My LiFePO4 Installation Plan

[sailorboy1]

I have 4 100aH "drop in" LFP batteries waiting to install. This is my installation plans for them:

The batteries say charge 14.4V +/- 0.2. The specs say 20 amp charge to max of 100 amp. They will all be a single parallel house bank.

I have a 100 amp Balamar with ARS-5 external regulator. I have it belt reduced to B3 and it normally puts about 75 amps net into the house batteries currently. It also has a temp sensor for the alternator. I plan to use 14.2V bulk with time of 6 min, a absorption of 13.6V with 6 minutes and a float of 13.4. Once I acturally get the LFP batteries I may reduce the absorption depending on their resting voltage. I am thinking to maybe reduce the bulk to 13.8-14.0V because I am concerned about charging to 90-95% and not burning us the alternator than I am about getting 100%.

The alternator feeds the house and start battery via a FET. Right now the house and alternator cable are on supply lug and the house can feed the start, but the start can not feed the house. I think I may change and make it so the house doesn't feed the start because it will end up always floating the start sealed battery. But the start battery with be a dump load if all the LFPs were to disconnect.

I have a 70 amp "smart" charger. It doesn't have a lithium setting but figure I can use the Gel or something to what is close to less that 14.4 setting. I would not be having this always on and only when I am running the generator because I need to charge.

I have 640W solar and an Outback controller that can be programed for anything. So can set the absorption voltage, time etc.

I have a BMS battery monitor to track the SOC etc.

I don't really see a need to change/add any equipment (maybe add an alternator protector) and I can make the change over from my acid batteries by adjusting the setpoint programing of the items.

Comments?

[wholybee]

I would drop the bulk voltage to 13.8V to start with, and I think you will find that gets you over 90% charge. Your absorption and float are probably ok where they are. Since PSOC isn't an issue with LFP, it's more important that you don't overcharge when motoring with an already full battery, than it is to charge it. So, I prefer to be very conservative with the alternator settings.

Check the parameters on your 70A charger carefully. The 14.4V isn't the issue, it is going to be the absorption time, and the float voltage. LFP need little to no absorption time, and even if the voltage is correct, can be over-charged with to long of an absorption phase. Same with float. Technically, LFP want NO float time, but because chargers have that setting it gets set really low, so the charger is effectively off.

Watch it very carefully after you install it, and if unsure, manually turn of charging. What you want to see is the LFP charge to whatever %SOC (90% is good) and then turn off and stop charging. If the charger changes stage, and current is still flowing into the battery, just a smaller current, then make an adjustment. In the case of solar, when bulk is done, you should see no current flowing into the battery, but solar will still produce some power in float and power the loads on the boat.

In all likelihood, if you watch it very carefully, you will find it just works fine. LFP is a heck of a lot simpler than L-A. It's just different so people get worked up over it.

Also, what are you using for an SOC meter? The built in BMS SOC meters need to cycle a few times to "learn" before they are accurate. And then, they will register 100% SOC as the top of where you charge it. So, that can lead to some confusion, if you are trying to keep the battery at < 90%. A victron BMV is a much better option.

[smac999]

if the batteries are passive balanced you need to fully charge them often to balance. charging at 14v and never full is actually a bad thing. some need to hold absorb for an hour to do that.

charging to 100% and then comsuming power from them is not bad for them. charging to 100% and leaving them there forever is.

[Pete7]

SB, sounds like a good plan. I think you will be surprised how quickly these batteries charge up compared to lead acid which is great if you have to use the generator.

Pete

[sailorboy1]

I don't really expect much improvement in the speed of charging. I get max out of the battery charger now till around 85% and would probably turn it off at about the same point once I start using the LFP. I am using a Honda generator and wouldn't really want a bigger charger as it really would make that Hinda scream.

On a long motor it doesn't really matter. And for the most part on a short to min length one my acid batteries accept all the charger can do till they are about 85%. So a shorter motor time will get the LFP to 100%, but that has danger with it.

Solar will be more effective toward the end I expect.

My big gain I hope is to truly not have to ever deal with PSOC again and to get a better voltage curve over the usable capacity range

[sailorboy1]

Originally Posted by smac999

if the batteries are passive balanced you need to fully charge them often to balance. charging at 14v and never full is actually a bad thing. some need to hold absorb for an hour to do that.

