LFP vs LA/AGM bank size

[Bmarler]

My panels are skewed a bit due to arch of hardtop. One side puts our more than the other depending on how I'm anchored or moored. Other installations vary widely, mostly sailboats with shading issues. And frankly, I suspect solar output and energy conservation is fudged as much as MPG claims.

Peter

Hmm, I think you may be right. Fudging the numbers, intentional or not probably happens quite a lot. I wonder if I tend to over generalize myself? I’ll have to make sure I guard against it.
My panels are skewed like yours are, and I do in fact have some shading issues. I can have one panel outputting 30 amps, and the other only 8 or 10, depending on if the mast is shading one. Or sometimes, I’m only getting 15 amps total. It really varies. I get better than the 50% Overall I was calculating though.
I have zero experience in warm climates, so it can be eye opening at times to hear what those norms are.

 

[Don L]

That's a big parasitic load. The idle draw for my 2kva Victron is just under 1 amp. Low idle draw was one of my selection criteria when I put the inverter in, as I knew I wanted to run it 24/7 when away from shore power.

I could leave it on in stby for that, but gives me the creeps to have it cycle on/off and the 4' walk to the switch isn't a big deal. Don't use it all that much anyway.

 

[mvweebles]

I think the issue with powerboaters and usage is they often have generators. I don't think they fudge the numbers, I just think that with generators and alternators, the usage is heavily masked. Ive recently come to the conclusion that unless you run your system to very low to 12.8v/25.6v (LFP 20% for 12v/24v), you just don't know how much energy you consume because the SoC calculations are crazy inaccurate.

My little Willard 36 is pretty simple, and I definitely self-identity with classic sail cruiser sensibility. I have no TV, no car stereo. Ambient lighting is all LED with individual switches to each fixture. I rarely leave VHF or MFD on. Fridges are old-school top loading with remote Secop BD50 compressors (albeit air cooled). No ice maker unless me and my ice cube trays qualify. As you can see, a bit of a throw-back compared to typical powerboats.

Still, inverter and Starlink left on 24/7 definitely pushed me well over the 400ah/day consumption. As Don L points out, 400ah doesn't set any records for conservation, but I really doubt the typically equipped 42 foot trawler/motoryacht is anywhere near 500AH/day restful state (maybe if 24v, but only maybe).

My hunch is the consumption numbers and use-case described by Kaanders/Kevin is probably pretty normal for a typical motoryacht or trawler where the owners are long past the conservation phase I'm stuck in. I thought 250ah would be more than enough for me. Maybe if I retire a freezer I might get close. Given the effort I've made and the small size of Weebles, hard for me to imagine the typical motoryacht subsisting on 500ah (12v) per day.

Not s competition, I'm just trying to be net zero. Much harder than I thought. At least in a warm climate. I'm envious of Don L

Peter

 

[tiltrider1]

Home style refrigerator, sub zero freezer, wine cooler, starlink, 49” TV, home style stereo system, Roku, computer network with 2 computers and NAS, and then the normal amount of Dc boat systems FW/bilge pumps, lights, this would be the norm for power boats in the PNW. Might explain why we like 1000 Ah battery banks.

 

[BruceK]

Slightly left of topic but worth knowing. I`m reading that the price of lithium has dropped 80% since 20 November 2022. To what extent is that reflected in battery prices?

 

[Mambo42]

Now we have lithium batteries were they say the batteries are good for 10,000 plus cycles. Has anyone done a 10,000 cycle test?

Don't believe marketing claims at face value.

The 10.000 cycles for a Lithium is based on not going lower than 50 % of charge. If you go down to 20 % each time you (apparently) will get to about 3000 cycles.
If you would use your boat 365 days per year and every day is one discharge you would need almost 27 years to figure out if those 10.000 cycles are realistic or not. I think we can safely conclude that nobody has ever done that. Is is marketing ? Perhaps, but if I get to 3000 or 6000 cycles I will also be happy.

 

[Mambo42]

Slightly left of topic but worth knowing. I`m reading that the price of lithium has dropped 80% since 20 November 2022. To what extent is that reflected in battery prices?

For me the price was slightly lower than before, but still paid around 2500 USD for a 200 Ah 24 V Victron LiFEPO4 battery. I know you can get them much cheaper at the moment, but no idea what the quality really is. I have seen prices of 800 USD for 200 Ah at 24 V.

 

[Hornloaded]

On a slight different subject, what about insurance? My broker said he’s seeing more and more insurance companies deny claims if a lithium bank is on board, regardless of whether it’s installed by ABYC certification or not.

