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

[fryedaze]

After reading this entire thread my head is spinning. A lot of things to juggle with the LiFePo battery install. My house bank of 8 235 amphr golf cart batteries is due for replacement. I am installing 2- 460 amphr Epoch via a Battery Manager system. I will start a thread after the new year to document the install. Attached is what it will look like.

 

[GMS]

Just a bit of additional encouragement for those still on the fence about LiFePO4 conversion from FLA. Our new to us 56 DeFever currently has a very large house bank (16 L16 6V batteries), I have already built a LiFePO4 replacement, but haven't had the time to haul all the heavy L16s out of the engine room.

I recently installed an Amazon Air Quality monitor in the engine room (mostly to monitor temperature and humidity). The monitor also measures VOCs. Under normal conditions, the VOCs are very low <10 (on the index provided by Amazon, unclear how the index is calculated). However, when the charger hits the house bank with a bulk charge, the VOCs skyrocket. While it is common knowledge the FLA off gas when charging, it was very interesting to see an objective measure of just how bad it can be (and this is on a FLA bank that hasn't really been discharged).

 

[Marco Flamingo]

Most all brands say that you can go 4 in parallel. I did find some support for the "safety in numbers" concept when installing LFP battery banks (my issue 1 in post #101). Then the issue is how does one know that a battery in the bank has "checked out." Since most BMSs have a reset feature, it could be that it would be back online in 30 seconds and one would never know.

Another item I came across on Marine How To was Rod saying that the maxim that "deep cycle lead batteries can't be used for starting" was a basically a myth. And the "dual purpose" lead battery is a hoax that feeds off of the same myth. My PO (an electrical engineer) seemed to have agreed. He installed (7 years ago) 4 FLA deep cycles in two banks. Either bank by itself can start my 80hp Lehman (I tried just to make sure). But I very rarely move the switch to isolate them, just keep it on "both" and go boating. I do carry a Noco jump starter in case somehow the bank(s) were too low. But the truth is that one simply needs enough CCA for starting, and that might take more than a single deep cycle lead battery. So, the maxim is really "one needs enough deep cycle FLA batteries to start the engine."

For a long time, the maxim was that LFP should not be used for starting. Now, the "dual purpose" LFP has reached the market. Hmmmmm. There may be some historical basis for the LFP "can't start" argument. First, the older LFP batteries were generally in standard automotive sizes. Maybe it was difficult to get enough CCA out of a Group 24 size LFP. Second, the BMSs were smaller. But on a trawler, we aren't looking to fit a single Group 24 under the hood. There are now big hurkin' LFP drop-ins that have very robust BMSs. And we are looking at battery banks, not what fits in a car. Third, many of the "can't use LFP to crank" arguments are based on cars, motorcycles, and outboards that have very basic (i.e., dumb) alternators and maybe a single battery. Yes, that would be a problem.

So, like the "deep cycle FLA starter myth," is the starter limitation on LFP batteries also a myth? Here is a battery that would make a substantial LFP bank. 6 of them, 3 in parallel in each bank, would provide about 1,500 usable amp hours, more than 6 times what I have now. Each battery has a 300 amp BMS. In theory, that could give me 1,800 CCA. I can't use that much to start my Lehman. Right now with the lead batteries, each bank has a 250A ANL fuse on it, so I know that I don't need (or want) the instant 1,800 amps that this battery bank could provide. The only reason to "re-fuse" would be to replace the ANL with T-class fuses (maybe also 250 amp?).

I would then simply put my two banks together, having already decided that a 6 battery bank gives me enough redundancy for "BMS shut down" protection. When starting, each of the LFP batteries would be responsible for its share of the cranking amperage. I've never seen 500 amps from my shunt when starting, but let's say it is cold out and the batteries are required to produce 500 amps (out of the 1,800 available) for a fraction of a second to start my Lehman. Big deal. If it is a big deal, why? I know that some LFP batteries state "not to be used as a starter battery," but does that mean "not to be used individually as a starter battery?) Is there something about LFP chemistry that allows each battery's 300A BMS to basically say "Hey, this 83.3 amp momentary discharge is going to a starter!! That is not allowed!!!"

Mark

 

[SteveK]

I have a cell phone size battery that I purchased for the motorcycle, now gone that started it. I decided to test the abilities, disconnected the start battery and started the car with it alone.
so yes I wonder why a house bank cannot be used for a starter. The only reason I have is I want a standby battery dedicated to start the engine.

