Questions from a non-Marine guy about a Marine System

Horsefly

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Greetings. I'm hoping to get some review and pointers from experts here on an LFP house battery upgrade for a sailboat.

I've been posting here for a bit about off-grid systems. I've got one in a cabin in the mountains of Colorado, and am moving from AGM to LFP. I'm also a retired Electrical Engineer and have a fairly good knowledge of most things electrical. I feel that I'm pretty well versed in off-grid systems, and am now comfortable with LiFePO4.

My sister and her husband have a 42-ft sailboat, and my brother-in-law (BIL) has been bugging me to help him with the house electrical on the boat for a couple of years. Now the house batteries are almost shot and he's decided that he wants to switch his house system to LFP. He has asked me to do most of the engineering and purchasing of parts. I have very little knowledge about sailboats (I get sea sick thinking about it) and their electrical except for what I've learned by visiting the boat in FL and documenting what is there.

The current system includes:
  • Three separate DC (12V) systems: 5 x 100Ah AGM house, 1 x 100Ah AGM starter/engine, and 1 x 100Ah bow thruster (Note: I only know stuff about the house system, as that is what he asked me to look at. I'm unsure how the bow thruster AGM gets charged.)
  • Solar - 2 x Kyocera KC130TM 130W panels ("12V", with a Vmp of 17V), and a Blue Sky 3000i MPPT Solar Charge Controller
  • A Mastervolt 12/80 battery charnger, connected via a transfer switch to either shore power or a Mastervolt 3.2kW diesel generator.
  • A 100A engine alternator with a Balmar ARS-5 "regulator" which I think today we would call a DC-to-DC charger
  • A currently non-functional wind turbine and an old Xantrex C40 charge controller and diversion/dump load.
  • A 1800W (unknown brand) inverter that is off most of the time. The navigation/GPS, radar, fridge, and all lights are 12VDC. The inverter is turned on if they need to run the microwave or charge up the laptop.
  • As far as I can tell, the nav / radar and refrigerator are the biggest loads on the house battery now, and they are not all that big. (He told me their 12VDC current draw, but I can't find it in my notes). He doesn't think the instantaneous draw will ever be over 20-30A.
Where we are leaning right now, after discussing it at length with my BIL (over multiple glasses of wine):
  • Replace the 5 x 100Ah AGM house battery with 4s2p 280Ah LFP (I guess this is more than "leaning" since he has already had me order the 8 280Ah EVE cells from Amy @ Shenzhen Luyaun, and 2 100A JBD BMSs).
  • Replace the two small panels with larger panels, and add two bifacial panels over the davits on the back of the boat. Not sure which panels in either case. This still will not be enough to actually keep the batteries charged, but will help. The SCC will obviously have to be replaced, and maybe with two new MPPTs if the two sets are not well matched (almost certain they won't be).
  • Replace the current wind turbine with one that works.
  • Probably have to replace some items just to be able to handle LFP charge profiles: DC-to-DC charger, SCC(s), AC-to-DC charger (or inverter / charger) and wind charge controller.
There really isn't any budget, and I think they will spend the money to do what is best. My BIL has read enough about Victron that he thinks he'd be fine with an all-Victron system if that is what I recommend.

I'd appreciate any thoughts on what we have, what we are planning, and alternatives. Thanks in advance!
 

wholybee

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Before starting, follow every wire and draw out what is there. There are countless ways to install a multiple battery system, with combiners, isolators, DC-DC chargers, etc. You will need to know how it is currently setup to know how to safely integrate Lifepo4.

The ARS-5 regulator is not a charger, it is a regulator. It adjusts the field voltage of the alternator to control it's output. But, it is a "smart" charger in the sense that it will regulate the alternator to correspond different charging stages like a charger would. The good news for you is that the ARS-5 can be programmed to work with Lifepo4. Alternator systems are one of the more difficult and expensive problems to work out on a boat, and that seems mostly done. However, balmar are quite difficult to program. You will probably need to contact Balmar support for help setting it up for Lifepo4. (noting that you are an electrical engineer *might* help. Check balmars website and download the instructions) Many of the suggestions that you will read about (DC-DC chargers) are solutions to not having an adequate alternator system. A balmar alternator and ARS-5 solve that for you.

