
Great read, thank you for sharing.
Now, I'm not a very concise person, & unfortunately, I'm kind of slow, (simple?) but want to understand clearly, so may I ask in a more simplistic kind of way :
Are you saying for those that aren't anal about it, that : (in your experience)
a) leaving a battery shelved w/out charging isn't a big thing in the long run ? (during on off use time)
b) charging just before you geaux out is best, especially if there could be a week or two between uses ?
c) Storing for long periods of time (like months) is best at considerably less than fully charged ?
Thank for your generous consideration for my clearer understanding,
Sincerely ...................
God bless.
 
Great read, thank you for sharing.
Now, I'm not a very concise person, & unfortunately, I'm kind of slow, (simple?) but want to understand clearly, so may I ask in a more simplistic kind of way :
Are you saying for those that aren't anal about it, that : (in your experience)
a) leaving a battery shelved w/out charging isn't a big thing in the long run ? (during on off use time)
b) charging just before you geaux out is best, especially if there could be a week or two between uses ?
c) Storing for long periods of time (like months) is best at considerably less than fully charged ?
Thank for your generous consideration for my clearer understanding,
Sincerely ...................
God bless.
B and C are correct as stated. For A, I was saying that for best life, you're better off at less than full charge but what level doesn't really matter as long as it's above about 40% and below 85%. If you know you aren't depleting it it's fine (best!) to store without charging. For instance, with my 100Ah battery that I use for trolling only (got an outboard for place-to-place) I know that 3 hours on the water doesn't get it below 40-50%, so I ignore it until the night I go fishing again. If I'm fighting a wind and back trolling at full speed for 3 hrs, that's different and I'll give it an hour or two of charge when I get home. That's before I got my monitor which pretty much confirmed my guesstimates.
Ask more if you like. I wasn't quite sure what you were getting at with A so I may have missed the point.
 
Great read, thank you for sharing.
Now, I'm not a very concise person, & unfortunately, I'm kind of slow, (simple?) but want to understand clearly, so may I ask in a more simplistic kind of way :
Are you saying for those that aren't anal about it, that : (in your experience)
a) leaving a battery shelved w/out charging isn't a big thing in the long run ? (during on off use time)
b) charging just before you geaux out is best, especially if there could be a week or two between uses ?
c) Storing for long periods of time (like months) is best at considerably less than fully charged ?
Thank for your generous consideration for my clearer understanding,
Sincerely ...................
God bless.
Just to be clear, he is refering to Lipo type batteries not lead acid or AGM type batteries!!
 
Bought a 100 ah lithium from Lithium Hub a little over a year ago for slightly over $600 (on sale). I use it to run my lights, electronics, and my 12v Power Drive trolling motor. I have a separate wet cell battery for starting with both on a NOCO charger that can be set for whatever type battery I have. My lithium battery comes with an 11-year warranty, and I can check the remaining capacity with an app on my phone while I am on the water. I do a lot of fishing where I utilize the Spot Lock feature on my trolling motor, and I have yet to take my battery down below 50%. I'm sure in heavy current or high winds that would change, but this battery will easily last me a day of fishing without worrying about how much capacity it has left. It has definitely been a great investment and I am glad I went with a higher-grade battery than some of the cheaper lithium options out there.
 
Bought a 100 ah lithium from Lithium Hub a little over a year ago for slightly over $600 (on sale). I use it to run my lights, electronics, and my 12v Power Drive trolling motor. I have a separate wet cell battery for starting with both on a NOCO charger that can be set for whatever type battery I have. My lithium battery comes with an 11-year warranty, and I can check the remaining capacity with an app on my phone while I am on the water. I do a lot of fishing where I utilize the Spot Lock feature on my trolling motor, and I have yet to take my battery down below 50%. I'm sure in heavy current or high winds that would change, but this battery will easily last me a day of fishing without worrying about how much capacity it has left. It has definitely been a great investment and I am glad I went with a higher-grade battery than some of the cheaper lithium options out there.
Great to hear, they are improving them all the time. When used as they are designed for, they perform quite well !! People just have to be sure to handle them correctly !!! I am doing some research on them now, so I will be ready when my current agm batteries give up..
 
Mostly to find anyone who uses a deep cycle Li battery and if they agree with the positives noted. I've never heard of a budget Li battery, but if it holds its charge better than lead batteries at mid-speed using the trolling motor, I might consider buying one for my light aluminum row boat. (Especially to save the back hauling it in and out of truck and boat!)

Thanks to all of you for help shooting me in the direction of a budget (?) Li.
I bought a budget LiFeP04 100AH battery on Amazon by TimeUSB for $249, and I am very happy with it:
https://www.amazon.com/gp/product/B0BBZL5BPR
So happy that I bought a second one. These things are awesome! I've also been using them with an inverter when camping, and WOW, they last forever! Very impressed.

As someone stated above, I'll probably never go back to lead acid batteries. 10 years from now, I'll probably still be using this pair. Now THAT is a thought worth considering.
 
Lithium batteries was the rave in the motorcycle world. Problem is they do not work well in cold weather. A lot of folks where getting stuck with a bike that would not start. Guess it would work for fishing.
I was one of those bikers. Bought it and it died completely within 8 months here in Wisconsin. I’m sticking with lead right now for the boat as it meets my needs inexpensively. I am generally always alone so the added weight actually helps smooth out my ride.
 
FYI- This is the battery charger I bought for my LiFePO4 batteries:

https://www.amazon.com/dp/B0BN1W15D6

This is a cheap "smart" charger, with a good digital display, and it does a good job. They make stronger ones, but the 10A are supposed to give the longest life for the battery.

The only negative I have for these chargers is that the cords are pretty short.

I now have two of them, one for each of my batteries. They work well for regular batteries, too. I've only had mine for a couple of months, now, so no idea of their longevity or resistance to water, so I keep mine in the garage and only use outside on dry days.

There are many similar chargers out there. I got this because I needed something fast and cheap, and it just happened to work out.
 
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I decided on this NOCO Charger for my 100Ah LiFePO4. It is very handy for onboard install in our little boats - small, has mounting holes, ring connections for battery, etc. I have used NOCO stuff for years and been impressed with the quality.
 
I decided on this NOCO Charger for my 100Ah LiFePO4. It is very handy for onboard install in our little boats - small, has mounting holes, ring connections for battery, etc. I have used NOCO stuff for years and been impressed with the quality.
I have the same charger a 20aH LifePO4, used just for the electronics. Running Noco on the LA too. No need to switch chargers when we upgrade the trolling motor battery’s.
 
Just wanted to comment that the TimeUSB batteries have been awesome. My only problem is I have never been able to run them down more than a few percentage, even after a long day of fishing.

I noticed that they are on sale right now on Amazon.
$219 for the 100AH Amazon.com

There is another offer of $229.00 with a $15 coupon for a net price of $214.99 - Amazon.com



My only wish is that they could be used as primary starting batteries. Those type are still not common and very, very expensive.
 

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