LiFePo4 Refresh

[jviss]

I'm posting this as a way of getting updates on the state of LiFePo4 batteries on sailboats as of 2022, because I'm considering them for my house bank refresh.

I have searched for previous threads, but none are really up to date, as far as I can tell, and several just wander off into other areas.

Let's call them LFP for short.

So, here are my important questions:

1. Are the Chinese(?) Amazon and eBay LFP any good? I now see a 100Ah 12V Group 27 or 31 with BMS for $300. Compare this to an equivalent Lithionics at $1700!
2. Can I just drop them in and reprogram my Freedom 20/Link 2000R? In particular, I think I can program it to not float after acceptance; I can also reprogram the max charging current up, since I'm limiting it for my FLA bank, and my serpentine belt upgrade and PowerMax 125A alternator can provide plenty of current.
3. How can I limit charging to 80% for storage purposes, i.e., for end-of-weekend charges?
   1. or should I design and build my own bleeder to bring them down to 80% for storage?
   2. related to that, can I implement some kind of switch to tell it to charge to 100%, for when I'm heading out to an anchorage?
4. How to integrate solar?

I'm sorry, that's a lot. But I have many questions. I am on a budget, too. I have no shore power charging need, I'm on a mooring, and I usually anchor. (I can count on the fingers of one hand the times I've tied up to a dock with shore power in 20 years.)

Thanks!

 

[Roy 845]

There's no great answer here because of so many options available these days but I would refer to a guy named Will Prowse that has a You Tube Channel that tests and will offer results on a bunch of different batteries. https://www.youtube.com/c/WillProwse

 

[dreuge]

Hi
I did the upgrade to DIY LFP last year. Replaced 2 deep cycle 12V house batteries with on 560AH LFP at a cost of about $800. It has been a game changer!

I wrote up my experience on my blog:

LFP battery build

Adding new LiFePo4 to the House Battery

Building a 560AH LiFePO4 House Battery for Under $1k The above left photo shows the new LiFePO4 battery compared to one of the two 105AH...

svjohannarose.blogspot.com

Solar and power upgrade

Electrical Power System w/ Solar, Inverter, and Alternator Charging

System Schematic Overview For a recent overview see: Other Uses for Solar Activity Talk I gave at local Amateur Radio Society meeting on...

svjohannarose.blogspot.com

Also, here is a link to a talk I gave about to a local Amateur Radio club:

Solar Off-Grid System

This is a talk I gave to the Tallahassee Amateur Radio Society on building an off-grid electrical system for remote RV/Marine operations. ...

svjohannarose.blogspot.com

 

[jviss]

Hi
I did the upgrade to DIY LFP last year. Replaced 2 deep cycle 12V house batteries with on 560AH LFP at a cost of about $800. It has been a game changer!

I wrote up my experience on my blog:

LFP battery build

Adding new LiFePo4 to the House Battery

Building a 560AH LiFePO4 House Battery for Under $1k The above left photo shows the new LiFePO4 battery compared to one of the two 105AH...

svjohannarose.blogspot.com

Solar and power upgrade

Electrical Power System w/ Solar, Inverter, and Alternator Charging

System Schematic Overview For a recent overview see: Other Uses for Solar Activity Talk I gave at local Amateur Radio Society meeting on...

svjohannarose.blogspot.com

Also, here is a link to a talk I gave about to a local Amateur Radio club:

Solar Off-Grid System

This is a talk I gave to the Tallahassee Amateur Radio Society on building an off-grid electrical system for remote RV/Marine operations. ...

svjohannarose.blogspot.com

Thank you very much!

 

[jviss]

Hi
I did the upgrade to DIY LFP last year. Replaced 2 deep cycle 12V house batteries with on 560AH LFP at a cost of about $800. It has been a game changer!

I wrote up my experience on my blog:

LFP battery build

Adding new LiFePo4 to the House Battery

Building a 560AH LiFePO4 House Battery for Under $1k The above left photo shows the new LiFePO4 battery compared to one of the two 105AH...

svjohannarose.blogspot.com

Solar and power upgrade

Electrical Power System w/ Solar, Inverter, and Alternator Charging

System Schematic Overview For a recent overview see: Other Uses for Solar Activity Talk I gave at local Amateur Radio Society meeting on...

svjohannarose.blogspot.com

Also, here is a link to a talk I gave about to a local Amateur Radio club:

Solar Off-Grid System

This is a talk I gave to the Tallahassee Amateur Radio Society on building an off-grid electrical system for remote RV/Marine operations. ...

svjohannarose.blogspot.com

One quick question, as I can't read all of this now; can you lay these batteries that you bought down on their sides? My battery compartment is height challenged.