I currently plan to handle that via solar and just change the setting once in a while. Maybe monthly, to do it.

I am hoping to leave for the Bahamas soon and mainly need to have the equipment needs sorted out before then.

[sailorboy1]

Originally Posted by wholybee

Also, what are you using for an SOC meter? .......... A victron BMV is a much better option.

I have a Victron BM

[Jenta]

If you have “drop in” LifePo4s that have their own internal BMS on each pack, you will definitely want to do full charges at least once in a while to keep them at a nice balance. Many BMS units with cell balancing won’t even start to balance until a cell is over 3.5 (14v) and they will need more than 6 minutes to do that.

As for float, all my research has landed me on accepting that floating them at 3.35 per cell (13.4) is not an issue. If I was not using any power on the boat (storage) I would drop that. But since while using the boat I am always drawing power, the cells will not overcharge and if I turn on the coffeemaker in the middle of the day my solar provides that power instead of the battery bank that way. (ideally)

Less cycles of the batteries.

I think the whole keeping it in the shoulders idea started as an exercise in playing it safe to not go into some sort of runaway situation. With the proper and decent monitoring available that is readily avoidable. As for being hard on the batteries, I also believe that is a bit of an overreaction. When you talk to the techs and engineers instead of the sales and marketing, most times it seems they recommend full cycles now and then at least.

As I understand it, if a LifePo4 has a rating of 3000 cycles that doesn’t mean it is then dead. It means it will have a reduced storage capacity. So maybe after 3000 full cycles, a 300 AH battery will only store 270 AH or whatever. In that case simply scale your capacity 10% higher and you bought yourself 1000’s of extra cycles at your needed capacity.

I do think your hardware and setup sounds good though.
However, you might consider spending the money you might spend on an alternator protect circuit on a spare alternator instead. The likelihood of all 4 batteries disconnecting at once seems minuscule and a spare alternator a better investment. But that is just an opinion of course.

I did a 24v house bank of LifePo4 and am LOVING the difference it makes for us. But I’m an IT guy still working and love gizmos and gadgets and we have 3 reefers plus 1 chest freezer as needed and a performance Starlink (ie power hungry) on top of all the regular stuff all sucking power. I have 1620w of solar but that won’t keep up with our consumption, only offset it. Instead, I fire up my generator once or twice a week and top off the bank which is good for the bank and also good for the generator. All the charging parameters for the Victron Quattro and the solar is managed by the REC-BMS directly. It is fast because I can dump 4.8kw into the 28kwh bank and burn less than 3 gallons to get from 0 to 100% if I ever needed to. My alternators only feed the single 12v AGM I have for engines and generator start. The rest of the 12v on the boat comes from my 24v bank converted. So far, it definitively lives up to that cliche “game changer” and with some thought to design as you are currently doing, I think you will be VERY pleased.

[CaptainRivet]

Originally Posted by smac999

if the batteries are passive balanced you need to fully charge them often to balance. charging at 14v and never full is actually a bad thing. some need to hold absorb for an hour to do that.

charging to 100% and then comsuming power from them is not bad for them. charging to 100% and leaving them there forever is.

Absolutely correct. Not charging your drop in till 100% =given voltage by your manufacturer (which is 14,6V or 3,65V per cell I believe) will cause in an imbalance and one cell will be limiting total voltage reached or even get a runner and destroy the battery.
Your drop in has a cheap BMS that only starts passive balancing at 3,5V with most likely 100mA, that’s typical for these BMS and if nowhere given precise information what it is really this is your best guess.

So that these will live a long life you Need a different charge strategy.
Charge daily or as often possible to 100%, so the balancer can work. So put your charge sources at 14.6V end of charge First, your drop in will cut off earlier, when just post here so we can help.
So the balancer gets more time to work you need to use adsorption, how long and from where is what you need to figure out by testing as this depends on your total system. I would start putting absorption to 3,45V and 1h, that slows to top end part down and give the balancers more time to work. Too long absorption can overcharge your battery too but 1h should be ok for the start.
@jenta:No float, that kills your LFP as floating them over hours can overcharge them, look at Nordkyn design. Float has no advantage in LFP, don‘t use it as it can only cause damage but does nothing valuable to a LFP. If you wanna give them more time to balance use a longer absorption time, voltage set to 0,5V below thereshold where you BMS passive balancing starts.