 

[J.T kearney]

Yes, but you have to recognize when the first battery shuts down and act promptly. Depending on the cause the batteries could shut down one by one, perhaps in quick succession.


Regulator voltage isn't going to affect charge rate, and should be set to the battery maker's spec, which is typically at least 1.0v below the BMS cutoff. Full protection when working.

Not really protection against a sudden disconnect, except that you may be running at lower output.

Mark, I bought 4 100 amp Epochs that came with remote monitors for each battery. They have a LED display for charge% and audio alarm for BMS shut down. Mounted them next to my main distribution panel. I had to use shielded cabling for a extension because they ran along 120 volt wiring in the chase.
Cheers J.T.

 

[BruceK]

I have a cell phone size battery that I purchased for the motorcycle, now gone that started it. I decided to test the abilities, disconnected the start battery and started the car with it alone.
so yes I wonder why a house bank cannot be used for a starter. The only reason I have is I want a standby battery dedicated to start the engine.

It can according to this:With lithium do we actually need a dedicated starter battery? - Cruisers & Sailing Forums
Not having gone to lithium, just installed 2 massive 65kg dual purpose 208Ah/1000CCA(they test at 1270CCA!) AGMs to suit the IG/Halvo/Integrity dual purpose battery design, I`m happy with batts designed (inter alia) for cranking.

 

[Delta Riverat]

I agree with Marco on both counts. Have 6 volt golf cart batteries for starters, 2 each in series, 4 total to start 2 5.5 liter Volvos. Each will start it's engine in 2 seconds or less and I have a 500 amp combiner to parallel if needed.

Have (3) 300 AH LIFePO4's for house, 200A continuous and 400A for 5 seconds. There is no doubt in my mind that 1200 amps would not start the engines.

 

[dpmcgarry]

Interesting you're going 48v - in some ways going to 48v can be more simple, not complex. The residential applications (off grid, battery backup) have driven some very elegant solutions that are super affordable compared to the Victron blue wall of parts with yards of cables/crimps.

I have several questions. What size (capacity) battery bank are you building? Why DIY build vs one of the many integrated battery offerings on the market? How will you charge at 48v? What inverter will you use?

I started a thread a few months ago posing questions of whether 48v made sense given the high AC loads people now demand on their boats and emergence of DIY-friendly all-in-one 48v solutions. Feedback was how to charge given very limited selection of 48vdc alternators. And resistance to having two DC systems aboard (I have to admit, the old Hatteras style of multi-DC systems is a bit cringeworthy).

Interested to hear more about your system and use case. Guessing your supplier mentioned January price increases because the next American president has firmly promised steep tariffs on Day 1 (no political opinion here, just reciting a policy statement).

Peter

Hey sorry I somehow missed this. I actually have some more up to date info as I have my system largely planned out at this point. Just waiting until first or second week in Jan to purchase everything…ironically I was looking to purchase in November but Victron is actually reducing battery prices first week in Jan so I am hoping to thread the needle before any tariffs potentially materialize.


Yeah the only reason I called it more complex was because I was adding another voltage to a boat that already has 12v and 24v systems.

48v is really about how fast you can put electricity into the system and how efficiently you can pull it out for inverting. I want to be able to run the boat entirely off of inverters so I need around 12kw of inverting capacity (give or take). Doing that at 48v is less expensive and more efficient than 12 or even 24. I need to do split phase so I will put in two Quattro 48/5000s.

I changed my mind on building my own bank from cells. I was a bit wary about the insurance situation changing down the road (my current insurer has no special lithium policy limitations at this time however there is rumint this may be changing). Originally I was doing it purely for cost. What I have since discovered is - at least for Victron - there is a fair amount of markup that happens with retail pricing. If you work with a dealer to purchase an entire package it becomes way more economical than the prices you see online. This is very interesting / alien to me coming from the world of IT / computer systems because I saw that most places retail prices were pretty much the same so I assumed that was the cost to consumer. I’m actually surprised someone hasn’t decided to take a low margin / high volume approach to this business.

Anyways at the end of the day the cost came out the same so I’m just gonna go pretty much all Victron and call it a day.