Also, do you mention the dimensions of these batteries?

Thanks,

jv

 

[Johann]

One quick question, as I can't read all of this now; can you lay these batteries that you bought down on their sides? My battery compartment is height challenged.

Also, do you mention the dimensions of these batteries?

Thanks,

jv

Most batteries with prismatic cells need to be vertical, and most batteries are using prismatic cells. Battleborn, and a few others I’m sure, use cylindrical cells and can be placed in any orientation.
When selecting an LFP battery, pay close attention to the BMS limits, and compare that to your expected use. Many drop in type batteries will be limited on maximum discharge amps, and may not run a windlass due to the “inrush” current exceeding the BMS limits. Same for inverters.

For charging purposes…. Well…

Charging Marine Lithium Battery Banks | Nordkyn Design

nordkyndesign.com

 

[jviss]

I'm doing some reading on LFPs, found a good DIY Solar Power forum. Yes, some cells are insensitive to orientation, it seems.

I'd like to build a bank that's short enough to comfortable fit in the batter locker that's about 400 Ah,

But here's the thing. I'd like a charger that has the following features:

1. knows LiFePo4 chemistry
   1. e.g., no float stage
2. can charge to the state of charge I specify
   1. 80% for most use
   2. 100% if I'm headed to an anchorage
   3. 50% for storage, i.e., at the end of the weekend
3. Can discharge to the state of charge I specify
   1. 50% for storage

On top of this, I'd like an automated engine control system, like a generator control, so it can safely start up, and stop, if necessary, unattended. And, I'd like to be able to tell it I'm on the way to the boat, and to bring the batts up to 80% or 100%, depending on the anticipated use. (Also could start cooling down the fridge).

Is that too much to ask?

 

[Johann]

I'm doing some reading on LFPs, found a good DIY Solar Power forum. Yes, some cells are insensitive to orientation, it seems.

I'd like to build a bank that's short enough to comfortable fit in the batter locker that's about 400 Ah,

But here's the thing. I'd like a charger that has the following features:

1. knows LiFePo4 chemistry
   1. e.g., no float stage
2. can charge to the state of charge I specify
   1. 80% for most use
   2. 100% if I'm headed to an anchorage
   3. 50% for storage, i.e., at the end of the weekend
3. Can discharge to the state of charge I specify
   1. 50% for storage

On top of this, I'd like an automated engine control system, like a generator control, so it can safely start up, and stop, if necessary, unattended. And, I'd like to be able to tell it I'm on the way to the boat, and to bring the batts up to 80% or 100%, depending on the anticipated use. (Also could start cooling down the fridge).

Is that too much to ask?

Victron Multiplus Inverter/chargers (maybe also the Phoenix charger), with an internet connected GX device (Cerbo, Venus…) and a BMV 712 or SmartShunt. I do this with my Lithionics drop ins (not using the genset control, but it’s there), but currently I am only using voltage as a control, not SOC. The capability is there though. My problem with SOC control is drift. If you reset to full every 2 weeks or so the BMV should stay within a couple percent.

 

[jviss]

I had a BMV on my previous boat which I found next to useless. Solar would fool it into thinking the batteries were fully charged as the sun went down and the current gradually diminished. Plus other issues. I wouldn't buy one again.

Voltage seems not a very good gauge for LFP as the voltage discharge curve is so flat. I don't know how to determine SOC for LFP, other than a BMV-like device.

 

[jviss]

By the way, those charger features that I mentioned, like bringing the bank to 50% or 80%, etc., is something that is already done in chargers for my model airplane LiPo (lithium polymer) battery packs. I don't know how they determine SOC, it's probably via very precise voltage measurement of the individual cells; the balance harness connects to each cell individually.

 

[Hayden Watson]

On my LFP build I plan to use the Samlex EVO 1212HW inverter/charger. It will let you charge pretty much any way you want. What you are describing, they would call a 2 stage, type 1. Set a low bulk charge voltage (CC), set a short absorb time (CV), then off. The Absorption time can be set from 0-600 minutes.
You can also set it to exit the absorption phase by a set tail current.

 

[Johann]

I had a BMV on my previous boat which I found next to useless. Solar would fool it into thinking the batteries were fully charged as the sun went down and the current gradually diminished. Plus other issues. I wouldn't buy one again.

Voltage seems not a very good gauge for LFP as the voltage discharge curve is so flat. I don't know how to determine SOC for LFP, other than a BMV-like device.