Your Smart shore power charger on gel is not ok for the LFP, used really seldom during bulk will be ok but a bit more then seldom will damage your drop in.

As smac Said charge them to 100% and let them sit there for eg 5h them is not damaging them, in your case that’s even good as more time to balance but keeping them at 100% for weeks does damage.
Forget trying to keep them at classic LFP rule 80/20 and thinking you will enhance their live, you will do the opposite damage them quickly as they get out of balance. That exactly what happens to solar support, his drop in only got to 13,9V and he cut it open to get to each cell individually to get it top balanced.

[sailorboy1]

You can see in these threads what turns people away from LFP (it did me 2.5 years ago). It is made so complex and confusing sounding and then you toss in all the different advices, So in end it sounds hard and then isn't a simple answer and people just go with want they know.

But is is simple really. Set charge sources to avoid overcharging and don't worry about it so much. I am only 5 days in so time will tell,

[Scubaseas]

If I could add a few things you might want to consider. Depending on the age of your AR5 it may have a set temp on the alternator at 108*C or around 226*F. Later than I think 2015? ones you can adjust the temperature. I don't know which Balmar alternator you have but the earlier ones were not really heat tolerant. Unless it's the newer dual fan XT model you might want to add a resistor or get an adjustable temp regulator like the MC618 where both temperature and output or belt load can be programmed along with having LiFePo4 profiles already installed. The AR5 is a great but pretty stupid regulator. Balmar also does not recommend using an AR5 on a lithium bank. If you set the program to AGM or Optima you'll be closer to what the lithium profile looks like. If you're worried about burning up your alternator I'd replace the regulator with one specifically made to accept LiFePo4 profiles or at least carry a spare alternator prior to leaving for the Out Islands.

I had a long chat with Rod at MarineHowTo just prior to his stroke and he recommended not running any alternator on a LiFePo4 bank at more than 50% capacity if you want it to last. I am currently using a Balmar XT 170 amp deregulated to 100 amps and it seems to work fine, runs cool enough and charges my 400AH LiFePo4 very quickly.

If using the AR5 you might want to program it to "small engine" to limit output by 50%.

Reroute or add an engine blower to remove heat directly from the alternator. I did this on my last two boats and it really helps with the alternator temps. Especially if you have an AT Balmar. My Pearson's alternator on a MD2 Volvo runs about 10*F to 15*F cooler with the engine room blower running where the inlet hose is directly above the alternator.

I would install an alternator protector. Small price for good insurance.

Good luck. You'll love lithium. Charges quickly, has steady voltage. Only down side is it can cut out suddenly. I put in two banks on my new to me boat. A House bank of 400AH and a separate 200AH bank dedicated to the autopilot and critical instruments. Both banks can be monitored via Blue Tooth or by a battery monitor gauge. So far it all works great.

[SV Confianza]

Originally Posted by Jenta

As I understand it, if a LifePo4 has a rating of 3000 cycles that doesn’t mean it is then dead. It means it will have a reduced storage capacity. So maybe after 3000 full cycles, a 300 AH battery will only store 270 AH or whatever. In that case simply scale your capacity 10% higher and you bought yourself 1000’s of extra cycles at your needed capacity.

One correction here. LFP batteries have a big drop off after their cycle life. There’s a cliff in the graph of amp hour rating sometime after (hopefully) their cycle life.

[sailorboy1]

Originally Posted by Scubaseas

If I could add a few things you might want to consider. Depending on the age of your AR5 it may have a set temp on the alternator at 108*C or around 226*F. Later than I think 2015? ones you can adjust the temperature. I don't know which Balmar alternator you have but the earlier ones were not really heat tolerant. Unless it's the newer dual fan XT model you might want to add a resistor or get an adjustable temp regulator like the MC618 where both temperature and output or belt load can be programmed along with having LiFePo4 profiles already installed. The AR5 is a great but pretty stupid regulator. Balmar also does not recommend using an AR5 on a lithium bank. If you set the program to AGM or Optima you'll be closer to what the lithium profile looks like. If you're worried about burning up your alternator I'd replace the regulator with one specifically made to accept LiFePo4 profiles or at least carry a spare alternator prior to leaving for the Out Islands.

I had a long chat with Rod at MarineHowTo just prior to his stroke and he recommended not running any alternator on a LiFePo4 bank at more than 50% capacity if you want it to last. I am currently using a Balmar XT 170 amp deregulated to 100 amps and it seems to work fine, runs cool enough and charges my 400AH LiFePo4 very quickly.