My bank will be 400Ah Victron at 48v (two sets of 2x24 batteries in series), Victron BMS, the inverters, and a handful of other things. This should give me enough juice to run downstairs AC on my split system overnight without changing that out (just adding soft start).

For DC to DC I’m actually going with master volt as they have a new MacPlus converter charger for 48 to 12v that is significantly better than anything Victron currently has.

I’m going to replace the stock alternator on my QSL9 with an American Power Systems 48v 165a alternator and wake speed regulator. That’s roughly 8kw of power off my main engine underway. That means we can do laundry and/or run some AC while underway without having to run the generator. I am going to keep my second pto mounted 12v 200a alternator to cover the house loads underway. I am keeping the 12v house system as is. Down the road I may change over some larger things to 48v (like my windlass motor because Maxwell has a way to convert it) but I really need to avoid over complicating this which is some thing I tend to do quite often.

For charging the Quattros will handle that. I have a 12kw gen set on board that I should be able to run at around 8-10kw just to charge the 48v bank. That will keep my generator running at a good load to keep it efficient. When I’m on shore power I will limit that input to the single 50A hookup my boat currently has but that will still charge things plenty fast.

 

[mvweebles]

...... I need to do split phase so I will put in two Quattro 48/5000s.........My bank will be 400Ah Victron at 48v (two sets of 2x24 batteries in series),

A few thoughts. First, if you go Victron, in my opinion it's crucial you find a dealer with food tech support and make all your purchases through that dealer. Victron support network is heavily dependent on dealers - pricing is similar throughout. Tech expertise varies widely. The buyer has little option but to work with the dealer they purchased through.

Second, largest Victron battery I could find is 200ah at 24v. Two in series would be 200ah at 48v (10kwh storage). Still a ton of storage.

Third, there are many native 48v batteries in the market now. Why go series (2 x 24v)?

Finally, instead of running dual Quattro's, have you considered some of the inverter/chargers that have more integrated capabilities including native split phase with onboard circuit protection and even MPPT if you add solar down the road?

This type of setup is bleeding edge for boats but well into adoption phase for residential setup (inverters are mostly UL listed these days due to permitting requirements). DIYSolar forum (Will Prowse monitors) has some extremely technical wonks if you have any questions.

Please keep updating your progress and decisions. In my opinion, definitely a place for 48v.

Peter

 

[slowgoesit]

Hi all
Has anyone heard from ABYC on requirements for lifepo batteries? Last I heard they where going to include remote monitoring, requiring both visual and audio. That was a few years back ,so any updates ?
Cheers J.T.

ABYC E-13 published earlier this year (2024)

Here is a brief synapses of the recommendations:

Obtaining Boat Insurance | ABYC E-13 Standards for Lithium-Ion Batteries

Ensure your boat is protected with comprehensive insurance coverage. Learn about ABYC E-13 standards for lithium-ion batteries.

battlebornbatteries.com

 

[SteveK]

Hi Scott, your link goes to a July 2023 article. Was there another published in 2024?

 

[slowgoesit]

Hi Scott, your link goes to a July 2023 article. Was there another published in 2024?

Steve, I didn't check the article date. If you are a member of MTOA, you can access the full ABYC recommendations through a membership benefit. Otherwise, excerpts should be available with internet searching. I don't have an open source link to the recommendations.

 

[NoRain]

Steve, I didn't check the article date. If you are a member of MTOA, you can access the full ABYC recommendations through a membership benefit. Otherwise, excerpts should be available with internet searching. I don't have an open source link to the recommendations.

According to the current Standards, E-13 was published 7/31/2022.

 

[SteveK]

According to the current Standards, E-13 was published 7/31/2022.

Thanks for this, I thought there was an update in 2024

 

[Helmsman]

Steve, there was an update planned. It was delayed until 2025. There is also a planned update to E-11. The last thinking from a knowledgeable resource was that both would be released in 2025. So, if one can wait, it might not be a bad move to see what changes there are in the updates. One comment I have heard is that fusing requirements will change. I don’t have any other info.

 

[J.T kearney]

Steve, there was an update planned. It was delayed until 2025. There is also a planned update to E-11. The last thinking from a knowledgeable resource was that both would be released in 2025. So, if one can wait, it might not be a bad move to see what changes there are in the updates. One comment I have heard is that fusing requirements will change. I don’t have any other info.