 

[mdstrum]

Went from FLA 600amp bank and in same space did the Battleborn LifePO with 600 amps. we are power hogs, we have solar, run gen as kevin said to heat water, make water, laundry and in our case to use stove. so we time it do all that at same time. Just spent a week out with 4 people, starlink, lots of computers, and TV's running, ice maker, freezer, refer/freezer combo, etc and LifePO bank never hit below 20%.
On the AGM side, I hate them I have killesd 3 sets of the (2 in our RV) and one on this boat, they hate dropping below 50% in my case even 2-3 times did some damage. Love my LifePO (have in RV as well. remember they are also much lighter. You need to address your engine/alternator charging or they eat you alternator (ie a 100amp engine alternator is not design to run continuously at 100amp for 5-6 hours found that out and burned out out...so Balmar charte controller is great solution (have dc to dc and not care for as much as my Balmar...also having larger inverter charge allows recharge the LifePO much faster then you can every charge a AGM (lifePO can accept 100amp per battery per hour)

 

[Captain DJ]

Interesting topic that I am late to contribute to the discussion. But I have a unique hybrid system that may give me comparative insights to the LFP vs LA battery issue for a small trawler/cruiser.

Firstly: I have a 34 ft pilothouse trawler with twin FL and common alternators (not high output/not externally regulated/not used for LFP battery bank)
Secondly: I have two house banks and a starting bank. House A is 800 amp hrs 12 volt FA Interstate Golfcart 6 volt batteries in series and parallel. House B is two 220 amp hour 12 volt batteries giving me 400-440 amp hours of lithium that is charged solely by 400 watts of solar (soon to be upgraded to 1,000 watts next Spring when I return to Washington) Lastly, I have two 6 volt GC FA batteries as start bank. All FA batteries are under 2 years old and Lithium about 18 months.

We have a fairly simple, non-air-conditioned vessel, but use electric range, microwave, convection oven, toaster, and full sized fridge/freezer unit ran through a 3500 watt MasterVolt inverter (that is not set up for Lithium charge profile so it charges FA batteries (8 GC 6V) when we use shore power or genset. Alternators charge only FA banks. Solar can charge either FA or FLP, but predominantly tops off both. Two separate charge controllers are used, one set for each different charge profiles. I have stayed a maximum of 12 days and nights in PNW unplugged without using the genset. Most trips are 7-10 days/nights and I have learned to do a few things to optimize how long we can remain unplugged and generator un-used by turning off inverter at bedtime and switching it back on at coffee time.
Water stays heated in large, well insulated tank for 4-6 days. Going to plumb it to get heated by one of the Lehmans when cruising. Overall: lessons learned in year one were:

Keeping the solar array clean. Dirty panels brought potential input down 25-40%.
Turn off inverter/fridge/gremlins at night.
Move every 3-5 days, meaning cruise for at least 5-6 hours to somewhere else.
Keep an eye on inflows, SOC, and consumption of each item that uses 120 volts.

Thoughts for improvement:
Add two more LFP batteries to get Lithium Bank to 800-900 amp hr (12 v range).
Add more solar panels (as mentioned earlier)
Get rid of 40+ year old, loud Onan 8.5 kw genset and replace with tiny 1 cylinder diesel that runs one or two high output alternators with external regulators and LFP charging profile.
Keep monitoring solar input vs cruising time (alternator input) vs small genset for 12 v charging only.
Possibly adding a wind generator. Our paravane support system offers a great place for radar, solar array and has space left for a wind generator. Neighbor has a 400 w wind generator on sailboat and on cloudy days, this might be just the ticket, plus we like the sound.

Just some thoughts on the subject and as always, happy to learn from the many.

"A wise man profits from the mistakes of others, Fools scarcely from their own"
Aristotle (I believe)

 

[Don L]

On a slight different subject, what about insurance? My broker said he’s seeing more and more insurance companies deny claims if a lithium bank is on board, regardless of whether it’s installed by ABYC certification or not.[/QUOT

I call BS!!!

Seems to be a regular rumor. Ask him what the insurance policy basis they are denying claims.

 

[Darlin]

One of the great advantages of lithium is the constant higher output voltage. No more "low battery" alarm on the vhf. Lithium will deliverv 13 volts down to about 25%. So no comparison to performance of either acid type battery.

 

[twistedtree]

On a slight different subject, what about insurance? My broker said he’s seeing more and more insurance companies deny claims if a lithium bank is on board, regardless of whether it’s installed by ABYC certification or not.[/QUOT

I call BS!!!

Seems to be a regular rumor. Ask him what the insurance policy basis they are denying claims.

I agree. Sounds like a good line for selling a boat with lead batteries. Unless you insurance policy has some specific exclusion for lithium batteries, or has some specific requirement that work be done to ABYC or some other standard, there is no basis to denie based on the battery type. And Inhabe never seen such an exclusion or requirement.