If using the AR5 you might want to program it to "small engine" to limit output by 50%.

Reroute or add an engine blower to remove heat directly from the alternator. I did this on my last two boats and it really helps with the alternator temps. Especially if you have an AT Balmar. My Pearson's alternator on a MD2 Volvo runs about 10*F to 15*F cooler with the engine room blower running where the inlet hose is directly above the alternator.

I would install an alternator protector. Small price for good insurance.

Good luck. You'll love lithium. Charges quickly, has steady voltage. Only down side is it can cut out suddenly. I put in two banks on my new to me boat. A House bank of 400AH and a separate 200AH bank dedicated to the autopilot and critical instruments. Both banks can be monitored via Blue Tooth or by a battery monitor gauge. So far it all works great.

I know you are trying to help, but see this is an example of how people get scared away from LFP by making it sound hard.

My ARS-5 regulator is between 11-21 years old. I have had the boat 11 years and know it was on it where I got the boat. The boat is 21` years old, so it isn't older than that.

I have the alternator temp set to 95C. I have never seen it go into the 90s. That as when it was set at a belt manager level of B3 and now it is at B4

It doeesn' t matter what factory set program battery type you use, the factory defaults are all wrong even for lead acid batteries . You have to go into the advanced programing and adjust it.

[Scubaseas]

My ARS-5 regulator is between 11-21 years old. I have had the boat 11 years and know it was on it where I got the boat. The boat is 21` years old, so it isn't older than that.

I have the alternator temp set to 95C. I have never seen it go into the 90s. That as when it was set at a belt manager level of B3 and now it is at B4

1st off I appreciate your cost of cruising series immensely, Thanks.

Not trying to scare anyone or complicate anything. Lithiums can accept much more charge faster and much longer than LA batteries can. Your alternator is going to get hot. If it gets too hot it burns up or if it stays hot long it'll shorten it's life substantially. If you change batteries to LiFePo4 you need to change up your charging system to fit the new batteries. Simple as that. If you can keep the alternator to 203*F/ 95*C the alternator should be fine as far as shortening the life from heat goes. I'd still try and keep it as cool as possible by moving the bilge blower or engine box fan flows if you have one to try and move cool air over the alternator. Your original alternator, regulator and battery bank never contemplated running full out charging for two or more hours. It simply wasn't designed for it. When you generate watts you will also generate heat. the newer Balmar alternators have braided wire fields and stators, dual fans, improved air flow and were designed specifically to be able to dump heat faster and charge quicker than your AT (presumably) model ever could.

The AR5 you have will surely work. But a dynamic regulator which can adjust automatically both for charge, temp and load would surely be more efficient and more reliable than the AR5. But your plan is sound, it should work as far as I know which isn't much admittedly. It might last longer and work better with components like the regulator designed for Lithium chemistry though. It would surely charge faster with a MC618 but your reasoning seems sound to me. You might want to talk to Balmar. I've found them very knowledgeable and not pushy at all about "upgrading" to different equipment. The only weak areas I see are trying to keep a small frame alternator cool while it's trying to put out a lot more power and heat than designed for and not fully reaching the potential of having a lithium bank by dumbing down the regulator.

Other things I ran into when installing my system you may want to have or think about. Do you have a non contact or infrared thermometer? Very handy to check and see how hot things are getting. Is your wiring from alternator to battery bank large enough for your new system? Are you going to use bus bars to connect the batteries? According to Victron and a few others ideally all of your wiring to all of your batteries would be the same length. I chose MRBF fuses at my + battery cabling.

The ABYC now has standards for lithium batteries. Might want to read up on that to make sure it's done right to keep your insurance guy happy or any future surveyor. Difference between right and wrong can sometimes be small but important. Other than that your plan sounds fine.

[sailorboy1]

I already said my alternator DOES NOT GET HOT. Motored 9 hours the other night and it got to 84C. Surely a 100A alternator can safety run at 70 amps almost all day at 84C, which is way below what Balmar says for temp.

People seem to mistake that because you CAN charge faster that you HAVE too. If people WANT to spend $1500+ for a bigger alternator with the belting to support, and $600 for a new reguator, and $1500 for a new battery charger, and then something to protect all that stuff then they can and that is just fine. But they don't NEED to do it