If money is no option, replacing the Balmar ARS-5 with a wakespeed ws-500 is a nice upgrade that is much easier to setup. But not a whole lot different once it is setup and working.

You should make sure that the ARS-5 (or wakespeed) has the temp probe option connected to the alternator, So that as the alternator heats up it will reduce output. Lifepo4 can cook alternators. Also, add a sterling alternator protection device. https://www.sterling-power-usa.com/SterlingPower12voltalternatorprotectiondevice.aspx to protect the alternator from damage if the BMS suddenly disconnects.

Confirm that the solar, shore, and wind chargers support Lifepo4 profiles, and replace if they don't. Solar and shore chargers options are plentiful. For wind you might need to add a DC-DC charger if a Lifepo4 charger isn't available.

Another question is BMS selection. Many people (myself included) use a FET based BMS like the Overkill or Daly. Best practice is to use something like the REC BMS with heavy duty relays and separate charge and discharge busses. Part of that is so that the Lifepo4 can be a backup for the engine start battery. Part of it is because of a belief that relays are more robust than FETS. You definitely want a smart BMS that you can monitor cell status with.

If you are completely new to boat electrical, pickup a copy of Boatowner′s Mechanical and Electrical Manual by Nigel Calder.
 

Horsefly

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Wow! Great reply, and very helpful!
Before starting, follow every wire and draw out what is there. There are countless ways to install a multiple battery system, with combiners, isolators, DC-DC chargers, etc. You will need to know how it is currently setup to know how to safely integrate Lifepo4.
Yeah, I'm hoping my BIL can do that. He does understand electrical and has already re-done some of what was on the boat when they bought it 7 years ago.
The ARS-5 regulator is not a charger, it is a regulator. It adjusts the field voltage of the alternator to control it's output. But, it is a "smart" charger in the sense that it will regulate the alternator to correspond different charging stages like a charger would. The good news for you is that the ARS-5 can be programmed to work with Lifepo4. Alternator systems are one of the more difficult and expensive problems to work out on a boat, and that seems mostly done. However, balmar are quite difficult to program. You will probably need to contact Balmar support for help setting it up for Lifepo4. (noting that you are an electrical engineer *might* help. Check balmars website and download the instructions) Many of the suggestions that you will read about (DC-DC chargers) are solutions to not having an adequate alternator system. A balmar alternator and ARS-5 solve that for you.
I already had the manual for the ARS-5. Pages and pages of instructions on using a pen-shaped magnet to turn on and off magnetic reed switches. Yikes! My BIL has already said he doesn't understand how the Balmar alternator and ARS-5 work, but he's willing to stick with it if we can make it work with LFP. Sounds like that is possible, so we just need to study it (and maybe contact Balmar).
If money is no option, replacing the Balmar ARS-5 with a wakespeed ws-500 is a nice upgrade that is much easier to setup. But not a whole lot different once it is setup and working.
I'll look into the wakespeed. Thanks for the pointer.
You should make sure that the ARS-5 (or wakespeed) has the temp probe option connected to the alternator, So that as the alternator heats up it will reduce output. Lifepo4 can cook alternators. Also, add a sterling alternator protection device. https://www.sterling-power-usa.com/SterlingPower12voltalternatorprotectiondevice.aspx to protect the alternator from damage if the BMS suddenly disconnects.
I've not heard my BIL talk about temperature control of the alternator. I'll ask him. The sterling device sounds like a really good thing to have. I was worried what the alternator would do if it went from a heavy load charging the LFP to no load because the BMS went into HVD. Glad to know someone thought of that.
Confirm that the solar, shore, and wind chargers support Lifepo4 profiles, and replace if they don't. Solar and shore chargers options are plentiful. For wind you might need to add a DC-DC charger if a Lifepo4 charger isn't available.
Yeah, that's a problem that we know we have to address. I've already looked at the charger (which runs off of shore and generator) and it will not support LFP, but BIL is keen to replace it. The current SCC is too small anyway, so he knows he needs to get a new one. As for wind... I've tried to talk him out of it, but he thinks it is worth using. The current equipment is a turbine that doesn't actually turn (no kidding) and the Xantrex C40 which may be older than the word "lithium", so he knows he has to replace all of that too. Programmable for LFP charge profiles is key.
Another question is BMS selection. Many people (myself included) use a FET based BMS like the Overkill or Daly. Best practice is to use something like the REC BMS with heavy duty relays and separate charge and discharge busses. Part of that is so that the Lifepo4 can be a backup for the engine start battery. Part of it is because of a belief that relays are more robust than FETS. You definitely want a smart BMS that you can monitor cell status with.
Based on my own positive experience with the Overkill BMS, that's what I recommended him to get. Since Overkill seems to be chronically out of stock, I went to the source and tried to get a JBD BMS, but that seems to be out of stock too. I've looked previously at REC but I'm not sure I can justify the cost.
If you are completely new to boat electrical, pickup a copy of Boatowner′s Mechanical and Electrical Manual by Nigel Calder.
Funny thing: I am certain my BIL has that book, and it is pretty dog-eared. I haven't looked at it, but he clearly has. (y)

