LFP/Solar chat - deals, design, Q&A, etc

[mvweebles]

LFP power systems and solar are a very regular topic but has a lot of updates that may not make sense for its own thread - deals on batteries, solar generators (I hesitated to start a thread last week).

Maybe it makes sense to have an ongoing thread of recent LFP or Solar minor topics?

What prompted me today is I see the LiTime 12v/230ah (3kw storage!!!) is $459, or $401/each if you buy a pair. For comparison, just a couple years ago, 6kw of LFP storage from BattleBorn would cost over $6000 (I went a similar route 4-years ago when I installed LFP)..

https://www.litime.com/products/12v-230ah-plus-lifepo4-battery

Or better, the Bluetooth version is only $30 more $489 for one, $428/ea for two) and is what is get now.

https://www.litime.com/products/12v-230ah-bluetooth-lithium-rv-battery

In my opinion, storage is cheap enough it's time to stop waiting for prices to reduce further.

Other cool observations out there?

Peter

 

[mvweebles]

Ready for new batteries and love the idea of LFP but hesitate due to perceived complexity? Rod Collins at Marine-How-To has an excellent article for a relatively simple conversion complete with parts list and links. You keep your existing alternator setup so no hassle with converting to Balmar. Don't get me wrong, I like hi-output (HO) alternators but for many DIYers, they really increase complexity and expense of installation and configuration.

Two observations. With the MHT setups your LFP charging is limited to the DC-DC charger, 50-amps. If your daily consumption is over 250 ah or so, you might consider a HO alternator setup (or plan to migrate to it over time).

Second, Collins recommends buying the Victron parts from a dealer and not just off Amazon (and he asks that you use his affiliate links where he gets a small commission). I cannot stress the importance of buying Victron from a credible dealer with tech support. Their prices are almost always competitive with Amazon.

Easy LiFePo4 Conversion - Marine How To

Easy LiFePo4 Conversion Before reading this article please read the 101 article on Drop-In's: Drop-In Batteries Be An Educated Consumer Hardly a day goes by where we don't see or hear

marinehowto.com

 

[Iggy]

It is a great price! I paid about 3x that 3yrs ago.

One thing I noticed, no heater. Which means, no charging below 32F. For me in Boston, I would need a battery with a heater. I keep 2 cameras up and running with the boat on the hard.

 

[mvweebles]

I don't see a heater either, but both the Bluetooth and non-BT version advertise low temperature protection. Of course, your cameras would go dark.

Would defer to Will Prowse teardown reviews to verify whether it is actually eauipped. For those who watch Prowse regularly, you know that not all batteries that advertise low temperature protection actually have it (pretty sure LiTime does - Prowse generally likes LiTime and Epoch).

How long would a battery last when it's heating itself? A friend with an off-grid cabin at 8500 foot elevation in Wyoming is considering LFP. Cabin is empty in the winter and he has decent solar. I have no idea if LFP batteries would survive even with under-temp protection, and heated.

Peter

 

[jtdums]

Just to throw one more into the mix. I agree with your assessment of pricing and just elected to take the plunge. My new battery just arrived this morning only three days after ordering. Looks in great shape.

I've went with the Epoch 12V 460Ah | Heated & Bluetooth & Victron Comms choice with their 15% off for black Friday and free shipping. This is a pricier option, but has some specific options that I like and this is the best price I have seen. The built in 500amp T class fuse helps to justify the extra expenditure as that should be included with any system design that I have contemplated. Also, since I have talked myself into a Victron based system the coms are a nice benefit.

 

[CharlieO.]

I went with a single 100ah Vatrer battery with BT and self heating for $269, and 18a DC to DC charger with the original alternator - 51amp. Boat the Victron charger from PKYS.
Can I just add another battery next season? The current battery shows it has only run 4 cycles. I will also get a lifepo4 specific battery charger for when I am on shorepower. We are just weekend warriors and maybe week trip every summer.
I’d also like to add a couple solar panels.
We never anchor for more than two days and are not a power hungry boat.

This my BT screen with the battery in the basement for the winter.

 

[mvweebles]

Just to throw one more into the mix. I agree with your assessment of pricing and just elected to take the plunge. My new battery just arrived this morning only three days after ordering. Looks in great shape.

I've went with the Epoch 12V 460Ah | Heated & Bluetooth & Victron Comms choice with their 15% off for black Friday and free shipping. This is a pricier option, but has some specific options that I like and this is the best price I have seen. The built in 500amp T class fuse helps to justify the extra expenditure as that should be included with any system design that I have contemplated. Also, since I have talked myself into a Victron based system the coms are a nice benefit.

