LiFePO4 gives $21k Return

[NorthernFocus]

I've now made a couple of cruises with the new battery. It's performing as hoped with no dedicated thruster battery. So I started wondering whether the up front investment pencils out.

The manufacturer claims the battery is good for 6000 charge cycles. I never trust such claims so half it. That's 3000 cycles. At the end of a week on the water it shows two charge cycles. We average 8 weeks on the water every summer so that's16 cycles per year. 3000/16 works out to 187 years. Historically I've averaged $125/yr on batteries for house and thruster banks. 187 x 125 = $23,375 saved less the $2k invested in the LiFePO4 and charger. That's a net return of $21,375. Now I just have to update my will.

 

[Mike and Sarah]

Ha this is funny!
It’s like me trying to justify the value of all the seafood we catch vs store bought.
But I think the lithium upgrade wins compared to seafood vs fuel cost. But then again we always have the freshest best seafood on the table. Plus we have the memory / stories about each catch we make. Priceless

 

[NorthernFocus]

Ha this is funny!
It’s like me trying to justify the value of all the seafood we catch vs store bought...

Typically when we invite friends to dinner we serve halibut and spotted shrimp. It's not the cheap $25/lb stuff from the market. It's the $200/lb stuff we catch ourselves.

 

[Submariner]

I've now made a couple of cruises with the new battery. It's performing as hoped with no dedicated thruster battery. So I started wondering whether the up front investment pencils out.

The manufacturer claims the battery is good for 6000 charge cycles. I never trust such claims so half it. That's 3000 cycles. At the end of a week on the water it shows two charge cycles. We average 8 weeks on the water every summer so that's16 cycles per year. 3000/16 works out to 187 years. Historically I've averaged $125/yr on batteries for house and thruster banks. 187 x 125 = $23,375 saved less the $2k invested in the LiFePO4 and charger. That's a net return of $21,375. Now I just have to update my will.

My first set of AGM's lasted me 90 days. My second set, I got a little over 14 months. Converting to LFP therefore has saved my boating as I couldn't afford to replace my batteries that often, year over year. Not to mention the health care costs associated with moving those heavy lead based batteries in and out of the boat so often.

 

[scross]

My first set of AGM's lasted me 90 days. My second set, I got a little over 14 months. Converting to LFP therefore has saved my boating as I couldn't afford to replace my batteries that often, year over year. Not to mention the health care costs associated with moving those heavy lead based batteries in and out of the boat so often.

Wow Martin! Your experience with the your AGMs sucks. No wonder you changed to LFP.
As a counterpoint, over the past 11 seasons with the R-25 Classic and now with our C-28, I have averaged over 4 years of use out of every single AGM battery before replacement. The replacements were solely due to preventive maintenance, not because of battery failure. I have never had a AGM failure in my boats.
That said, I buy the best AGMs I can get and they are not cheap. But still far cheaper than LFP batteries.

 

[Submariner]

Wow Martin! Your experience with the your AGMs sucks. No wonder you changed to LFP.
As a counterpoint, over the past 11 seasons with the R-25 Classic and now with our C-28, I have averaged over 4 years of use out of every single AGM battery before replacement. The replacements were solely due to preventive maintenance, not because of battery failure. I have never had a AGM failure in my boats.
That said, I buy the best AGMs I can get and they are not cheap. But still far cheaper than LFP batteries.

My hat's off to you... 4 years on AGM batteries... I can't relate, not even sure I can imagine what that's like. Everybody boats different. For us, power is everything, and the more the better. Solar is mission-critical onboard as it provides about 80% of all the power we consume. (420 watts of solar, 320ah of LFP)

Since I converted Channel Surfing to LFP in February 2022, we have not had a single electrical issue on the boat. We run our inverter daily, water heater, microwave, coffee machine. I can pull 150 amps at 12volt DC to power the coffee maker. We've ran the coffee maker with only 25% SOC. Voltage will hit 11.7volts, which causes the inverter to beep (low voltage warning is 11.8 volts). If voltage were to hit 11.5, the inverter would shut off, but we've never had that happen.

I spent $7k for parts, and about 50 hours of my own labor to convert Channel Surfing to LFP. It was a lot of work and was worth every cent and hour spent.

 

[scross]

My hat's off to you... 4 years on AGM batteries... I can't relate, not even sure I can imagine what that's like. Everybody boats different. For us, power is everything, and the more the better. Solar is mission-critical onboard as it provides about 80% of all the power we consume. (420 watts of solar, 320ah of LFP)

Since I converted Channel Surfing to LFP in February 2022, we have not had a single electrical issue on the boat. We run our inverter daily, water heater, microwave, coffee machine. I can pull 150 amps at 12volt DC to power the coffee maker. We've ran the coffee maker with only 25% SOC. Voltage will hit 11.7volts, which causes the inverter to beep (low voltage warning is 11.8 volts). If voltage were to hit 11.5, the inverter would shut off, but we've never had that happen.