Thanks again!
 

Horsefly

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Hey @wholybee - Your great response made me think of another question. I had assumed the Balmar ARS-5 was a DC-to-DC charger, but you said it actually regulates the output of the alternator. In my sister's / BIL's boat they plan to convert the house battery to LFP, but leave the other two as AGM. The two AGM batteries will obviously have a different charging profile than the LFP. So if I program the ARS-5 for LFP (I did skim the manual, and I'm not looking forward to that), what do I do to provide a different charging profile for the lead acid batteries?
 

wholybee

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Hey @wholybee - Your great response made me think of another question. I had assumed the Balmar ARS-5 was a DC-to-DC charger, but you said it actually regulates the output of the alternator. In my sister's / BIL's boat they plan to convert the house battery to LFP, but leave the other two as AGM. The two AGM batteries will obviously have a different charging profile than the LFP. So if I program the ARS-5 for LFP (I did skim the manual, and I'm not looking forward to that), what do I do to provide a different charging profile for the lead acid batteries?
That is the main purpose of a DC-DC charger. To charge from one battery to another when they require different profiles. If the batteries are the same then a simple ACR or combiner switch will work. So the alternator charges one battery, and the DC-DC charger charges the other.
 

Horsefly

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That is the main purpose of a DC-DC charger. To charge from one battery to another when they require different profiles. If the batteries are the same then a simple ACR or combiner switch will work. So the alternator charges one battery, and the DC-DC charger charges the other.
Got. Thanks.
 

Philtao

Sailor, EE & Designer of the TAO BMS
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Another question is BMS selection. Many people (myself included) use a FET based BMS like the Overkill or Daly. Best practice is to use something like the REC BMS with heavy duty relays and separate charge and discharge busses. Part of that is so that the Lifepo4 can be a backup for the engine start battery. Part of it is because of a belief that relays are more robust than FETS. You definitely want a smart BMS that you can monitor cell status with.
Some resources on this Forum...
BMS Comparison chart

Contactor (EMR) or Solid State Relay (SSR)?
 

Horsefly

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Ok, that makes me think of another question for you @wholybee (You are going to wish you hadn't replied in the first place): So since the house battery is the biggest (in Ah) of the three banks, is the assumption that we would use the Balmar to charge the LFP house bank, and use two different DC-to-DC chargers to charge the starter battery and the bow thruster battery? It seems like since the Blamar is set up for the AGMs, it would be easiest to let it stay with one of the two AGMs, and use a DC-to-DC to charge the LFP, but would that be bad because the LFP bank is so much larger than the two single 100Ah banks?
 

wholybee

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You can potentially charge the bank faster if you charge the LFP bank directly from the alternator. You don't work the alternator as hard and reduce risk by charging the LFP through a DC-DC charger. This long and technical article might help answer questions, and probably create even more.
 

Horsefly

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You can potentially charge the bank faster if you charge the LFP bank directly from the alternator. You don't work the alternator as hard and reduce risk by charging the LFP through a DC-DC charger. This long and technical article might help answer questions, and probably create even more.
I did bring up the MarineHowTo article, and recognized it from a couple of years ago when my BIL and I first started talking about doing LFP on their boat. I had completely forgotten about it, so thank you for pointing it out. I need to go read it again now that we're getting serious.

I think your statement kinda supports the idea of using the DC-DC charger to charge the LFP, even though it would take longer. Since my last post I went back and tried again to read the Balmar ARS-5 manual about reprogramming it. This magnet pen thing, and all these magnetic reed switches.... Geesh. I feel like I need to go to Archeology school to understand the hieroglyphs. I know the ARS-5 has been working fine with the AGMs, so maybe that should be left alone.
 

