Lithium House with AGM Start and Windlass

[dwilkieo]

Hello All. I am adding solar to my Nordic Tug 32 and contemplating Lithium for the house bank. Everything is 12 volt. I am a neophyte at this.

Right now -- I have three separate battery banks. A 440 AH AGM (four 6 volt batts series to parallel) house bank, a 4D AGM start battery and 220 AH AGM bank for windlass and bow thruster.

I have a Cummins stock alternator, which I think is about 105 amps or so. It goes to a battery combiner to charge all three banks.

I would like to swap out my house bank for 400 AH of lithium.

My concern is can I still charge all three banks through the combiner with the stock alternator, or the on board 20 Amp shore power charger. Do I need special equipment and or is this something that is available?

What questions should I ask instead of these?

David

 

[DavidM]

In your current setup, all three battery banks are of the same type, AGMs that have the same charging parameters, so they coexist just fine. I am a little puzzled that you say all three batteries are charged through a combiner. I suspect it is an isolator, so it does have voltage drops through the diodes which limits charging. If it is a three battery combiner which typically doesn't have diode voltage drops, could you tell us the model?

I am a little puzzled by why you would change to lithiums, particularly since you don't have a very robust charging system: a stock Cummins alternator and a 20A shore power charger. Do you plan to upgrade them?

David

 

[Bacchus]

You didn't mention what makes up the windlass bank and if any are end of life and need replacing. Also assume you have a gen with its own start as a back-up?
You might consider combining eng start w thruster / windlass. I recently combined start w windlass with the thinking that start needs short and once eng running alternator supplements the need for windlass / thruster needs.
I know little about Li as I'm not considering them but wonder if alt charging start / windlass & a DC to DC tuned to charge house would work.
If AGM house are still usable and windlass thruster is also a pair of AGM GCs why not just combine for a larger bank as use for start.
AGMs perform well for both start & deep cycle needs but in your case it would be primarily a hi amp short to med duration for the combined bank.

 

[Jeff F]

Solar can be hooked up to the house bank without messing with anything else.

What are you hoping to gain with Lithium? Not arguing against it, but as DavidM points out, other significant changes would have to be made to take advantage of the possible benefits.

 

[Pau Hana]

In your current setup, all three battery banks are of the same type, AGMs that have the same charging parameters, so they coexist just fine. I am a little puzzled that you say all three batteries are charged through a combiner. I suspect it is an isolator, so it does have voltage drops through the diodes which limits charging. If it is a three battery combiner which typically doesn't have diode voltage drops, could you tell us the model?

I am a little puzzled by why you would change to lithiums, particularly since you don't have a very robust charging system: a stock Cummins alternator and a 20A shore power charger. Do you plan to upgrade them?

David

Solar can be hooked up to the house bank without messing with anything else.

What are you hoping to gain with Lithium? Not arguing against it, but as DavidM points out, other significant changes would have to be made to take advantage of the possible benefits.

Winners!

Steve, LiFePo4 is not a drop in technology. A proper install would entail a revamp of the charging system (alternator(s), chargers, and wiring) to take advantage of the charging requirements for the lithium bank. Your current setup is not sufficient.

We made the change last year, from 600aH of AGM to 600aH of lithium for the house bank. The start bank remains 1 8D per engine. Along with the batteries, the following changes were made:

• removal of the house bank (40A) and start bank (20A) chargers, and a 2000W standalone inverter. All were replaced with a Victron Quattro inverter/charger feeding only the house bank. A Victron DC-DC charger feeds the start bank from the house bank. shorepower AC and the generator output feed into the Quattro.
• removal of the stock 55A alternators, replaced with 2 Lee-Niceville 105A externally regulated alternators, controlled by Wakespeed WS500 regulators. The alternators feed the house bank.
• installation of the Victron Lynx distribution system to manage the house bank and feed DC to the Quattro.
• all DC wiring replaced, properly sized, lugged, and fused.
  
  There a whole lot more to it, and i plan on posting a complete description with photos shortly. One major benefit is that we no longer worry about transferring loads (shorepower to genset), as the Quattro does it all automatically. Also, using the Victron Cerrbo GX, I can monitor/manage my power systems from anywhere in the world.
  
  So, plan your install, then execute.
  