I spent $7k for parts, and about 50 hours of my own labor to convert Channel Surfing to LFP. It was a lot of work and was worth every cent and hour spent.

View attachment 27757

We do multi week cruising like you do. Not to Alaska though! We just never use the inverter. Oh I test it for a minute every other year or so to see if it still works but that’s it. We live very comfortably in our 12 volt world. Even in marinas with shore power we only hook up to 120 volts about 1/2 the time. The only 120 volt thing we have on board is the microwave and it’s not used much even when on shore power….

 

[NorthernFocus]

My hat's off to you... 4 years on AGM batteries... I can't relate, not even sure I can imagine what that's like. Everybody boats different. For us, power is everything, and the more the better. Solar is mission-critical onboard as it provides about 80% of all the power we consume. (420 watts of solar, 320ah of LFP)

Since I converted Channel Surfing to LFP in February 2022, we have not had a single electrical issue on the boat. We run our inverter daily, water heater, microwave, coffee machine. I can pull 150 amps at 12volt DC to power the coffee maker. We've ran the coffee maker with only 25% SOC. Voltage will hit 11.7volts, which causes the inverter to beep (low voltage warning is 11.8 volts). If voltage were to hit 11.5, the inverter would shut off, but we've never had that happen.

I spent $7k for parts, and about 50 hours of my own labor to convert Channel Surfing to LFP. It was a lot of work and was worth every cent and hour spent.

View attachment 27757

Sounds like the battery that you need is called a generator 😕

 

[NorthernFocus]

Wow Martin! Your experience with the your AGMs sucks. No wonder you changed to LFP.
As a counterpoint, over the past 11 seasons with the R-25 Classic and now with our C-28, I have averaged over 4 years of use out of every single AGM battery before replacement. The replacements were solely due to preventive maintenance, not because of battery failure. I have never had a AGM failure in my boats.
That said, I buy the best AGMs I can get and they are not cheap. But still far cheaper than LFP batteries.

"Deep cycle" batteries and AGM are little more than marketing schemes by the battery manufacturers. Which worked. They've sold millions of them to replace the ones that people ruin by using them exactly as they're advertised to be used. Every lead/acid battery whether deep cycle or not begins to "sulfate" when it drops to 12.3 volts. So basically if you actually use what labeled as a deep cycle battery as advertised you're killing it every time you draw it down into "deep cycle" territory. AGM is essentially the same chemistry as flooded cell and suffers the same issues. It dies a little bit every time it's drawn down to fully utilize its name plate amp hours. If lead acid/AGM batteries are used in a manner to optimize their life they are basically half the advertised capacity(in Ah).

I've only made two one week trips so far with the LFP battery and as far as I'm concerned it has already proven that it's worth the money. Simply the piece of mind of knowing how much capacity that I have left and that always being way more than necessary is worth it. Not to mention shedding 160 lbs of lead.

And no, if you do the math the AGMs are not cheaper in the long run than the LFP.

 

[scross]

"Deep cycle" batteries and AGM are little more than marketing schemes by the battery manufacturers. Which worked. They've sold millions of them to replace the ones that people ruin by using them exactly as they're advertised to be used. Every lead/acid battery whether deep cycle or not begins to "sulfate" when it drops to 12.3 volts. So basically if you actually use what labeled as a deep cycle battery as advertised you're killing it every time you draw it down into "deep cycle" territory. AGM is essentially the same chemistry as flooded cell and suffers the same issues. It dies a little bit every time it's drawn down to fully utilize its name plate amp hours. If lead acid/AGM batteries are used in a manner to optimize their life they are basically half the advertised capacity(in Ah).

I've only made two one week trips so far with the LFP battery and as far as I'm concerned it has already proven that it's worth the money. Simply the piece of mind of knowing how much capacity that I have left and that always being way more than necessary is worth it. Not to mention shedding 160 lbs of lead.

And no, if you do the math the AGMs are not cheaper in the long run than the LFP.