Rocketman

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Another thought on charging different batteries is to add a second alternator (many boat engines can handle two alternators). One for your lithium batteries and the second for the starting and bow thrust batteries.
 

wholybee

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FWIW, my setup is a balmar with ARS-5, connected to the Lead Starting battery, and a DC-DC charger. It limits charging rate to the Lithium, but I have enough solar that alternator charging isn't necessary anyway. That would probably be my last suggestion, spend time and money on more solar. I have 670W of solar and can be off-grid indefinably without other sources of charging. So, my alternator setup really doesn't matter. If I did it again, I might not connect the alternator to the Lithium at all.
 

BobR

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FWIW, my setup is a balmar with ARS-5, connected to the Lead Starting battery, and a DC-DC charger. It limits charging rate to the Lithium, but I have enough solar that alternator charging isn't necessary anyway. That would probably be my last suggestion, spend time and money on more solar. I have 670W of solar and can be off-grid indefinably without other sources of charging. So, my alternator setup really doesn't matter. If I did it again, I might not connect the alternator to the Lithium at all.
This is a little off topic but since I am installing solar on my new boat I was wondering if you could tell what your electrical load consists of and your house bank size and anything else you think is relevant and you are willing to share.
I am shifting from sailboat to power boat. Thanks.
 

wholybee

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This is a little off topic but since I am installing solar on my new boat I was wondering if you could tell what your electrical load consists of and your house bank size and anything else you think is relevant and you are willing to share.
I am shifting from sailboat to power boat. Thanks.
I don't have a huge load. All my navigation stuff, a laptop, and a 12V cooler/fridge. No watermaker, and no autopilot which are both large loads. I use about 100-150Ah per day. I have a 300Ah Lithium, so I can go several days with reduced solar output. Prior to upgrading to Lithium, I had 230Ah of Lead, and was abusing them by taking them down to 50% everyday, and much lower than that on occasion.
 

Horsefly

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FWIW, my setup is a balmar with ARS-5, connected to the Lead Starting battery, and a DC-DC charger. It limits charging rate to the Lithium, but I have enough solar that alternator charging isn't necessary anyway. That would probably be my last suggestion, spend time and money on more solar. I have 670W of solar and can be off-grid indefinably without other sources of charging. So, my alternator setup really doesn't matter. If I did it again, I might not connect the alternator to the Lithium at all.
Maybe that works for my BIL too. He's going to replace the two 130W panels with larger ones, and he wants to mount a couple of bifacials off the davits on the back of the boat. I'm not sure how big any of these will be, but I know he doesn't have lots of room. 670W certainly seems possible.
 

wholybee

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Maybe that works for my BIL too. He's going to replace the two 130W panels with larger ones, and he wants to mount a couple of bifacials off the davits on the back of the boat. I'm not sure how big any of these will be, but I know he doesn't have lots of room. 670W certainly seems possible.
My boat is 38', and I don't have any panels on my bimini. I think that is a bad location due to shade, and I like to be able to take it down.
I am a fan of having panels on the lifelines, sticking out the side with sticks to hold them up. I just hold them on with zip ties. They are out of the way and one side of the boat will almost always have good sun. They work surprisingly well while sailing. I leave them out in up to about 30kts of wind. More than that I remove the sticks and tie them down. Best to have each side on a separate controller, so if one side gets shade it doesn't affect the other side. Then, a 3rd controller for all the other panels on the bimini, davits, deck etc.
 

Horsefly

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My boat is 38', and I don't have any panels on my bimini. I think that is a bad location due to shade, and I like to be able to take it down.
I am a fan of having panels on the lifelines, sticking out the side with sticks to hold them up. I just hold them on with zip ties. They are out of the way and one side of the boat will almost always have good sun. They work surprisingly well while sailing. I leave them out in up to about 30kts of wind. More than that I remove the sticks and tie them down. Best to have each side on a separate controller, so if one side gets shade it doesn't affect the other side. Then, a 3rd controller for all the other panels on the bimini, davits, deck etc.
Not to be too nosey, but would you happen to have any pics of the panels mounted that way? It may make sense to my BIL, but I'm having trouble visualizing.
 
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