Yes, it’s a common issue with the Victron BMV if you use the default settings that it will falsely sync to 100% with solar. You must set the charged voltage at .2v below absorption voltage and then set 1-3% tail current. The default settings assume a system with a shore charger only. I don’t know why Victron doesn’t change that since using .2v below absorption works in all situations. They do recommend this when you have solar, but it’s at the end of the video instructions so most people miss it. Anyway my BMV 712 is more accurate than the Lithionics internal SOC.

The voltage settings I use that work:
12.9 bulk/abs/float = 25-40% SOC
13.2 bulk/abs/float = 50-70% SOC
13.3 bulk/abs/float = 70-90% SOC

https://lithionicsbattery.com/wp-content/uploads/2022/02/FAQ-Voltage-Vs-State-of-Charge-RA.pdf

 

[Johann]

One quick question, as I can't read all of this now; can you lay these batteries that you bought down on their sides? My battery compartment is height challenged.

Also, do you mention the dimensions of these batteries?

Thanks,

jv

What about a server rack battery, these are pretty short. 400ah @12.8v. 17.4”x18.5”x6.1”. $1499.

12V 400AH Battery by EG4

DESCRIPTION SPECS & MANUAL VIDEOS SHIPPING 12V 400AH Battery by EG4 GYLL HAS REBRANDED TO EG4. SAME GREAT BATTERY, DIFFERENT NAME. This EG4 12.8V 400AH (12V) LiFePo4 5.12kWh Lithium Battery is a premium battery with only 16 prismatic 3.2V cells in series versus the typical 300+ AA-Style Lithium...

www.signaturesolar.com

 

[jviss]

What about a server rack battery, these are pretty short. 400ah @12.8v. 17.4”x18.5”x6.1”. $1499.

12V 400AH Battery by EG4

DESCRIPTION SPECS & MANUAL VIDEOS SHIPPING 12V 400AH Battery by EG4 GYLL HAS REBRANDED TO EG4. SAME GREAT BATTERY, DIFFERENT NAME. This EG4 12.8V 400AH (12V) LiFePo4 5.12kWh Lithium Battery is a premium battery with only 16 prismatic 3.2V cells in series versus the typical 300+ AA-Style Lithium...

www.signaturesolar.com

That is very cool, thanks! Kinda pricey, but....

 

[Tally Ho]

What about a server rack battery, these are pretty short. 400ah @12.8v. 17.4”x18.5”x6.1”. $1499.

12V 400AH Battery by EG4

DESCRIPTION SPECS & MANUAL VIDEOS SHIPPING 12V 400AH Battery by EG4 GYLL HAS REBRANDED TO EG4. SAME GREAT BATTERY, DIFFERENT NAME. This EG4 12.8V 400AH (12V) LiFePo4 5.12kWh Lithium Battery is a premium battery with only 16 prismatic 3.2V cells in series versus the typical 300+ AA-Style Lithium...

www.signaturesolar.com

Do those kind of batteries handle the shock and vibration of living on a sailboat? Just curious as racks (and computers) don’t usually get much bouncing around.

Greg

 

[Johann]

Do those kind of batteries handle the shock and vibration of living on a sailboat? Just curious as racks (and computers) don’t usually get much bouncing around.

Greg

Good question, really the only battery out there that is UL tested for shock and vibration in mobile use is the Lithionics, and that cost them $80k+. I watched the Will Prowse tear down of the EG4 and it looks pretty solid to me. Just as solid as a Multiplus in my opinion.

 

[Johann]

That is very cool, thanks! Kinda pricey, but....

I think $375 per 100ah (12v) is actually a good deal, especially with all its features.

 

[jviss]

I'm gradually absorbing knowledge about LFPs and BMSs. It's funny, some things that are probably common knowledge just dawn on me and I say, "Oh, yea, that's how it works, or that's how it's going to happen."

Maybe I'm wrong, but it occurs to me that a couple of aspects of BMSs aren't very desirable. One, in particular, is that the BMS will disconnect the battery in an overcharge condition. That means the alternator will be open, and without a zap protector or having a lead acid batter connected to the alternator you will zap the alternator. And, you will lose house power! Everything will go dark.

Second, there's no feature of a BMS I've been able to find that allows one to specify the desired state of charge in and the BMS will target that, including discharging the battery. You would need a load, of course, but none I've found can do this.

I guess I want a BMS that also manages the alternator and can control the application of an external load, like the AC water heater, for example, through an inverter.

Does anyone make a complete power management system for LFPs on yachts?

Still a bit naive here.

Thanks

 

[Hayden Watson]

There are several BMS's that will control the chargers and other devises, but they are much more expensive.

 

[jviss]

There are several BMS's that will control the chargers and other devises, but they are much more expensive.

That's good to know. Now if I could only find them!