Mid LiFePO4 Cruisers?

[Stu Jackson]

I remember raising an eyebrow when I saw the fridge‘s draw in amps, I’m guessing at the number of hours it runs.

At the risk of repeating myself: 60 h per day. Period. Four decades of input. How? 5 A when running, 24 hours per day, runs 50% of the time when everything is cooled off inside. How do we know about the 50%? Because thousands of people already did what you're asking about and measured it and wrote in and told us. Literally: some guys sat around with volt meters and ammeters and stop watches in the 70s and 80s and did all this. Really. It is now 40 bloody years later. Really. You can only reduce the run time by installing very good insulation, really a separate topic. A friend of mine on his C34 did a great job and got 60 ah per day down to a tad under 40. Is it worth it? Not necessarily if you have good recharging sources.

This is what I mean by not reinventing the wheel. Look, I learned this before the internet in 1998 when I got my boat with a fridge. My owners association has a great magazine with tech notes that started for my C34 in 1987 and my PO gave me all his hard copies in 1998. Nice guy. i read them all. Fridge load was one of the first articles BEFORE THE INTERNET! Same MATH is true today.

 

[SoSound]

From what I can see, your only real problem will be how to control your alternator. If you do not do anything to modifiy it, I would suspect that you will need to add a DC 2 DC charger to take amps from the start battery to charge the alternator. I personally would not want to go that way becasue it greatly reduces the amps you have to recharge your FLP bank. Most of the D2D chargers are only 30A-40A so you are a long way from what you are making with your 120A alternator.

I’m not opposed or even reluctant to modify my alternator. I would also put this on the priority list, as evaluate best cost and time effective options between alternator modification/protection or DC to DC charger between the existing FLA bank and the LFP bank.

And, yes, I see that limiting the rate of charge to the LFPs from the alternator to such a low rate is a very poor choice. I believe external regulation is possible for this alternator, and I need to research that. Is either approach (external regulation or thermal limitation) significantly more effective or efficient?

 

[Stu Jackson]

Is either approach (external regulation or thermal limitation) significantly more effective or efficient?

Both are included with an external regulator, so it's not an either / or choice.

Maine Sail's website includes an article on converting a Leece Neville alternator from internal to external.

Another choice you have is to simply increase your FLA wet cell house bank size before you start throwing $$ around. Many have chosen golf cart batteries, four 6V for 425 ah at 12V. Maine Sail also documents why AGMs are a poor choice for cruisers, too.

 

[SoSound]

At the risk of repeating myself: 60 h per day. Period. Four decades of input. How? 5 A when running, 24 hours per day, runs 50% of the time when everything is cooled off inside. How do we know about the 50%? Because thousands of people already did what you're asking about and measured it and wrote in and told us. Literally: some guys sat around with volt meters and ammeters and stop watches in the 70s and 80s and did all this. Really.

Thanks, Stu… I really do get it, and appreciate your insights. My fridge manual said 2A, and I guessed at 10 hours instead of 12, so I put 20 Ah in my energy budget. I also appreciate the references to previous articles, etc.. If somebody else comes across this thread, it will help both of us.

I’m just grateful that I don’t have to go spend and entire day with a volt meter and a stop watch…

 

[Stu Jackson]

Glad to help, Dave, but dontcha furget yer ammeter!

 

[Hayden Watson]

I’m not opposed or even reluctant to modify my alternator. I would also put this on the priority list, as evaluate best cost and time effective options between alternator modification/protection or DC to DC charger between the existing FLA bank and the LFP bank.

And, yes, I see that limiting the rate of charge to the LFPs from the alternator to such a low rate is a very poor choice. I believe external regulation is possible for this alternator, and I need to research that. Is either approach (external regulation or thermal limitation) significantly more effective or efficient?

External regulation is the best option because then you have full control of the charge voltage. Any with external regulation, I would always have thermal protection. I have dreams of changing to a WS500 but it is not currently in my budget. I am usinh my 30-year old Ample Power 108A alternator with a Heart Interface InCharge regulator which is the same age. They did not even dream of the challenges of LFP charging when it was built. To control it, I put a 1.0-ohm 100W resistor in the field wire which cut the max output to 70A on a deeply discharged battery and 60A on normal voltages. I then moved my bilge blower hose so that it pulls air from the front of the alternator and wired it so that it is always on when the enine is running. I then installed a $15 Inkbird thermostat that is attached to the alternator case at the hottest spot I could find with my buddies Flir. Its relay is put into the wire that turns the regulator on when the oil pressure comes up. I set it to turn off at 200ºF and come back on when the temp drops to 190ºF. With this setup, at 1900rpm, it will charge for 20-minutes and then shut off for 2-3.