Question: what was the final price on this battery and how much does it weigh? That's a massive amount of energy storage. I ask for a friend with an off grid place in the mountains so heated battery is needed

Peter

 

[mvweebles]

I went with a single 100ah Vatrer battery with BT and self heating for $269, and 18a DC to DC charger with the original alternator - 51amp. Boat the Victron charger from PKYS.
Can I just add another battery next season?
I’d also like to add a couple solar panels.
We never anchor for more than two days and are not a power hungry boat.

You could absolutely just add another 100ah battery in parallel. The 18A DC-DC charger is small for this but adding solar would help. Since you only use it occasionally, perhaps a portable folding set would suffice. I recently purchased a 400w folding panel for backup charging to my tiny solar generator. The 400w panel is surprisingly heavy (45 lbs!) and large but seems to work okay even though it's obviously cheap Chinese built. Caution about Temu: first, it's the "Harbor Freight" of the Internet. Second, prices vary widely on any given day. Finally, if you have shopped there, be prepared for a dizzying array of useless discount bundles. That said, price is attractive. The day I purchased the following, price was $275.

https://share.temu.com/xzmIEWWRoKA

400w would likely give you a solid 60-100 amp hours of charging per day (bit of a WAG) so definitely help at anchor. But you'd need room to spread out the panels.

Final option for you would be a small generator to run the 120VAC charger.

At some point, if your energy demands grow, you might consider a larger 100a alternator and larger 50A DC-DC charger. You could easily feed 400ah-500ah of battery storage with they setup.

Hope this helps

Peter

 

[SteveK]

would it make sense to build an insulated box around LFP in cold climates?

 

[jtdums]

Question: what was the final price on this battery and how much does it weigh? That's a massive amount of energy storage. I ask for a friend with an off grid place in the mountains so heated battery is needed

Peter

Final price $1640 and 99lbs

 

[DavidM]

There are two considerations for below freezing installations of Li batteries: 1) storage only, ie little or no charging, and 2) heavy charging while below freezing by having a big solar array.

For 1, you may not need to do anything. Charging while below freezing is what kills unprotected Libatteries. So if you don’t charge, ie you disconnect them but leave them in place or you leave them connected but no shorepower or solar charging, you should be fine.

For 2, the possibility of heavy charging requires either automatic disconnection below freezing or a built in battery heater to keep them above freezing so charging is ok. The question is how much power does the battery heater draw at say 10 F and what happens if/when it depletes the batteries. Will dead batteries be harmed by trying to charge at high currents well below freezing?

This can happen if you have several hundred watts of panels putting out 15-20 amps at midday. That is probably too much current with unprotected batteries below freezing. So if the batteries simply cut off at low temps, that should be fine. But if the batteries have internal heaters they will draw down the battery with no solar input at night. If it stays cloudy for several days, the heater may completely deplete the batteries. What happens when the sunlight returns?

For my application, storing outdoors with little solar charging at well below freezing temps, a cut off seems to be the most reliable and safe protection for the batteries.

David

 

[Marco Flamingo]

I've just gone over the idea of a FLA to LFP change on my boat. It fits the Marine How To example fairly close: a small trawler with conservative usage. Prior owner had replaced start and house with 4 Dyno 260Ah 6V lead acid. There is a 1-2-both switch, but I've not used it much. Just keep it on both and that's plenty to use for a start on my 4 cyl. diesel. I monitor volt/amp hours etc. with a simple $40 shunt. The batteries are at least 7 years old, seem to be okay, but I haven't done a stress test in a couple years. By far the biggest downside is checking/adding water every few months, although mine are easily accessible in a nice battery box. I have a Balmer 100A alternator, an external regulator, and a Freedom 30 invertor/charger that can charge at 140 amps from shore power.

I did add a 120Ah lithium battery that it dedicated to my new induction stove top. And I bought a 100Ah lithium battery for the dinghy electric motor. So I am familiar with the power and weight benefits, although weight isn't really important for my house batteries (other than during installation). If I simply replace the existing FLA batteries with FLA, that would only require a drive to Fisheries Supply, spending $1,100 for four batteries, and the rest of the afternoon installing. That 520AH FLA battery bank gives me 260-416Ah usable (50 or 80% SOC). We use about 100Ah a night at anchor.

