Replacing FLA with LiFePo4 charging question

[newhaul]

Originally Posted by ForeverDes

!

However, I tend to align more closely with this approach.
I've never seen anyone build a pole barn and afterwards wish they had built it smaller, and I've yet to see anyone on this forum or elsewhere downsizing a working house bank's capacity after the fact.

.

The thing is right now you are running an 8D battery which is 220ah capacity at best ( aside from the fact its not a deep cycle battery) so you have a 100ah usable for longevity. As well as a need to fully recharge on a consistent basis or suffer a premature PSOC failure.
A single 200ah lfp would give you a good 140ah usable capacity with no need to recharge fully ( lfp actually like being between 20% and 80% charge)
So even just putting in a single 200ah setup would be a power upgrade.

[newhaul]

Originally Posted by Adelie

There are several issues to consider.

Let's start with winter storage. Does it get below freezing during winter storage? Is there shore power available during storage. LFP doesn't like to be stored below freezing, I understand that it damages the battery. Is removal from the boat realistic? For sure trying to charge it below freezing damages the battery. When a LFP battery goes into storage make sure it is down between 50-60% SoC, storing at 100% is bad for them. If it goes down to 0-32F then leaving a small 40-60W light bulb in the battery compartment that is sealed from the rest of the boat is probably enough to maintain battery temp above 32F. Below 0F I would probably install a small 350W forced air heater with a thermostat.

I believe BattleBorn batteries use their internal BMS to provide fine control of battery charging so your regular charger should continue working. The big thing to worry about is frying your alternator because the batteries will accept so much power, so you need a special regulator. If you are going with a different brand you should look into how that brand's BMS works.

For cold storage, if an FLA is fully charged it should be able tolerate temperatures below -50F without freezing. As charge state drops, ability to withstand cold temps drops too. If the start at full charge it is reasonable to believe they will make it thru the winter. If the boat has access to power a trickle charger could maintain the batteries at full charge. Alternatively if some light is still falling on the panels, they will be putting out a trickle charge, maybe enough to maintain the batteries.

Regarding your starting battery. A 10-30W panel with a PWM controller will provide 2-7Ahr/d. Each time you start your engine it uses less than 1Ahr of power. You don't need special electronics to charge the starting battery.

Having a connection switch so that the house bank can start the engine is not a bad idea. The harder to get to the better so it isn't accidentally turned to combine the banks and not noticed for a long time.

Economics.
LFP batteries are going to max out somewhere near 10yr. They need BMSs and the electronics in there will have a calendar life expectancy. If for no other reason than some of the capacitors will start leaking electrolyte. Depends on exactly what is in the electronic package. If the BMSs are external to the battery then replacement is easier and will depend on whether the vendor is still in business and supplying replacements for 10yr old equipment. The cells themselves could last nearly 30yr cycling every day. Hard to say. Best to count on 3,000 or so cycles. LFP batteries are considered dead when they reach 70% capacity. LFPs should be cycled between 80-20% capacity. I believe Battleborn cuts of charging when they get to 80% so you can't damage the battery. So for a 100Ahr battery you really get to use 80Ahr and you don't know about that top 20%.

Deep cylcle FLA will go 1,000 or so cycles if not cycled too deep too often and are recharged as soon as possible. Death is usually defined as 80% original capacity remains.

So how do you compare costs when batteries have different capacities and life expediencies? By calculating all the energy you will get out of them over all the battery cycles then dividing by purchase cost.

I don't know what your Sams club batteries are but I can get info for Trojan 6v golfcart batteries.:
Trojan T-105, 6v, 225Ahr@R20 rate, 1200 cycles per trojan but we will use 1,000 anyway, $150-185 online, lets say $170. 80% capacity at death, so average will be 90%. Batteries are cycled from 100-50% so 50% of capacity is used.
https://www.trojanbattery.com/produc...ine-flooded-2/

BattleBorn 12v-100Ahr, 3600cycles (10yr), $899 from BB, 70% capacity at death of cells, but we are looking at about 1/3 that time so 90% when electronic dies and we'll say 95% average. As indicated about you will cycle thru 80% of battery capacity.