My problems with heat is more sever than most because this alternator case has very poor ventilation with only a few holes in the back face. I have also fully insulated all four sides and top of the small engine space for sound which means that the space is already at 160ºF without any heat from the alternator. That is why this week I added a 120mm fan that pulls cool air from the space between the floor and hull and blows it directly onto the back of the alternator. I have not had a change to test this out yet. My plan is to get a better alternator from a wrecking yard to build a new alternator from. I am planning on basing it on a Denso large case Hair pin type stator with dual internal fans and an output somewhere around 200A or above. Then I will modify it for external regulator heat control and a PWM max output controler. I would also change from v-belts to serpinene. That way, I can run it at very high current to recharge at anchor or low motoring speeds but still lower it down to where my little 23-hp can keep me moving near hull speed if needed.

But then half of my enjoyment of my boat is tinkering with the systems.

 

[Hayden Watson]

Both are included with an external regulator, so it's not an either / or choice.

Maine Sail's website includes an article on converting a Leece Neville alternator from internal to external.

Another choice you have is to simply increase your FLA wet cell house bank size before you start throwing $$ around. Many have chosen golf cart batteries, four 6V for 425 ah at 12V. Maine Sail also documents why AGMs are a poor choice for cruisers, too.

Yep. the thermal switch is a stop gap measure. Most any alternator can be converted to external regulation with very little trouble.

 

[dLj]

I cannot see what I am missing.

• I have protection for the alternator with a continuous charge path.
• Battery monitoring for the house bank of all power used and replaced.
• Proper charge voltage for both battery banks.
• No need to remember to do anything to make it operate.

I don't see how your start battery is being charged when you have stopped your engine, but maybe you have a way.

For what you are doing I'm sure it's a fine setup.

I personally want to know the SOC of my entire system - including all my AGMs. By running all power in and out of my house bank, I monitor through my house bank monitor. If I were to run my electric windlass, for example when anchoring, and I then shut down my engine, my house bank continues to recharge those AGMs without me doing anything until they are done.

I have one point of energy flow where I measure through a Maretron monitoring system. That one point captures all incoming and outgoing current flow to the house bank. Don't know if that makes sense?

dj

 

[Davidasailor26]

On our 37 we have a very similar setup, but without solar. One of our G31 house batteries does fit in the aft cabin next to the start battery, and another is in front of the engine. I can give another agreeing data point to Stu’s 60 AH per day refrigerator estimate - that’s very close to what mine does in summer. This time of year the duty cycle is much less (closer to 20%). With our two G31’s we figured we could expect about 20 hours of runtime on a typical day. Our house batteries went bad last year and we took that opportunity to add a third G31 in the lazarette. The wire run there was a little longer than the run to the engine compartment battery but not too much longer so we felt it was worth the compromise. We can now do a daysail, night at anchor, and second daysail without worrying about capacity. If we motor for a little while we can add a second night. If we had solar we’d be in much better shape too.

 

[Hayden Watson]

I don't see how your start battery is being charged when you have stopped your engine, but maybe you have a way.

For what you are doing I'm sure it's a fine setup.

I personally want to know the SOC of my entire system - including all my AGMs. By running all power in and out of my house bank, I monitor through my house bank monitor. If I were to run my electric windlass, for example when anchoring, and I then shut down my engine, my house bank continues to recharge those AGMs without me doing anything until they are done.

I have one point of energy flow where I measure through a Maretron monitoring system. That one point captures all incoming and outgoing current flow to the house bank. Don't know if that makes sense?

dj

My start battery is only charged by the alternator and has never been connected to any other charge source for the 25-years I have owned Papillon. The current start battery is a Group-31 that I installed in 2009 so the system must be working good enough. In those years, it has sat off charge for up 6-months over the winter and started the engine in spring commissioning without a problem. My start system has no parasitic loads and I keep the master start battery switch off when not aboard.

I have never heard of the Maretron monitoring system. On your system, how to you differentiate between the power in the house bank and what is sent to the AGMs with the DC-to-DC chargers.