Dan, Agree with what you are saying. I do spend time every morning and evening monitoring my house bank SOC. My AGMs only get 1/2 the draw of the LFPs. In 11 years while cruising and when stored on the trailer my house batteries have never been drawn down below 45% SOC or 11.0 volts.
In short term of 11 years on my two boats I have replaced 9 AGMs at a total cost of under $2500. In the short run of 11 years, I do believe that AGMs have been more cost effective than a LFP conversion when paired with a robust solar system and conservative energy consumption practices. Using Martin’s expense of $7k per boat converting from AGM to LFPs on both boats that cost total would have been $14,000.
We don’t use the inverter because we really don’t need a microwave oven, coffee maker, satellite internet, television or other power hungry devices while cruising. For us those things are the antithesis of why we are cruising. And we don’t plan on keeping our boat for another 187 years.
I understand that not everyone wants to be as conservative as I am with energy consumption. LFPs are a great solution for those folks.

 

[NorthernFocus]

Dan, Agree with what you are saying. I do spend time every morning and evening monitoring my house bank SOC. My AGMs only get 1/2 the draw of the LFPs. In 11 years while cruising and when stored on the trailer my house batteries have never been drawn down below 45% SOC or 11.0 volts.
In short term of 11 years on my two boats I have replaced 9 AGMs at a total cost of under $2500. In the short run of 11 years, I do believe that AGMs have been more cost effective than a LFP conversion when paired with a robust solar system and conservative energy consumption practices. Using Martin’s expense of $7k per boat converting from AGM to LFPs on both boats that cost total would have been $14,000.
We don’t use the inverter because we really don’t need a microwave oven, coffee maker, satellite internet, television or other power hungry devices while cruising. For us those things are the antithesis of why we are cruising. And we don’t plan on keeping our boat for another 187 years.
I understand that not everyone wants to be as conservative as I am with energy consumption. LFPs are a great solution for those folks.

Yeah I'm pretty OCD about battery health. We're all 12V on our boat other than a tiny inverter to supply power for a laptop that does double duty as chart plotter/entertainment center. Our typical trip lasts a week and we anchor in remote locations every night. Never see a dock much less tie up to one. I was beginning to think about installing solar panels on my boat. But the real revelation with the LFP has been the rapid recharge. We move around enough to run the engine at least an hour a day and that pretty well tops the battery back up.

I couldn't justify the conversion to government specs. I had to go with Alaska fishing boat specs which was(apparently) only 30% the cost. Maybe I'm blissfully ignorant.

 

[rheimb1]

Dan, I found your numbers interesting, but I found mine even more interesting.

I ran the numbers a little differently. Invest the $2,000 at 10%, withdraw $1,200 every six years to buy new AGM batteries, and after 187 years you'd still have around $24 billion.

The good news is your descendants won't have to worry about battery prices....Just saying!

 

[NorthernFocus]

Dan, I found your numbers interesting, but I found mine even more interesting.

I ran the numbers a little differently. Invest the $2,000 at 10%, withdraw $1,200 every six years to buy new AGM batteries, and after 187 years you'd still have around $24 billion.

The good news is your descendants won't have to worry about battery prices....Just saying!

Well if you're going to get critical with the numbers... the reason we're buying the LFP to start with is that it's needed now. So for the AGM you have to spend $1200 today. That only leaves you $800 to invest. Plus you have to account for inflation for all of the future AGMs. And I'd spend the $800 on something else anyway...

 

[venajeff]

I believe in investing in the future. The future memories of what I spent my money on today!

 

[Submariner]

That said, I buy the best AGMs I can get and they are not cheap. But still far cheaper than LFP batteries.

It's been proven over and over again by many, that the cost of LFP is less than AGM, when you compare against time and amp-hours consumed. However, context matters with any analysis.

The conversion costs from AGM to LFP are high. Buy once, cry once as the saying goes. One would have to consider a 10-15 year period of time where LFP would most likely last that duration, and AGM would be replaced many times. Add in the cost of batteries plus the labor to swap them out.

If the boat stays with the owner for less than 5 years before they trade up, than staying with AGM is less expensive to the owner.

Example
Now that I've re-wired my boat to support LFP, it'll also support going back to AGM without needing any additional wiring changes.

I could put in 4 AGM batteries at 110ah each, (440aH total, leaving 198aH usable). If they cost $400/each, and last me 3 years, that's $4,800 in just the cost of the batteries over 9 years. (not including labor costs of doing the replacement).

My LFP battery (Lithionics Li3, 320ah total with 256aH usable, and will easily last in excess of 9 years. (it came with a 7 year warranty). It sells today for $4,700, and is more expensive than a pair of Dakota 320Ah or Epoch 300ah (both are about 1/2 the cost of Lithionics).

 

[NorthernFocus]

It's been proven over and over again by many, that the cost of LFP is less than AGM, when you compare against time and amp-hours consumed. However, context matters with any analysis.