Formula is Voltage x Ahr (gives Whr) x Ave % lifetime capacity x Average % used per cycle x cycles / $
Trojan T-105: 6v x 225Ahr x 90% x 50% x 1,000 / $170 = 3,573Whr/$
BattleBorn: 12v x 100Ahr x 95% x 80% x 3,000 / $899 = 3,043Whr/$

Here in San Diego I can get T-105s for $125+9% tax no shipping. Using that price I get 4,433Whr/$ purchase price. That's about 50% more power for the money. If I was using the batteries daily year round I would have to replace the battery bank about every 3yr or so so there is an inconvenience price to be paid too.

In reality given your usage patterns, the FLAs will probably last as long as BattleBorns would.

It doesn't sound like you are getting BBs so the particulars of what you are looking at will be slightly different but not much so.

If you want to convert to an electric galley, the lithium would be the better way to go, they can support the high current draws for cooking. With FLAs you probably would want to have an 700-1,000Ahr house bank and you've said you don't have room.

Sorry but didn't read past your first part but you are incorrect lfp don't care about sub freezing Temps or even sub 0 f for storage they are just sensitive to charging if the cells themselves are below freezing..

[ForeverDes]

Wow, thanks for the detailed and informative response! I'll consider everything you've said, and I'll touch a few points here.

Originally Posted by Adelie

There are several issues to consider.

Let's start with winter storage. Does it get below freezing during winter storage? Is there shore power available during storage. LFP doesn't like to be stored below freezing, I understand that it damages the battery. Is removal from the boat realistic? For sure trying to charge it below freezing damages the battery. When a LFP battery goes into storage make sure it is down between 50-60% SoC, storing at 100% is bad for them. If it goes down to 0-32F then leaving a small 40-60W light bulb in the battery compartment that is sealed from the rest of the boat is probably enough to maintain battery temp above 32F. Below 0F I would probably install a small 350W forced air heater with a thermostat.

It definitely gets below freezing here in the winter, but I do have access to shore power. Keeping the battery compartments above freezing is not a problem, but neither would be removing the batteries for winter storage. That's a decision I'll likely make year by year depending.

Originally Posted by Adelie

I believe BattleBorn batteries use their internal BMS to provide fine control of battery charging so your regular charger should continue working. The big thing to worry about is frying your alternator because the batteries will accept so much power, so you need a special regulator. If you are going with a different brand you should look into how that brand's BMS works.

That's why I plan to keep a FLA start battery and run the alternator to it, with a dc to dc charger from start to house.

Originally Posted by Adelie

Having a connection switch so that the house bank can start the engine is not a bad idea. The harder to get to the better so it isn't accidentally turned to combine the banks and not noticed for a long time.

I've got easy access to my engine room. I'd probably forego a switch and just have a dedicated set of jumpers for emergencies.

Originally Posted by Adelie

In reality given your usage patterns, the FLAs will probably last as long as BattleBorns would.

My current usage, yes, probably, my planned usage in 3 years, maybe not as much. I'm trying to make life easier on future me as much as possible by making good long-term choices now!

Originally Posted by Adelie

If you want to convert to an electric galley, the lithium would be the better way to go, they can support the high current draws for cooking. With FLAs you probably would want to have an 700-1,000Ahr house bank and you've said you don't have room.

That may be a consideration in the future. But unless I seriously increase my solar output, which is problematic on a boat this small, it may be unfeasible.

[ForeverDes]

Originally Posted by newhaul

The thing is right now you are running an 8D battery which is 220ah capacity at best ( aside from the fact its not a deep cycle battery) so you have a 100ah usable for longevity. As well as a need to fully recharge on a consistent basis or suffer a premature PSOC failure.
A single 200ah lfp would give you a good 140ah usable capacity with no need to recharge fully ( lfp actually like being between 20% and 80% charge)
So even just putting in a single 200ah setup would be a power upgrade.