Going with the Marine How To setup, I would need to replace the battery switch ($60), buy a FLA starter battery ($300), a DC-DC charger ($330), and buy an Epoch 460 LFP ($1,400 or $1,850 for the fancy one). Going from a 4 FLA to a LFP with an AGM start means I could likely use most of the same cables and fuses. Right now I have de-rated my alternator so that I rarely get more than 65 amps dumped into the FLA at bulk. With the Victron DC/DC recommended on Marine How To, I would be limited to 50 amps into the LFP batts. Neither my external regulator or my Freedom 30 using shore power have lithium profiles, but there are some semi-clumsy work arounds. Because of the charge profile used for lithium, the LFP would probably still charge faster. And because of the usable DOD on the lithium, that 460Ah battery could put out a usable 414Ah, so basically the same amount of usable amps for twice the money of replacing the FLA.

If changing battery chemistry was my favorite hobby, I'd switch. But I have yet to see a +$1,000 benefit, especially when FLA wins the KISS principal. Maybe I'm still missing something.

Mark

 

[CharlieO.]

I woul

You could absolutely just add another 100ah battery in parallel. The 18A DC-DC charger is small for this but adding solar would help. Since you only use it occasionally, perhaps a portable folding set would suffice. I recently purchased a 400w folding panel for backup charging to my tiny solar generator. The 400w panel is surprisingly heavy (45 lbs!) and large but seems to work okay even though it's obviously cheap Chinese built. Caution about Temu: first, it's the "Harbor Freight" of the Internet. Second, prices vary widely on any given day. Finally, if you have shopped there, be prepared for a dizzying array of useless discount bundles. That said, price is attractive. The day I purchased the following, price was $275.

https://share.temu.com/xzmIEWWRoKA

400w would likely give you a solid 60-100 amp hours of charging per day (bit of a WAG) so definitely help at anchor. But you'd need room to spread out the panels.

Final option for you would be a small generator to run the 120VAC charger.

At some point, if your energy demands grow, you might consider a larger 100a alternator and larger 50A DC-DC charger. You could easily feed 400ah-500ah of battery storage with they setup.

Hope this helps

Peter

I was planning on doing the 30 dc to dc charger but Peter at PKYS recommended going with the 18 with the 51a alternator.
The solar addition is something I am still researching and appreciate any knowledge shared.

 

[mvweebles]

I've just gone over the idea of a FLA to LFP change on my boat. It fits the Marine How To example fairly close: a small trawler with conservative usage. Prior owner had replaced start and house with 4 Dyno 260Ah 6V lead acid. There is a 1-2-both switch, but I've not used it much. Just keep it on both and that's plenty to use for a start on my 4 cyl. diesel. I monitor volt/amp hours etc. with a simple $40 shunt. The batteries are at least 7 years old, seem to be okay, but I haven't done a stress test in a couple years. By far the biggest downside is checking/adding water every few months, although mine are easily accessible in a nice battery box. I have a Balmer 100A alternator, an external regulator, and a Freedom 30 invertor/charger that can charge at 140 amps from shore power.

I did add a 120Ah lithium battery that it dedicated to my new induction stove top. And I bought a 100Ah lithium battery for the dinghy electric motor. So I am familiar with the power and weight benefits, although weight isn't really important for my house batteries (other than during installation). If I simply replace the existing FLA batteries with FLA, that would only require a drive to Fisheries Supply, spending $1,100 for four batteries, and the rest of the afternoon installing. That 520AH FLA battery bank gives me 260-416Ah usable (50 or 80% SOC). We use about 100Ah a night at anchor.

Going with the Marine How To setup, I would need to replace the battery switch ($60), buy a FLA starter battery ($300), a DC-DC charger ($330), and buy an Epoch 460 LFP ($1,400 or $1,850 for the fancy one). Going from a 4 FLA to a LFP with an AGM start means I could likely use most of the same cables and fuses. Right now I have de-rated my alternator so that I rarely get more than 65 amps dumped into the FLA at bulk. With the Victron DC/DC recommended on Marine How To, I would be limited to 50 amps into the LFP batts. Neither my external regulator or my Freedom 30 using shore power have lithium profiles, but there are some semi-clumsy work arounds. Because of the charge profile used for lithium, the LFP would probably still charge faster. And because of the usable DOD on the lithium, that 460Ah battery could put out a usable 414Ah, so basically the same amount of usable amps for twice the money of replacing the FLA.

If changing battery chemistry was my favorite hobby, I'd switch. But I have yet to see a +$1,000 benefit, especially when FLA wins the KISS principal. Maybe I'm still missing something.

Mark

Not sure the Marine-How-To article is relevant for your situation because you already have an externally regulated alternator that can be set for LFP.