Thanks all for the update!!
I have a feeling about 90% on the forum are either thinking about lifepo4, in the process of install, or have done it already. I'm sure the insurance companies will watch it closely.
Cheers J.T.

 

[ksanders]

One thing that I noticed and that I'm concerned about is the people might stop the idea of fusing, only relying on the BMS

This could be a very dangerous decision, and if you had a problem, it could fall under the policy language in most policies that address the idea of improper or incorrect repairs or modification.

I just got done with my installation this week and decided to fuse all three of the parallel batteries at the battery terminal, before going to the bus bar

 

[Delta Riverat]

Me too. Fuses right on the all the house batts.

I'll add that I love my LiFePO4 house. Over the Christmas span I haven't been out to the boat in well over a week. When I got there the boat was dark. I ran the bank down to BMS shutoff. Ice in the freezer melted. Turned on the charger and everything lit up fine. Yeah, I probably took off a few extra cycles but nothing like sulfating a LA eh?

 

[J.T kearney]

One thing that I noticed and that I'm concerned about is the people might stop the idea of fusing, only relying on the BMS

This could be a very dangerous decision, and if you had a problem, it could fall under the policy language in most policies that address the idea of improper or incorrect repairs or modification.

I just got done with my installation this week and decided to fuse all three of the parallel batteries at the battery terminal, before going to the bus bar

That's what I did on my install also. I have 4 epoch 100 amp batteries and wired MBRF 125 amp fuse off each positive battery post. From there to a buss bar for all 4 batteries, then to house T fuse. I feel that between the battery internal BMS ,125 amp MBRF and the T fuse it should be safe
Cheers J.T.

 

[Helmsman]

That's what I did on my install also. I have 4 epoch 100 amp batteries and wired MBRF 125 amp fuse off each positive battery post. From there to a buss bar for all 4 batteries, then to house T fuse. I feel that between the battery internal BMS ,125 amp MBRF and the T fuse it should be safe
Cheers J.T.

JT, Are you set up to know how each battery is doing, with Bluetooth or some other method)? The setup you have will work well, but if one of the MBRF fuses blow, you may not know it did otherwise. You could add a look at the MBRF fuses during engine checks.

 

[SteveK]

I just got done with my installation this week and decided to fuse all three of the parallel batteries at the battery terminal, before going to the bus bar

Can't hurt. What made you consider doing this. One main overcurrent fuse to protect the main load wire has worked well, at least have not heard otherwise. Would like to hear yours and others reasoning.

 

[J.T kearney]

JT, Are you set up to know how each battery is doing, with Bluetooth or some other method)? The setup you have will work well, but if one of the MBRF fuses blow, you may not know it did otherwise. You could add a look at the MBRF fuses during engine checks.

Helmsman
The epoch batteries each have there own hard wired led display that gives you state of charge and also audio alarm for booth under and over charge. I can also monitor each battery state through blue tooth on my phone. It's quite a leap forward from my old fla bank. I paired it with a Xantrex 2000 marine pro xc with blue tooth to control charge rate voltage, so when away from boat for a while I can drop charge state to 13.4 and when leaving for a trip, bump it up to 14.2.
Cheers J.T.

 

[ksanders]

Can't hurt. What made you consider doing this. One main overcurrent fuse to protect the main load wire has worked well, at least have not heard otherwise. Would like to hear yours and others reasoning.

If a battery has a internal short then fusing each one will interrupt that fault current.

 

[SteveK]

If a battery has a internal short then fusing each one will interrupt that fault current.

Thanks for the reply. Just looking for a reason I would want to do this. Nothing wrong with anticipated protection.
For now I will expect the BMS to shut down/isolate that battery. This feature was not available in our FLA batteries that killed the bank with one cell down.

 

[Helmsman]

Helmsman
The epoch batteries each have there own hard wired led display that gives you state of charge and also audio alarm for booth under and over charge. I can also monitor each battery state through blue tooth on my phone. It's quite a leap forward from my old fla bank. I paired it with a Xantrex 2000 marine pro xc with blue tooth to control charge rate voltage, so when away from boat for a while I can drop charge state to 13.4 and when leaving for a trip, bump it up to 14.2.
Cheers J.T.

Thanks! I like the set up. The ability to remotely drop the charge state is a really nice feature.

 

[Marco Flamingo]

Can't hurt. What made you consider doing this. One main overcurrent fuse to protect the main load wire has worked well, at least have not heard otherwise. Would like to hear yours and others reasoning.