 

[SteveK]

On a slight different subject, what about insurance? My broker said he’s seeing more and more insurance companies deny claims if a lithium bank is on board, regardless of whether it’s installed by ABYC certification or not.

Are you sure your broker said more insurance companies are not insuring boats with LFP. That may be possible due to the ignorance of non boater agents. But denying a claim (broad statement) if LFP found on board is ridiculous.

 

[micksbuddy]

I'm dealing with this at the moment. I'm in the process of replacing my house battery bank(16 GC2) and my insurance company(Markel) requires LFP batteries be of US manufacture, be installed professionally to current ABYC bulletin requirements and then they will apply a significant surcharge(in my case 30-35%). This just may send me back to LA, probly Trojan's new AES version of AGM.

 

[rslifkin]

I'm dealing with this at the moment. I'm in the process of replacing my house battery bank(16 GC2) and my insurance company(Markel) requires LFP batteries be of US manufacture, be installed professionally to current ABYC bulletin requirements and then they will apply a significant surcharge(in my case 30-35%). This just may send me back to LA, probly Trojan's new AES version of AGM.

Out of curiosity, where did you find that information about Markel and LFP? The policy documents I have for my policy with them don't mention LFP or lithium, or anything else about battery types, etc.

 

[Don L]

I'm dealing with this at the moment. I'm in the process of replacing my house battery bank(16 GC2) and my insurance company(Markel) requires LFP batteries be of US manufacture, be installed professionally to current ABYC bulletin requirements and then they will apply a significant surcharge(in my case 30-35%). This just may send me back to LA, probly Trojan's new AES version of AGM.

you need a new insurance company if they think 16 GC2 batteries are safer than LFP

 

[micksbuddy]

Out of curiosity, where did you find that information about Markel and LFP? The policy documents I have for my policy with them don't mention LFP or lithium, or anything else about battery types, etc.

My agent.

 

[micksbuddy]

you need a new insurance company if they think 16 GC2 batteries are safer than LFP

Unfortunately 40 year old boats seem to be somewhat less popular with insurance companies, so there aren't quite so many options.

 

[SteveK]

I'm dealing with this at the moment. I'm in the process of replacing my house battery bank(16 GC2) and my insurance company(Markel) requires LFP batteries be of US manufacture, be installed professionally to current ABYC bulletin requirements and then they will apply a significant surcharge(in my case 30-35%). This just may send me back to LA, probly Trojan's new AES version of AGM.

You were told there would be a surcharge if LFP is installed. This cannot be the same with all insurers.

 

[rslifkin]

My agent.

I guess I'll have to inquire before I look at replacing batteries. If my policy has the same requirement, then I guess I'll either be staying with lead or finding a new insurance company. Those restrictions on LFP would be unacceptable to me, as I won't even consider paying someone to install batteries or want the massive insurance cost increase.

 

[guy with a boat]

This comes up pretty frequently, and most of us don’t have the battery issue mentioned at all in our policies. A knowledgable insurer would be less concerned about LFP batteries than about many of the other systems on a boat. As mentioned, they are likely less of a risk than the lead acid batteries they are replacing.

 

[twistedtree]

Out of curiosity, where did you find that information about Markel and LFP? The policy documents I have for my policy with them don't mention LFP or lithium, or anything else about battery types, etc.

They are the ONLY insurance company that I have heard takes issue with LFP. To me, the solution is easy - find a new insurance company. Their policy is ridiculous since there are maybe one or two US manufactured battery companies, and those are final assembly only. No LFP cells are made in the US. And their policy precludes use of the better/best products on the market.

 

[rslifkin]

They are the ONLY insurance company that I have heard takes issue with LFP. To me, the solution is easy - find a new insurance company. Their policy is ridiculous since there are maybe one or two US manufactured battery companies, and those are final assembly only. No LFP cells are made in the US. And their policy precludes use of the better/best products on the market.

That gives me some comfort. I guess I'll need to cough up the money to get a fresh survey done before I wear out my current house batteries so I can do some insurance shopping.

 

[Bmarler]

I'm dealing with this at the moment. I'm in the process of replacing my house battery bank(16 GC2) and my insurance company(Markel) requires LFP batteries be of US manufacture, be installed professionally to current ABYC bulletin requirements and then they will apply a significant surcharge(in my case 30-35%). This just may send me back to LA, probly Trojan's new AES version of AGM.

i'd reach out to peter ricks regarding this. he's an insurance agent and handles markel. he's on this forum under username "pau hana"
peter is my agent, and i have markel too. i will likely be going to lfp batteries when my current agm bank needs replacing.
if this is really a markel policy i hope it gets changed. it's pretty ignorant on their part.