I'm only slightly above average on this, but my first blush is to consider a pair of 230AH batteries (LiTime's are $400/each in pairs). If they fit in the same space as your four-6V batteries then just swing the alternator cable there and change the settings on the Balmar. Xantrex was late to the LFP game so you'd need to check whether it supports LFP charging.

What is your start battery setup right now? Do you just use your FLA house bank? If so, then you would need a FLA/AGM start battery and a small DC-DC charger from the LFP/House bank to keep it charged.

I dunno - keeping FLA watered and only having half the usable AHs doesn't really strike me as KISS. In the end, the LFP conversion outlined above would be roughly similar money and you'd end up with almost 2x the usable AHs (assuming your Xantrex supports LFP).

Peter

 

[Iggy]

The heater is only used when charging below 32F. That power comes from the charger, not from the battery.

So in the winter time I put some insolation over them. Once the batteries reach temp, the BMS shuts down the heater and starts charging the battery. Fool proof.

 

[Marco Flamingo]

What is your start battery setup right now? Do you just use your FLA house bank? If so, then you would need a FLA/AGM start battery and a small DC-DC charger from the LFP/House bank to keep it charged.

I dunno - keeping FLA watered and only having half the usable AHs doesn't really strike me as KISS. In the end, the LFP conversion outlined above would be roughly similar money and you'd end up with almost 2x the usable AHs (assuming your Xantrex supports LFP).

Peter

My "start" battery is just using all 4 deep cycle FLA at once. No need for a separate start battery as with Lithium. My Balmer alt, external regulator, and Xantrex inverter/charger all support this with no extra gadgets. No blowing diodes as supposedly is a concern with LFP (hence the Marine How To need for a separate start battery and DC to DC limiting to 50 amps.)

There are LFP dual crank/deep cycle batteries coming on the market. With two of these 300Ah dual crank/deep batteries for $3,000, I'd have 540Ah usable. That would double my present amp hours, but for 3 times the cost of replacing the FLA. At first glance, a simpler drop-in system in that either "bank" (i.e. either battery) could start my diesel. Just like the redundancy I have now. No need for a separate start battery. Just like I have now. The down side is that should they shut down, I would blow the diodes because there isn't a FLA in the system.

One upside to new LFP is that battery conditions can be monitored in detail through bluetooth. I've not felt the need for detailed monitoring of my FLA, but it is almost required with LFP. If the app gave some kind of a warning of imminent shutdown, then it is possible to wire my external regulator with an alternator off switch, assuming I receive the warning in time to throw the switch. I checked it out but it doesn't really meet my definition of KISS.

Although my external regulator doesn't have a dedicated LFP program, it is possible to customize the settings such that it wouldn't overcharge (and eliminate one likely cause of a shutdown of the BMS). Basically, the setting could tell the alternator that the battery is full at 90% instead of 100%. The theory is that an accidental 91% won't cause a shutdown whereas 101% will (and damage diodes). Of course, that means that one's effective LFP SOC is from 10% to 90% using a programmed regulator with a safety factor. So I said above that for $3,000 I'd have 540Ah. Not quite. Playing it safe I'd only have 480Ah available. So not quite twice as many amps for 3 times the money.

Charging LFP to only 90% isn't recommended as it isn't enough to allow the BMS to go through the balancing of the cells. But that only needs to be done every few months. My Xantrex can charge to 100% from shore power and if the batteries shut down on the Xantrex it doesn't cause any problems. But since it doesn't have a LFP setting, it would float too high and I would probably need to manually turn it off after sitting at 100% (how much time?). Might mean sticking around the boat at the marina and remembering to always leave with the charger turned off. Another KISS failure.

To keep every thing working right with LFP for me, I should get a LFP battery ($1,800), a new LFP regulator ($650), a new inverter/charger for LFP ($3,000), I would still need a lead start battery ($300), and a DC/DC gadget ($330). I'm probably forgetting something. But for under $6k, I would have almost twice the amperage of $1,000 of simple drop-in FLA. Somehow that doesn't sound like a good idea. I have room for two more lead batteries.

 

[Delta Riverat]

I'm excited about the thin film solar I got for the bimini. For a long time I considered how to do it but there was no easy way that didn't require some kind of hard top or using the roof of the forward cabin. But people like to sit there and chat.

But hey, 20 extra pounds of very flexible solar panels on a nice sturdy Bimini with no holes through the canvas...
Yeah baby! The frame of this thing is strong, 1 inch SS tubing and fittings, lot's of bracing plus it's tied to the mast.