 

[C lectric]

Different battery types require different voltages so the Li and AGM may not play well. One may end up undercharged and the other overcharged causing poor performance and shortened life. There are usually ways around that but you need to factor that in. It is not just dump a different battery type into place and away you go.

One of them will suffer unless you make some changes in your charging setup.

DavidM raises a good point about your "Combiner" .
Take a good photo of it and post it here. Also copy the Model name and number and mfgr name and post that.

If as DM wonders it is a diode isolator then that can account for a substantial reduction in charging unless your alternator has a remote sensing wire attached at the battery that will override the normal internal regulator control.

What is the alternator? Same deal with the model, rating, mfgr.

Same cautions stand for the 120V charger.

And no I am not an expert but have to a degree dug into this enough to understand many of the cautions.

Before I forget what is the engine HP rating, the Model and year built. I assume a Cummins but is it?

 

[Simi 60]

Absolutely loving the LFP upgrade we did
Absolute game changer, soooooooo much better than AGM and cost considerably less money (some assembly required)

 

[catalinajack]

Absolutely loving the LFP upgrade we did
Absolute game changer, soooooooo much better than AGM and cost considerably less money (some assembly required)

Simi, your cost savings experience is because you live in Oz. Cost comparison is much different in North America.

 

[Simi 60]

Simi, your cost savings experience is because you live in Oz. Cost comparison is much different in North America.

Not sure about that
Most everything in Oz is more expensive than US
And I paid for the LFP in usd
1 Oz peso = 0.71 usd.

 

[mvweebles]

There are benefits to running LiFePO4 beyond ability to accept higher charge rates. Weight, depth of discharge and lifespan being a few.

Assuming the OPs current setup works fine, the simplest swap would be a 12v DC-DC charger inline on cable to LiFePO4 house bank. This will groom the voltage and regulate the charge current. Challenge is the largest DC-DC charger I could quickly find is 40 amps. Still not bad since it will be a consistent 35+ amps which is likely more than the AGMs would consistently accept.

A better but more complicated and expensive option is to run the main charge feed to the house bank, then charge the start/thruster batteries with a smaller DC-DC. Challenge is the charger and the alternator would need to be configured for LiFePO4 battery voltage.

Personally, I'd go with the larger DC-DC charger described in first scenario above. When time comes to replace your inverter/charger, might take the opportunity then to reconfigure alternator to charge house bank.

BTW - I've seen some favorable reviews on these 200 ah batteries. $1031 each.

https://www.us.sokbattery.com/produ...yWUB_kUyINR6XOzXjOuhCJ8o1q7dVKeYaAjGAEALw_wcB

Peter.

 

[FF]

Unless all the virtues of lithium are worth the expense to your cruising style , you may find that "messing around in boats" has become "adventures in battery electronics".

There are multiple ways to have a simple/reliable great cruising setup, not sure lithium is in the mix.

 

[Iggy]

Winners!

Steve, LiFePo4 is not a drop in technology. A proper install would entail a revamp of the charging system (alternator(s), chargers, and wiring) to take advantage of the charging requirements for the lithium bank. Your current setup is not sufficient.

We made the change last year, from 600aH of AGM to 600aH of lithium for the house bank. The start bank remains 1 8D per engine. Along with the batteries, the following changes were made:

• removal of the house bank (40A) and start bank (20A) chargers, and a 2000W standalone inverter. All were replaced with a Victron Quattro inverter/charger feeding only the house bank. A Victron DC-DC charger feeds the start bank from the house bank. shorepower AC and the generator output feed into the Quattro.
• removal of the stock 55A alternators, replaced with 2 Lee-Niceville 105A externally regulated alternators, controlled by Wakespeed WS500 regulators. The alternators feed the house bank.
• installation of the Victron Lynx distribution system to manage the house bank and feed DC to the Quattro.
• all DC wiring replaced, properly sized, lugged, and fused.
  
  There a whole lot more to it, and i plan on posting a complete description with photos shortly. One major benefit is that we no longer worry about transferring loads (shorepower to genset), as the Quattro does it all automatically. Also, using the Victron Cerrbo GX, I can monitor/manage my power systems from anywhere in the world.
  
  So, plan your install, then execute.
  

Yep, to the above.