The conversion costs from AGM to LFP are high. Buy once, cry once as the saying goes. One would have to consider a 10-15 year period of time where LFP would most likely last that duration, and AGM would be replaced many times. Add in the cost of batteries plus the labor to swap them out.

If the boat stays with the owner for less than 5 years before they trade up, than staying with AGM is less expensive to the owner.

I started this thread sort of tongue in cheek but also to make the point about the finances involved. But here and elsewhere there's a lot of talk about cost on this topic and little discussion about the other benefits. This is the first time in half a century of boating that I'm confident that I have a good handle on energy management on the boat. Regardless of how much instrumentation you have reading the state of lead acid batteries is an estimate at best. With LFP both standalone and integrated BMS takes the guesswork out of it. How much that is worth is an individual decision for each of us.

Now that I've re-wired my boat to support LFP, it'll also support going back to AGM without needing any additional wiring changes.

This is a good point that I've not seen mentioned before. The DC/DC charger functions very similar to and ACR albeit in one direction. So the switch to LFP can be reversed by simply dropping lead acid technology back in.

..My LFP battery (Lithionics Li3, 320ah total with 256aH usable, and will easily last in excess of 9 years. (it came with a 7 year warranty). It sells today for $4,700, and is more expensive than a pair of Dakota 320Ah or Epoch 300ah (both are about 1/2 the cost of Lithionics).

The range in prices for LFP batteries is crazy. Lithionics are twice what Epoch cost which in turn are at least twice as much as less expensive alternatives. Within the various Epoch models there is a 2x range in prices. Like any marine rated equipment there is a step change for IP rated batteries from any manufacturer. Ironically the smaller/lighter/higher energy density models tend to be the least expensive. Financially and functionally very tempting(i.e. small/light) but for a marine environment maybe not the right choice.

 

[Submariner]

The range in prices for LFP batteries is crazy. Lithionics are twice what Epoch cost which in turn are at least twice as much as less expensive alternatives. Within the various Epoch models there is a 2x range in prices. Like any marine rated equipment there is a step change for IP rated batteries from any manufacturer. Ironically the smaller/lighter/higher energy density models tend to be the least expensive. Financially and functionally very tempting(i.e. small/light) but for a marine environment maybe not the right choice.

The range in price follows name brands, it also follows features.

As an example, not all LFP batteries support being able to start the engine in an emergency. To jump an engine requires 700-1200 amps for a second, depending on the engine in the boat. Some LFP batteries have bluetooth connectivity to the BMS on the battery for better instrumentation, other brands offer no such connectivity/visibility. There's also a range offered in the fine print of what the max rated continuous draw of the battery is possible. The least expensive LFP's I've looked at are usually 100amps continuous, max. UL rating, of which there are many different standards of UL rating, is another feature that adds cost to the battery.

My Li3 battery can do 1200amps in an emergency to jump start my engine (which needs 680amps) and is rated for 150amps of continuous draw, with short bursts to 200amps supported. On the R27, I designed the electrical system to support 150 amps, continuous draw. I also have a UL rated system (not just the battery) in that, there's an external 250 amp DC breaker located right next to the Li3, with a wired connection to the BMS inside the LFP battery. This provides the Li3 battery the ability to disconnect itself from the boat by tripping the external 250amp breaker (in addition to it's internal breaker, inside the battery). This UL rating was important to me, in addition to all the other features of Li3.

 

[Cutwater28GG]

fascinating discussion.

ive owned our C28 for 12 years. I have changed the AGMs twice and they are the Universals. only time I replace the AGM's is when CCA failed to get the engine started and I took it as a sign to replace all the batteries. Since switching to an X2 for engine starting, I don't even think about AGM replacement. My summer cruising plans may force my 3rd battery replacement this summer - fingers crossed they don't.

The game changer was a 340Wh solar panel and a Victron solar charger that actually charges the AGMs to a real 100% SOC by pushing the volts beyond what the shorepower charger can achieve. Gives me more power to use and treats the batteries better.

 

[Cutwater28GG]

I am curious for folks who did the drop in replacement path for a house LFP and use a DC to DC charger from the engine AGM - what your real world experience is of being able to charge the house battery quickly enough off the engine alternator and shorepower (that are wired to the AGM)

 

[NorthernFocus]

I am curious for folks who did the drop in replacement path for a house LFP and use a DC to DC charger from the engine AGM - what your real world experience is of being able to charge the house battery quickly enough off the engine alternator and shorepower (that are wired to the AGM)

After a typical overnight (12 hrs on the hook) I'm at 85% SOC on my 300Ah battery. With all electronics, etc operating and with 50A DC/DC charger I net 40A going into the LFP. Takes a little over an hour to get back to 100% SOC.