I have never had any problems keeping my start battery full but until I switched to LFP, keeping enough power in the house bank was a constant struggle so that is the only thing that I monitor, and it is a simple and old Link-10 battery monitor. It is also a single point capture system but only tells me Ah in and out of that one battery. It does not tell me anything about where it comes from or where it goes. I have not yet gone down the Victron rabbit hole with their admittedly wonderful Cerbo GX system because I just can't quite stomach the $600 price of admission.

 

[BarryL]

Hey,

I'm not an expert on batteries, etc. I'm also thinking about new batteries for my boat. Some of my thoughts on a battery system:

You need a way of GENERATING the electrical energy.
You need a way of STORING the electrical energy
You need to know how much electrical energy you need each day, week, etc.

The LiFePO batteries are better at storing the energy (accept charge faster, can be deeply discharged, are lighter, allow for more charge cycles). If you don't have a good way of generating the electricity then I don't know how much of a benefit the batteries really are. If you have solar, wind, towed generator, etc then I'm sure that LiFePO4 batteries are a good idea. If you need to run your engine or diesel / gasoline generator to replace the used AMPS, then I'm not so sure. Sure you may not have to run your generator morning and night to have a fully charged battery bank but you still need to run it for X hours a day, so you haven't really gained anything.

Barry

 

[dLj]

My start battery is only charged by the alternator and has never been connected to any other charge source for the 25-years I have owned Papillon. The current start battery is a Group-31 that I installed in 2009 so the system must be working good enough. In those years, it has sat off charge for up 6-months over the winter and started the engine in spring commissioning without a problem. My start system has no parasitic loads and I keep the master start battery switch off when not aboard.

You are clearly running that battery well....

I have never heard of the Maretron monitoring system. On your system, how to you differentiate between the power in the house bank and what is sent to the AGMs with the DC-to-DC chargers.

I can't differentiate - it's all power in, and all power out. Everything runs through my house bank, in and out. So I simply monitor my house bank. I may put in a simple voltage check on my AGM's just to be sure that those circuits are working properly, easy to do. That would still not tell me how much is being used in the two separate systems. My start battery is a system, and my two forward bow thruster/windlass batteries are a system.

I have never had any problems keeping my start battery full but until I switched to LFP, keeping enough power in the house bank was a constant struggle so that is the only thing that I monitor, and it is a simple and old Link-10 battery monitor. It is also a single point capture system but only tells me Ah in and out of that one battery. It does not tell me anything about where it comes from or where it goes. I have not yet gone down the Victron rabbit hole with their admittedly wonderful Cerbo GX system because I just can't quite stomach the $600 price of admission.

The Maretron was not cheap either... But it gives me real time battery temperature, voltage, current (positive is charging, negative is drawing, and how many amps) and House SOC.

dj

 

[dLj]

If you don't have a good way of generating the electricity then I don't know how much of a benefit the batteries (LFP) really are. If you have solar, wind, towed generator, etc then I'm sure that LiFePO4 batteries are a good idea. If you need to run your engine or diesel / gasoline generator to replace the used AMPS, then I'm not so sure. Sure you may not have to run your generator morning and night to have a fully charged battery bank but you still need to run it for X hours a day, so you haven't really gained anything.

Barry

I disagree - this is exactly when LFP batteries really excel. LFP batteries don't care where they reside in SOC. You can leave them at 50% as long as you like and cycle around there or whatever. They do not undergo sulfation as ALL lead acid batteries suffer. The primary cause of lead acid batteries dying is not bringing them up to full charge after use and having them die due to sulfation. So if you don't have a good charging system and you are going to leave your batteries in a partial state of charge frequently, LFP's are definitely the way to go.

dj

 

[Hayden Watson]

I disagree - this is exactly when LFP batteries really excel. LFP batteries don't care where they reside in SOC. You can leave them at 50% as long as you like and cycle around there or whatever. They do not undergo sulfation as ALL lead acid batteries suffer. The primary cause of lead acid batteries dying is not bringing them up to full charge after use and having them die due to sulfation. So if you don't have a good charging system and you are going to leave your batteries in a partial state of charge frequently, LFP's are definitely the way to go.

dj

Yep! And add to that, for most of us, the power we use is not a function of the amount stored to any great extent. So, for me that meant that if I go for a 4-day cruise, I will never need to worry about producing energy because my stored power will last that long without needing to recharge. With lead, I needed to charge from day-1!