I to am changing over as soon as spring hits. Too cold out right now! I have been reading and talking to the manufacturer that I am buying from.

You may want to upgrade ALT and install a temp sensor. Just in case it over heats. Its cheap insurance!

I am approaching it by separating the Li house bank from the starting bank. By removing the combiner and adding A DC to DC charger from the starting bank to the Li house bank. So the ALT and on-board charger can remain the same. In other words, there charging profiles.

The DC to DC charger can be set up to the new house bank. Once the DC to DC charger seances charging voltage it turns on charging the new house bank. As a VSR or a combiner would.

But the other very important thing is that any set up must meet ABYC standards. Good forbid there is a Ins. claim, the install must be done properly.

 

[mvweebles]

Unless all the virtues of lithium are worth the expense to your cruising style , you may find that "messing around in boats" has become "adventures in battery electronics".

There are multiple ways to have a simple/reliable great cruising setup, not sure lithium is in the mix.

I am in process of converting on my boat (725 AH LFP; 800W solar; 225A Balmar alternator) so do not have that data, but I converted my pop-top camper van last spring and love it - size of the system is roughly similar to what OP is considering. I had two FLA 6v golf cart batteries for 225AH of capacity that I replaced with two 110AH LFP batteries. To convert the alternator output, I added a DC-DC charger, though in my case, the DC-DC charger is also an MPPT controller and accepts solar input as well (I have 320W of solar on my van). The DC-DC/MPPT pushes up to 25A of solar plus 25A of alternator current for a peak of 50A, though realistically seems to top-out at around 30A-35A.

What a difference compared to FLA. Because the discharge rate on LFP is so much higher than FLA/AGM, I can use an electric tea kettle to heat water, cook with an Instant Pot (2-hour pot of stew consumed about 25AH of energy total), cook with an Induction Hob, run microwave, even run a small window-mount A/C for a couple hours. None of these were consistently feasible with the FLA battery setup I had without tripping low-voltage - maybe the 2x capacity the OP has would be feasible (certainly I have run a microwave off that capacity, but a no-brainer with LFP), but there is much to be said for LFP technology.

Yes, the upfront costs are high for LFP batteries. And you still have to replenish the energy somehow so charging is important. But what a convenience. I'm a buyer/advocate for those who can afford it.

Peter

 

[Pau Hana]

Yep, to the above.

I to am changing over as soon as spring hits. Too cold out right now! I have been reading and talking to the manufacturer that I am buying from.

You may want to upgrade ALT and install a temp sensor. Just in case it over heats. Its cheap insurance!

I am approaching it by separating the Li house bank from the starting bank. By removing the combiner and adding A DC to DC charger from the starting bank to the Li house bank. So the ALT and on-board charger can remain the same. In other words, there charging profiles.

The DC to DC charger can be set up to the new house bank. Once the DC to DC charger seances charging voltage it turns on charging the new house bank. As a VSR or a combiner would.

But the other very important thing is that any set up must meet ABYC standards. Good forbid there is a Ins. claim, the install must be done properly.

Our Wakespeed external regulators include a temp sensor as well as some other cool programming features. I elected to install a Sterling APD (alternator protection device) to protect the alternators from a voltage spike if the battery BMS shuts down the charging process. Some use a FLA battery- I chose the APD because I wanted the fully utilize the charging parameters of the LFP (LFP can be charged at 50% of the banks aH size).

That is als the reason to use a DC-DC charger to maintain the start banks.

 

[Iggy]

Our Wakespeed external regulators include a temp sensor as well as some other cool programming features. I elected to install a Sterling APD (alternator protection device) to protect the alternators from a voltage spike if the battery BMS shuts down the charging process. Some use a FLA battery- I chose the APD because I wanted the fully utilize the charging parameters of the LFP (LFP can be charged at 50% of the banks aH size).

That is als the reason to use a DC-DC charger to maintain the start banks.

As they say, to each there own. There is more than one why to do things.

I wanted to make this as simple and safe as possible. Thats why I did not want the Li on the ALT side of things. If the BMS shuts down on the house side it would not affect the ALT. Also, if the BMS did shut down I could turn two switches and be on the starting bank until it resets itself or I fix the problem. I don't want to be without lighting or my electronics. Keep in mind, if this did happen the ALT would keep charging the starting bank. My boat could keep going to get me home.