 

[mvweebles]

To keep every thing working right with LFP for me, I should get a LFP battery ($1,800), a new LFP regulator ($650), a new inverter/charger for LFP ($3,000), I would still need a lead start battery ($300), and a DC/DC gadget ($330). I'm probably forgetting something. But for under $6k, I would have almost twice the amperage of $1,000 of simple drop-in FLA. Somehow that doesn't sound like a good idea. I have room for two more lead batteries.

If you're happy with your FLA setup, then by all means - replace it like for like. But in all fairness, the costs and components you've mentioned are way out of bounds. No new regulator needed - you just need to manually set the charge points on your Balmar instead of blindly selecting "LFP" setting (which is not optimal even when available). A FLA G31 start battery is around $125 (maybe $200 for AGM). Because you'd be going the reverse direction of the configuration in the Marine-How-To article (large house bank to small start), you only need a small DC-DC charger ($150), not the 50A ($300) one Rod Collins linked. A decent 3kw inverter/charger is around $1k (Amazon.com). And you end up with 450-ish usable AH vs 250-ish. It will cost a few hundred bucks to complete the conversion. So for $300-$500 more than the $1k to replace FLA, you can have a vastly superior system that has much more capacity, charges faster, has no voltage lag with high amperage draws, requires no watering, and will last 10-15 years longer than FLA.

In all likelihood, you will be transitioning to LFP opportunistically when the batteries need replacement. Whether you do that now or in 5-years is up to you. You've done the hard part - getting a high output alternator in place.

Good conversation - guessing there are more than a few who are wondering the same thing.

Peter

 

[Delta Riverat]

I agree. I switched the house to LiFePO4 when the old lead acid ones were shot. So far so good. They are light enough to move and install you don't even need help. The capacity is amazing, I think I could leave the boat at the dock for a week with both fridges running and no charge and the beer would still be cold.

No corrosive acid, no hydrogen gas, much less self discharge, higher charge rates...what's not to like?

But yeah, the big ponder will come when those lead acid clunkers need replacement.

 

[Barking Sands]

Just to throw one more into the mix. I agree with your assessment of pricing and just elected to take the plunge. My new battery just arrived this morning only three days after ordering. Looks in great shape.

I've went with the Epoch 12V 460Ah | Heated & Bluetooth & Victron Comms choice with their 15% off for black Friday and free shipping. This is a pricier option, but has some specific options that I like and this is the best price I have seen. The built in 500amp T class fuse helps to justify the extra expenditure as that should be included with any system design that I have contemplated. Also, since I have talked myself into a Victron based system the coms are a nice benefit.

I have a pair of the Epoch 460 Marine batteries with Victron comms with a full Victron set up now for quite some time. They have been great. Check out the Epoch Marine group on Facebook. Lots of good tips there.

 

[Barking Sands]

Rod Collins pitches the Epoch brand as a upper tier product, but he also just pitched a company called WattCycle. They have a 100ah basic lifepo4 and at times it has been sold for $159. It passed all tests on Will Prowse video. They have a 300AH version too, but they seem to sell out as fast as they make them.

Epoch is currently having a 15% off sale.

 

[Ithaka7]

I work in the industry (grid scale storage) and can share current pricing trends and my views on the market.

LFP batteries with integrated BMS system and inverter/chargers average around $125/kWh today for cells that have over 8,000 guaranteed cycles. In the retail market you will get lower quality B cells (still good for 3-5,000 cycles) at probably slightly higher prices. I have seen EVE 314Ah cells for $80/kWh locally, so it should be possible to build a good system in this price range. The trend in grid scale storage is that container solutions become more dense to reduce installation costs with more cycles but battery chemistry is not changing dramatically. Thus for the average boater the new developments will not make a difference.

A typical golf cart size battery is 6V x 225 Ah or about 0.6 kWh useable, and it definitely costs more than the above. One should be able to build the equivalent battery bank of 8 GC2's for about $500. Clearly, the inverter/chargers for a small system represent more of the costs but these items improve in price performance very rapidly. It is strongly advisable to install the cells in a climate controlled area... the benefits in longevity, charge/discharge performance outweigh the cost of climate control.

Since LFP can accept 0.5C or higher with no problem, I strongly believe in charging via the engine or a generator. You could run the engine for 1h and charge the batteries every 2-3 days. You can still have a small PV as a back-up but it is not practical to install that much PV on a boat, and it looks ugly too. Personal choice though. My plan is to install 5kWh or 10kWh on the 48-ft boat this summer, charging from 2x 24V-70A alternators (3 kW charging capacity when underway). This makes it possible to run a 24V air-conditioner through the night (quiet) with no concerns.