That's actually a very good point, and I've considered it as well. I'd be able to spend about 2x what FLAs from Sam's would be and have at least 2 days with 0 charging of usable capacity. Probably more, since the days where there's virtually no sun for solar rarely get hot enough to put much strain on the fridge.
I'd have more usable capacity from the FLA's (x4) by about 50%, but then charging them back to full would likely be a multiple day ordeal. I'm rarely away from the boat for more than 4-5 days in the sailing season, so that's not ideal.

[Scubaseas]

(This may mean I have to keep the ignition switch "on" to energize the charger, and since I've added EFI to my Atomic Four engine that is presumably acceptable)

Definitely not acceptable even with Electronic Spark or Fuel Injection. You'll probably fry the ignition coil or the power transistor to the ECU. Tell me what unit you have added and I can tell you if you can get away with leaving the key ON engine OFF.

[AMX]

Don't Waste Your Money On Batteries - The Shocking Truth I Discovered When Testing RV Batteries
Much Cheaper batteries than Battleborn straight from China
https://diysolarforum.com/

https://www.youtube.com/watch?v=iy3hga_P5YY

[walbee]

I have a 2x8D FLA house bank in my trawler. Been contemplating an upgrade strategy for some time now. Most of my time to date has been spent educating myself to battery chemistries available and their behaviors, charging schemes and equipment and understanding DC electrical systems design, ABYC best practices and learning from others.

Here are some of the resources I have used:
https://marinehowto.com/lifepo4-batteries-on-boats/

https://marinehowto.com/understandin...ttery-charger/
MarineHowTo.com has many other beneficial articles.

MTOA.net forum. Many members have experience with all things related to boat DC/AC electrical systems.

https://gilwellbear.wordpress.com/Home/
Jim Healy’s personal web site. Jim writes monthly engineering articles for MTOA and is a frequent contributor to the MTOA and AGLCA forums.

Pacific Yacht Systems, Jeff Cote owner

https://www.pysystems.ca/
Many useful videos on YouTube. They also provide a design review service.

For me, I’ve pretty much resigned myself to an incremental upgrade plan. Primarily because my boat is 1k miles away, we’ve only had about 2 months aboard since purchase, the PO’s have added a number of electrical updates/upgrades since 1999, and I need to throughly document and understand what I have and how it all works along with performing a proper Ah requirements analysis.

Initial plan: replace 2x8D’s with new FLA’s (GC2’s?) that will fit in existing 2x8D battery boxes. Objectives being, to allow us to anchor out more as we make our way from Seneca IL to SC via the inland rivers/AICW. Low cost upgrade to gain additional Ah’s. Minimal changes to existing charging systems/hardware.

Once we get to our home port, a more robust energy systems upgrade may be appropriate depending how satisfied I am with the initial upgrade with meeting our future cruising plans.

[ForeverDes]

Originally Posted by Scubaseas

Definitely not acceptable even with Electronic Spark or Fuel Injection. You'll probably fry the ignition coil or the power transistor to the ECU. Tell me what unit you have added and I can tell you if you can get away with leaving the key ON engine OFF.

Definitely is a very strong term, especially considering the instructions that came with the unit specifically say it will not burn out the coil to leave the key in the on position.

It's likely moot point, though, because if I go forward with this battery switch I won't be using the Renogy 40 amp dc to dc charger I initially thought I would, and the Victron unit I'm looking at has a different set-up than the Renogy.

[newhaul]

Originally Posted by ForeverDes

Definitely is a very strong term, especially considering the instructions that came with the unit specifically say it will not burn out the coil to leave the key in the on position.

It's likely moot point, though, because if I go forward with this battery switch I won't be using the Renogy 40 amp dc to dc charger I initially thought I would, and the Victron unit I'm looking at has a different set-up than the Renogy.

Remember like almost everything marine they are repurposed from the rv market.
The renogy ignition wire is to ensure the system is energized when the alternator is running and not when its not . There are actually instructions in the installation manual that tell how to install it without using the ignition specifically. But my question is why would you want the b2b to energize without the alternator putting out power to charge? Any other will just discharge your start battery. Considering the fact that the use of a b2b like this is to protect your alternator.