 

[Helmsman]

This insurance issue has cropped up on the AGLCA forum, and Markel was specifically mentioned as having the requirements listed above. There were a couple of others mentioned as having stipulations about lithium but I don’t remember which ones.

 

[Bmarler]

This insurance issue has cropped up on the AGLCA forum, and Markel was specifically mentioned as having the requirements listed above. There were a couple of others mentioned as having stipulations about lithium but I don’t remember which ones.

got it. i guess i'll make that decision when the time arises. i would bet, that there are a great many of their customers already running lfp batteries completely unaware of their stand on the technology. would be an eye opener when claim time happens.

 

[catalinajack]

DonL makes a good point, that AGM has the ability to use beyond the 50% SOC if needed. If you routinely use 90-100% of your LFP, you have almost no reserve capacity. Most of us that have converted to LFP have added more capacity for the reasons mentioned.

The biggest advantage to LFP for us (in addition to increased capacity) is that you can charge them very fast and whenever you want. We typically run our gen once or twice a day for other reasons (some 240v devices) and all the charging we need happens at the same times. Gen run times are usually about an hour unless we need/want AC. We have lots of charging capacity and can pour the amps into the bank when we have a gen running. We also have some solar that carries some of the load during daylight hours. Between solar and large alternators, we rarely “need” to run the gen just to charge batteries on our power-hungry boat.

For AGM/lead acid batts, having a high-output alternator and some solar panels can help tremendously with charging to 100% SOC, while avoiding the 5-hr gen run with minimal load.

We have large alternators with external regulators that limit the output to 84% of max and we typically arrive at our destination each day with the house bank fully charged, with no gen run time.

I had a 932 Ah FLA bank on my boat. Our usage pattern gave us about 14 hours to get to 50% DOD. A five hour run the next day charged the bank to 100%. Our cruising style was mostly just one night in a particular location. LFP would give me nothing except a depleted bank account. Every boat, every cruising style, every useage pattern is different. For many, like myself, old-fashioned FLA makes perfect sense

 

[TBill36]

I had a 932 Ah FLA bank on my boat. Our usage pattern gave us about 14 hours to get to 50% DOD. A five hour run the next day charged the bank to 100%. Our cruising style was mostly just one night in a particular location. LFP would give me nothing except a depleted bank account. Every boat, every cruising style, every useage pattern is different. For many, like myself, old-fashioned FLA makes perfect sense

Catalinajack - as the original poster, you're response is exactly what my original question was all about. Your usage would indicate that a LFP bank about 1/2 the size you are carrying would provide the same energy. Buying 1/2 as many LFPs at today's prices would probably cost you less and I don't see how that depletes your bank account assuming your charging system can be modified to handle charging LFPs. Respectfully, the industry quoted performance of LFPs vs FLAs does not support your position.

 

[SteveK]

Reading the AGM battery charger thread got me thinking about battery bank size and differences between LFP and AGMs. Maybe this is common knowledge and I'm just behind the times.

Since the allowable DODs of LFPs is up to 95% and AGMs is 50% then the bank of LFPs can be significantly smaller and still deliver the same allowable amp hr consumption.

A 600 amp hr AGM bank give you 300 amp hrs, where as a 316 amp hr LFP bank gives you the same 300 usable.

Does it really work like that and is that real world experience?

Catalinajack - as the original poster, you're response is exactly what my original question was all about. Your usage would indicate that a LFP bank about 1/2 the size you are carrying would provide the same energy. Buying 1/2 as many LFPs at today's prices would probably cost you less and I don't see how that depletes your bank account assuming your charging system can be modified to handle charging LFPs. Respectfully, the industry quoted performance of LFPs vs FLAs does not support your position.

Since you mentioned it I brought post 1 forward as well.
Disclosure, I had FLA 860Ah 8-6v batteries that were no longer giving the 50% after 5 years. So I went into the LFP club with at first 400Ah of LFP which worked as advertised, I now had my needs met in 24 hours, but the batteries needed to be charged as they had no reserve left. I like to have the option of two days without a recharge need. My choice for double cost.

Went and got another 400Ah of LFP solved the need, but created a new one, now after two days I need to recharge 800Ah.
I created my own monster and have it tamed and working with ability to charge with 200A.

Would I do it again?
8 FLA would have cost me the same (OK very close) as the 4 LFP. Short answer is YES.
You see the FLA needed physical condition checks of water level, they needed to be watched to cycle at around the 50% mark and then fully recharged. The LFP are easy, just glance at the SOC on gauge, charge fully or just add a bit, no need to fully charge.

Unintentioally have tested them when the marina power went out and they ran until depleted, BMS shut down at low voltage, so not dead. Recharged, and no signs of wear. The FLA would have been toasted.