 

[Stu Jackson]

If you don't have a good way of generating the electricity then I don't know how much of a benefit the batteries really are.
... but you still need to run it for X hours a day, so you haven't really gained anything.

While you're correct about energy, storage and generating power to refill the storage medium, you are missing the inherent advantage of LiFePO4 technology. This technology can be charged more rapidly than FLA because the acceptance of the battery is even across the entire charging regimen, unlike FLA where acceptance drops off rapidly as the battery gets charged.

Of course, this means that the generating source must be adequate to be able to provide this amount of power. Most stock alternators are not. Shorepower is great for doing so, but a cruising boat isn't connected to shorepower, by definition. Solar is great but in reality is limited because of real estate for the panels so usually not large enough for bulk levels, and the reality for cruisers, as repeatedly discussed on cruisersforum is that the bulk replenishment is done by fossil fueled generation (engines/alternators or onboard gas or diesel fueled generators) and solar is used to float charge (LiFePO4 doesn't need long absorption times).

 

[dlochner]

While you're correct about energy, storage and generating power to refill the storage medium, you are missing the inherent advantage of LiFePO4 technology. This technology can be charged more rapidly than FLA because the acceptance of the battery is even across the entire charging regimen, unlike FLA where acceptance drops off rapidly as the battery gets charged.

Of course, this means that the generating source must be adequate to be able to provide this amount of power. Most stock alternators are not. Shorepower is great for doing so, but a cruising boat isn't connected to shorepower, by definition. Solar is great but in reality is limited because of real estate for the panels so usually not large enough for bulk levels, and the reality for cruisers, as repeatedly discussed on cruisersforum is that the bulk replenishment is done by fossil fueled generation (engines/alternators or onboard gas or diesel fueled generators) and solar is used to float charge (LiFePO4 doesn't need long absorption times).

In practical terms, a Group 31 AGM with 100 ah capacity discharged to 50% SOC charged at .4c (40 amps) will take about 5.5 hours to reach 100% SOC. A LFP battery of the same sized and discharged to 50% SOC will take a little over an hour to reach 100% SOC, if the alternator can produce that much power without overheating. There in lies the big difference. Less engine run time, lower fuel costs, less noise while charging. And when traveling and anchoring nightly most of the energy consumed can be replaced as a by product of normal anchoring and setting/dousing sails.

 

[SoSound]

One of the hopes when I started this thread was that there would be Black Friday specials on LiFePO4 batteries that would make them even more affordable, and that does appear to be possible. Epoch Batteries has a Black Friday discount code to apply at checkout. A 300 Ah battery in approximately a Group 31 footprint is available at a little more than 30% total discount off of its original price.

A single 300 Ah battery would more than double my usable capacity compared to my two 105 Ah FLA G31. The two FLA that I have now have been in place for two years, may be starting to show their age, and might need to be replaced next season anyway. At a little more than $800 (similar cost for one 300 Ah, or two 105 Ah), even if they only outlasted my 220 Ah of FLA batteries by double the typical FLA lifespan, I could break even on the actual cash outlay by the time that I paid for the second set of FLA batteries (maybe only a couple of years).

There are differing opinions expressed on LFPs biggest benefits, also different options for taking advantage of each of those characteristics. From my perspective, the biggest benefit is the increased capacity in the same (or smaller) footprint, not the fast charge capabilities. I don’t have the components necessary for fast charging, so that characteristic drops to about third place as I rank them. The reason I added solar was to either slowly charge the FLA house bank, or at least to slow the rate of discharge so that we could spend more time away from marinas or running the engine when cruising. This past September, we managed to stay out for nine straight days without having to connect to shore power…. pretty much any increase in battery capacity beyond what I have will mean that holding tank capacity will be the determining factor as to when we need to visit a marina.

If my priority is increased capacity and length of time between shore power or engine powered charging sessions, and LFPs can increase my battery capacity by multiples, at roughly double the purchase price of FLAs, then I would say that meets my original post criteria of giving me a big bang for my battery buck.