[newhaul]

Originally Posted by Scubaseas

Definitely not acceptable even with Electronic Spark or Fuel Injection. You'll probably fry the ignition coil or the power transistor to the ECU. Tell me what unit you have added and I can tell you if you can get away with leaving the key ON engine OFF.

Wrong . What do you do when the engine is running for hours on end ? Leaving the key in the run position will not damage the coil anymore than actually running the engine . The coil don't care.

[ForeverDes]

Originally Posted by newhaul

Remember like almost everything marine they are repurposed from the rv market.
The renogy ignition wire is to ensure the system is energized when the alternator is running and not when its not . There are actually instructions in the installation manual that tell how to install it without using the ignition specifically. But my question is why would you want the b2b to energize without the alternator putting out power to charge? Any other will just discharge your start battery.

You have a different take than I do, albeit my view comes only from reading the Renogy manual. It's entirely possible and probable I've missed or misunderstood something.

There's a D+ connection to the charger that connects to the "accessory" side of the ignition switch. That connection being powered is what "turns on" the charger.
I would have planned to only ever leave the key on with the engine not running when hooked to shore power and needing to add some charge to the house bank.

The Victron unit senses alternator voltage and has an algorithm to determine when to start and stop house bank charging. So merely turning the ignition switch on to charge from shore power is not even an option with that unit.
However the lowest cutoff charging voltage for the Renogy looks to be 14v, and the Victron is programmable via Bluetooth. I'd prefer 13.8 or even 13.7 so charging would stop near 90% soc for LiFePo4.

Originally Posted by AMX

Don't Waste Your Money On Batteries - The Shocking Truth I Discovered When Testing RV Batteries
Much Cheaper batteries than Battleborn straight from China

The video is very interesting and highlights a concern of mine, to wit, {My} solar doesn't fully recharge my FLA batteries each day, and that could, and likely will, bring on early degradation of their usable capacity.
I have no idea how old the current house battery is, but I believe noticed a decrease in capacity from July to September of last year, when my boat was moored and had no access to shore power.

[ForeverDes]

Originally Posted by newhaul

Wrong . What do you do when the engine is running for hours on end ? Leaving the key in the run position will not damage the coil anymore than actually running the engine . The coil don't care.

I actually did burn out my coil last season by leaving the key in the on position while the engine was off, for less than 30 minutes. The round ignition switch had become a little loose, and when I turned the key to what I thought was off, it had rotated enough that it was still on.
My understanding is that only happens if one of the points is closed while the rotor is not spinning.
But with my efi module, the coil only energizes when the rotor turns as the engine is turning. It has a logic unit/ computer that, among other things, feeds the coil power.

[Scubaseas]

Originally Posted by ForeverDes

Definitely is a very strong term, especially considering the instructions that came with the unit specifically say it will not burn out the coil to leave the key in the on position.

It's likely moot point, though, because if I go forward with this battery switch I won't be using the Renogy 40 amp dc to dc charger I initially thought I would, and the Victron unit I'm looking at has a different set-up than the Renogy.

Wrong . What do you do when the engine is running for hours on end ? Leaving the key in the run position will not damage the coil anymore than actually running the engine . The coil don't care.

I'll assume this is an electronic ignition (not FI as stated and not a CDI) and a Pertronix unit at that. I would not do it without knowing what he's put it and assume he's got more than just the ignition on the KO position. I am aware of what Pertronix says. I wouldn't use a Renology DC/DC for this either. If it is an EIS make sure you are using resistor wires, not solid wires.

[Scubaseas]

My understanding is that only happens if one of the points is closed while the rotor is not spinning.

Yes that is not wrong. If the points are closed, key on, engine not running you can fry the coil.
Curious what motor you have and what did you put in?

[ForeverDes]

Originally Posted by Scubaseas

Yes that is not wrong. If the points are closed, key on, engine not running you can fry the coil.
Curious what motor you have and what did you put in?

I have a 1960 Atomic Four, and I put in the the electronic ignition module from Indigo Electronics.
(Sorry I misspoke earlier by saying EFI)