 

[Marco Flamingo]

But in all fairness, the costs and components you've mentioned are way out of bounds. No new regulator needed - you just need to manually set the charge points on your Balmar instead of blindly selecting "LFP" setting (which is not optimal even when available). A FLA G31 start battery is around $125 (maybe $200 for AGM). Because you'd be going the reverse direction of the configuration in the Marine-How-To article (large house bank to small start), you only need a small DC-DC charger ($150), not the 50A ($300) one Rod Collins linked. A decent 3kw inverter/charger is around $1k (Amazon.com). And you end up with 450-ish usable AH vs 250-ish. It will cost a few hundred bucks to complete the conversion. So for $300-$500 more than the $1k to replace FLA, you can have a vastly superior system that has much more capacity, charges faster, has no voltage lag with high amperage draws, requires no watering, and will last 10-15 years longer than FLA.

I have the Balmer AR-5 regulator, which doesn't have an LFP setting. I can further configure it, as I did with my lead acid, and I added a battery temp and alternator temp sensor. I also changed the PO's factory "plain vanilla" settings with belt management, bulk time settings, etc. The AR-5 can "sort of" be set for LFP, but to get the most out of LFP, I'd really need a new regulator. The Wakespeed 500 is $600. I used that for my estimate (minus installation costs). I spec-ed a high quality start battery at $300, but cheaper is possible. I liked the Victron inverter you linked. Although smaller than what I have now, it is pure sine wave. Of course, with smaller means slower charging, but since the charger would only be used when tied to shore power in our marina, probably not that important. So switching to LFP would be closer to the same $ per amp hour as lead (not including the installation time and cost for the LFP changes). That makes a change over closer to neck and neck.

My research has me doubting that the Rod Collins setup can be reversed. Even if so, I'm not sure that would be a game changer. I read that one must first go from the alternator to the FLA battery (start) and then to the LFP battery (house) via the DC-DC charger. One reason being that the FLA can absorb the spike should the LFP BMS shutdown. But if reversed, I read that the spike can't get through the DC-DC charger such that the FLA can do it's job. Another reason for Rod's setup is that the DC-DC from the FLA does have a true lithium charging profile. It then doesn't matter if the alternator's external regulator doesn't have a lithium profile. An external regulator like mine can simply be set to the AGM setting (a profile that I have) for the start battery and the DC-DC takes care of the LFP profile, saving the $600 for a new regulator.

If neither of these is an issue, then reversing the setup, even using a smaller DC-DC charger, might work because once we start we usually motor for several hours. It is likely that one might still require upgrading the external regulator to something like a new Wakespeed 500 to get the full benefit when going first to the the LFP battery. Or, if tripping the BMS isn't a problem, I could just do that every time the batteries were charge. Doesn't sound right. I don't think that reversing is practical.

The potential benefits to me would be that 1) after a night at anchor an LFP house battery would charge back up in a 3 hour cruise instead of a 6 hour cruise (we usually use about 125Ah a night). 2) Once fully charged, with a 460Ah lithium house we could likely stay 3 nights anchored at the same place (never had a reason to do that). 3) Both batteries would be maintenance free (no more watering). 4) I could tell people that I have a lithium house battery (even if they don't ask). 5) Bluetooth. 6) the cost per usable amp hour is close to FLA (maybe not with the $600 Wakespeed). Problem is, spending $600 buys me 260 amp hours of lead (which I have room for) including cables. God, I never thought that thinking about lithium would have me considering adding more lead batteries.

Number 3 is still the best reason for me. Number 5 is also appealing instead of crawling in the engine room.

The cost of LFP is coming down. My aversion to crawling in the engine room to check/water 12 (or 18) battery cells is going up. I can see that they will meet in the near future. But when?

 

[dpmcgarry]

I am doing something a bit more complex - changing the majority of my house bank to 48V, having 48-12 DC-DC charger, keeping a small 12V bank to carry house load surges.

I decided to construct my own bank from cells that I am sourcing from a distributor in the US. I chatted with them last week and they mentioned that they are anticipating the price of cells (and therefore dropins) to increase in Jan. So if you are considering purchasing (like I am) now seems to be a good time to go ahead with that.