This is unlikely, but it meets ABYC standards to have a 2nd source.

Now there is more to this in keeping both banks charged.

 

[dwilkieo]

Thanks to all for steering me in the right direction. I am out of town until Weds, but will research and update system info for those trying to help me.

One thing to say: This is my last boat and I have zero other vices, so I am prepared to spend a fair sum of money to get exactly what I want, which is more days on anchor without running the boat. I mostly move around from anchorage to anchorage on my typical trips, which keeps my batteries charged from the engine alternator..... but I want the option to stay put and still have the power to enjoy my boat.

I have a Cummins 6BTA at 270 HP. It has a Delco Remy 105 amp alternator. I just bought a Victron 712 battery monitor, and will build a table of battery usage to work with, but I already have a fair idea of typical daily usage needs.

All three of my banks are Lifeline AGMs purchase SIX years ago. None of them have ever been even close to being flattened or even stressed, and only the house bank has been taken down as far as 12.5 volts. Thought I would add another 220 AH to the house bank, but Lifeline techs told me my new batteries would instantly degrade to match the old ones.... I haven't ruled that out, though - pretty cost effective from where I am right now.

My wife has a small RV with 300 watts of solar panels and 200 AH of Lithium. It works really great and I am impressed with the Lithium technology -- being able to run it way down without damage. Switching my 440 AH AGM house bank to 400 AH of Lithium would appear to conservatively net me another 200 +/- AH from a similar sized bank -- yes, I know I'm spending some boat bucks here.

More later.... lots to read and asimilate. Thanks ago for all the good stuff.

David

 

[Mischief Managed]

You could keep the AGMs and run a 100AH 48V (same capacity as a 400AH 12V) LFP through a couple of 100/75, 12V MPPTs to do DC to DC charging of the 12V bank from the 48V LFP. You could then charge the 48V LFP with solar (and a 120VAC 48V charger as a backup).



The boat would still operate on 12V, but the LFP battery would keep the AGMs topped up until the LFP is dead, then you's still have 200AH @12V of AGM power available. This way you basically triple your house capacity for less money than you were going to pay to double it. The only caveat is that you need to find room to add the LFP battery, but since it cannot reside in the engine room due to the temperature, this might be a plus, assuming the AGMs are in the engine room.



By using a 48V LFP instead of 12V, your cables from the solar panels to the solar controllers to the LFP, and the cables from the LFP to the MPPT controllers used as DC to DC 12V chargers can be very small.


When you are charging your 12V AGM bank with your engine and they reach absorption phase, turn on the inverter and power up the 120VAC 48V charger to top up the LFPs (if the sun has not already taken care of that for you).

 

[Southern Boater]

Not sure about that
Most everything in Oz is more expensive than US
And I paid for the LFP in usd
1 Oz peso = 0.71 usd.

I often do comparison/conversion from USD to AUD when costs are mentioned on the forum, and the prices are definitely lower in the US.

 

[Patrick4002]

i have a different setup but every system has his pro en cons.
we live aboard and need a lot of elektricity

the main service bank is 24v 650ah full traction
pro : very stable and last +10 jears
con : very heavy 700kg and need a special air extraction on top of the pack
charge to 32v so it has his own charger and mmpt bank
the 3400wp solar system is only to this bank connected with 3 mppt and a control box to sync the mppt units
most electronics cant handel the 32v so there is a 24v/24v invertor to stabelase the 24v for electronics
the main use is to convert to 220v 8000w (victron can use 22v to 33v)

the 2de service bank is 2x 240Ah 12v semi-traction batterys
pro cheap, eaxy to load, most electronics can connect to it directly
con when used hard they only last 4 years
i use this bank only for electronics on 12v, lightning, and the build in bow truster (i woud prefer a 24v bow thruster but it was before the 24v upgrade installed by the builder)
then i have a 12v 240ah for starting the motors and a 12v 80ah for starting the alternator

the 12v batterys are charged form the invertor 220v out of the 24v service bat
(if needed) and the loader take care of the daily use or they are charged from the motors

in the winter i need shore power, from end feb till end nov i only need the solar power and we use a 7kwh daily most of the day

the shore power cost is with this system reduced to between 1/3 and 1/4 so the turnover investment point was 1 year and 7 months (i did 90% of the work myself)

the turnover point was so quik due the high shore elek. cost and the high volume of elek used. and i could by my main service pack very cheap (industrial batterys)

 

[Bob M]

1) If cost wasn't a consideration, I'd go with lithium.