I'm also looking into this. Right now, I have 2 banks with 2 batts each. Both legs are protected with a 250A fuse. If one battery in a bank dropped out for some reason, the other battery (now working as a single) still couldn't put out more than 250A without tripping the fuse.

If working on the premise that the fuse is to protect the wire then, when fusing two batteries in parallel, an MBRF fuse on positive terminal #1 only protects the 9 inches of cable linking it with positive terminal #2. Having a MBRF on terminal #2 only "protects" the 7 inches of cable before the 250A line fuse (Max 7 inches as allowed by ABYC). What am I missing? There is no "load" to fuse against other than somehow a dead short if the cable insulation was breached. Maybe the possibility that an axe gets loose in rough seas?

If the idea is to fuse it at less than the BMS shutoff, to what purpose? Fused individually with a 200A MBRF, the fuse should blow before a 250A BMS cutoff. One could identify this by checking the Bluetooth and seeing either a fault (BMS shutdown) or no in/out current for that battery (MBRF fuse blown). Then the difference is that my BMS will reset in 10 seconds or, if the MBRF has blown, I have to find a fuse, shut down that battery bank, climb into the ER, disconnect the cable from the battery terminal, etc. etc. The MBRF better address a much bigger problem than I can see.

Side note #1. In all my preparation of a schematic of what I have and what changes will be required for going LFP, I realized that I did not make a notation of the wire gauge for the various legs. Fuses I made notes of, but it turns out that wire gauge info throughout the electrical system would be nice.

Side note #2. Here's a question about fusing and wire guage. Say each bank is properly fused on the positive leg based on the cable size. If each positive is fused at 250A, doesn't that mean that the common ground could see sustained 500A? I think my common ground is the same AWG as the positives. Is it possible that the ground wire needs to be sized to handle twice the positive for two bank? Or three times if three banks? I don't think I've ever seen anything about this.

 

[tpbrady]

I have been puzzling over batteries with Bluetooth connections to their BMS. After reading several posts on DIY Solar, apparently more than one app will work with a BMS in some cases and some BMS provide better data to apps than others. I currently have 2 Chins 100AH batteries in an RV and the app, EE-BMS, is pretty poor.

While I view the app connection to a battery as secondary to a battery monitoring system, has any one seen or used a particularly good app and with what battery?

Tom

 

[CharlieO.]

I have been puzzling over batteries with Bluetooth connections to their BMS. After reading several posts on DIY Solar, apparently more than one app will work with a BMS in some cases and some BMS provide better data to apps than others. I currently have 2 Chins 100AH batteries in an RV and the app, EE-BMS, is pretty poor.

While I view the app connection to a battery as secondary to a battery monitoring system, has any one seen or used a particularly good app and with what battery?

Tom

What information would you want from your bluetooth?
I get - state of charge/remaining capacity, total volts, current(amps), power(watts), cell voltage(high, low, average, difference), number of cycles, battery temperature, individual cell voltage.

With the current and power, that tells me whether power is going out(being consumed), or power coming in(charging), I currently only charge with an 18 amp DC2DC charger. So if my current is showing +8 amps I know my load is 10 amps and I am still putting 8 amps into my battery. If it shows -current I know I am consuming more than my charge.

 

[tpbrady]

I get that information if I drill down in the app, but the app is so poorly designed that you have to hop on foot and pat your head to get it. You can only look at one battery at a time and the process of switching batteries is clunky and slow. There is no control of the battery at all and no means of getting notification of problems with the batteries.

I am going to try a couple other apps that supposedly will work with the batteries and provide a different level of information that is easier to get. What I looking for is a battery/app combination that gives me the information on the batteries as a group and lets me know that something is wrong.

Tom

 

[CharlieO.]

I get that information if I drill down in the app, but the app is so poorly designed that you have to hop on foot and pat your head to get it. You can only look at one battery at a time and the process of switching batteries is clunky and slow. There is no control of the battery at all and no means of getting notification of problems with the batteries.

I am going to try a couple other apps that supposedly will work with the batteries and provide a different level of information that is easier to get. What I looking for is a battery/app combination that gives me the information on the batteries as a group and lets me know that something is wrong.

Tom

Yes, I only have a single battery but will be adding another. I believe I will have to toggle between batteries to get the information from each battery individually.