 

[mvweebles]

I have the Balmer AR-5 regulator, which doesn't have an LFP setting. I can further configure it, as I did with my lead acid, and I added a battery temp and alternator temp sensor. I also changed the PO's factory "plain vanilla" settings with belt management, bulk time settings, etc. The AR-5 can "sort of" be set for LFP, but to get the most out of LFP, I'd really need a new regulator. The Wakespeed 500 is $600. I used that for my estimate (minus installation costs). I spec-ed a high quality start battery at $300, but cheaper is possible. I liked the Victron inverter you linked. Although smaller than what I have now, it is pure sine wave. Of course, with smaller means slower charging, but since the charger would only be used when tied to shore power in our marina, probably not that important. So switching to LFP would be closer to the same $ per amp hour as lead (not including the installation time and cost for the LFP changes). That makes a change over closer to neck and neck.

My research has me doubting that the Rod Collins setup can be reversed. Even if so, I'm not sure that would be a game changer. I read that one must first go from the alternator to the FLA battery (start) and then to the LFP battery (house) via the DC-DC charger. One reason being that the FLA can absorb the spike should the LFP BMS shutdown. But if reversed, I read that the spike can't get through the DC-DC charger such that the FLA can do it's job. Another reason for Rod's setup is that the DC-DC from the FLA does have a true lithium charging profile. It then doesn't matter if the alternator's external regulator doesn't have a lithium profile. An external regulator like mine can simply be set to the AGM setting (a profile that I have) for the start battery and the DC-DC takes care of the LFP profile, saving the $600 for a new regulator.

If neither of these is an issue, then reversing the setup, even using a smaller DC-DC charger, might work because once we start we usually motor for several hours. It is likely that one might still require upgrading the external regulator to something like a new Wakespeed 500 to get the full benefit when going first to the the LFP battery. Or, if tripping the BMS isn't a problem, I could just do that every time the batteries were charge. Doesn't sound right. I don't think that reversing is practical.

The potential benefits to me would be that 1) after a night at anchor an LFP house battery would charge back up in a 3 hour cruise instead of a 6 hour cruise (we usually use about 125Ah a night). 2) Once fully charged, with a 460Ah lithium house we could likely stay 3 nights anchored at the same place (never had a reason to do that). 3) Both batteries would be maintenance free (no more watering). 4) I could tell people that I have a lithium house battery (even if they don't ask). 5) Bluetooth. 6) the cost per usable amp hour is close to FLA (maybe not with the $600 Wakespeed). Problem is, spending $600 buys me 260 amp hours of lead (which I have room for) including cables. God, I never thought that thinking about lithium would have me considering adding more lead batteries.

Number 3 is still the best reason for me. Number 5 is also appealing instead of crawling in the engine room.

The cost of LFP is coming down. My aversion to crawling in the engine room to check/water 12 (or 18) battery cells is going up. I can see that they will meet in the near future. But when?

A Balmar APM (Alternator Protect Module - HERE) protects against sudden disconnect when LFP bank is direct to your Balmar so you can get full charging benefit without going through a DC-DC charger choke-point. Still need a small DC-DC charger to your Start battery if it's a different chemistry.

HERE is a pretty good discussion on CF about programming the ARS-5 for LFP batteries. The author of the thread cruised the Bahamas and Florida full-time with this setup for a couple years with no issues and remains a vocal proponent of relatively simple LFP setups.

A good friend of mine has a Roughwater 37. The guy is a genius - he has forgotten more about boats, diesels, and electrical systems than I'll ever learn and is a fierce defender of old-school setup with a Leece-Neville large frame alternator to a fully lead-acid/AGM start/house setup. While I'm relatively happy with my LFP/Balmar setup with its high charging potential, it feels a bit more fragile than the old school setup my friend advocates. The Rod Collins setup is a happy medium.

Peter

 

[Delta Riverat]

Just ordered up a 100 AH LiTime 12 volt mini for $180. Going in my tool shed to replace a SLA getting dim.

 

[Marco Flamingo]

A Balmar APM (Alternator Protect Module - HERE) protects against sudden disconnect when LFP bank is direct to your Balmar so you can get full charging benefit without going through a DC-DC charger choke-point. Still need a small DC-DC charger to your Start battery if it's a different chemistry.

HERE is a pretty good discussion on CF about programming the ARS-5 for LFP batteries. The author of the thread cruised the Bahamas and Florida full-time with this setup for a couple years with no issues and remains a vocal proponent of relatively simple LFP setups.

I had already read that Cruiser Forum thread. I'm starting to feel like I'm going in circles. That thread was one of those that talked about simplifying adding LFP house to a FLA start battery by changing the ARS-5 settings. One should lower the bulk voltage (which increases charge time). Charge only to 90% (which decreases total amps). Derate the alternator by 50% (which increases charge time). So the much-touted benefits of LFP (storage and charge speed) are both reduced. Maybe not down to FLA numbers, but the advantages, including the $ per usable amp, are not what is on the side of the battery (as is true with FLA). And in the end there was the recommendation to spend $600 for an upgraded regulator if adding LFP.