2) If I didn't have the bucks but had the space, am able to check battery electrolyte level at least once a month and the batteries are easily accessible, I'd go with lead acid.


3) If I was willing to double the expense of lead acid, had the space and didn't want to mess with battery fluid levels, I'd go with AGM.

 

[Patrick4002]

only on industrial full traction you can have a aqua-auto-fill option, each cell then has a floting valve to fille the water level up when charging in the equlization state of the loading process.

Always check the level regular if it is to low your cell plates can bend, or oxydise so you lose capacity of the cell.

Lithium is great but still expencive

one thing with gel batterys is that they need a rest period of a few hours after charging, most manufactures forget to mention that, if you use your gel battery without settelilng time after loading it effect there lifespan and storing capacity.

the easy battery setup are still lead acid simi traction batterys

 

[stevemitchell]

I would highly recommend consulting a marine electrician who has expertise in this area. That can be hard to find, as most electricians I've worked with still believe LiFePO4 aren't worth the investment, or have issues understanding the technology.

I've had 3 boats which I've converted to LiFePO4, and am in the process of doing the same on the new boat. I've also provided hundreds of designs for other folks moving to LiFePO4, and in all cases a good survey of what you're trying to do, and specifically looking at your charging systems is essential to making sure you get the most out of your investment.

There are more choices when it comes to the battery side of things, and I am a proponent of both drop-in and non-drop-in solutions depending on budget and goals. Even with drop-in solutions, you can see benefits without changing your charging system, but they will not be as extensive.

 

[Capt Dan]

"ssuming the OPs current setup works fine, the simplest swap would be a 12v DC-DC charger inline on cable to LiFePO4 house bank. This will groom the voltage and regulate the charge current. Challenge is the largest DC-DC charger I could quickly find is 40 amps. Still not bad since it will be a consistent 35+ amps which is likely more than the AGMs would consistently accept.

Research claims you can parallel DC to DC chargers.

My understanding is that it's best to have order of 1-regulated alternator (including temp sensors on alternator and battery), the lead acid type battery, then baby, then LiFePo. Lead acid is a fail-safe place for alternator to send charge in case lithium shuts down.

Of course it also matters your priorities, which bank do you want to charge first. B2B only charges through B2B after first bank is charged.

You definitely need to upgrade to external regulation on a well designed alternator, there are some real dinosaurs out there and the work poorly on any deep cycle, especially AGM and Lithium.

 

[Pau Hana]

"ssuming the OPs current setup works fine, the simplest swap would be a 12v DC-DC charger inline on cable to LiFePO4 house bank. This will groom the voltage and regulate the charge current. Challenge is the largest DC-DC charger I could quickly find is 40 amps. Still not bad since it will be a consistent 35+ amps which is likely more than the AGMs would consistently accept.

Research claims you can parallel DC to DC chargers.

My understanding is that it's best to have order of 1-regulated alternator (including temp sensors on alternator and battery), the lead acid type battery, then baby, then LiFePo. Lead acid is a fail-safe place for alternator to send charge in case lithium shuts down.

Of course it also matters your priorities, which bank do you want to charge first. B2B only charges through B2B after first bank is charged.

You definitely need to upgrade to external regulation on a well designed alternator, there are some real dinosaurs out there and the work poorly on any deep cycle, especially AGM and Lithium.

The fact that LFP can take a large charge input is the reason I chose to use a DC-DC charger from the LFP to the house bank. Having the ability to throw 200-300 amps at the house bank for a quick recharge simply made more sense- especially if the runtimes of the genset or mains is relatively short.

 

[BruceK]

I often do comparison/conversion from USD to AUD when costs are mentioned on the forum, and the prices are definitely lower in the US.

I know someone who bought Australian made(and exported) Ronstan sailboat traveller parts from USA. Even including freight, it was cheaper than buying locally. True, "the little Aussie bleeder"(the AUD) exchange rate was better (for us) back then.