My current thinking, If I want to upgrade now, starting with what I have;
- Sterling PCU30 charger (with LFP charging profile or custom profiles)
- 220W solar w/ Victron MPPT 100/30 controller (LFP and custom profiles)
- Valeo 120A alternator (would only charge FLA start battery directly, as is)
- MOSFET battery isolator/combiner (might not really be doing anything?)
- FLA G24 start battery (would supply a DC-DC charger to pass alternator charge LFP house bank)

So am I correct in thinking that the only thing I might actually need to make the system work is a DC-DC charger (A Victron Orion 12/30 Isolated charger is available for $257 on Amazon via MarineHowTo Storefront). I had to spend more than that just to upgrade to my Sterling PCU30 when I put in the G31s to replace two G27 house batts a couple of years ago. But, I don’t really want to stop at just the minimum requirements and just drop in a different battery and call it good, so… I would also add a Victron Smart Shunt to monitor the system for $130.

If there are budget constraints now, and IF I decided to be cheap and only install one 300 Ah LFP now, could I add a second 300 Ah battery after next season without overly complicating things? Or, should I determine (or reduce) my total capacity needs and buy it all this year? Three 105 Ah batts would fit in the space that I have at a lower total purchase price than two 300 Ah batts. But, a 600 Ah capacity would definitely put me into the “Game Changer” range that @Hayden Watson has managed to build. It is also possible that I would also upgrade to an Inverter/Charger (if I can find space for it), if I decide to completely ignore budgeting and decide to install as much as 600 Ah of capacity now.

Here are my favored battery options:
- Max capacity; Epoch 300 Ah $856 ea. (or x 2 = $1758) $2.93/Ah
- Best use of existing space; Epoch 105 Ah $399 ea. (x 2 = $798 or x 3 = $1197) $3.80/Ah
- Best pricer per Ah; Basen Green 160 Ah $416 ea. (x 2 = $832) $2.60/Ah

Charging system upgrade options: I will add a battery monitor, Victron Smart Shunt $130
Which of these makes the most sense?
- A DC - DC charger, Victron Orion 12/30 Isolated $257
- Or an external regulator kit for Valeo 120 A alternator
Balmar ARS-5 $410
Balmar ARS-618 $535

WWTF do?
(What Would The Forum do?)

 

[dLj]

Glad you stated what wwtf meant, my mind was wandering....

As far as adding another LiFePo battery later, the biggest hurdle I see is making sure your wire lengths remain exactly the same. You are obviously going to run them in parallel so for charging, both batteries need the exact same cable length/size...

dj

 

[dlochner]

Responding in between cooking tasks and watching the bird in the oven, so short answers to some of the questions.

The problem with ACRs and FET based battery isolators is the matching the charging profile. These devices work well when the two banks have the same charging voltages. The charging voltages for LFP and LA batteries are different enough that one of the banks will not be charged properly when an ACR or FET is used to isolate the banks. Thus, a Battery to Battery or DC-DC charger or separate alternators for the house and start/reserve banks are the only viable options. Of the two, the DC-DC charger is the easier and cheaper alternative. The size of the charger depends on whether the house or start/reserve bank is receiving the charge current, if the smaller bank is receiving the alternator's current, then a smaller DC-DC charger is appropriate.

Don't even consider the ARS-5. Once you try to program the ARS-5 with magnetic reed switches, you will regret not purchasing a 618 and the bluetooth module. There is an article on MarineHowTo.com on programming the 614, the process is basically the same for the ARS-5. Without the BT module the 618 is programmed the same way as the 614.

Back to the turkey.

 

[Johann]

You can add an additional 300Ah Epoch next season no problem. Regarding the wiring, with two paralleled batteries you cannot improve on the diagonal wiring method with equal length interconnecting cables. To make it easier (and cheaper) next year when you upgrade be sure you have sufficient cable to reach the positive of one battery and the negative of the second one in their final configuration. I am using the diagonal method with three 315Ah LFP and it is working well. The cable resistance in my case is actually irrelevant compared to the internal resistance differences between the batteries.

I would not get the Orion Smart 12/12-30A. Either wait a month for the new Orion XS 12/12-50A, which is 98% efficient vs 81%, or move to external regulation direct to the LFP.

Orion XS 12/12-50A DC-DC Battery Charger - Victron Energy

Engineered from the ground up, the Orion XS redefines adaptive DC-DC charging. For use in dual battery systems charged with an (intelligent) alternator.

www.victronenergy.com