I'm not convinces the Balmer APM solves many issues during a BMS cutoff. Balmer's first avalanche diode ($30) popped off during a voltage spike and you replaced it (after noticing that you were no longer charging and diagnosed/fixed the issue and had a spare onboard). Balmer's new diode (APM at $84) has a blinking light and a beep when it pops off. As it is attached to the back of the alternator, I couldn't see it when running, of course, and am not sure I could hear it. I would definitely notice it at the end of the day. It could be that a bluetooth app on an LFP battery might also notify charging had stopped? Probably not.

It is rated at only 60 Amps. Unfortunately, is isn't common for an alternator spike from a battery shutdown to hit 120V. Does the APM still save the day by sacrificing itself? Or does a huge spike take out the APM and the alternator diodes? Does one need to carry a spare $84 APM? The advertising copy for the APM is a bit vague.

It could be that it is only able to protect the alternator diodes when the disconnect is during low voltage/current charging, like a float stage (a stage which a true LFP program doesn't have). $84 up in a puff of smoke? Better than the alt diodes, I guess. Time to buy an APM and send it to Will Prowse for a bench test.

 

[SteveK]

It is rated at only 60 Amps.

I only saw 60V mentioned in the link, so the 120V should not occur. But I have been wondering if the Balmar APM may be a slightly better approach. Since I have twins, I could try it on one alternator.

 

[Barking Sands]

I had already read that Cruiser Forum thread. I'm starting to feel like I'm going in circles. That thread was one of those that talked about simplifying adding LFP house to a FLA start battery by changing the ARS-5 settings. One should lower the bulk voltage (which increases charge time). Charge only to 90% (which decreases total amps). Derate the alternator by 50% (which increases charge time). So the much-touted benefits of LFP (storage and charge speed) are both reduced. Maybe not down to FLA numbers, but the advantages, including the $ per usable amp, are not what is on the side of the battery (as is true with FLA). And in the end there was the recommendation to spend $600 for an upgraded regulator if adding LFP.

Only need to lower absorption voltage so that the maximum voltage sent to the LFP bank does not trigger the overvolt disconnect. Typically 14.6v. So you just need to stay away from that point. A safe typical absorption for LFP would be 13.8 to 14.2. Lowering the absorption to say...14 volts hardly reduces charge time except for the top few percent as you get to the upper knee. But that slow down of the top few % pales in comparison to lead acid. After absorption you should float. Does the ARS-5 have a float stage?

There is no reason at all to charge to 90%. Charge to 100% on each cycle. If you trust Will Prowse...you should check out his latest series on the topic of charging LFP. The key is really just to not hold the batteries above the natural resting voltage for extended periods...hence a float stage right around resting voltage...which after an absorption cycle...still maintains 100 capacity. You can charge LFP to 100% capacity with as little as 13.6 volts. Charge time to 100% capacity between 13.6 and 14.2 is substantial. But the difference between 14.2 and 14.6 is not much at all. Charge to 100% using an absorption voltage that steers well clear of BMS overvolt and then turn down the voltage with float. Long life...100% capacity.

Derating the alternator applies exactly equally to lead acid. It has nothing to do with the batteries and everything to do with not taxing the alternator. Depending on the lead acid bank size you may not need to derate the alternator because the acceptance rate is so low. But even a moderate LFP bank the acceptance rate is very high...so we set the alternator output with the equipment and programming to as high as we dare.....to the last %, nearly guaranteeing a much higher equivalent charge rate vs lead acid (provided you are comparing a lead acid bank size that does not naturally tax the alternator due to a naturally low acceptance rate. If you had a large enough lead acid bank then all alternator derating rules apply, same as LFP.


I read your replies. LFP may not make sense for you...but it appears that may be true only due to the fact that your power requirements are so low. A very small bank suits you fine. But many boaters these days are becoming power hungry. IMO any bit more than your requirements and LFP becomes a no brainer. Especially if your mission requires it. And of course cost considerations.

 

[SteveK]

power hungry! Yes.
I have noticed that this time of year with the electric heaters running that on the 30A shore power I have to use both inverters to use the stove/oven plus DC lights.

My fridge runs 100% off the house bank as does all 12V lights, the inverter charger keeps the house fully charged with 13.5V float.
Should I set charging to less than 100% when not on boat? I have not since the house bank is in continuous use as opposed to storage fully charged and not used.